Login required to started new threads

Login required to post replies

DCRainmaker preview of Stryd running power meter
Quote | Reply
http://www.dcrainmaker.com/...d-first-running.html

Looks pretty good.

I wonder if the TIckr X could provide data for their algorithms? Maybe Wahoo could license Stryd's software.

I've got a Magellan Echo that would be great for showing this data. Garmin GPS watches could show it easily as well although I think I purchased my last Garmin a few years ago.
Last edited by: Tom Fort: Jan 30, 15 12:28
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
About as useful as a Stages as a cycling power meter.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
I just read the review and I'm more than a little skeptical that the device is providing an accurate measure of absolute power. Ray made it obvious that the developers of the device were leading him through the testing protocol (which is fine as long as he's upfront about it) and I think they left out some very important tests.

For instance the device wasn't tested with varying wind conditions. Running into the wind obviously requires more power than running out of the wind at the same pace. Presumably the hardware is simply a multiaxis accelerometer. I would be very surprised to find that the developers can account for wind speed in the algorithms they use to determine power output.

Secondly, it wasn't tested on a lighter (or heavier) runner. All other things being equal, a heavier running should require more power to maintain the same pace. Simply throwing a weight vest on Ray would have resulted in significantly more power to run the same pace (although this could be confounded by changes in running dynamics... but I'm just spit balling). Perhaps there's a calibration step that requires a runner's accurate weight in order to accurate determine absolute power measurements. But I don't recall seeing a calibration discussed.

Which brings me to running dynamics: Galen Rupp running at 6:00 min/mi is (probably) going to run much more efficiently than I am at 6:00 min/mi. An interesting test would have been to line up three or four runners of equal weight but varying ability and have them run the same pace around the track.

Anyway, this device is not a direct measurement tool (e.g. a strain gauge) and will be limited as such. But I'd like to see a much more thorough testing before I'd consider purchasing one. That said, a running power meter is a super cool idea... I hope that people continue to develop these devices.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Nick B] [ In reply to ]
Quote | Reply
Nick B wrote:
About as useful as a Stages as a cycling power meter.

you are being generous. i believe the comparable cycling "power meter" is the ibike
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [echappist] [ In reply to ]
Quote | Reply
Wouldn't pace and heart rate be a far more direct measure of effort for training purposes?
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply

Quote:
For instance the device wasn't tested with varying wind conditions. Running into the wind obviously requires more power than running out of the wind at the same pace. Presumably the hardware is simply a multiaxis accelerometer. I would be very surprised to find that the developers can account for wind speed in the algorithms they use to determine power output.

Isnt the Garmin 620/920 equipped with this as well? If so just have garmin data (albiet it inaccurate for points you've already mentioned) into the Stryd software.

Quote Reply
Re: DCRainmaker preview of Stryd running power meter [franktheguard] [ In reply to ]
Quote | Reply
I don't think that would work. In the review, Ray states:

The pod itself is effectively not much different than your average modern running footpod, similarly with some accelerometers in it. In many ways, the magic here isn’t the hardware. It’s the software. It’s the algorithms that enable the company to see through all the noise of running and produce something that feels and looks like regular power meter data that you’d see while cycling.

The algorithms he's speaking of are probably very specific to the location of the accelerometer on the runner's body. A device placed on the swinging arm of a runner will experience significantly difference forces than one placed on the torso; or back as the case may be.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
I just want to be able to display Strava's Grade Adjusted Pace as a field on my watch. That works as a pretty good proxy for my RPE.

/kj

http://kjmcawesome.tumblr.com/
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [franktheguard] [ In reply to ]
Quote | Reply
franktheguard wrote:

Quote:
For instance the device wasn't tested with varying wind conditions. Running into the wind obviously requires more power than running out of the wind at the same pace. Presumably the hardware is simply a multiaxis accelerometer. I would be very surprised to find that the developers can account for wind speed in the algorithms they use to determine power output.

Isnt the Garmin 620/920 equipped with this as well? If so just have garmin data (albiet it inaccurate for points you've already mentioned) into the Stryd software.

Wouldn't wind just affect how far you travel (or how fast you go) and not how much power you are putting out, just like a bike power meter? In that sense, who cares. If this thing is measuring (or estimating) push off force to estimate power, then wind should not matter.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
Yeah, good point. I guess I thought maybe there was something better than a battery in the HRM.

Not sure how on the torso/back you will ever get wind dynamics either.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [echappist] [ In reply to ]
Quote | Reply
echappist wrote:
Nick B wrote:
About as useful as a Stages as a cycling power meter.


you are being generous. i believe the comparable cycling "power meter" is the ibike


It's still early, but if it in fact, responds in the range of what DCrainmaker is showing, it'll be a ton better than the ibike.

This graph from his review is pretty impressive if it's in fact the real deal. Note how HR lags big time (the green flat line), whereas the run power correlates really well with the hill elevation.


Last edited by: lightheir: Jan 30, 15 14:12
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
Too many flat lines in the Pace line, not sure how they are measuring, but poor sampling rate. Also I would say inaccurate, how does HR go up in a 3 minute test on the uphill, but still goes up on the down….with out an increase in pace?

Also a 3 min test with a few 5m hills? The test appears to "look good"……I see zero relevant Data in that chart.

….test is too short. not enough sustained output at any grade or speed to show any value….what so ever.

Maurice
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
I wouldn't be too fast to discount it yet, the initial results over the hilly terrain seem to point to it actually giving out legitimate data which is quite surprising. Will be interested to see a further test with his lady and a fat dude with wind, terrain etc.

That being said.. I don't see the point or any usefulness in it! Seems like a proper triathlete toy.. gadgets over training

I learned a long time ago that the only pertinent information you offer is found within the last sentence.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [kjmcawesome] [ In reply to ]
Quote | Reply
kjmcawesome wrote:
I just want to be able to display Strava's Grade Adjusted Pace as a field on my watch. That works as a pretty good proxy for my RPE.

x 2
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Quote:
Wouldn't wind just affect how far you travel (or how fast you go) and not how much power you are putting out, just like a bike power meter?

No. The key here is at the end of the sentence: "at the same pace." Running a 6:00 min/mi pace into a dead on 20 mph head wind is harder (requires more power to maintain) then running a 6:00 min/mi pace directly out of a 20 mph. If the Stryd only uses accelerometers on your torso to estimate power output then it is unlikely that it can account for certain environmental changes like wind. Mind you this is my presumption based on my knowledge of accelerometers and signal processing; I don't know what the Stryd algorithms are actually doing.

Bike power meters work the same way: ride into a head wind at 20 mph, then turn around and coast along with the wind at 20 mph and the power outputs will be very different.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
The absolute accuracy need not be that great if it is consistent for each individual. Ray wrote about using it in racing but I would be more interested in using it to judge training effort levels. Maybe I'm not well trained but my heart rate on different days at a given effort or pace varies a lot. If I had a more consistent measure, that also took into account more effectively the effect of hills it would be nice.

Another thought. If you can use this to hold a fixed target power while running a hilly loop with known profile maybe you can use a similar protocol to the platypus thread thing to calculate running efficiency (analogously to calculating CdA)?
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
Just fill me with millions of nanobots that monitor all my bodily functions in real time.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [davros] [ In reply to ]
Quote | Reply
goodboyr wrote:
Wouldn't pace and heart rate be a far more direct measure of effort for training purposes?
you bet. this has been stated by those with much more experience than i: the powermeter for running is called a stop watch (at least on the track), and with grade adjusted pace, you get a really good estimate of the effort you are putting in. The only thing you don't get in return is the work done in joules, but everything else can be taken into account (training load, training intensity, etc) when grade adjusted pace is used.



davros wrote:
The absolute accuracy need not be that great if it is consistent for each individual. Ray wrote about using it in racing but I would be more interested in using it to judge training effort levels. Maybe I'm not well trained but my heart rate on different days at a given effort or pace varies a lot. If I had a more consistent measure, that also took into account more effectively the effect of hills it would be nice.
quite a low bar to clear, as effort can already be gauged quite well using time and gradient.

Quote:
Another thought. If you can use this to hold a fixed target power while running a hilly loop with known profile maybe you can use a similar protocol to the platypus thread thing to calculate running efficiency (analogously to calculating CdA)?

calculating CdA requires absolute accuracy, and not just the "consistency" that people like to throw out.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Nick B] [ In reply to ]
Quote | Reply
Nick B wrote:
About as useful as a Stages as a cycling power meter.

If Stages were the only cycling power meter available, it'd be pretty valuable.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
SwimGreg3 wrote:
Quote:
Wouldn't wind just affect how far you travel (or how fast you go) and not how much power you are putting out, just like a bike power meter?


No. The key here is at the end of the sentence: "at the same pace." Running a 6:00 min/mi pace into a dead on 20 mph head wind is harder (requires more power to maintain) then running a 6:00 min/mi pace directly out of a 20 mph. If the Stryd only uses accelerometers on your torso to estimate power output then it is unlikely that it can account for certain environmental changes like wind. Mind you this is my presumption based on my knowledge of accelerometers and signal processing; I don't know what the Stryd algorithms are actually doing.

Bike power meters work the same way: ride into a head wind at 20 mph, then turn around and coast along with the wind at 20 mph and the power outputs will be very different.

Exactly my point. On a bike, power to go a specific speed varies with wind direction. Same with this system. This is exactly what you want. It IGNORES wind, just like a bike power meter and measures only the power you are producing. It does not have to account for wind and should not. On a bike, you have speed and power. On this device you have pace and power. That is all you need. In other words, this system is estimating power by measuring acceleration. The estimate of power is dependent of wind, as it should be.

Using your example, run a 6:00 pace into a head wind VS tail wind and you will have to produce a higher acceleration into the wind, which presumably this device will measure, therefore more watts. Just like a bike pwoermeter. Wind does not matter for measurement purposes.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
goodboyr wrote:
Wouldn't pace and heart rate be a far more direct measure of effort for training purposes?

Or how about the Powercal? It seems like it would be a better attempt at generating a Watt number than this device.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Mike Prevost wrote:

Using your example, run a 6:00 pace into a head wind VS tail wind and you will have to produce a higher acceleration into the wind, which presumably this device will measure, therefore more watts. Just like a bike powermeter. Wind does not matter for measurement purposes.

If external power as represented by force plates is the gold standard, then running on force plates into a headwind at speed of x will give a different force and therefore acceleration profile particularly for horizontal forces.

Though as you point out since some of the external force changes between the wind vs no wind condition are accounted for by differences in acceleration at toe off, it may very well be good enough. As Ray points out in the review, we won't really know if it's good enough for a little while yet.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Kevin in MD] [ In reply to ]
Quote | Reply
Kevin in MD wrote:
Mike Prevost wrote:


Using your example, run a 6:00 pace into a head wind VS tail wind and you will have to produce a higher acceleration into the wind, which presumably this device will measure, therefore more watts. Just like a bike powermeter. Wind does not matter for measurement purposes.


If external power as represented by force plates is the gold standard, then running on force plates into a headwind at speed of x will give a different force and therefore acceleration profile particularly for horizontal forces.

Though as you point out since some of the external force changes between the wind vs no wind condition are accounted for by differences in acceleration at toe off, it may very well be good enough. As Ray points out in the review, we won't really know if it's good enough for a little while yet.

Hi Kevin

Yes, thanks. You put it more clearly that I could. I don't really have a good sense of how much that force or acceleration direction changes into a headwind for example. We do tend to lean a bit into head winds, so that may offset the required change in acceleration trajectory a bit and as a result little or no adjustment may be necessary, resulting in the device being "good enough" in the wind.

Frankly, I am not sure how the device can be verified at this point. Comparing the acceleration data to ground reaction forces using a treadmill with force plates is a good start, but I am not sure this tells the whole story.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Kevin in MD] [ In reply to ]
Quote | Reply
Kevin in MD wrote:
If external power as represented by force plates is the gold standard, then running on force plates into a headwind at speed of x will give a different force and therefore acceleration profile particularly for horizontal forces.

However, the underlined part of the statement is not strictly true. Force plates fixed to the ground will measure the force applied to the ground by the runner's foot (F_ground) which would be equal to the sum of forces required to move the runner's center of mass (COM) forward. When running at a constant speed in a fluid like air the sum of forces would be:

0 = F_runner + F_drag + F_ground ---> -F_ground = m*a + 1/2 * rho * v^2 * C_d * A

Where F's are forces, m is the runner's mass, a runner's acceleration, rho is the air density, v is the runner's velocity relative to the fluid, C_d is the runner's coefficient of drag, and A is the runner's frontal surface area. Obviously drag is a pretty complicated topic and has components of form drag, skin drag, parasitic drag, etc. but I think this simplification will work to a reasonable approximation.

So, my point is that a force plate will measure the sum of forces from which power can be calculated. Conversely the Stryd (I believe) only measures the acceleration of the COM of the runner (a in the equation above). Thus variations in the other variables of the equation like a runner's mass or the velocity of the wind relative to the runner will go unaccounted.

However, what I failed to consider earlier is that during the time period in which the running is not contacting the ground and is effectively floating, The F_ground drops out of the equation and any acceleration (or more accurately deceleration) would be due to the fluid. Therefore measuring larger magnitude decelerations during this phase of the gait, and subsequent accelerations during the toe-off or other speed producing phases of the gait, may be an effective way to account for wind speeds.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Mike, I think your statement that power meters "ignore wind" threw me off. I think I now understand what you mean: that wind speed need not be known to calculate power.

I had initially assumed that a runner's acceleration vector in time would be unchanged by wind, and therefore unmeasurable by an accelerometer. However, I neglected to consider the period of a runner's gait in which they are not in contact with the ground. In stronger winds, the magnitude of accelerations and declerations required maintain a constant speed would be greater than in weaker wind. Therefore, perhaps it is possible to obtain accurate power measures using only a COM accelerometer.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
Oo! That's actually a very interesting idea! I wonder if they are indeed incorporating that. If they are, and reasonably well, I could see this product actually being more than just a relatively simple algorithm
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [mopshiv] [ In reply to ]
Quote | Reply
mopshiv wrote:
I wouldn't be too fast to discount it yet, ...Seems like a proper triathlete toy.. gadgets over training

Ha! So true.

----------------------------------------------------------
Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
SwimGreg3 wrote:
Mike, I think your statement that power meters "ignore wind" threw me off. I think I now understand what you mean: that wind speed need not be known to calculate power.

I had initially assumed that a runner's acceleration vector in time would be unchanged by wind, and therefore unmeasurable by an accelerometer. However, I neglected to consider the period of a runner's gait in which they are not in contact with the ground. In stronger winds, the magnitude of accelerations and declerations required maintain a constant speed would be greater than in weaker wind. Therefore, perhaps it is possible to obtain accurate power measures using only a COM accelerometer.

Yes, I guess time will tell. What is also interesting is that if you know power, you can estimate calorie expenditure better than with heart rate. Of course, run economy varies, so that factor will always be an issue but the large variability in max heart rate makes heart rate based approaches questionable. This might be better.

Since accelerometers have become so small and cheap, I expect that we will see much more of this, with more companies getting into playing with the data. Should be really interesting!

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
I realize I am being a bit pedantic here, but there is no direct measurement power meter.

An SRM etc has a device that emits an electrical charge based on how much it bends.

You then have to do math to turn that voltage into a guess about what the torque must have been, given assumptions about the material and the environmental conditions at the time.

And then you make a guess as to the velocity of the crank based on intermittent cadence signals from a magnet and an imperfect timing device (everything is imperfect!), and then you compute power.


Anyway everything is an estimate, the question is just how good or bad the estimate is.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Mike Prevost wrote:
Frankly, I am not sure how the device can be verified at this point. Comparing the acceleration data to ground reaction forces using a treadmill with force plates is a good start, but I am not sure this tells the whole story.

I was thinking about this point yesterday.

Having a bit of experience in calibration, the only thing I can see is running with some sort of shoe with a 2d load cell in it.

I know some folks have built them for study with diabetics, but not sure if there is anything in sports.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
I wonder. I've spent some time on a treadmill with my Ambit3, which uses an accelerometer to try and figure out pace, and it's not close enough to be considered valid. Use a foot pod and it's great. Something on my wrist can't figure out what my feet are doing and I don't see how something on my back could either. If I'm running in the wind and apply force x with my foot against the ground and travel, say, 4 feet (just for illustrations sake) in one stride of my 30" leg, with a cadence of say 90 strides per minute, how can it tell the difference between me with my short legs applying more force to do that than someone else with longer legs? It's one thing for a foot pod accelerometer to give you speed accurately, this is measurable, but force, or work? Wrong tool for the job. It seems like it would be reasonable to use it as an approximation, but it should advertise the limitations explicitly, as the PowerCal does...that it's not an accurate representation, and that any resemblance to real numbers is purely coincidental.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [fisherman76] [ In reply to ]
Quote | Reply
fisherman76 wrote:
I wonder. I've spent some time on a treadmill with my Ambit3, which uses an accelerometer to try and figure out pace, and it's not close enough to be considered valid. Use a foot pod and it's great. Something on my wrist can't figure out what my feet are doing and I don't see how something on my back could either. If I'm running in the wind and apply force x with my foot against the ground and travel, say, 4 feet (just for illustrations sake) in one stride of my 30" leg, with a cadence of say 90 strides per minute, how can it tell the difference between me with my short legs applying more force to do that than someone else with longer legs? It's one thing for a foot pod accelerometer to give you speed accurately, this is measurable, but force, or work? Wrong tool for the job. It seems like it would be reasonable to use it as an approximation, but it should advertise the limitations explicitly, as the PowerCal does...that it's not an accurate representation, and that any resemblance to real numbers is purely coincidental.

