That is nonsense. This device does not measure distance or speed and so every single one of your formula is irrelevant. You can rearrange formulas as much as you like, but this device is only measuring certain things and cannot possibly calculate power.

I'm sorry, but you are simply wrong. As I indicated before, biomechanists have been relying on this approach since at least the 1970s.

BTW, for a device that you claim can't measure speed, it is amazingly accurate, I.e., within 1% of my carefully calibrated treadmill over a wide range of speeds (and therefore stride lengths). This is because it relies on double-integration of the accelerometer signal to measure the length of each and every stride, rather than assuming this is a constant like other footpods.

I feel your pain brother. I too have heart and BP problems.

I would be in good shape for me and have a resting HR of 48-53 depending on the day. I'd warm up on the run say and within about 2 minutes, of light jogging (say 5:30 per km) I'd be over 150BPM HR. I would half marathon at 180-185 BPM average! and still barely break 2 hours! Even at 50 years old, I could hit 200BPM in the pool, on the bike and easily on the run, without being maxed out.

I remember my first treadmill test with my cardiologist. I'd ramped up to 175BPM and the cardiologist stopped the test. I said I was feeling fine, had 2 more gears and reckoned I could manage the 2 minute interval at 210BPM. He stopped the test. after I'd showered off, he said I had the highest BP he'd ever personally seen. at just 185 BPM, I had 285/105. He told me to never go that hard again. :-(

I had to wear my HRM all the time when training and limit myself to 155BPM. My training buddies were great and just let me set the pace, but eventually I stopped riding with them because I was holding them back, riding at a pace that even I felt was way too easy. After a while I fired my cardiologist because he couldn't answer any of my questions. My new cardiologist let me train up to 170 BPM but that was just cruising all the time.

I got slower and slower and slower and eventually, boredom set in and I gave up training and racing. Now I'm fat and incredibly unfit, and not happy about it.

While I had a high exercise HR, I used my monitor to judge my output, within the limits I'd had set for me. After a while I realized my kids were older, the house was paid off and I was well insured, so if I died, everyone would miss me for a while then move on (we all die eventually so not really a biggie). I slowly ignored my imposed HR limits but it got to be such a big focus in my life that I was miserably that I couldn't train properly any more. Limited training meant crappy race times so I decided to do other things instead.

Now I hang out with friends, do cool building projects around the house, travel and hang out with my family doing stupid (fun) family stuff.

I'm not really sure where I was going with this, but just to let you know that we all have limitations, and can only do what we can do. I don't know why your HR isn't a great metric for you, but it's probably still worth using it. It might be that you're like me and cant simply train at the same HR as the average person. You might want to do what I did. I sent my HRM back to Polar a couple of times for ridiculously high readings. :-) Eventually I realized it was me, not the monitor. During one of my treadmill tests I wore my own HRM as well as the 12 wire version at the clinic. I found my Polar was accurate to within 1 BPM (rounding obviously), so I trusted it a lot more. I learned to ignore training HR's in books or training manuals, and just adjust for what was real for me. I'd adjust my HR numbers for zones, to suit what I am. That worked well for a while.

The other reason I'd wear a HRM when training was that I also have tachycardia. When my HRM would beep at 200BPM say, I'd see 235 or so, and I'd realize I'd be having an episode. Most times it would only last 5-15 seconds and I'd barely notice it. If it lasted more than about 30 seconds, I'd start to feel out of breath. After it would return to normal (normal for me at least) it would take about 5 minutes for me to feel normal again. Having the HRM on would allow me to A) slow down as soon as I'd have an episode B) tell me how long it lasted C) allow me to know approximately how long it was going to take to feel normal again.

Once, during a half IM, my HR pegged at 200-220 for 8 minutes, (even lying down). I pulled the pin on trying to race and after it got below 200 BPM I walked to the finish line. Even after half an hour lying down in the ambulance being monitored my HR hadn't dropped below 150BPM. The printout of my heart looked like a 2 year old had drawn it, left handed. Unless you knew what you were looking at, you wouldn't have recognized it as a heart printout. The amazing thing is that except for the 8 minutes my heartbeat was whirring in my ears, I felt fine the whole time (OK, a little tired, but I had pretty much just finished a 1/2 IM so that was to be expected). My cardiologist shook his head when he saw the printout.

Soooo, even though your HRM might not be ideal, don't throw it away, just get used to your numbers and any of the oddities it may highlight to you. It may be worthwhile to use a run power meter in conjunction with your HRM. Talk to your cardiologist of course, preferably one that knows about athletes, not just old me with dodgy tickers.