Of course, we don't have any real data yet, so to say that it is not an accurate representation at this point is pure speculation. Same as saying it is accurate. Also, the point is not to predict what the feet are doing, but rather, to predict what the overall center of mass is doing. Short legs and longer legs shouldn't really matter. It is trying to predict power, not speed. Same as the bike powermeter argument. The bike powermeter does not know if you are pedaling at 30 mph with a tailwind or 15 mph with a head wind. Does not matter. 250 watts is 250 watts. Speed or pace is another factor entirely, but we have lots of other ways to measure speed/pace.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
The amount of force required for a 6'4" runner to travel 4 feet with one stride as opposed to a 5'4" runner to travel the same assuming the same vertical oscillation, holding all else constant, cannot be the same. For one it's a tight gait and for the other a long stride, the longer stride requires more engagement and more energy. A power meter on a bike doesn't have anything to say about how efficient the rider is, it just measures the strain. An accelerometer has to make assumptions about efficiency to arrive at a power number, that's my point. Those assumptions are not just formulas, they vary between individuals, no?
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [fisherman76] [ In reply to ]
Quote | Reply
fisherman76 wrote:
The amount of force required for a 6'4" runner to travel 4 feet with one stride as opposed to a 5'4" runner to travel the same assuming the same vertical oscillation, holding all else constant, cannot be the same. For one it's a tight gait and for the other a long stride, the longer stride requires more engagement and more energy. A power meter on a bike doesn't have anything to say about how efficient the rider is, it just measures the strain. An accelerometer has to make assumptions about efficiency to arrive at a power number, that's my point. Those assumptions are not just formulas, they vary between individuals, no?

Measuring acceleration accounts for all of that. Think about it. And efficiency has nothing to do with it.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
I keep thinking about it and keep thinking the same, that acceleration is not the whole thing. An accelerometer on a semi hauling a full load would show it goes slowly from a full stop to traveling speed. It tells me nothing about the engine. Create the same acceleration profile in a Cooper and tell me you have the same power between the two. Please help me understand what's missing. I don't see how you can hold efficiency as a constant.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [fisherman76] [ In reply to ]
Quote | Reply
fisherman76 wrote:
I keep thinking about it and keep thinking the same, that acceleration is not the whole thing. An accelerometer on a semi hauling a full load would show it goes slowly from a full stop to traveling speed. It tells me nothing about the engine. Create the same acceleration profile in a Cooper and tell me you have the same power between the two. Please help me understand what's missing. I don't see how you can hold efficiency as a constant.

Couple of things. I think we are talking about two different things with regards to efficiency. I am talking in terms of "economy" or energy expenditure for a given amount of external work. For example, for cycling, efficiency is about 20%. Meaning that about 20% of energy expended goes to making watts at the pedals. A power meter does not care about human metabolic efficiency and it should not. I don't know it this is the same efficiency you are thinking about.

For the second point, consider this. Power = force X distance / time. If a given acceleration pushes a heavy weight a short distance or a light weight a longer distance, the power is the same. Could be I am thinking about this wrong but I don't think so. If so, the engineers on here can straighten me out.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Not metabolic efficiency. Force is acceleration times mass, Newton's second law. Can't make assumptions about mass from the back of a runners shorts with an accelerometer. Also can't disregard or make constant friction.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [fisherman76] [ In reply to ]
Quote | Reply
fisherman76 wrote:
Not metabolic efficiency. Force is acceleration times mass, Newton's second law. Can't make assumptions about mass from the back of a runners shorts with an accelerometer. Also can't disregard or make constant friction.

Well, the only thing I know for sure is that the burden of proof is on the company. I don't have a dog in that fight. I think they are going to have to supply some data to really convince the skeptics. I just can't figure out how they would test it. It is an interesting idea though. Hope it works out for them.

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Agree 100% and I hope it works. You and I have the same goals here, I'm sure of it.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [fisherman76] [ In reply to ]
Quote | Reply
Quote:
Force is acceleration times mass, Newton's second law. Can't make assumptions about mass from the back of a runners shorts with an accelerometer.

Exactly. Stryd must utilize the runner's body weight if it is to provide accurate measurements.

I also agree with Mike in that it should not attempt to account for efficiency or economy. I expect a power meter to tell me the amount of power that I'm generating to drive me forward regardless of my efficiency.

But yes, the burden is, and always should be, on the claimant. It will be great if it stands up to rigorous cross examination.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [jackmott] [ In reply to ]
Quote | Reply
I relish pedantry. You're right, if it requires a calculation it's not a direct measurement.

To be more precise, a cycling power meter measures (indirectly or otherwise) all components of power: torque and angular velocity. If the torque measurement requires certain assumptions then that is a limitation of the instrument which must be considered by the user when interpreting the measurements. Conversely I do not believe that the Stryd is capable of measuring all of the components of running power.

Facebook and Strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Nick B] [ In reply to ]
Quote | Reply
Nick B wrote:
About as useful as a Stages as a cycling power meter.

Meaning highly useful for pacing, tracking training load and better than GPS & elevation for calculating a normalized pace... and far more responsive and accurate than HR or RPE. But not as precise as a lab grade treadmill with a mask hooked up to your face to measure oxygen consumption. I'm waiting for the portable version of that for IM races.

I'd like to see more testing to get a better picture of variability.

I suspect that it will be like the Stages, and be fairly consistent in a steady stage and within a range of power near where you tested your FTP. But have some inaccuracy further out from there and during sudden changes in power.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
Nick B wrote:
About as useful as a Stages as a cycling power meter.


Meaning highly useful for pacing, tracking training load and better than GPS & elevation for calculating a normalized pace... and far more responsive and accurate than HR or RPE. But not as precise as a lab grade treadmill with a mask hooked up to your face to measure oxygen consumption. I'm waiting for the portable version of that for IM races.

I'd like to see more testing to get a better picture of variability.

I suspect that it will be like the Stages, and be fairly consistent in a steady stage and within a range of power near where you tested your FTP. But have some inaccuracy further out from there and during sudden changes in power.

You know, there is a portable metabolic cart for measuring oxygen consumption. In fact, both sensormedics and Cosmed make portable devices you can run and bike with. I have used the Cosmed personally. Battery life is too short for Ironman though ; )

Simplify, Train, Live
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
Nick B wrote:
About as useful as a Stages as a cycling power meter.

Meaning highly useful for pacing, tracking training load and better than GPS & elevation for calculating a normalized pace... and far more responsive and accurate than HR or RPE. But not as precise as a lab grade treadmill with a mask hooked up to your face to measure oxygen consumption. I'm waiting for the portable version of that for IM races.

I'd like to see more testing to get a better picture of variability.

I suspect that it will be like the Stages, and be fairly consistent in a steady stage and within a range of power near where you tested your FTP. But have some inaccuracy further out from there and during sudden changes in power.

Nope. Not better than NGP, not accurate for quantifying training load, way less useful than RPE, maybe as useful as HR.

This device is less useful than a Stages, which is about as useful as a HRM.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Nick B] [ In reply to ]
Quote | Reply
You generate more watts via the body , but it looks here they are trying to equate it to bike watts so people can be familiar with the numbers. The arms swinging generate watts, etc... bicycle is at an isolated point, with some power lost due to drive train. So on a similar effort bike work out of 220 watts, you are probably doing 360 running... this why running stress scores are higher

http://www.coupleofathletes.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Change battery in T2
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [ In reply to ]
Quote | Reply
A few thoughts...

Knowledge of a person's actual power output while cycling is immensely valuable, because:

1) mechanical power is what moves the bike down the road, and

2) cycling economy/efficiency does not vary dramatically between individuals, such that power provides a reasonable proxy for actual metabolic demand.

With that in mind, consider a running power estimator, i.e., one that relies on GPS, acceleromters, etc., to calculate power:

1) since power is being determined indirectly, the reported values provide no further insight into someone's actual performance than does knowledge of their pace and changes in elevation (although if accurate, estimated power does have the benefit of pinning a single number on things), and

2) running economy varies much more between individuals than does cycling economy/efficiency, such that the calculated power may not provide a valid/reliable indication of actual metabolic demand.

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.
Last edited by: Andrew Coggan: Feb 2, 15 10:24
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
I'd disagree with Coggans comments above, in that if someone developed a true, 100% (or close to) accurate running powermeter, it would be extremely useful, and likely game-changing. Just like cycling, you could have accurate metrics that incorporate incline effects, pacing, etc.

I dont' think the differences in running vs group cycling racing make that big a difference. If anything, triathlon has shown that powermeters are probably even MORE helpful for steady-state effort racing than they are for pure bike racing where often times the powermeter pacing effects are meaningless since if you can't hold onto the pack in the acceleration, you're gone.

As it stands, using run pacing and elevation to calculate/estimate run efforts is just as bad as using something like an iBike. That said, I'm not sure I have faith that this new product will be anywhere near accurate enough to be valuable as a training/racing tool - for sure, it's not going to be in the same league as a bike powermeter, so in that regards, given the fuzziness of the data that will arise, it's likely it'll turn out like COggan predicts, meaning not so useful.

But make a 99-100% accurate running powermeter? Game changer for sure.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
Quote | Reply
Mike Prevost wrote:
motoguy128 wrote:
Nick B wrote:
About as useful as a Stages as a cycling power meter.


Meaning highly useful for pacing, tracking training load and better than GPS & elevation for calculating a normalized pace... and far more responsive and accurate than HR or RPE. But not as precise as a lab grade treadmill with a mask hooked up to your face to measure oxygen consumption. I'm waiting for the portable version of that for IM races.

I'd like to see more testing to get a better picture of variability.

I suspect that it will be like the Stages, and be fairly consistent in a steady stage and within a range of power near where you tested your FTP. But have some inaccuracy further out from there and during sudden changes in power.


You know, there is a portable metabolic cart for measuring oxygen consumption. In fact, both sensormedics and Cosmed make portable devices you can run and bike with. I have used the Cosmed personally. Battery life is too short for Ironman though ; )

Yeah, but the RQ's can run a bit high on those things... you won't be able to tell how many carb kcal's your burning to refuel properly.

To the others: It needs to know your body weight.

The above poster is a physiologist employed by PEARL iZUMi. However, statements are not made on behalf of nor reflective of PEARL iZUMI in any manner... unless they're good, then they count.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
Disclosure: I am on the Stryd team.

SwimGreg3 wrote:
For instance the device wasn't tested with varying wind conditions. Running into the wind obviously requires more power than running out of the wind at the same pace... I would be very surprised to find that the developers can account for wind speed in the algorithms they use to determine power output.


That is correct. We have a development plan to handle the influence of changes to wind properly, but don't have solid testing data on that yet. We will do our best to surprise you.

SwimGreg3 wrote:
Presumably the hardware is simply a multiaxis accelerometer.


There are several other sensors in it, including an air pressure sensor.

SwimGreg3 wrote:
Secondly, it wasn't tested on a lighter (or heavier) runner.


Stryd reports unit-mass power unless the runner enters his or her mass, in which case it reports absolute power. We don't yet know which most runners will prefer, but I personally suspect that unit-mass power will be used more commonly because it can be used to set training zones and it is easier to usefully compare the unit-mass power values of different runners.

SwimGreg3 wrote:
All other things being equal, a heavier running should require more power to maintain the same pace.


Right, and based on our testing so far, we believe Stryd would produce the right result in that case.

SwimGreg3 wrote:
I'd like to see a much more thorough testing before I'd consider purchasing one.


That's why we are presently planning to cap the initial production round so we can work closely with the first group of 1,000 owners. Our tests with runners have been going well so far, we believe Stryd is at the point where people can benefit from its use, but we want get more data and feedback before scaling up production. Also, the hardware platform we developed is surprisingly flexible. As we learn more from the first owners, we will be able to remotely upgrade their devices. We will do our best to treat our initial supporters right.

SwimGeg3 wrote:
That said, a running power meter is a super cool idea... I hope that people continue to develop these devices.


Thanks. If enough people see the potential, we will do that.
Last edited by: robert-stryd: Feb 2, 15 19:53
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [mauricemaher] [ In reply to ]
Quote | Reply
Disclosure: I am on the Stryd team.

mauricemaher wrote:
Too many flat lines in the Pace line, not sure how they are measuring, but poor sampling rate. Also I would say inaccurate, how does HR go up in a 3 minute test on the uphill, but still goes up on the down….with out an increase in pace?


I would like to clarify that the power number came from Stryd. The pace and heart rate numbers in this test came from other products.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
A few thoughts...

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.

Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

Wind is just as painful to a runner as it is to a cyclist, run a marathon into a headwind and you'll understand. Similarly, varying terrain is just as much of a factor for runners as it is cyclists. This is especially true for longer formats (i.e. half marathon and beyond) in courses with rolling terrain or worse.

I could see trying to argue it makes it's of little benefit for situations such as windless flat surfaces. But to try and argue that runners aren't impacted by hills or wind comes across a bit...out of place?


-
My tiny little slice of the internets: dcrainmaker.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [dcrainmaker] [ In reply to ]
Quote | Reply
dcrainmaker wrote:
Andrew Coggan wrote:
A few thoughts...

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.

Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

Wind is just as painful to a runner as it is to a cyclist, run a marathon into a headwind and you'll understand. Similarly, varying terrain is just as much of a factor for runners as it is cyclists. This is especially true for longer formats (i.e. half marathon and beyond) in courses with rolling terrain or worse.

I could see trying to argue it makes it's of little benefit for situations such as windless flat surfaces. But to try and argue that runners aren't impacted by hills or wind comes across a bit...out of place?

Sorry, but I think that your assertions are incorrect. Runners are clearly not impacted by wind as much as cyclists. (And yes, I say that having run a fair bit while living on a wind-swept barrier island, as well as having to finish a 30 km race under my goal of 2 h flat by running the last 2 mi as hard as I could straight into a block headwind.) Way back in 1971, for example, Pugh tested runners in a climactic chamber and demonstrated that overcoming wind resistance accounted for only 7.5% of energy expenditure when running on the flat at 3.75 m/s and 13% at 4.47 m/s. This is in contrast to cycling, whereas as we all know, overcoming wind resistance accounts for the vast majority of energy expenditure. It therefore follows that it takes a much, MUCH stronger wind to have the same impact on a runner as it does on a cyclist.

As for hills, while the effects of gradient on energy expenditure are the same in runners and cyclists, how many runners do you know are willing to routinely venture up grades so steep that they are reduced to walking, or at best, a very slow jog? Yet, thanks to gearing cyclists regularly ride up such slopes.

Now add in the fact that, in running, true sprinters generally don't race longer distances, and distance runners rarely have to truly sprint, yet cyclists in mass start races regularly have to do both, combined with the fact that a power estimator can't account for differences in runnnig economy, which are far greater between individuals than cycling economy, and the fact that running tracks (where runners typically go when they want to perform structured training) are ubiquitous whereas velodromes are relatively rare, and, well, I just don't see the point (as I told Steve McGregor almost a decade ago when he came up w/ rTSS).
Last edited by: Andrew Coggan: Feb 3, 15 7:44
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
I probably would concede that wind impacts cyclists more than runners, but certainly not that it doesn't impact runners. A 13% change in energy for a mere 10MPH headwind in your example is pretty substantial. I don't know how that maps to impact on potential power and/or finishing times (perhaps it's been studied, perhaps not), but, no doubt there's some impact. Would it be 5% faster? 10% faster? And again, 10MPH isn't all that much actually.

As for hills, I'm not sure why it'd have to be steep enough to walk to matter. Hills of even a few percent have a pretty big impact on a runner (in both directions). To the same end, I'm not sure why we're bringing sprinters in this. As I noted above, this is likely more valid for long distance runners. But, if we decide to pull in the concept of sprinting - it's not terribly different in a world class marathon where pros will pickup and vary the pace, effectively aiming to drop someone. Whether or not that person could sustain said X pace on Y terrain with Z wind gets to the core of power would be about, or rather, is about today already in cycling. The same power that's widely used in the professional cycling.

Finally, I know you keep going back to runners going to tracks to do structured training. But I'd wager the majority of long-distance runners don't actually. Just like the majority of cyclists don't train in velodromes. They train out on open roads and trails.


-
My tiny little slice of the internets: dcrainmaker.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
I too am surprised by this response.

I agree that typically, running is more steady state, but that still doesn't mean that GPS and HR data provide a better picture on output than this device might provide.

If I'm running a 50k ultra, off road, I will routinely be faced with deciding to walk vs. run on a steep grade to maintain a steady output, which will result in the best finish time. Reducing variability is equally important in running as cycling. So is quantifying training load over a variety of terrain.

I also disagree that all quality work will be done on a track. Why would it? Is all quality work for cycling done on a trainer, track or perfectly flat roads? No, but a power meter allows you to be more precise in your training despite varying conditions and compare one effort to another.

I would argue that since there is almost always less cooling airflow, heat and humidity have a larger impact on running than cycling.

Cycling is impacted more by wind yes, but to say there's no impact in running isn't accurate either, unless you have data to quantify it as such, but the combination or wind, terrain and changes in mechanics due to fatigue, can be vary large and unpredictable.

Add to that, in cycling, while inertia is less when climbing, the overall mechanics do not change dramatically unless you shift from seated to standing. In running, your mechanics change based on grade, both uphill and especially downhill and based on surface conditions.

I'm a little disappointing you'r not more interested in this device. I know you focus is on cycling. But combining whats been learned about cycling to run performance I think would be a great opportunity and the ability to reach a large audience (think more funding for research).


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
For my athletes, one of the most useful test I would like to perform would be comparing pace to output on a track and identify the efficiency of the athlete at different paces, cadence, different shoes, weather conditions. You could use a database like WKO+ to then more accurately determine threshold pace and predict race performance based on evaluating a combination of HR, Pace, etc.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
dcrainmaker wrote:
Andrew Coggan wrote:
A few thoughts...

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.

Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

Wind is just as painful to a runner as it is to a cyclist, run a marathon into a headwind and you'll understand. Similarly, varying terrain is just as much of a factor for runners as it is cyclists. This is especially true for longer formats (i.e. half marathon and beyond) in courses with rolling terrain or worse.

I could see trying to argue it makes it's of little benefit for situations such as windless flat surfaces. But to try and argue that runners aren't impacted by hills or wind comes across a bit...out of place?

Sorry, but I think that your assertions are incorrect. Runners are clearly not impacted by wind as much as cyclists. (And yes, I say that having run a fair bit while living on a wind-swept barrier island, as well as having to finish a 30 km race under my goal of 2 h flat by running the last 2 mi as hard as I could straight into a block headwind.) Way back in 1971, for example, Pugh tested runners in a climactic chamber and demonstrated that overcoming wind resistance accounted for only 7.5% of energy expenditure when running on the flat at 3.75 m/s and 13% at 4.47 m/s. This is in contrast to cycling, whereas as we all know, overcoming wind resistance accounts for the vast majority of energy expenditure. It therefore follows that it takes a much, MUCH stronger wind to have the same impact on a runner as it does on a cyclist.

As for hills, while the effects of gradient on energy expenditure are the same in runners and cyclists, how many runners do you know are willing to routinely venture up grades so steep that they are reduced to walking, or at best, a very slow jog? Yet, thanks to gearing cyclists regularly ride up such slopes.

Now add in the fact that, in running, true sprinters generally don't race longer distances, and distance runners rarely have to truly sprint, yet cyclists in mass start races regularly have to do both, combined with the fact that a power estimator can't account for differences in runnnig economy, which are far greater between individuals than cycling economy, and the fact that running tracks (where runners typically go when they want to perform structured training) are ubiquitous whereas velodromes are relatively rare, and, well, I just don't see the point (as I told Steve McGregor almost a decade ago when he came up w/ rTSS).

It would be very easy for Andrew Coggan to jump on the running power meter band waggon and I'm sure if he did his ideas would be embraced just as enthusiastically by runners and running coaches as is the case in cycling.

The fact that he holds this opinion may be surprising but it does show he isn't interested in making easy money.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
If I'm running a 50k ultra, off road, I will routinely be faced with deciding to walk vs. run on a steep grade to maintain a steady output, which will result in the best finish time.

Edge case.

motoguy128 wrote:
Reducing variability is equally important in running as cycling.

Running is inherently less variable than cycling. After all, if you're not running, you're walking, and you certainly can't coast.

motoguy128 wrote:
So is quantifying training load over a variety of terrain.

The limitations to quantifying training load and leveraging that information does not lie in the device - being able to accurately measure (not estimate) running power won't help you there.

motoguy128 wrote:
I also disagree that all quality work will be done on a track. Why would it?

All, no, but most, yes. Heck, we used to drive ~1 h one-way from Galveston to run on a high school track (as the one on the island wasn't open to the publci...grrr).

motoguy128 wrote:
Is all quality work for cycling done on a trainer, track or perfectly flat roads? No, but a power meter allows you to be more precise in your training despite varying conditions and compare one effort to another.

That's an argument why cyclists benefit from powermeters, not runners.

motoguy128 wrote:
I would argue that since there is almost always less cooling airflow, heat and humidity have a larger impact on running than cycling.

So? If it does, you'll run slower, which a watch will tell you...no powermeter required.

motoguy128 wrote:
Cycling is impacted more by wind yes, but to say there's no impact in running isn't accurate either, unless you have data to quantify it as such, but the combination or wind, terrain and changes in mechanics due to fatigue, can be vary large and unpredictable.

Runners are clearly affected far LESS by wind than cyclists. As for fatigue, etc., causing you to slow down, that's something a watch can already tell you.

motoguy128 wrote:
Add to that, in cycling, while inertia is less when climbing, the overall mechanics do not change dramatically unless you shift from seated to standing. In running, your mechanics change based on grade, both uphill and especially downhill and based on surface conditions.

...which is 1) why runners tend to avoid really steep slopes, and 2) why estimating metabolic demands from running speed and grade and expressing it as a power is fraught with difficulties.

motoguy128 wrote:
I'm a little disappointing you'r not more interested in this device. I know you focus is on cycling. But combining whats been learned about cycling to run performance I think would be a great opportunity and the ability to reach a large audience (think more funding for research).

Yes, I'm a cyclist, such that my personal interest in such a device is nil. That said, if my prediction proves wrong so be it...it's not that I want devices like the Stryde to fail to have a significant impact, it's just that I don't forsee that they will.

As for your comments about research funding, you clearly don't understand what I do for a living, or where money for research can actually be found.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
For my athletes, one of the most useful test I would like to perform would be comparing pace to output on a track and identify the efficiency of the athlete at different paces, cadence, different shoes, weather conditions.

That would require a portable metabolic system (which have been available for >100 y), not a running powermeter.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [dcrainmaker] [ In reply to ]
Quote | Reply
dcrainmaker wrote:
I probably would concede that wind impacts cyclists more than runners, but certainly not that it doesn't impact runners. A 13% change in energy for a mere 10MPH headwind in your example is pretty substantial. I don't know how that maps to impact on potential power and/or finishing times (perhaps it's been studied, perhaps not), but, no doubt there's some impact. Would it be 5% faster? 10% faster? And again, 10MPH isn't all that much actually.

Actually, 10 mph at ground level is a quite strong wind, strong enough to nearly double or halve the speed of a cyclist riding on level ground if it were directly behind or ahead. A runner, OTOH, would speed up or slow down by only ~10%, or about 1/10th as much as a cyclist.

dcrainmaker wrote:
As for hills, I'm not sure why it'd have to be steep enough to walk to matter. Hills of even a few percent have a pretty big impact on a runner (in both directions).

Roughly speaking, while running a 1% change (increase) in grade increases metabolic cost by 4%. So, not a huge amount, but certainly enough to result in slower times in hilly races (e.g., Boston) and faster times in those that are net downhill (e.g., Austin marathon). But, runners already have perceived exertion to rely on for pacing purposes, and when training already know not to compare their pace in hilly runs with that in flat runs. IOW, the question is, in what way would knowing (estimating) your power while running in the hills represent new, highly valuable, "actionable intelligence"?

dcrainmaker wrote:
To the same end, I'm not sure why we're bringing sprinters in this. As I noted above, this is likely more valid for long distance runners.

Because it is the far-ranging demands of cycling that, in part, make measuring actual power in that sport so valuable. But for distance runners? Not so much...

dcrainmaker wrote:
But, if we decide to pull in the concept of sprinting - it's not terribly different in a world class marathon where pros will pickup and vary the pace, effectively aiming to drop someone.

Even in athletics, the variations in pace pale in comparison to the demands of, e.g., a criterium.

dcrainmaker wrote:
Finally, I know you keep going back to runners going to tracks to do structured training. But I'd wager the majority of long-distance runners don't actually.

That's not been my experience, but even if you assume it is true, what it says is that simply going out and pounding the pavement that starts at your front door with a watch on your wrist must already be "close enough" that people don't see any benefit from standardizing conditions/training to a greater degree. In turn, that implies that measuring power isn't going to have a significant impact either.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
SwimGreg3 wrote:
Mike, I think your statement that power meters "ignore wind" threw me off. I think I now understand what you mean: that wind speed need not be known to calculate power.

I had initially assumed that a runner's acceleration vector in time would be unchanged by wind, and therefore unmeasurable by an accelerometer. However, I neglected to consider the period of a runner's gait in which they are not in contact with the ground. In stronger winds, the magnitude of accelerations and declerations required maintain a constant speed would be greater than in weaker wind. Therefore, perhaps it is possible to obtain accurate power measures using only a COM accelerometer.

I think your ignoring that the important measurement is just like a power meter, it's the force vector and frequency, then subtracted all deaccleration after the positive acceleration stops. The net balance between the two would be your forward momentum. But that's based on my basic college level physics... I'm probably missing something there. But by making the statement, I can virtually guarantee an expert will reply to correct me, in very short order.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
I think for me, the key point that Dr. Coggan makes is that what "actionable intelligence" is there with a running power meter that pace cannot give you? I totally understand why a cycling power meter does provide this actionable intelligence. As of yet in this discussion, no one has demonstrated how that works for running. It seems there is conjecture and hypothesis, but no actual data and analysis to support its use.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
goodboyr wrote:
I think for me, the key point that Dr. Coggan makes is that what "actionable intelligence" is there with a running power meter that pace cannot give you? I totally understand why a cycling power meter does provide this actionable intelligence. As of yet in this discussion, no one has demonstrated how that works for running. It seems there is conjecture and hypothesis, but no actual data and analysis to support its use.


You're putting the cart before the horse. Until there is a truly accurate running powermeter, people won't spend a ton of time trying to devise useful metrics for it other than using rough cycling analogies.

I 100% guarantee that if someone indeed developed a running powermeter that was every bit as accurate and precise as cycling powermeters, it would be a complete game changer at all levels for training and racing, just as it was for cycling. And you'd surely see some new and very useful metrics be developed.

It's true that running is somewhat less affected by conditions such as hills and wind, but the notion that you can use GPS/HR calculations to get performance data with the same robustness as a cycling powermeter is a joke. It's literally as bad (if not worse) than using an ibike and saying it's really robust (it's not.)
Last edited by: lightheir: Feb 3, 15 9:09
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
If you go on the stryd website log, they show a plot of speed and "stryd power" superimposed. As an example, if I was to use the stryd power instead of the pace to determine optimum running pace, I would slow down too much. It appears that there are some artifacts of how the "power" is calculated, and the devil is in the details. At steady state its no different than pace, but at the start and at the interval transition, it looks like its overestimating the number. which would cause me to slow down for no reason, if I was using that value to run at a steady power....

http://blog.stryd.com/...ower-and-heart-rate/
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
goodboyr wrote:
I think for me, the key point that Dr. Coggan makes is that what "actionable intelligence" is there with a running power meter that pace cannot give you? I totally understand why a cycling power meter does provide this actionable intelligence. As of yet in this discussion, no one has demonstrated how that works for running. It seems there is conjecture and hypothesis, but no actual data and analysis to support its use.

What can a stopwatch or GPS not do:
1) Determining pace in increments less than 15-20 seconds is difficult. Especially uphill, down hill, or with wind.
2) Determine output when your mechanics have changed due to fatigue or because your going uphill or downhill. It also assumes you output is linear with pace. It's most likely not for most people.

Are the 2 scenarios above important for training or racing?

I would prefer that the units used were Intensity Factor, not Power. It's only an accelerator, not a strain gauge so it cannot measure power or force. It can measure acceleration and calculate power based on the weight of the subject. That will be one limitation of the device I could see... calibration based on weight. Unless I'm missing something here.

More specifically, it can measure a net average velocity vector and the overall economy of motion. Those are 2 items that GPS cannot accurately determine. The argument could be if the variability of those, is enough to matter.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
goodboyr wrote:
If you go on the stryd website log, they show a plot of speed and "stryd power" superimposed. As an example, if I was to use the stryd power instead of the pace to determine optimum running pace, I would slow down too much. It appears that there are some artifacts of how the "power" is calculated, and the devil is in the details. At steady state its no different than pace, but at the start and at the interval transition, it looks like its overestimating the number. which would cause me to slow down for no reason, if I was using that value to run at a steady power....

http://blog.stryd.com/...ower-and-heart-rate/

I'm not arguing that there are likely limitations in the stryd that make it suboptimal for ideal use.

But what I was arguing that if you had a run powermeter that was as good as a bike powermeter, it would change the game.

I think it's too early to tell at this point if Stryd is it, but I have my doubts just given that it's a computational algorithm rather than a real measurement (like a strain gauge.)
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
lightheir wrote:
goodboyr wrote:
If you go on the stryd website log, they show a plot of speed and "stryd power" superimposed. As an example, if I was to use the stryd power instead of the pace to determine optimum running pace, I would slow down too much. It appears that there are some artifacts of how the "power" is calculated, and the devil is in the details. At steady state its no different than pace, but at the start and at the interval transition, it looks like its overestimating the number. which would cause me to slow down for no reason, if I was using that value to run at a steady power....

http://blog.stryd.com/...ower-and-heart-rate/

I'm not arguing that there are likely limitations in the stryd that make it suboptimal for ideal use.

But what I was arguing that if you had a run powermeter that was as good as a bike powermeter, it would change the game.

I think it's too early to tell at this point if Stryd is it, but I have my doubts just given that it's a computational algorithm rather than a real measurement (like a strain gauge.)

Running power meters will catch on. People like gadgets.

The point Andrew Coggan is making is that even if they do work, they won't improve the way people train.

They will certainly waste a lot of people's time.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
I totally disagree with your notion that WORKING run powermeters will not change the way people train. The will absolutely change the way people train if they are committed to the power numbers, same as it changed cycling. And it will improve the way people train, to have accurate power numbers, rather than the constant guesstimations that we are currently doing whenever we do hill repeats or any outdoor course with elevation changes.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
Unless you can back up your certainty with some actual numerical or factual examples, I remain unconvinced.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
goodboyr wrote:
Unless you can back up your certainty with some actual numerical or factual examples, I remain unconvinced.

All the evidence I need is how it affected cycling, both at amateur and pro levels.

If you presented people with a not-so-good powermeter like the 'i-bike', you'd make all the same old arguments you make, but they wouldn't be valid with a good, accurate PM.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
Quote | Reply
I guess we will have to wait. We both agree that whatever the case, Stryd isn't the one that will prove or disprove this.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [goodboyr] [ In reply to ]
Quote | Reply
Here's examples.

I want to do hill repeats at threshold pace. Currently, I run based on guessing my RPE, breathing rate, etc.

I want to compare repeats efforts I did last month to today, but I've lost 4lbs since then. How much of the improvement is from weight or fitness?

I'm trying to measure improvements in run economy from today vs. 3 months ago. Right now I need to use HR or use a treadmill in a test lab.

I'm out for a run on a trail wooded off road rugged, hilly trail. I want to hold a steady effort around 65%.

I'm doing a 50 mi Ultra. I don't want to exceed 80% up any hills. I want to measure fatigue and hydration by output compared to pace and HR respectively.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
Here's examples.

I want to do hill repeats at threshold pace. Currently, I run based on guessing my RPE, breathing rate, etc.

I want to compare repeats efforts I did last month to today, but I've lost 4lbs since then. How much of the improvement is from weight or fitness?

I'm trying to measure improvements in run economy from today vs. 3 months ago. Right now I need to use HR or use a treadmill in a test lab.

I'm out for a run on a trail wooded off road rugged, hilly trail. I want to hold a steady effort around 65%.

I'm doing a 50 mi Ultra. I don't want to exceed 80% up any hills. I want to measure fatigue and hydration by output compared to pace and HR respectively.


Why?

How would any of those things you listed make training more effective?
Is there any evidence not exceeding 80% (of what?) or holding a steady effort of 65% ( of what? ) improves training or performance?

What actionable intelligence would a running power meter give you?

Edit: I've been thinking about this and I can see uses for accurate power data running.

The treadmills at my gym show power in watts. I doubt it is accurate but it seems consistent. They have a card system where you insert your card and it account for weight, speed and slope.

Yesterday After a 5000m row, I did 30 minutes on the treadmill. Due to a knee injury I can't run so I set the slope to 10% to 15% and walk at 3mph to 4mph. This gets the watts up to a over 300 watts.

Now I can see that if these wattage numners are accurate I would been able to compare walks or runs at different times at different slopes on different machines in different gyms. I would be able to track training. Now I could just use pace and take note of the slope but watts gives me a single number so I can see the difference between various speeds and slopes over time.

If I were to run outdoors over variable terrain and if the power were accurate so I can make direct comparisons I can see they being able to compare the wattage at different speeds and gradients would be of use.

But I can always track fitness by doing a run on the flat. I can see having power would really change the way I train but I can see it being useful.

I was surprised how much the power on the treadmill varied. Up the slope and the human mind tends to maintain the speed until it gets feed back that the effort has increased and then moderates pace. I was surprised by how the wattage jumps up when you up the slope.

As for tracking training, would power be any better than heart rate? If and its a big if, if the power were accurate it could be useful.

I like the minimalism of running, I don't want to get my running (or fast walking) to become all numners and software, but surely all the arguments for using it cycling are valid for running even if runners are not so affected by wind and drag?

So I think I'm changing my mind having considered the arguments. But only if the power data is accurate.

But running is about pace not power. Does an increase in power always mean an increase in pace? What if your form goes bollox and you are putting out more power but just stamping up and down more and not increasing pace?

I don't know. More opinions required. More info required.
Last edited by: Trev: Feb 4, 15 3:11
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
Treadmill in my gym shows power in watts.
Did an easy 25 minutes at 10kph level or 1% slope. Was doing 220/230 watts. I'm 14st 7lbs.

No idea if that is accurate. Yesterday I was getting approx 200 watts for 3mph up 15% gradient which works out at 182 watts, using the formula below,

Weight in lbs x 2 x mph x gradient%

So it looks like an overestimate.



But if I did have an accurate running power meter I could compare indoor runs at various gradients to outdoor runs over undulating ground. On different treadmills in different gyms, could compare power over different hills, could compare runs at different weights enabling me to see if the increased pace is due to weight loss alone or increased power as well, compare runs into the wind to runs with the wind.

I know the wattage differences won't be as great as in cyclimg but surely it would be useful to make those sorts of comparisons?

But does power work with running? Does more power necessarily = more speed? What if the wattage increases but form breaks down and more watts results in no increase in speed? In that case watts could prove to be rather misleading.

On a bike more power must = more speed unless you change position and create more drag but is running the same?

Then you would have to weigh up the hassle factor, the time spent making sure the data is accurate etc etc.

I don't need a running power meter, I dont think I would enjoy running as much with one, but if I was coaching someone I can see uses.