---

TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

but this 'power' is measured on one data point, and not taken as an average of all the lever body parts on a human, which should be averaged out for total true power... as end goal is to understand energy out put of the entire body

Ahhh, the great Andrew Coggan self-love arrives in its full glory, demonstrating its belief in argumentum ad verecundiam in order to judge someone else as wrong. Well colour me surprised.

I've read enough of your posts to realise that is your standard MO, how highly you hold yourself in esteem and how you love to patronise others. I, for one, don't respect you or think highly of your pronouncements. You need to find a believer to preach your sermons to.

If you use the center-of-mass and only the forward and upward accelerations, it is the positive external* power, i.e., that exerted against the environment. This of course ignores the downward and backwards accelerations, which when running on level terrain at constant velocity are exactly equal in magnitude. IOW, the net external power when running on the flat is zero. However, there is close correlation between metabolic demand and the gross external power, so as long as you recognize these distinctions, knowing your gross external power can still be useful.

*There is also internal power, i.e., that utilized to move the limbs relative to the center of mass, but measuring that directly would require placing accelerometers on your limbs, as well as knowing their exact mass. In biomechanical studies internal power has therefore usually been estimated by videoing people and making assumptions about limb mass.

It was not an argument from authority, but simply directions as to where to find more detailed information should you be willing to educate yourself further. Now that I'm at a computer and not on a phone, here's a more direct pointer to an example:

https://www.ncbi.nlm.nih.gov/pubmed/11374057

As an aside, note that precisely the same approach (i.e., application of accelerometry + basic physics) is used by the iBike to calculate the power that goes into changing the speed of a bike. The difference is that there are numerous other energy "sinks" during cycling that are generally much larger in magnitude and also harder to quantify, which makes the total power more variable. If all you wish to measure is your acceleratory power (e.g., from a standing start in a fixed gear), then the iBike works fine, at least up until the point that speed is high enough for rolling and wind resistance start to really matter.

Nice of you to design is with your presence and educate us. Sadly I am too lazy to make myself as clever as you.

Not that there is ever anything of a patronising know-it-all about your posts.

Let's not pretend there is anything altruistic about you posting. This is narcissism and self-interest.

Speaking of which, you give a lecture on the Stryd website extolling the benefits of running power.
http://blog.stryd.com/...ng-runningwithpower/

How much did you receive in $ or benefits to appear on their advertising blog? And as the Coggan brand is linked to running power your future earnings would be damaged by this being revealed as nonsense? Notably, you don't declare a conflict of interest in any of your 3 posts.

If a medical Dr appeared in a video on a pharmaceutical company website and their career was linked to the success of one of the Company's drugs no one would believe they were independent when they said the drug worked.

You mean "deign."


Then sadly you will remain uneducated.


Apparently you haven't read the entire thread, as I already pointed out that I am a consultant for Stryd.

EDIT: Sorry, that was in some other threads, which I confused with this one. So, let me be clear: I am a consultant for Stryd, Happy now?


Considering the rampant abuse and significant financial conflicts of interest that exist within biomedicine even today (despite attempts to improve matters), I find your comparison amusing.

General reply to the thread.

I think all you want to measure is the force applied to the ground x velocity, which gives power applied to the ground for forward motion. All the energy used per second swinging arms, swinging legs, bobbing head side to side etc, is not worth measuring, just like you are not measuring all the wasted motion from bobbing head, rocking hips, turning legs around in circles fighting and working with gravity on the bike...that's all just input motion/energy that's kind of meaningless....it affects how you move forward but it's not mechanical work moving the body forward, it just generates a ton of heat and that's it. Some guy with fat heavy legsand big muscular arms will have a lot more energy expended in angular swing motion (not the linear motion of moving this bulk forward which is accounted for in the strain gauge etc) that's useless energy in terms of forward motion. Its kind of why really good long distance runners have really long achilles with a short calf tucked up high near the back of the knee....less swing weight.

General reply:

Anyone seen / used these http://www.triathlonbusiness.com/...running-power-meter/

...same here. I have the Stryd, but I don't use it much, if at all anymore. My issue is the IOS app crashing more often than it works. The few times I have completed an entire run with it, I did find the data interesting and useful. But the majority of the time, I start an activity in the app and by the time I take a glance at it, I realize it crashed. I'm hoping things will improve when I eventually upgrade my Garmin 910xt to something that supports it. Or maybe enough Stryd units will sell so that they can afford a better IOS developer. Either way, be prepared to accept some bugs as this tech is clearly still in it's infancy.