The more I think about it the more I'm astounded Andrew Coggan does not see the point of one... Unless he knows that power does not necessarily translate into more speed and would be too misleading to be of benefit?
Last edited by: Trev: Feb 4, 15 6:34
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [dcrainmaker] [ In reply to ]
Quote | Reply
dcrainmaker wrote:
Andrew Coggan wrote:
A few thoughts...

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.


Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

I'm not surprised and I agree with Coggan. Cyclists regularly remark at how they witness tremendous variability in average speed for the same power output because of the strong effect from wind. The Stryd looks to be an interesting data point but I suspect for many runners it will correlate so strongly with their time piece that it won't add much value. The one case where it may be useful is to aid pacing over longer runs on unfamiliar terrain, but I think most endurance runners already know when they are running a sustainable vs unsustainable pace. This device could help them abide by the plan better.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [dgran] [ In reply to ]
Quote | Reply
dgran wrote:
dcrainmaker wrote:
Andrew Coggan wrote:
A few thoughts...

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.


Honestly, I'm surprised to see you write. Mostly because it really makes no sense.


I'm not surprised and I agree with Coggan. Cyclists regularly remark at how they witness tremendous variability in average speed for the same power output because of the strong effect from wind. The Stryd looks to be an interesting data point but I suspect for many runners it will correlate so strongly with their time piece that it won't add much value. The one case where it may be useful is to aid pacing over longer runs on unfamiliar terrain, but I think most endurance runners already know when they are running a sustainable vs unsustainable pace. This device could help them abide by the plan better.


I can see a running power meter changing the way people train - but would it be a change for the better.

I can see a massive market for online power based training plans and software, it will go the way cycling has. In no time runners will be assuming you can't train effectively without a running power meter and will be going out training tying to stay in zones and worrying about if they have their FTP set correctly and how many TSS they score.
Last edited by: Trev: Feb 5, 15 2:00
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
This gadget is priced at $120. That is incredibly cheap.

If we set aside accuracy there is another consideration here.

If you have power, you don't need heart rate. So it is a minimalist and affordable option.
Last edited by: Trev: Feb 5, 15 2:17
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
A few thoughts...

Knowledge of a person's actual power output while cycling is immensely valuable, because:

1) mechanical power is what moves the bike down the road, and

2) cycling economy/efficiency does not vary dramatically between individuals, such that power provides a reasonable proxy for actual metabolic demand.

With that in mind, consider a running power estimator, i.e., one that relies on GPS, acceleromters, etc., to calculate power:

1) since power is being determined indirectly, the reported values provide no further insight into someone's actual performance than does knowledge of their pace and changes in elevation (although if accurate, estimated power does have the benefit of pinning a single number on things), and

2) running economy varies much more between individuals than does cycling economy/efficiency, such that the calculated power may not provide a valid/reliable indication of actual metabolic demand.

Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.

A running power meter would have to be accurate.

To give an example of how inaccurate or unreliable power readings can be I did a little experiment on a treadmill at the gym which shows speed gradient and watts.

I don't know how they calculate power but it was misleading and thus useless.

I was getting approx 240 watts for running 6 mph on the flat and 180 watts for walking 3 mph at 15% gradient. But heart rate and perceived effort and breathing was harder at 180 watts. The machine although it alegedly takes into account weight seems to vastly overestimate flat running. Incidentally if you do a quick wattage calculation from speed gradient and weight the 3 mph 180 watts is near enough.

A cycling power meter when calibrated etc correctly is +/- 1% to 2% accurate. Even a slight gradient in cycling results in a massive wattage increase to hold the same speed. 20 mph on a 2% gradient would need 80 more watts than a 1% gradient for an 180lb rider. But the same increase in gradient for a 180lb runner at 8 mph would require only approx 30 watts more. So for a running power meter to detect changes in power on small gradients it would need to be very accurate. Note most triathletes wont weigh 180lbs.

To detect any changes in wattage due to slight wind or slight gradients a running power meter would have to be even more accurate than a cycling power meter.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
There are many power points needed for data collection... the shoulders and arms, quad, calf (for high kick back), top of foot. As that one mount point will report only 240watts just like a bike... but here there are more moving parts the influence power that really the person is probably at 340w

http://www.coupleofathletes.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [synthetic] [ In reply to ]
Quote | Reply
synthetic wrote:
There are many power points needed for data collection... the shoulders and arms, quad, calf (for high kick back), top of foot. As that one mount point will report only 240watts just like a bike... but here there are more moving parts the influence power that really the person is probably at 340w

The wattage will always be an estimate because you're measuring acceleration, not force. The contribution of the arms would partially show in the acceleration, but there's probably some reasonable assumptions to be made. Those with good leg mechanics, probably tend to have equally good arm mechanics.

The point isn't that the wattage value is accurate, it's that it's repeatable and represents your output in a more precise way than GPS data and you don't need a measured route and stopwatch.


TrainingBible Coaching
http://www.trainingbible.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
synthetic wrote:
There are many power points needed for data collection... the shoulders and arms, quad, calf (for high kick back), top of foot. As that one mount point will report only 240watts just like a bike... but here there are more moving parts the influence power that really the person is probably at 340w


The wattage will always be an estimate because you're measuring acceleration, not force. The contribution of the arms would partially show in the acceleration, but there's probably some reasonable assumptions to be made. Those with good leg mechanics, probably tend to have equally good arm mechanics.

The point isn't that the wattage value is accurate, it's that it's repeatable and represents your output in a more precise way than GPS data and you don't need a measured route and stopwatch.


Out of interest, how accurately do running GPS devices measure speed?

Would they be accurate to 0.1 mph? The study below is a bit mixed and I'm not sure they tested the sort of device commonly available to runners.

http://www.ncbi.nlm.nih.gov/pubmed/25254901
Last edited by: Trev: Feb 8, 15 1:49
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
Trev wrote:
Out of interest, how accurately do running GPS devices measure speed?

Would they be accurate to 0.1 mph? The study below is a bit mixed and I'm not sure they tested the sort of device commonly available to runners.

http://www.ncbi.nlm.nih.gov/pubmed/25254901

Accuracy depends on all sorts of factors. Speed and direction of movement, location (forest, mountains, city, open field, etc), type of gps, is a differential gps used, etc. Walking at 5kph in a straight line on open roads, probably very accurate. Running on a soccer field with quick changes of speed and direction, probably not so accurate.

Team sports have switched to local positioning systems for accurate measurement of speed and acceleration.
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
Quote | Reply
motoguy128 wrote:
synthetic wrote:
There are many power points needed for data collection... the shoulders and arms, quad, calf (for high kick back), top of foot. As that one mount point will report only 240watts just like a bike... but here there are more moving parts the influence power that really the person is probably at 340w


The wattage will always be an estimate because you're measuring acceleration, not force. The contribution of the arms would partially show in the acceleration, but there's probably some reasonable assumptions to be made. Those with good leg mechanics, probably tend to have equally good arm mechanics.

The point isn't that the wattage value is accurate, it's that it's repeatable and represents your output in a more precise way than GPS data and you don't need a measured route and stopwatch.

yes well in the end it is to be used for personal improvement, not comparing vs other people like you can with a bike.

http://www.coupleofathletes.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
Talking with the Stryd folks this Friday to present them with feedback/questions. While my own curiosity, DC Rainmaker's feedback and posts already in this thread provide some great areas for conversation, let me know what questions/feedback you have....

Thanks!

___________________________________
milesthedog on strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
Quote | Reply
Trev wrote:
motoguy128 wrote:
synthetic wrote:
There are many power points needed for data collection... the shoulders and arms, quad, calf (for high kick back), top of foot. As that one mount point will report only 240watts just like a bike... but here there are more moving parts the influence power that really the person is probably at 340w


The wattage will always be an estimate because you're measuring acceleration, not force. The contribution of the arms would partially show in the acceleration, but there's probably some reasonable assumptions to be made. Those with good leg mechanics, probably tend to have equally good arm mechanics.

The point isn't that the wattage value is accurate, it's that it's repeatable and represents your output in a more precise way than GPS data and you don't need a measured route and stopwatch.


Out of interest, how accurately do running GPS devices measure speed?

Would they be accurate to 0.1 mph? The study below is a bit mixed and I'm not sure they tested the sort of device commonly available to runners.

http://www.ncbi.nlm.nih.gov/pubmed/25254901

Sampling rate is important and something that study identified (at least from a read of the abstract). Most commercial sport GPS devices currently available sample at best at 1Hz. Accuracy (or precision) is very definitely going to be directly related to sampling rate.

Garmin suggest GPS accuracy of 15m is not unreasonable for commercial devices. In practice I've seen better than 5m in clear sky conditions but GPS is very susceptible to overhead conditions affecting line-of-sight to satellites as well as a number of other factors.

Trust me I’m a doctor!
Well, I have a PhD :-)
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [PhilipShambrook] [ In reply to ]
Quote | Reply
PhilipShambrook wrote:
Sampling rate is important and something that study identified (at least from a read of the abstract). Most commercial sport GPS devices currently available sample at best at 1Hz. Accuracy (or precision) is very definitely going to be directly related to sampling rate.

Garmin suggest GPS accuracy of 15m is not unreasonable for commercial devices. In practice I've seen better than 5m in clear sky conditions but GPS is very susceptible to overhead conditions affecting line-of-sight to satellites as well as a number of other factors.

Odd that they used the devices that they did, since those aren't used by anyone in the running community (except for perhaps, studies like this)*. I suppose I could pay for another study, but we all know how that turned out last time...

(*I don't know anything about those specific devices, other than that they aren't used by consumers. They could be and likely are perfectly fine.)


-
My tiny little slice of the internets: dcrainmaker.com
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [SwimGreg3] [ In reply to ]
Quote | Reply
I've been thinking about this thread a bit. First - thanks to @robert-stryd for his contributions from the mfr POV - excellent (and welcome to ST). Now, I think that @SwimGreg3 is onto something here wrt the phase of the run when you're not touching the ground. There are a number of ways to achieve the same run pace against and with the wind. Let's consider one possibility - the turnover and stride length are identical. In this case, the initial push off must be a higher acceleration into the wind vs with the wind, since this hypothetical runner is covering the same distance per stride either way, but we can agree (I think) that she would travel further with the wind than against when not in contact with the ground. So, there must be compensation in the ground contact phase of the cycles - into the wind, push off harder and then slow more while not touching the ground vs against the wind, pushing off less hard and slowing less while not touching the ground to make the total cycle time and total cycle distance identical. Even *I* could do the signal processing on that one to assess into the wind vs with the wind from an accelerometer POV. Now, what about the *many* other cases? Cadence and stride length can change with and against wind, for example. But I'll bet that the accelerometer data during the non-ground contact time is pretty clearly different into and with the wind regardless of changes in cadence. Could this be converted into accurate power for all (or most) conditions? I duuno. But can the accelerometers sense the difference between running into the wind vs against the wind. My guess is - you betcha. And *that* is the start of a signal processing algorithm that might provide a useful estimate of power that reflects the relative wind vector and speed vs the run vector and speed. I think that the objectives of Stryd are a challenge, but not impossible, based on what I assess the physics of running and measurement capabilities of the accelerometers to be. Might appear to be magical to some, but just straight up physics to the rest of us!
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
Quote | Reply
I am most interested in if they can/will collaborate with other companies with their intellectual property. I've got a Wahoo Tickr X and would love to experiment with power using their algorithms. Can/would they use data from other sensors and make their money from selling their app or licensing their algorithms the other companies?
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
Quote | Reply
Right. I've been thinking about this as well.

This would also be the business model for Bioshift's automatic shifting algorithm. It would seem they need sell the algorithm directly to hardware manufacturers to include the algorithm as OEM. Selling directly to consumers brings with it the chance of pirated algorithms; unless Stryd will be selling a proprietary pod bundled with the algorithm download (don't know how Bioshift can sell their algorithm to consumers without proprietary hardware - btw, wireless sram seems to be a great opportunity for their product).

___________________________________
milesthedog on strava
Quote Reply
Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
Quote | Reply
Good conversation with Phoenix, a physics phd student at CU, who helped designed Stryd's algorithm. Here are some points I remember from this morning's conversation - if I'm wrong on any of these points, please let me know and I'll edit this post:

  • It's a proprietary motion sensor pod, much more advanced than Garmin's/Polar's/Wahoo's accelerometers. So, it will not be an algorithm that can be paired with the Wahoo Tickr-x. From Stryd: It is a more advanced accelerometer, however Stryd goes beyond just "motion sensing", we measure both "motion and the environment"

    • If synced with a phone beforehand, a runner can run with only the pod and the pod will record the activity, with auto-stop as a default feature, and will then automatically upload once back in range of the phone.
    • At this point in time, it does not measure speed, but works with GPS devices to record speed.
    • Wind, from Stryd: It measures acceleration and calculates force from the acceleration. If one change running form when encountering wind, which will register as a change in acceleration, then we can account for that perspective of wind impact. But we CANNOT measure every aspect that wind effect has on a runner currently. We have a plan to properly account for the impact of changes in wind speed but we don't have solid testing results on this now. We'll follow up here, and on our blog (http://blog.stryd.com), when we have more news on this.
    • When they launch, they will have ensured that their data will appear when uploaded to all major platforms: TP, Strava, Garmin Connect, RunKeeper. From Stryd: Our own website will always support the data. With open source API such as Strava, we can make sure that our data will be supported. As far as TrainingPeaks' and Garmin Connect's API, we are trying as hard as we can to get our data on their platform and we are quite confident that things will work out, but again it is impossible to promise we will be able to reach all major platforms.
    • It is their goal for it to be used as a cycling power meter is currently used, with the emphasis being more in line with how triathletes and TT cyclist ride: maintaining an even power and maximizing efficiency.


    ___________________________________
    milesthedog on strava
    Last edited by: milesthedog: Feb 16, 15 11:31
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
    Quote | Reply
    I made some edits in my above post relaying on my conversation with Stryd

    ___________________________________
    milesthedog on strava
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
    Quote | Reply
    milesthedog wrote:
  • It is their goal for it to be used as a cycling power meter is currently used, with the emphasis being more in line with how triathletes and TT cyclist ride: maintaining an even power and maximizing economy.

  • Not to be pedantic, but:

    http://forum.slowtwitch.com/...post=5425148#5425148
    Last edited by: Andrew Coggan: Feb 16, 15 11:06
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    changed it to "efficiency" - the idea being to run at a faster pace producing less power - this reduction in power possibly indicating more efficient movement. I'm sure there will be some interesting research that can come from this if the device truly does correspond strongly with the data provided by a force-plate treadmill.

    ___________________________________
    milesthedog on strava
    Last edited by: milesthedog: Feb 16, 15 11:35
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
    Quote | Reply
    milesthedog wrote:
    changed it to "efficiency" - the idea being to run at a faster pace producing less power

    That's not correct either - efficiency is energy out/energy in x 100%.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    With power being a proxy for caloric utilization, if a runner maintained their speed at a lesser wattage (flat surface, no wind), one possibility could be that the movement pattern of the runner's limbs had become more efficient in either or both their swing phases and/or their foot strike. No?

    ___________________________________
    milesthedog on strava
    Last edited by: milesthedog: Feb 16, 15 12:14
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [milesthedog] [ In reply to ]
    Quote | Reply
    milesthedog wrote:
    With power being a proxy for caloric utilization, if a runner maintained their speed at a lesser wattage (flat surface, no wind), one possibility could be that the movement pattern of the runner's limbs had become more efficient

    That's circular logic.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.

    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    I can see a running power meter changing the way people train - but would it be a change for the better.

    I can see a massive market for online power based training plans and software, it will go the way cycling has. In no time runners will be assuming you can't train effectively without a running power meter and will be going out training tying to stay in zones and worrying about if they have their FTP set correctly and how many TSS they score.

    This, definitely 100%. Agreed it's close to using pace/HRM but using power is just plain superior. Time will tell ...
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [howlingmadbenji] [ In reply to ]
    Quote | Reply
    In cyclimg power is particularly useful because an increase in speed as a percentage requires a far greater percentage imcrease in power.

    Back in 1996 I got a Concept 2 Rowing Machine, which accurately gives pace and power.

    All the rowing training books talked about pace and there was no mention of power, but it became obvious to me it is so much simpler to train with power.

    200 watts is 500m / 2min pace. But to increase pace to only 1min 58sec pace a mere 3% faster, requires 10% more power.

    So for working out improvement, working out % of FTP to train at, quantifying work done etc, pace / speed can be very misleading.

    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?


    If this is the case I can see Dr Coggan's point of view.
    Last edited by: Trev: Feb 17, 15 2:35
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?
    If this is the case I can see Dr Coggan's point of view.

    This is pretty much the case especially at the speeds triathletes typically run which I believe has been Andy's main point all along.

    Hugh

    Genetics load the gun, lifestyle pulls the trigger.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [sciguy] [ In reply to ]
    Quote | Reply
    sciguy wrote:
    Trev wrote:
    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?
    If this is the case I can see Dr Coggan's point of view.

    This is pretty much the case especially at the speeds triathletes typically run which I believe has been Andy's main point all along.

    Hugh

    Yep. So you might as well use pace.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:

    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?

    I hope I don't come across as pedantic, as subtleties such as this can result in mis-communication or misunderstanding:

    "A function of" does not necessarily mean a 1:1 ratio. For example, pace could go up with the square root of power, Power = speed^2, and it would still be a function of pace. In the same sense, assuming flat ground and no wind,for cycling speed is indeed a function of power, it's just a more complicated one.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [YTS] [ In reply to ]
    Quote | Reply
    YTS wrote:
    Trev wrote:

    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?

    I hope I don't come across as pedantic, as subtleties such as this can result in mis-communication or misunderstanding:

    "A function of" does not necessarily mean a 1:1 ratio. For example, pace could go up with the square root of power, Power = speed^2, and it would still be a function of pace. In the same sense, assuming flat ground and no wind,for cycling speed is indeed a function of power, it's just a more complicated one.

    No not pedantic at all. This is exactly why I was asking the question, because I wasn't sure of the exact meaning.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [davearm] [ In reply to ]
    Quote | Reply
    davearm wrote:
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.

    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?

    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Okay, then how do I go about determining how hard/fast I should I run up that hill I come upon in my Ironman race? I don't know its length or its grade. Heck I've never been on the course before. I just know I'm going uphill.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [davearm] [ In reply to ]
    Quote | Reply
    davearm wrote:
    Okay, then how do I go about determining how hard/fast I should I run up that hill I come upon in my Ironman race? I don't know its length or its grade. Heck I've never been on the course before. I just know I'm going uphill.

    Perceived exertion. At least in experienced athletes competing under conditions they've been exposed to before, it works just as well any theoretically-optimal pacing strategy (see, e.g., Alex Simmon's "pacing optimization index").
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    Perceived exertion. At least in experienced athletes competing under conditions they've been exposed to before, it works just as well any theoretically-optimal pacing strategy (see, e.g., Alex Simmon's "pacing optimization index").


    That's a lot of assumptions.

    Perceived exertion is probably the worst measure for the less experienced athletes especially in endurance events where the conditions, course or both is not familiar. I can think of numerous times when I'm running uphill at what I think is steady effort, yet my HR spikes to sub threshold levels. I'd argue that Biking Power meters helps LESS experienced athletes more then more experienced athletes and IF this device works consistently and as billed will be a game changer.
    Last edited by: Olu: Feb 17, 15 8:42
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Olu] [ In reply to ]
    Quote | Reply
    Olu wrote:
    Andrew Coggan wrote:
    Perceived exertion. At least in experienced athletes competing under conditions they've been exposed to before, it works just as well any theoretically-optimal pacing strategy (see, e.g., Alex Simmon's "pacing optimization index").


    That's a lot of assumptions.

    Not really - like I said, see Alex's paper.

    Olu wrote:
    Perceived exertion is probably the worst measure for the less experienced athletes especially in endurance events where the conditions, course or both is not familiar.

    First, note my caveats above.

    Second, ask youself this: are novice runners who can't pace themselves well based on perceived exertion going to benefit more from learning how to do just that, or relying on a device that only provides a crude estimate of the metabolic demands?*

    *Note that an important difference between running and cycling is that the economy of movement is much more variable in the former than in the latter. Also, muscle use varies more in the former than in the latter, e.g., even if you keep your estimated power constant when transitioning from the flats to up hill, you will be placing more demand on your quads as a result. So, should you really be aiming for an iso-power effort, or an iso-metabolic one?

    Finally, note that entire argument in favor of a running powermeter has now seemingly been reduced to a single application, i.e., as a pacing aid when running in hilly terrain. "Game-changing" indeed...
    Last edited by: Andrew Coggan: Feb 17, 15 9:34
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.

    I bet you can imagine that it's very difficult for triathletes (or anyone really) to believe that cycling and running are so fundamentally different that a tool that can accurately and predictably measure power* is vital in cycling, but worthless in running. The parallels between the two seem way too clear for this to be true.

    * assuming this Stryd or something else like it could achieve this
    Last edited by: davearm: Feb 17, 15 10:14
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    "Game-changing" indeed...

    You seem pretty certain...I guess you're the expert.

    Only time will tell if you're right.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [davearm] [ In reply to ]
    Quote | Reply
     

    * assuming this Stryd or something else like it could achieve this[/quote]
    I think this is his point (not to speak for anyone), If you had a perfect scenario where the device works in the same fashion as a PM and has the same clarity with running IE power correlates reasonably to metabolic demands then maybe a great pacing tool.

    I don't think this is the case yet….perhaps I will be proven wrong or maybe better/different products will evolve.

    The Issue is that with the bike holding a power level that is even and achievable throughout the ride (in order to run well) should correlate to an RPE of "pretty easy to moderate" from minute 1 to 5-7hours, with the run even pacing or a slight positive/or negative split usually correlates to a variable RPE through out.

    So a simple stopwatch for me is the best tool for IM run, it is the one event (IM Run) where there is perhaps a really strong negative correlation to RPE and pace….(talking as a coach) If this was actually proven to work then I could see it as a really good "slow the F*&k down" meter in the first 10km.

    But for now we do something really simple, in the first 5-10km of the run you hold 15-30seconds SLOWER than goal pace, 10-32km hold goal pace, 32-42km…..it's a F%$king race….dig deep.

    Maurice
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [sciguy] [ In reply to ]
    Quote | Reply
    sciguy wrote:
    Trev wrote:
    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?
    If this is the case I can see Dr Coggan's point of view.


    This is pretty much the case especially at the speeds triathletes typically run which I believe has been Andy's main point all along.

    Hugh

    I suspect it's far from linear. In particular when you become more fatigued. Also at certain paces or uphill vs. downhill.

    It is true over a range of paces on relatively flat ground.

    But I don't have hard data, it's what I've come to believe looking at me own data and some of my clients. Below a certain pace, their run mechanics change and the ratio of pace to energy output changes.

    I also know one athlete that has a very narrow range between aerobic threshold and lactate threshold. Very narrow. I suspect it's a main reason he performs much better in 70.3 compared to IM. You can cross that line frequently without penalty. You cannot in IM.


    TrainingBible Coaching
    http://www.trainingbible.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
    Quote | Reply
    I think the primary point and benefit/value, and Coggan points towards this, running has variable mechanics. They vary uphill, downhill, at different paces and with fatigue. For elite runners with very well refined mechanics, I think there would be less value for this device. But for triathletes, or more recreational runners, with more variability in mechanics, might see greater benefit.

    Right now if I improve my run mechanics I have to use RPE and HR to gauge improvement compared to pace. I don't know how hard I'm accelerating in a horizontal direction. I don't know if HR shifts are due to fatigue, hydration, heat, fitness gains, too much food in my stomach, excitement, a range is variables. Pace is impacted by weight, grade, wind, road surface.


    TrainingBible Coaching
    http://www.trainingbible.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [mauricemaher] [ In reply to ]
    Quote | Reply
    Targeting particular run paces over given distances is all well and good, but I'm still left wondering about how much I should slow down when I'm on the course, and come to a hill. The answer is surely somewhere between "not at all" and "walk it", but I've got no good guess as to where that optimal pace/effort adjustment lies.

    This is information I figured a run powermeter (properly executed) would tell me, just as my bike powermeter does already.

    Maybe the answer is, slow down however much it takes to keep the RPE the same. That just seems highly unscientific, where some science might be available.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [davearm] [ In reply to ]
    Quote | Reply
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.

    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Olu] [ In reply to ]
    Quote | Reply
    Olu wrote:
    Andrew Coggan wrote:
    "Game-changing" indeed...

    You seem pretty certain...I guess you're the expert.

    Only time will tell if you're right.

    I'm simply explaining the logic behind my prediction.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.

    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.

    Feel is the most valuable tool. Sadly since the advent of heart rate monitors and power meters it is often neglected.

    When you talk of perceived exertion, are you referring to it in a narrow scientific Borg scale sense or in a more broad sense as another way of referring to feel in general?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
    Quote | Reply
    motoguy128 wrote:
    sciguy wrote:
    Trev wrote:
    But I understand running pace is a function of power. Does this mean a 10% increase in pace requires 10% more power?
    If this is the case I can see Dr Coggan's point of view.


    This is pretty much the case especially at the speeds triathletes typically run which I believe has been Andy's main point all along.

    Hugh

    I suspect it's far from linear. In particular when you become more fatigued. Also at certain paces or uphill vs. downhill.

    It is true over a range of paces on relatively flat ground.

    But I don't have hard data, it's what I've come to believe looking at me own data and some of my clients. Below a certain pace, their run mechanics change and the ratio of pace to energy output changes.

    I also know one athlete that has a very narrow range between aerobic threshold and lactate threshold. Very narrow. I suspect it's a main reason he performs much better in 70.3 compared to IM. You can cross that line frequently without penalty. You cannot in IM.

    On a constant grade, the metabolic cost of running is directly proportional to speed from ~4 mph up to as fast as you can run for several minutes (hard to say beyond that point, as a steady-state in VO2 won't be achieved, and biomechanical estimates of power output are just that, i.e., estimates).

    There is some drift over time/effect of fatigue, but it's really only large at supra-threshold intensities (same is true for cycling). One study in J Appl Physiol that I recall, for example, had ultra marathoners running on a treadmill for ~5 h, allowing them to adjust the pace as they desire. VO2 stayed essentially constant over time, as they slowed down by (IIRC) 8% (implying that if they hadn't slowed down, VO2 would have risen by about the same amount).

    A 1% increase in grade typically results in a 4% increase in metabolic demand. As I mentioned before, though, there is also a significant shift in muscle use (e.g., see Costill's classic study of glycogen utilization in the gastroc vs. v. laterals), something that wouldn't be captured by a running pwoermeter.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [motoguy128] [ In reply to ]
    Quote | Reply
    motoguy128 wrote:
    I think the primary point and benefit/value, and Coggan points towards this, running has variable mechanics. They vary uphill, downhill, at different paces and with fatigue. For elite runners with very well refined mechanics, I think there would be less value for this device. But for triathletes, or more recreational runners, with more variability in mechanics, might see greater benefit.

    Right now if I improve my run mechanics I have to use RPE and HR to gauge improvement compared to pace. I don't know how hard I'm accelerating in a horizontal direction. I don't know if HR shifts are due to fatigue, hydration, heat, fitness gains, too much food in my stomach, excitement, a range is variables. Pace is impacted by weight, grade, wind, road surface.

    Sounds like what you'd really like to able to measure are things like stride length, contact time, flight time, etc., not power.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.


    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.

    The radical departure I was alluding to is that training and racing with a powermeter is quantified, precise, accurate, and backed by loads of science.

    Perceived exertion is basically the opposite of all these things.

    So you can imagine how odd it seems when the same expert advocates one approach for one discipline, and the complete opposite approach for the other.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    motoguy128 wrote:
    I think the primary point and benefit/value, and Coggan points towards this, running has variable mechanics. They vary uphill, downhill, at different paces and with fatigue. For elite runners with very well refined mechanics, I think there would be less value for this device. But for triathletes, or more recreational runners, with more variability in mechanics, might see greater benefit.

    Right now if I improve my run mechanics I have to use RPE and HR to gauge improvement compared to pace. I don't know how hard I'm accelerating in a horizontal direction. I don't know if HR shifts are due to fatigue, hydration, heat, fitness gains, too much food in my stomach, excitement, a range is variables. Pace is impacted by weight, grade, wind, road surface.


    Sounds like what you'd really like to able to measure are things like stride length, contact time, flight time, etc., not power.

    I sure would. That and ground reaction forces. I would rather know those things than power (for running).

    Simplify, Train, Live
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [davearm] [ In reply to ]
    Quote | Reply
    davearm wrote:
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.


    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.

    The radical departure I was alluding to is that training and racing with a powermeter is quantified, precise, accurate, and backed by loads of science.

    Perceived exertion is basically the opposite of all these things.

    So you can imagine how odd it seems when the same expert advocates one approach for one discipline, and the complete opposite approach for the other.

    I advocate that all endurance athletes calibrate their perceived exertion against a reasonable surrogate for their metabolic rate, especially when the latter is also an absolute reflection/critical determinant of their actual performance ability. So, pace for runners, but power for cyclists.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.


    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.


    The radical departure I was alluding to is that training and racing with a powermeter is quantified, precise, accurate, and backed by loads of science.

    Perceived exertion is basically the opposite of all these things.

    So you can imagine how odd it seems when the same expert advocates one approach for one discipline, and the complete opposite approach for the other.


    I advocate that all endurance athletes calibrate their perceived exertion against a reasonable surrogate for their metabolic rate, especially when the latter is also an absolute reflection/critical determinant of their actual performance ability. So, pace for runners, but power for cyclists.


    http://www.uta.edu/...rior%20statement.pdf

    It would be unscientific to ignore RPE.
    Last edited by: Trev: Feb 18, 15 10:11
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
    Quote | Reply
    in terms of ground reaction forces. DC Rainmaker's article did show that Stryd's data closely matches the impact forces recorded on a lab grade force-plate treadmill. If validated, I definitely see the benefit in possibly doing a greater number of field studies outside of the lab - maybe putting the pod on the shorts of elite marathoners who live and train in the Rift Valley region and using the device on elite runners during races - capturing data over the course of an entire marathon, for example. The potential to research mechanical efficiency is real. And future [lab] studies comparing Stryd's running power to glycogen utilization over varying speeds and gradients will be interesting.

    ___________________________________
    milesthedog on strava
    Last edited by: milesthedog: Feb 19, 15 8:43
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
    Quote | Reply
    Kickstarter just opened up for the Stryd less then 1 hour ago and has almost met it's goal...


    https://www.kickstarter.com/projects/stryd/stryd-the-worlds-first-wearable-power-meter-for-ru/



    Jeff Dell
    Endurance Tracker - For the data driven athlete.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.


    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?


    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.


    Is this still your opinion?

    http://club.stryd.com/...n-flat-vs-hilly/1175

    You seem to have changed your mind.
    Last edited by: Trev: Dec 20, 15 2:27
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Yikes! And he actually used the word "shill"......
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.


    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?


    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.


    Is this still your opinion?

    http://club.stryd.com/...n-flat-vs-hilly/1175

    You seem to have changed your mind.

    Let's just say that:

    1) I like Li's and Robert's vision; and

    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:


    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [lightheir] [ In reply to ]
    Quote | Reply
    lightheir wrote:
    I 100% guarantee that if someone indeed developed a running powermeter that was every bit as accurate and precise as cycling powermeters, it would be a complete game changer at all levels for training and racing, just as it was for cycling. And you'd surely see some new and very useful metrics be developed.

    Speaking of precision:



    (From http://club.stryd.com/...wer-in-children/1330)
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Does the Stryd device give precise values under varying wind conditions and surfaces?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    Trev wrote:
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.


    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?


    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.


    Is this still your opinion?

    http://club.stryd.com/...n-flat-vs-hilly/1175

    You seem to have changed your mind.


    Let's just say that:

    1) I like Li's and Robert's vision; and

    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:



    Let's just say that you changed your mind.

    Do you still agree with the following comments you made earlier in this thread?


    Andrew Coggan wrote:

    "I can't see a running power meter having a significant impact on how people actually train and perform.

    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.


    Second, ask youself this: are novice runners who can't pace themselves well based on perceived exertion going to benefit more from learning how to do just that, or relying on a device that only provides a crude estimate of the metabolic demands?*

    *Note that an important difference between running and cycling is that the economy of movement is much more variable in the former than in the latter. Also, muscle use varies more in the former than in the latter, e.g., even if you keep your estimated power constant when transitioning from the flats to up hill, you will be placing more demand on your quads as a result. So, should you really be aiming for an iso-power effort, or an iso-metabolic one?

    Finally, note that entire argument in favor of a running powermeter has now seemingly been reduced to a single application, i.e., as a pacing aid when running in hilly terrain. "Game-changing" indeed...



    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.

    On a constant grade, the metabolic cost of running is directly proportional to speed from ~4 mph up to as fast as you can run for several minutes (hard to say beyond that point, as a steady-state in VO2 won't be achieved, and biomechanical estimates of power output are just that, i.e., estimates).

    There is some drift over time/effect of fatigue, but it's really only large at supra-threshold intensities (same is true for cycling). One study in J Appl Physiol that I recall, for example, had ultra marathoners running on a treadmill for ~5 h, allowing them to adjust the pace as they desire. VO2 stayed essentially constant over time, as they slowed down by (IIRC) 8% (implying that if they hadn't slowed down, VO2 would have risen by about the same amount).

    A 1% increase in grade typically results in a 4% increase in metabolic demand. As I mentioned before, though, there is also a significant shift in muscle use (e.g., see Costill's classic study of glycogen utilization in the gastroc vs. v. laterals), something that wouldn't be captured by a running pwoermeter.



    Sounds like what you'd really like to able to measure are things like stride length, contact time, flight time, etc., not power.


    I advocate that all endurance athletes calibrate their perceived exertion against a reasonable surrogate for their metabolic rate, especially when the latter is also an absolute reflection/critical determinant of their actual performance ability. So, pace for runners, but power for cyclists.

    thoughts...

    Knowledge of a person's actual power output while cycling is immensely valuable, because:

    1) mechanical power is what moves the bike down the road, and

    2) cycling economy/efficiency does not vary dramatically between individuals, such that power provides a reasonable proxy for actual metabolic demand.

    With that in mind, consider a running power estimator, i.e., one that relies on GPS, acceleromters, etc., to calculate power:

    1) since power is being determined indirectly, the reported values provide no further insight into someone's actual performance than does knowledge of their pace and changes in elevation (although if accurate, estimated power does have the benefit of pinning a single number on things), and

    2) running economy varies much more between individuals than does cycling economy/efficiency, such that the calculated power may not provide a valid/reliable indication of actual metabolic demand.

    Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform. "

    What has brought about such a volte-face?
    Last edited by: Trev: Dec 20, 15 15:23
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Ohh. o.k., got it.
    Just wondering if you can write that with a straight face, as I clearly remember you ridiculing others for that exact point of view....




    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.


    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.


    The radical departure I was alluding to is that training and racing with a powermeter is quantified, precise, accurate, and backed by loads of science.

    Perceived exertion is basically the opposite of all these things.

    So you can imagine how odd it seems when the same expert advocates one approach for one discipline, and the complete opposite approach for the other.


    I advocate that all endurance athletes calibrate their perceived exertion against a reasonable surrogate for their metabolic rate, especially when the latter is also an absolute reflection/critical determinant of their actual performance ability. So, pace for runners, but power for cyclists.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:


    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:


    You're still in a logical trap with your quote. It clearly asserts that common sense is a sufficient condition to accomplish everything that's possible, with or without a powermeter.

    Post shill transition, you want want this instead:

    Quote:
    Because there's something a smart runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.
    Last edited by: trail: Dec 20, 15 18:17
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Nick B] [ In reply to ]
    Quote | Reply
    Nick B wrote:
    Does the Stryd device give precise values under varying wind conditions and surfaces?

    No. Or rather, not yet.


    -
    My tiny little slice of the internets: dcrainmaker.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [windschatten] [ In reply to ]
    Quote | Reply
    windschatten wrote:
    Ohh. o.k., got it.
    Just wondering if you can write that with a straight face, as I clearly remember you ridiculing others for that exact point of view....

    Disagreeing with others is not ridiculing them.
    Quote Reply
    Post deleted by Andrew Coggan [ In reply to ]
    Re: DCRainmaker preview of Stryd running power meter [dcrainmaker] [ In reply to ]
    Quote | Reply
    dcrainmaker wrote:
    Nick B wrote:
    Does the Stryd device give precise values under varying wind conditions and surfaces?

    No. Or rather, not yet.

    I don't think that can be said. The only way to truly test the precision under different conditions would be to repeatedly test under different conditions. Given the data I presented and how power is being determined, though, you'd expect the precision to be comparable regardless of the wind or surface conditions (i.e., a device on your chest measuring acceleration is agnostic as to why your center-of-mass is speeding up or slowing down).
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [trail] [ In reply to ]
    Quote | Reply
    trail wrote:
    Andrew Coggan wrote:


    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:


    You're still in a logical trap with your quote. It clearly asserts that common sense is a sufficient condition to accomplish everything that's possible, with or without a powermeter.

    Accomplishing the things I see possible is also going to take knowing more than just power.

    Spring constants, anyone?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    dcrainmaker wrote:
    Nick B wrote:
    Does the Stryd device give precise values under varying wind conditions and surfaces?


    No. Or rather, not yet.


    I don't think that can be said. The only way to truly test the precision under different conditions would be to repeatedly test under different conditions. Given the data I presented and how power is being determined, though, you'd expect the precision to be comparable regardless of the wind or surface conditions (i.e., a device on your chest measuring acceleration is agnostic as to why your center-of-mass is speeding up or slowing down).

    In this case, this was after spending an hour discussing it with their full team on a conference call a few weeks ago. They readily admit they don't deal with wind today, nor have a specific plan for how to do so.

    Same goes for surface conditions.

    (Side note: There are super-easy tests for both of these, running with a parachute vs not, and running on a path next to a beach vs not.)


    -
    My tiny little slice of the internets: dcrainmaker.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    trail wrote:
    Andrew Coggan wrote:


    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:


    You're still in a logical trap with your quote. It clearly asserts that common sense is a sufficient condition to accomplish everything that's possible, with or without a powermeter.


    Accomplishing the things I see possible is also going to take knowing more than just power.

    Spring constants, anyone?


    If this device cannot account for wind or other horizontal drag factors, is it really a power meter?

    Granted, under most conditions it would not matter, but having run directly up and downwind at the Surfside Beach half marathon ( you are likely familiar with area & potential conditions) I know it is possible to have pace varied as much as 1 min/mile by wind with similar effort.
    Last edited by: J_R: Dec 21, 15 6:25
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    Speaking of precision:



    (From http://club.stryd.com/...wer-in-children/1330)

    Do you have data for different treadmill inclinations?

    Ale Martinez
    www.amtriathlon.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Hahaha, I'm disappointed you deleted your reply! I thought it was entirely appropriate...
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [dcrainmaker] [ In reply to ]
    Quote | Reply
    dcrainmaker wrote:
    Andrew Coggan wrote:
    dcrainmaker wrote:
    Nick B wrote:
    Does the Stryd device give precise values under varying wind conditions and surfaces?


    No. Or rather, not yet.


    I don't think that can be said. The only way to truly test the precision under different conditions would be to repeatedly test under different conditions. Given the data I presented and how power is being determined, though, you'd expect the precision to be comparable regardless of the wind or surface conditions (i.e., a device on your chest measuring acceleration is agnostic as to why your center-of-mass is speeding up or slowing down).

    In this case, this was after spending an hour discussing it with their full team on a conference call a few weeks ago. They readily admit they don't deal with wind today, nor have a specific plan for how to do so.

    Same goes for surface conditions.

    (Side note: There are super-easy tests for both of these, running with a parachute vs not, and running on a path next to a beach vs not.)

    They may not be willing to make the claim just yet, but if my understanding of how they are calculating power is correct, then the value provided does account for varying wind conditions and running surfaces (although the metabolic cost of producing that power could vary).

    As for a parachute, it would be simpler to just run a cord over a pulley behind a treadmill, and hang a known mass from it. In fact, this is an experiment I've been meaning to perform, although having pulled a calf muscle this a.m. it may take me a while to get around to it.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Ale Martinez] [ In reply to ]
    Quote | Reply
    Ale Martinez wrote:
    Andrew Coggan wrote:
    Speaking of precision:



    (From http://club.stryd.com/...wer-in-children/1330)

    Do you have data for different treadmill inclinations?

    No, at least not yet, as the Stryd relies on a barometric pressure sensor to detect changes in elevation. That means it doesn't account for the additional power requirement of running uphill on a treadmill unless you collect data using the iOS or Android app, which allows you to specify the grade. To date, though, I've only been using a Garmin watch, so haven't elevated the treadmill.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    J_R wrote:
    Andrew Coggan wrote:
    trail wrote:
    Andrew Coggan wrote:


    2) it's going to take more than just common sense to take maximum advantage of the data that the Stryd can provide. Fortunately, some of us have more than just common sense at their disposal:


    You're still in a logical trap with your quote. It clearly asserts that common sense is a sufficient condition to accomplish everything that's possible, with or without a powermeter.


    Accomplishing the things I see possible is also going to take knowing more than just power.

    Spring constants, anyone?


    If this device cannot account for wind or other horizontal drag factors, is it really a power meter?

    Granted, under most conditions it would not matter, but having run directly up and downwind at the Surfside Beach half marathon ( you are likely familiar with area & potential conditions) I know it is possible to have pace varied as much as 1 min/mile by wind with similar effort.

    As I replied to Ray, I think it does account for a wind...and yes, I agree, Galvetraz Island can be quite windy!
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [aw3] [ In reply to ]
    Quote | Reply
    aw3 wrote:
    Hahaha, I'm disappointed you deleted your reply! I thought it was entirely appropriate...

    Me too, but I thought I should at least attempt to maintain some level of decorum.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:

    They may not be willing to make the claim just yet, but if my understanding of how they are calculating power is correct, then the value provided does account for varying wind conditions and running surfaces (although the metabolic cost of producing that power could vary).

    As for a parachute, it would be simpler to just run a cord over a pulley behind a treadmill, and hang a known mass from it. In fact, this is an experiment I've been meaning to perform, although having pulled a calf muscle this a.m. it may take me a while to get around to it.


    Andrew Coggan wrote:

    No, at least not yet, as the Stryd relies on a barometric pressure sensor to detect changes in elevation. That means it doesn't account for the additional power requirement of running uphill on a treadmill unless you collect data using the iOS or Android app, which allows you to specify the grade. To date, though, I've only been using a Garmin watch, so haven't elevated the treadmill.

    I'm afraid I don't understand how these two statements can be reconcilied: I don't see how they could account for varying wind conditions without measuring wind, but couldn't account for varying slope without altimeter data

    Ale Martinez
    www.amtriathlon.com
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Ale Martinez] [ In reply to ]
    Quote | Reply
    Ale Martinez wrote:
    I'm afraid I don't understand how these two statements can be reconcilied: I don't see how they could account for varying wind conditions without measuring wind, but couldn't account for varying slope without altimeter data

    I think you'll get it if you think about it a bit.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
    Quote | Reply
    I am interested in this product, however I will wait to see what others have to say before purchasing.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [mamilner26] [ In reply to ]
    Quote | Reply
    mamilner26 wrote:
    I am interested in this product, however I will wait to see what others have to say before purchasing.


    I've got some via the coaches package. Some feedback:
    • The devices I gave out to some people I coach don't get used properly. They are not techy and didn't get excited about the data like I hoped they would so the other points relate to my experiences. I think when power is supported by watches while in run mode, it will be more easily digestible.
    • I've been recording data since August and find it interesting looking at the power data. Most of the time I train via heart rate or pace and don't feel like I NEED power. Given you can't cover as much ground on foot as by bike it normally means I'm running on the same terrain most of the time so I can compare overall training progress using pace @ heart rate.
    • My run test (4x1 mile all out effort) is on a flat path with little risk of injury with another person so I can do it outside. I wouldn't feel comfortable about doing a bike test outside as I would be more susceptible to riding into the back of a car or something.
    • I actually found then when I was running on sand the Stryd did seem to incorporate the terrain (i.e. watts on sand were worth less than watts on asphalt). I didn't do any specific testing to prove, it was just my perception so may be wrong.
    • I have a run test I did the other week and wish I had the power data to look into it (it was recording but the power was incorrect due to a firmware bug). I ran 4 miles (with a recovery) at exactly the same average heart rate but the times were very different (one I ran 5:28 and another at 5:57). This seemed like a huge difference and felt like power would have given me a chance to try and digest it. The bug is fixed now, so hoping to understand a bit more about pacing from the power data in future.

    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [dado0583] [ In reply to ]
    Quote | Reply
    dado0583 wrote:
    mamilner26 wrote:
    I am interested in this product, however I will wait to see what others have to say before purchasing.


    I've got some via the coaches package. Some feedback:
    • The devices I gave out to some people I coach don't get used properly. They are not techy and didn't get excited about the data like I hoped they would so the other points relate to my experiences. I think when power is supported by watches while in run mode, it will be more easily digestible.
    • I've been recording data since August and find it interesting looking at the power data. Most of the time I train via heart rate or pace and don't feel like I NEED power. Given you can't cover as much ground on foot as by bike it normally means I'm running on the same terrain most of the time so I can compare overall training progress using pace @ heart rate.
    • My run test (4x1 mile all out effort) is on a flat path with little risk of injury with another person so I can do it outside. I wouldn't feel comfortable about doing a bike test outside as I would be more susceptible to riding into the back of a car or something.
    • I actually found then when I was running on sand the Stryd did seem to incorporate the terrain (i.e. watts on sand were worth less than watts on asphalt). I didn't do any specific testing to prove, it was just my perception so may be wrong.
    • I have a run test I did the other week and wish I had the power data to look into it (it was recording but the power was incorrect due to a firmware bug). I ran 4 miles (with a recovery) at exactly the same average heart rate but the times were very different (one I ran 5:28 and another at 5:57). This seemed like a huge difference and felt like power would have given me a chance to try and digest it. The bug is fixed now, so hoping to understand a bit more about pacing from the power data in future.

    I agree with this completely. I would consider myself as quite techie, but running in bike mode (even with pace added via the Stryd Garmin ConnectIQ app on 920XT) just becomes a pain for managing data. I have swim, bike, run workouts scheduled in training peaks. I have my devices download to Garmin connect and then automatically pushed to Training Peaks. All Runs come up as Bike workouts in both GC and TP. I need to go into TP delete the Stryd run, manually change the GC file from bike to run, download the corrected GC file to my desktop, and then upload the corrected file to TP. Unfortunately, just changing TP file from bike to run doesn't fix all issues that are created by having a run file incorrectly loaded as a bike file.

    By worth less, do you mean that a run at the same power is slower?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
     


    "... if my understanding of how they are calculating power is correct..."


    If your understanding of how power is calculated is correct, would the Garmin HRM run device (or device coupled with appropriate Garmin watch) be basically only a firmware update away from providing power? The accelerometer is already being used to provide stride frequency, vertical displacement, and ground contact time.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [mamilner26] [ In reply to ]
    Quote | Reply
    mamilner26 wrote:
    I am interested in this product, however I will wait to see what others have to say before purchasing.


    My 2 cents as someone who has a Stryd but only used it twice - until Garmin supports power in "run mode" I don't see myself using it any more. It's really interesting to see the power numbers during a run, but being in "bike mode" definitely has its drawbacks. Additionally, the file uploads to TP as a ride and makes TSS inaccurate (unless your critical run power just so happens to exactly match your FTP) even after you change it to a run so you really have to manually enter your stats as a run, then you lose all the analytics in the expanded view (charts, etc.)
    Last edited by: The1Jacker: Dec 23, 15 7:20
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [The1Jacker] [ In reply to ]
    Quote | Reply
    The1Jacker wrote:
    mamilner26 wrote:
    I am interested in this product, however I will wait to see what others have to say before purchasing.


    My 2 cents as someone who has a Stryd but only used it twice - until Garmin supports power in "run mode" I don't see myself using it any more. It's really interesting to see the power numbers during a run, but being in "bike mode" definitely has its drawbacks. Additionally, the file uploads to TP as a ride and makes TSS inaccurate (unless your critical run power just so happens to exactly match your FTP) even after you change it to a run so you really have to manually enter your stats as a run, then you lose all the analytics in the expanded view (charts, etc.)

    Fixed as of today, apparently (note that I don't use TP, so may not know what the heck I'm talking about!):

    http://club.stryd.com/...o-trainingpeaks/1385
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    J_R wrote:


    "... if my understanding of how they are calculating power is correct..."


    If your understanding of how power is calculated is correct, would the Garmin HRM run device (or device coupled with appropriate Garmin watch) be basically only a firmware update away from providing power? The accelerometer is already being used to provide stride frequency, vertical displacement, and ground contact time.

    As with all such things, the devil is in the details.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    I can't see a running power meter having a significant impact on how people actually train and perform.

    In an IM race, I know...

    I should target a NP of 68-70% of my FTP
    I should target a VI of around 1.05
    I should keep MaxP ~ FTP

    Intuitively, all of these same concepts of optimal average and maximum power production, and variance, seem like they would apply to running as well.

    Specifically, it would stand to reason that a robust running power meter would answer the question of how fast an IM racer should run up a hill, just as a power meter already does for the same athlete on his bike. Since there is an optimal power output when climbing a hill on the bike course, surely there is a corollary for climbing a hill on the run course.

    Given that, I don't at all understand why you don't see value in a device that would provide athletes the same data on the run as they use (often to the exclusion of all else) on the bike. Naturally the target ranges would need to be recalibrated for running, but the underlying principles would be the same -- average X watts, don't exceed Y watts. Why don't you see that as an improvement on things like pace, HR, RPE?

    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense.

    Is this still your opinion?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    davearm wrote:
    Andrew Coggan wrote:
    davearm wrote:
    It's crazy to me that you think perceived exertion is the best solution to the running scenario, given what a radical departure it is from your position on cycling.


    Not a radical departure in the least.

    Consider, for example, the possibility of pacing by power...despite exploring the idea of calculating a theoretically-optimal strategy based on the physics and physiology of cycling long before, e.g., bestbikesplit.com, my advice to people on this matter has always been to simply use their powermeter to make sure they "don't go out too hard".

    Similarly, a couple of my PPPs have always been:

    "If you know your power, then at best knowing your heart rate is redundant, but at worst it is misleading"

    and

    "If it feels hard, then it is hard"

    with the point being that along side power (pace for a runner), perceived exertion is a highly valuable tool.

    The radical departure I was alluding to is that training and racing with a powermeter is quantified, precise, accurate, and backed by loads of science.

    Perceived exertion is basically the opposite of all these things.

    So you can imagine how odd it seems when the same expert advocates one approach for one discipline, and the complete opposite approach for the other.

    I advocate that all endurance athletes calibrate their perceived exertion against a reasonable surrogate for their metabolic rate, especially when the latter is also an absolute reflection/critical determinant of their actual performance ability. So, pace for runners, but power for cyclists.

    And is this still your opinion?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    dcrainmaker wrote:
    Andrew Coggan wrote:
    A few thoughts...

    Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.



    Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

    Wind is just as painful to a runner as it is to a cyclist, run a marathon into a headwind and you'll understand. Similarly, varying terrain is just as much of a factor for runners as it is cyclists. This is especially true for longer formats (i.e. half marathon and beyond) in courses with rolling terrain or worse.

    I could see trying to argue it makes it's of little benefit for situations such as windless flat surfaces. But to try and argue that runners aren't impacted by hills or wind comes across a bit...out of place?

    Sorry, but I think that your assertions are incorrect. Runners are clearly not impacted by wind as much as cyclists. (And yes, I say that having run a fair bit while living on a wind-swept barrier island, as well as having to finish a 30 km race under my goal of 2 h flat by running the last 2 mi as hard as I could straight into a block headwind.) Way back in 1971, for example, Pugh tested runners in a climactic chamber and demonstrated that overcoming wind resistance accounted for only 7.5% of energy expenditure when running on the flat at 3.75 m/s and 13% at 4.47 m/s. This is in contrast to cycling, whereas as we all know, overcoming wind resistance accounts for the vast majority of energy expenditure. It therefore follows that it takes a much, MUCH stronger wind to have the same impact on a runner as it does on a cyclist.

    As for hills, while the effects of gradient on energy expenditure are the same in runners and cyclists, how many runners do you know are willing to routinely venture up grades so steep that they are reduced to walking, or at best, a very slow jog? Yet, thanks to gearing cyclists regularly ride up such slopes.

    Now add in the fact that, in running, true sprinters generally don't race longer distances, and distance runners rarely have to truly sprint, yet cyclists in mass start races regularly have to do both, combined with the fact that a power estimator can't account for differences in runnnig economy, which are far greater between individuals than cycling economy, and the fact that running tracks (where runners typically go when they want to perform structured training) are ubiquitous whereas velodromes are relatively rare, and, well, I just don't see the point (as I told Steve McGregor almost a decade ago when he came up w/ rTSS).

    And is this also still your opinion?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    Andrew Coggan wrote:
    dcrainmaker wrote:
    Andrew Coggan wrote:
    A few thoughts...

    Combining the above with the fact that runners don't generally have to be able to rapidly change pace the way cyclists do, that they aren't as influenced by environmental conditions (e.g., wind), that they tend to utilize flat surfaces (tracks) for structured training, etc., and I can't see a running power meter having a significant impact on how people actually train and perform.


    Honestly, I'm surprised to see you write. Mostly because it really makes no sense.

    Wind is just as painful to a runner as it is to a cyclist, run a marathon into a headwind and you'll understand. Similarly, varying terrain is just as much of a factor for runners as it is cyclists. This is especially true for longer formats (i.e. half marathon and beyond) in courses with rolling terrain or worse.

    I could see trying to argue it makes it's of little benefit for situations such as windless flat surfaces. But to try and argue that runners aren't impacted by hills or wind comes across a bit...out of place?


    Sorry, but I think that your assertions are incorrect. Runners are clearly not impacted by wind as much as cyclists. (And yes, I say that having run a fair bit while living on a wind-swept barrier island, as well as having to finish a 30 km race under my goal of 2 h flat by running the last 2 mi as hard as I could straight into a block headwind.) Way back in 1971, for example, Pugh tested runners in a climactic chamber and demonstrated that overcoming wind resistance accounted for only 7.5% of energy expenditure when running on the flat at 3.75 m/s and 13% at 4.47 m/s. This is in contrast to cycling, whereas as we all know, overcoming wind resistance accounts for the vast majority of energy expenditure. It therefore follows that it takes a much, MUCH stronger wind to have the same impact on a runner as it does on a cyclist.

    As for hills, while the effects of gradient on energy expenditure are the same in runners and cyclists, how many runners do you know are willing to routinely venture up grades so steep that they are reduced to walking, or at best, a very slow jog? Yet, thanks to gearing cyclists regularly ride up such slopes.

    Now add in the fact that, in running, true sprinters generally don't race longer distances, and distance runners rarely have to truly sprint, yet cyclists in mass start races regularly have to do both, combined with the fact that a power estimator can't account for differences in runnnig economy, which are far greater between individuals than cycling economy, and the fact that running tracks (where runners typically go when they want to perform structured training) are ubiquitous whereas velodromes are relatively rare, and, well, I just don't see the point (as I told Steve McGregor almost a decade ago when he came up w/ rTSS).


    It would be very easy for Andrew Coggan to jump on the running power meter band waggon and I'm sure if he did his ideas would be embraced just as enthusiastically by runners and running coaches as is the case in cycling.

    The fact that he holds this opinion may be surprising but it does show he isn't interested in making easy money.


    It would seem Andrew Coggan has changed his opinion and jumped on the running power meter band wagon.
    Last edited by: Trev: Dec 23, 15 12:43
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [The1Jacker] [ In reply to ]
    Quote | Reply
    The1Jacker wrote:
    mamilner26 wrote:
    I am interested in this product, however I will wait to see what others have to say before purchasing.


    My 2 cents as someone who has a Stryd but only used it twice - until Garmin supports power in "run mode" I don't see myself using it any more. It's really interesting to see the power numbers during a run, but being in "bike mode" definitely has its drawbacks. Additionally, the file uploads to TP as a ride and makes TSS inaccurate (unless your critical run power just so happens to exactly match your FTP) even after you change it to a run so you really have to manually enter your stats as a run, then you lose all the analytics in the expanded view (charts, etc.)

    Actually, that's not the case in TrainingPeaks. You just have to set things first in your athlete settings. Hopefully this helps...












    And if you have past files that you've already changed, but haven't recalculated according to the run power ftp, then just do this last image's instructions for those workouts. A little time intensive if you have a lot of files, but won't need to do it after that.

    Jim Vance
    http://TodaysPlan.com.au (Disclosure: I am contracted with Today's Plan)
    http://www.CoachVance.com/
    Twitter @jimvance
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [JimVance] [ In reply to ]
    Quote | Reply
    But even with all of that, if you already had a run in you schedule, the initial run will not be marked as completed by editing a "bike" to a run. You will end up with an uncompleted run (red box), along with an unscheduled run (grey box). Really surprised that they haven't managed to work with Garmin to allow power in the run mode.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    J_R wrote:
    But even with all of that, if you already had a run in you schedule, the initial run will not be marked as completed by editing a "bike" to a run. You will end up with an uncompleted run (red box), along with an unscheduled run (grey box). Really surprised that they haven't managed to work with Garmin to allow power in the run mode.


    Well, your original complaint was inaccurate TSS and a longer work around. Not hard to delete the workout that didn't get data filled, and copy the details of it into the one you uploaded. And as someone else mentioned, the workout type has now been fixed, where the workout will load as a run file from Stryd's PowerCenter into TP. So it is just a matter of fixing the past workouts.

    Hope this helps.

    Jim Vance
    http://TodaysPlan.com.au (Disclosure: I am contracted with Today's Plan)
    http://www.CoachVance.com/
    Twitter @jimvance
    Last edited by: JimVance: Dec 23, 15 21:08
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [JimVance] [ In reply to ]
    Quote | Reply
    That was someone else's original complaint. While the Stryd Power center may now push to TP as a run workout, Garmin Connect will not. In an age where my Garmin 920xt will auto connnect to my phone or wifi router automatically, upload workout to GC and then push to TP before I am even back inside of the house, it seems ridiculous to have to make so many manual edits. Real fix, Stryd works with Garmin to allow power in run mode. I think that it will be vital to there existence.
    Last edited by: J_R: Dec 23, 15 21:18
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    That's a simple fix. Will happen very soon.

    Jim Vance
    http://TodaysPlan.com.au (Disclosure: I am contracted with Today's Plan)
    http://www.CoachVance.com/
    Twitter @jimvance
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [JimVance] [ In reply to ]
    Quote | Reply
    Do you have anything to base that on, or is it just speculation?

    When implementing new features, the technical impediments are often minor compared to the political ones. The question is whether Garmin want to support run power, not whether they can.

    I wouldn't be surprised if we don't see native Garmin support for Run Power for a long time yet, but having said that, the launch of the new Connect IQ platform that allows writing to FIT files could solve this problem. Whether the current generation of devices (e.g. 920xt and fenix 3) support that is another matter.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [JimVance] [ In reply to ]
    Quote | Reply
    One problem I foresee is people learning to run and sustain more power but not necessarily more speed.

    Or does Stryd not measure true power but calculates estimated power from speed / exceleration / weight / gradient etc?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    One problem I foresee is people learning to run and sustain more power but not necessarily more speed.

    Or does Stryd not measure true power but calculates estimated power from speed / exceleration / weight / gradient etc?

    Is that similar to biking with more power but not more speed?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Mike Prevost] [ In reply to ]
    Quote | Reply
    Mike Prevost wrote:


    Exactly my point. On a bike, power to go a specific speed varies with wind direction. Same with this system. This is exactly what you want. It IGNORES wind, just like a bike power meter and measures only the power you are producing. It does not have to account for wind and should not. On a bike, you have speed and power. On this device you have pace and power. That is all you need. In other words, this system is estimating power by measuring acceleration. The estimate of power is dependent of wind, as it should be.


    Absolutely and provably not true.

    On a bike, the power you expend is:

    P = CdA * 0.5 * rho * w^2 * v + m*( a + Crr*g)*v + m*g*s*v ,
    where
    w is airspeed
    v is ground speed
    s is slope

    How does measuring only "a", "v", and "s" give you the total power, P? What kind of sorcery is this? :-)

    Quote:

    Using your example, run a 6:00 pace into a head wind VS tail wind and you will have to produce a higher acceleration into the wind, which presumably this device will measure, therefore more watts. Just like a bike pwoermeter. Wind does not matter for measurement purposes.


    No, that's not the way physics works.

    Newton's Second Law of Motion states that:
    m*a = sum of forces on a body

    So acceleration is 1/m times the net sum of forces on a body. Acceleration is the result of net power application. Not the cause of it.

    AndyF
    http://alphamantis.com
    #findyouraero
    Last edited by: AndyF: Dec 24, 15 6:30
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    AndyF wrote:
    Acceleration is the result of net power application. Not the cause of it.

    Weight gain is the result of excess caloric intake, not the cause of it. Yet, by measuring the former I can calculate the latter, at least provided other factors are constant. :)
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    J_R wrote:
    Real fix, Stryd works with Garmin to allow power in run mode.

    Or with some other major manufacturer, anyway.
    Last edited by: Andrew Coggan: Dec 24, 15 7:08
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Jctriguy] [ In reply to ]
    Quote | Reply
    On a bike speed is also dependent on aerodynamics.

    Running only marginally so if at all.

    It's possible to run in such a manner as to produce considerable power but generate little speed if you run inefficiently or with ineffective style.

    So cycling if you increase power you will increase speed but running an increase in power does not necessarily increase speed.

    Style or technique makes little or no difference to power output when cycling, but running is a very different kettle of fish.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    AndyF wrote:
    Acceleration is the result of net power application. Not the cause of it.


    Weight gain is the result of excess caloric intake, not the cause of it. Yet, by measuring the former I can calculate the latter, at least provided other factors are constant. :)

    I was just using this as a teaching opportunity, re-stating a law of motion that carefully differentiates between applied forces and state variables. The distinction between state parameters -- variables that intrinsically describe the object's state (like x, v, CdA, and Crr) -- and forces is an important one in mechanics.

    I'll leave you with this provocative (and completely tangential) quote from one of the masters of mechanics, V.I. Arnold ( in Mathematical Methods of Classical Mechanics ):

    Quote:
    The initial state of a mechanical system ( the totality of positions and velocities of its points at some moment of time) uniquely determines all of its motion.

    It is hard to doubt this fact, since we learn it very early. One can imagine a world in which to determine the future of a system one must also know the acceleration at the initial moment, but experience shows us that our world is not like this.
    Just to be clear: I'm not arguing your point, Andy. I just wanted to add the notion of Newton's law of determinacy. Teaching moment, once again.

    AndyF
    http://alphamantis.com
    #findyouraero
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    AndyF wrote:
    I'm not arguing your point, Andy.

    No, you were arguing rroof's.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    AndyF wrote:
    I'm not arguing your point, Andy.


    No, you were arguing rroof's.

    I just meant that I wasn't challenging what you had said.

    AndyF
    http://alphamantis.com
    #findyouraero
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [ In reply to ]
    Quote | Reply
    Stryd thought experiment:

    1) Picture a person wearing a spacesuit standing on a tiny planet. The planet is so tiny that not only is the gravitational field too weak to hold an atmosphere (hence the need for the spacesuit), but also so weak that the individual can achieve orbital velocity by pushing off in a single step. They do so, and now orbit the planet forever without ever touching down again. What is their "running" speed over the surface of the planet? What is their power output?

    2) Picture the exact same person wearing exactly the same spacesuit standing on Earth, while wearing the Hoverbelt^tm they got for Christmas. The Hoverbelt^tm reduces their weight to exactly the same value as in scenario #1 above. They push off exactly as before as well. Do they achieve orbital velocity, or do they eventually settle back down to Earth and have to push off again? if the latter, how does their power output differ/compare to scenario #1?
    Last edited by: Andrew Coggan: Dec 26, 15 5:48
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Though experiment aside, Is there a way to measure or infer impact forces? As opposed to forces to overcome?

    Maurice
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    All objects in earth's orbit, unless they have a limitless supply of fuel, will eventually fall to earth due to orbital decay, even if they do reach orbital velocity and go into orbit they will eventually fall to earth.

    You need to be looking at thrust to weight ratio not power. It's a bit like confusing strength with power, don't confuse thrust with power.

    I told you running power meters would waste a lot of people's time.

    An interesting and entertaining thought experiment though.
    Last edited by: Trev: Dec 26, 15 14:30
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Quote:
    All objects in earth's orbit, unless they have a limitless supply of fuel, will eventually fall to earth due to orbital decay, even if they do reach orbital velocity and go into orbit they will eventually fall to earth.


    Not to nitpick but the moon is moving further away every year. ;)

    Quote:
    I told you running power meters would waste a lot of people's time.


    So QED. But where did you prove it? All I've read are critiques of Coggan's posts. I'm simply interested in whether or not Stryd is viable tech. Ignoring Coggan's assertions, where do you think is the point where Stryd's approach fails?

    [Sorry Trev. I've edited as I realized my post was coming off as an attack whereas I'm actually just curious.]
    Last edited by: feedthereed: Dec 26, 15 18:28
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [feedthereed] [ In reply to ]
    Quote | Reply
    feedthereed wrote:
    Quote:
    All objects in earth's orbit, unless they have a limitless supply of fuel, will eventually fall to earth due to orbital decay, even if they do reach orbital velocity and go into orbit they will eventually fall to earth.


    Not to nitpick but the moon is moving further away every year. ;)

    Quote:
    I told you running power meters would waste a lot of people's time.


    So QED. But where did you prove it? All I've read are critiques of Coggan's posts. I'm simply interested in whether or not Stryd is viable tech. Ignoring Coggan's assertions, where do you think is the point where Stryd's approach fails?

    [Sorry Trev. I've edited as I realized my post was coming off as an attack whereas I'm actually just curious.]


    They say the moon is moving away from Earth due to tidal bulge which doesn't apply to Andrew's man in the thought experiment.

    I'm just ribbing Andrew because he seems to have changed his mind.

    Andrew Coggan wrote earlier in this thread, "I can't see a running power meter having a significant impact on how people actually train and perform.

    Because there's nothing a runner could accomplish using a powermeter that couldn't already be accomplished using a measured distance, a watch, and some common sense."

    I'm pursuaded by his earlier arguments like those above.

    If Sryd measures actual power there might be a use in refining technique and style to get more speed out of a given power.

    But whatever the power in the end it will boil down to whatever technique and style makes a given speed feel easier.

    Stryd does not measure power directly but looks at exceleration, gradient etc, then estimates power. It's entirely possible to generate more power but fail to increase speed because you are running inefficiently. Can Stryd tell the difference between running efficiently along the ground and running in a manner which wastes power running upwards too high and landing with more force covering less ground with each stride?
    Last edited by: Trev: Dec 27, 15 1:00
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [feedthereed] [ In reply to ]
    Quote | Reply
    Interesting article here.

    http://athletictimemachine.com/...6/thoughts-on-stryd/

    Watts:MPH ratio?

    I'm not sure if Stryd measures power in such a way as to do this in a useful way as it isn't measuring forces but is using speed / exceleration to estimate watts.

    I'm reluctant to ignore easily gathered data but I can see people being mislead by the watts numbers or wasting a lot of time playing with the data but not putting the info to good use.

    Will it help people train better? If not it's a waste of time. More power does not mean more speed. Concentrate on speed.

    As Andrew Coggan said earlier in this thread,

    "2) running economy varies much more between individuals than does cycling economy/efficiency, such that the calculated power may not provide a valid/reliable indication of actual metabolic demand. "


    ""*Note that an important difference between running and cycling is that the economy of movement is much more variable in the former than in the latter. Also, muscle use varies more in the former than in the latter, e.g., even if you keep your estimated power constant when transitioning from the flats to up hill, you will be placing more demand on your quads as a result. So, should you really be aiming for an iso-power effort, or an iso-metabolic one? ""



    How does Stryd measure speed / distance and how accurate is its measurement of speed and distance?
    Last edited by: Trev: Dec 28, 15 4:31
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [J_R] [ In reply to ]
    Quote | Reply
    mamilner26 wrote:
    By worth less, do you mean that a run at the same power is slower?

    Yes, although that's just my perception. I haven't done any proper testing to know if that's true
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
    Quote | Reply
    Say what you will about the product, the one thing I love about DC's reviews is that he leaves no stone unturned. Very very in depth.

    With that being said, I aint wasting my money on one of these

    _________________________________________________
    When all is said and done. More is usually said than done
    Ba Ba Booey

    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    How does Stryd measure speed / distance and how accurate is its measurement of speed and distance?

    It doesn't.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Trev] [ In reply to ]
    Quote | Reply
    Trev wrote:
    One problem I foresee is people learning to run and sustain more power but not necessarily more speed.

    Or does Stryd not measure true power but calculates estimated power from speed / exceleration / weight / gradient etc?

    You're getting to the heart of the matter with power for running. The answer to your question is no. At least, not yet. But analysis for this is coming soon, very soon.

    Jim Vance
    http://TodaysPlan.com.au (Disclosure: I am contracted with Today's Plan)
    http://www.CoachVance.com/
    Twitter @jimvance
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Tom Fort] [ In reply to ]
    Quote | Reply
    I don't own the stryd device (yet!), but have produced actionable running power based information using the di prampero running model (that is available for free in the literature) for the better part of the last 10 years:

    http://www.biketechreview.com/...thlon-pacing-sort-of


    http://www.biketechreview.com/...555-triathlon-pacing


    Although I haven't written about it on BTR lately, I've used this model for setting pacing targets on "lumpy" race courses I've never run on before:


    https://www.strava.com/activities/283534744


    If anyone wants the spreadsheet I've created based on the di Prampero model, shoot me an email at kraig@biketechreview.com and I'll send you a copy.


    In summary, I find the di prampero model, combined with my PE, a good field test venue, a stopwatch, and a bathroom scale, very handy for assessing my current fitness and setting achievable running goals/performance targets. YMMV, of course, and I look forward to playing with the stryd device - but this stryd "fun" might have to wait until it becomes available on the used market (like the iBike I purchased and then toyed with/evaluated).

    =================
    Kraig Willett
    http://www.biketechreview.com - check out our reduced report pricing
    =================
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Ignoring the dependence of orbital velocity on planetary radius (on a small planet the orbital velocity would be much smaller) your experiment does hit on the problem of aerodynamics in power calculations a la stryd.

    The orbital velocity of earth is about 29800 m/s and to keep things simple that represents a LOT of aero drag in the atmosphere. Totally remove this atmosphere on the small planet and all the drag disappears which drastically change the behavior of the person between the two scenarios. So in situation one velocity can be maintained without acceleration due to there is not drag to counter the original force of the step. On earth maintaining a velocity while running will always require additional acceleration because the atmosphere does exists and force can only be applied at discrete points. In any case converting power based on acceleration and velocity requires having an excellent constraint on the force of air resistance and large errors will creep in if air resistance changes. My guess is this is where wind speed comes into play and that in wind conditions the Stryd won't work well.

    On a side note what Stryd needs is some way do differentiate vectors of human acceleration from terrain. In other words it needs to be able to differentiate the components of vertical acceleration due to bad running form (bouncing up and down) from vertical acceleration due to changing elevation. This could be done by looking at the total movement of the subjects center of mass relative to the net movement the center of mass. Such a metric would diagnose bad form and get around some of the issues previously brought up in the thread.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [scott8888] [ In reply to ]
    Quote | Reply
    scott8888 wrote:
    The orbital velocity of earth is about 29800 m/s and to keep things simple that represents a LOT of aero drag in the atmosphere. Totally remove this atmosphere on the small planet and all the drag disappears which drastically change the behavior of the person between the two scenarios. So in situation one velocity can be maintained without acceleration due to there is not drag to counter the original force of the step. On earth maintaining a velocity while running will always require additional acceleration because the atmosphere does exists and force can only be applied at discrete points.

    Or IOW, wind resistance causes you to slow down more during the flight phase, requiring that you re-accelerate yourself more during the stance phase to maintain a constant velocity. Wind resistance also resists that acceleration during the stance phase. I therefore believe that the Stryd therefore doesn't need a separate wind sensor to account for the (generally rather small) effect of aerodynamic drag while running.
    Last edited by: Andrew Coggan: Jan 4, 16 4:34
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    When a runner passes you it's surprising what a gust of air you feel as they go by.

    It may be minimal but it still requires some power to move through the air.

    Does Stryd account for this power?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Bill Tyndale] [ In reply to ]
    Quote | Reply
    Bill Tyndale wrote:
    When a runner passes you it's surprising what a gust of air you feel as they go by.

    It may be minimal but it still requires some power to move through the air.

    Does Stryd account for this power?

    Back in the 1970s, LGCE Pugh measured the effects of wind on the energy requirements of running, by placing a treadmill in a wind tunnel. Under most conditions, <5% of total energy is expended against the wind* - only at very fast running speeds (e.g., Olympic sprinter) or under hurricane-like conditions does it really rise much above this.

    As I attempted to illustrate with my thought experiment and as I described just a few posts above, I believe that Stryd's approach to measuring (positive) power does account for wind resistance (even if they won't claim so themselves).

    *Thus explaining the 1% rule-of-thumb for treadmill running....that amount of grade increases energy costs by ~4%, thus better equating speed between indoor and outdoor conditions.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    Or IOW, wind resistance causes you to slow down more during the flight phase, requiring that you re-accelerate yourself more during the stance phase to maintain a constant velocity. Wind resistance also resists that acceleration during the stance phase. I therefore believe that the Stryd therefore doesn't need a separate wind sensor to account for the (generally rather small) effect of aerodynamic drag while running.

    I've read several times that aero drag is a small effect in running, but the position of a runner must lead to CdAs close to 0.5 m^2. Even at 5 m/s, that's equivalent to 30-40W at sea level. With a 5 m/s head wind, that could climb to 150W.

    AndyF
    http://alphamantis.com
    #findyouraero
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    Bill Tyndale wrote:
    When a runner passes you it's surprising what a gust of air you feel as they go by.

    It may be minimal but it still requires some power to move through the air.

    Does Stryd account for this power?

    Back in the 1970s, LGCE Pugh measured the effects of wind on the energy requirements of running, by placing a treadmill in a wind tunnel. Under most conditions, <5% of total energy is expended against the wind* - only at very fast running speeds (e.g., Olympic sprinter) or under hurricane-like conditions does it really rise much above this.

    As I attempted to illustrate with my thought experiment and as I described just a few posts above, I believe that Stryd's approach to measuring (positive) power does account for wind resistance (even if they won't claim so themselves).

    *Thus explaining the 1% rule-of-thumb for treadmill running....that amount of grade increases energy costs by ~4%, thus better equating speed between indoor and outdoor conditions.

    Entirely anecdotal, but consistent with Stryd's own claims, is my experience with it. I've noticed that running in windy conditions actually tends to produce the opposite power numbers of what you'd expect...higher power for lower RPE at same pace with a tail wind, lower power into headwind. My best guess is that because it measures/estimates force using accelerometer, there's not really a way to distinguish whether the forward/backward force is coming from me or the wind.

    IG: idking90
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    There appears to be a lot of confusion between air resitance and 'aerodrag/wind resitance' which is also where I think Stryd fails.

    Air resistance is a frictional force determined by how fast you move relative to the air. Assuming stationary air (no wind) the force of air resistance is small over the speed changes on the scale of running. That is to say a runner experience minimal additional air resistance when running at a 6min/mile versus a 7 min mile. The same is true for cycling in that small speed changes at overall low speed result in minimal aero drag changes. Now once the wind starts blowing its a different ball game because the magnitude of speed changes are far far greater. The difference between a 15mph tail wind and 15mph head wind is equal to a 30 mph change in the relative motion of the runner and the wind. Think riding a bike a 10mph and then at 40mph and its clear there is a significant change in force. Your calculation are correct in this respect.

    I don't understand how Stryd corrects for this effect. Yes its easy to correct for air resistance if you assume the subjects total velocity is equivalent to the relative difference of their velocity and the velocity of the air. In fact at cycling speeds this is often a good assumption which is why small yaw angles are most relativistic for aero testing. At running speeds however wind speed often exceeds total running velocity.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [BikeTechReview] [ In reply to ]
    Quote | Reply
    BikeTechReview wrote:
    I don't own the stryd device (yet!), but have produced actionable running power based information using the di prampero running model (that is available for free in the literature) for the better part of the last 10 years:

    http://www.biketechreview.com/...thlon-pacing-sort-of

    Kraig,

    Thanks for the link to the post above. I'd never seen your thoughts on this and find them pretty darn interesting and certainly worth discussion as well as further investigation. It's pretty obvious that the majority of triathletes over allocate effort on the bike side of the equation and the development of more tools or guidelines for the allocation would seem prudent.

    "What does this all tell me? I think it means that getting real small aerodynamically on the bike (since you really don't have to put out big power) becomes even more important -> just gotta progress on the deal so you can get comfy over time. I think this takes diligent, hard, consistent work to get aero and comfy - it doesn't happen overnight.

    I also reckon that one's run speed/power is the limiter on the deal -> that will steer how slow/low power one should go on the bike.

    BTW, this analysis changed my gut feeling on how to pace an ironman -> I gut felt an even split was the way to go. I reckon I was wrong..."

    Hugh

    Genetics load the gun, lifestyle pulls the trigger.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    AndyF wrote:
    Andrew Coggan wrote:
    Or IOW, wind resistance causes you to slow down more during the flight phase, requiring that you re-accelerate yourself more during the stance phase to maintain a constant velocity. Wind resistance also resists that acceleration during the stance phase. I therefore believe that the Stryd therefore doesn't need a separate wind sensor to account for the (generally rather small) effect of aerodynamic drag while running.

    I've read several times that aero drag is a small effect in running, but the position of a runner must lead to CdAs close to 0.5 m^2. Even at 5 m/s, that's equivalent to 30-40W at sea level. With a 5 m/s head wind, that could climb to 150W.

    I think several things explain the apparent discrepancy:

    1) 5 m/s is PDQ, requiring that you either be a pretty good runner (e.g., 5 km in 16:40) and/or that winds at ground level are pretty high;

    2) for perfectly-logical physiological reasons, the (positive) power output of a runner is significantly higher than the (net) power output of a cyclist (i.e., the demoninator is larger than you are used to seeing); and

    3) relative energy cost and relative power requirements aren't quite the same thing.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [iank] [ In reply to ]
    Quote | Reply
    iank wrote:
    Entirely anecdotal, but consistent with Stryd's own claims, is my experience with it. I've noticed that running in windy conditions actually tends to produce the opposite power numbers of what you'd expect...higher power for lower RPE at same pace with a tail wind, lower power into headwind. My best guess is that because it measures/estimates force using accelerometer, there's not really a way to distinguish whether the forward/backward force is coming from me or the wind.

    You know, I believe I have seen you mention this before, but until reading the above it didn't really click. I now realize that I've been viewing things from the perspective of the environment (ground), e.g., as if the runner were running across a force plate. Stryd, however, relies on Newton's 2nd law, which certainly complicates things. I'm therefore going to take back what I said, at least until I've had the chance to experiment/ruminate a bit more.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    I'm quite a light chap and I definitely notice the difference running into a stiff headwind versus a tasty tailwind. Ideally the power numbers would reflect this.

    I haven't tested, but my understanding is the Stryd will give me the same power number for the same pace in both conditions. My understanding (which I'm trying to double check) is that Coggan, you're saying that the Stryd model does account for wind resistance but not varying wind resistance?
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [dado0583] [ In reply to ]
    Quote | Reply
    dado0583 wrote:
    My understanding (which I'm trying to double check) is that Coggan, you're saying that the Stryd model does account for wind resistance but not varying wind resistance?

    I don't know how Stryd calculates power (although I can guess), but up until moments ago I would have said that it accounts for the power required to push forward through the air. Now, I see it is more complicated
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Thank you -- that completely makes sense.

    AndyF
    http://alphamantis.com
    #findyouraero
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [AndyF] [ In reply to ]
    Quote | Reply
    AndyF wrote:
    Thank you -- that completely makes sense.

    You're welcome!

    (For the benefit of others: to run at 5 m/s requires a power output of ~5 W/kg.)
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Yea, I live in a completely flat place, so I don't hills besides overpasses to compare too, but it can be pretty windy. If nothing else, I have been able to "wake up" the Stryd by just shaking it a lot and my watch will show 1,000+ W on it when I do that.

    IG: idking90
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Andrew Coggan] [ In reply to ]
    Quote | Reply
    Andrew Coggan wrote:
    Bill Tyndale wrote:
    When a runner passes you it's surprising what a gust of air you feel as they go by.

    It may be minimal but it still requires some power to move through the air.

    Does Stryd account for this power?


    Back in the 1970s, LGCE Pugh measured the effects of wind on the energy requirements of running, by placing a treadmill in a wind tunnel. Under most conditions, <5% of total energy is expended against the wind* - only at very fast running speeds (e.g., Olympic sprinter) or under hurricane-like conditions does it really rise much above this.

    As I attempted to illustrate with my thought experiment and as I described just a few posts above, I believe that Stryd's approach to measuring (positive) power does account for wind resistance (even if they won't claim so themselves).

    *Thus explaining the 1% rule-of-thumb for treadmill running....that amount of grade increases energy costs by ~4%, thus better equating speed between indoor and outdoor conditions.


    Worked out roughly, if 4% of a total power of 250 watts, to overcome air resistance at a running speed of 8 mph is 10 watts, then if there is an 8mph head wind which increases the speed through the air to 16 mph, the power to overcome wind resistance will not double but increase to approx 40 watts.


    8 mph is hardly hurricane force but pretty normal. 8 mph is hardly sprinting. But it will take 40 watts more power to run into an 8mph wind than it would with an 8 mph tail wind.

    If Stryd does not allow for wind speed it really isn't going to give you any better information than pace.

    A man running presents a pretty big CdA, more than a cyclist, I can't see that the power to run into a cross wind isn't going to be substantial.

    Anyone care to experiment with a mannequin in a wind tunnel?
    Last edited by: Bill Tyndale: Jan 4, 16 7:57
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Bill Tyndale] [ In reply to ]
    Quote | Reply
    Bill Tyndale wrote:
    Anyone care to experiment with a mannequin in a wind tunnel?

    As I said, Pugh addressed this question decades ago.
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [iank] [ In reply to ]
    Quote | Reply
    iank wrote:
    Andrew Coggan wrote:
    Bill Tyndale wrote:
    When a runner passes you it's surprising what a gust of air you feel as they go by.

    It may be minimal but it still requires some power to move through the air.

    Does Stryd account for this power?


    Back in the 1970s, LGCE Pugh measured the effects of wind on the energy requirements of running, by placing a treadmill in a wind tunnel. Under most conditions, <5% of total energy is expended against the wind* - only at very fast running speeds (e.g., Olympic sprinter) or under hurricane-like conditions does it really rise much above this.

    As I attempted to illustrate with my thought experiment and as I described just a few posts above, I believe that Stryd's approach to measuring (positive) power does account for wind resistance (even if they won't claim so themselves).

    *Thus explaining the 1% rule-of-thumb for treadmill running....that amount of grade increases energy costs by ~4%, thus better equating speed between indoor and outdoor conditions.


    Entirely anecdotal, but consistent with Stryd's own claims, is my experience with it. I've noticed that running in windy conditions actually tends to produce the opposite power numbers of what you'd expect...higher power for lower RPE at same pace with a tail wind, lower power into headwind. My best guess is that because it measures/estimates force using accelerometer, there's not really a way to distinguish whether the forward/backward force is coming from me or the wind.



    A gadget which says you are using less power to run into a headwind than you are at the same speed with a tailwind is not just useless, but downright misleading - utterly stupid.

    Furthermore, Stryd won't know if you are running behind another runner which eliminates 80% of the wind resistance, so again you will be seriously mislead by the power numbers in bunch running situations. It will give you power numbers approx 3% to 7% too high.

    It really looks like you might as well use a watch.
    Last edited by: Bill Tyndale: Jan 4, 16 9:32
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Bill Tyndale] [ In reply to ]
    Quote | Reply
    Bill Tyndale wrote:

    Worked out roughly, if 4% of a total power of 250 watts, to overcome air resistance at a running speed of 8 mph is 10 watts, then if there is an 8mph head wind which increases the speed through the air to 16 mph, the power to overcome wind resistance will not double but increase to approx 40 watts.


    8 mph is hardly hurricane force but pretty normal. 8 mph is hardly sprinting. But it will take 40 watts more power to run into an 8mph wind than it would with an 8 mph tail wind.



    Here's my math on this using my derivative of the di Pamprero model (offer is still out there, if you want this spreadsheet, just drop me an email) :



    =================
    Kraig Willett
    http://www.biketechreview.com - check out our reduced report pricing
    =================
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [Bill Tyndale] [ In reply to ]
    Quote | Reply
    Bill Tyndale wrote:
    It really looks like you might as well use a watch.

    I don't have enough information regarding the stryd product to disagree with this; however, I do think there could be further insights derived from adding a good math model, a good field testing venue/process, and a good bathroom scale to your list.

    =================
    Kraig Willett
    http://www.biketechreview.com - check out our reduced report pricing
    =================
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [sciguy] [ In reply to ]
    Quote | Reply
    sciguy wrote:
    BikeTechReview wrote:
    I don't own the stryd device (yet!), but have produced actionable running power based information using the di prampero running model (that is available for free in the literature) for the better part of the last 10 years:

    http://www.biketechreview.com/...thlon-pacing-sort-of


    Kraig,

    Thanks for the link to the post above. I'd never seen your thoughts on this and find them pretty darn interesting and certainly worth discussion as well as further investigation. It's pretty obvious that the majority of triathletes over allocate effort on the bike side of the equation and the development of more tools or guidelines for the allocation would seem prudent.

    "What does this all tell me? I think it means that getting real small aerodynamically on the bike (since you really don't have to put out big power) becomes even more important -> just gotta progress on the deal so you can get comfy over time. I think this takes diligent, hard, consistent work to get aero and comfy - it doesn't happen overnight.

    I also reckon that one's run speed/power is the limiter on the deal -> that will steer how slow/low power one should go on the bike.

    BTW, this analysis changed my gut feeling on how to pace an ironman -> I gut felt an even split was the way to go. I reckon I was wrong..."

    Hugh


    Thanks for reading, Hugh :-)

    Yeah, this plot has been around for awhile:



    I don't think the insight was anything new, but putting a ballpark number on it for an ironman type effort at the elite-ish level probably was at the time I did the analysis. Regardless, it was a fun and insightful exercise creating that plot! I hope others find it useful.

    (ETA link to contour plot.)


    =================
    Kraig Willett
    http://www.biketechreview.com - check out our reduced report pricing
    =================
    Last edited by: BikeTechReview: Jan 4, 16 19:53
    Quote Reply
    Re: DCRainmaker preview of Stryd running power meter [BikeTechReview] [ In reply to ]
    Quote | Reply
    BikeTechReview wrote:
    Bill Tyndale wrote:

    It really looks like you might as well use a watch.


    I don't have enough information regarding the stryd product to disagree with this; however, I do think there could be further insights derived from adding a good math model, a good field testing venue/process, and a good bathroom scale to your list.


    Scales yes.

    I once checked over several years run times on regular routes. Simply dividing minutes by lbs then using that number to predict time over a route run at a lighter or heavier weight was remarkably accurate. It puts a spotlight on periods where there was improvement in fitness and when performance improved due to weight loss. Most of my runs were on undulating roads but I can predict times over flat courses just as accurately.

    I didn't get anything like the same accuracy of prediction cycling, which isn't surprising, although there was obviously the same general trend of lighter = faster.

    As we can so easily and accurately weigh and time ourselves over known courses or distances, I don't see there is a need to move from accurate weight and pace data to a 'dubious estimate of power' which does not take into account head or tail winds or reduced drag from running behind another runner and use that to track, plan and execute training.
    Last edited by: Bill Tyndale: Jan 5, 16 2:09
    Quote Reply