Interesting information. As a consultant, though, maybe you should recommend they hire an editor.

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Instagram | Team Kiwami North America

Out of curiosity, what makes you say that? Speaking as someone who spends much of their time reading scientific papers and grant applications, I thought that the article was very well-written. In fact, when I finished it I even scrolled back up to the top to see if it had a by-line.

There are many grammatical errors, beginning with the "whom" in the first paragraph (it should just be "who").

What is the math behind LSS? What metrics go into that math?

I skimmed it pretty quickly, but stating they rode 120 miles is incorrect. Quite a few grammatical errors as was mentioned.

An example:
"...the hill on Pilani which proceeds..."
Should read "the hill on Palani drive which precedes..."

On a forum I try not to get too picky with stuff like that, but if a company is publishing an article or blog, I would expect facts to be correct and have a little higher overall standard.

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Instagram | Team Kiwami North America

FFS - it was readable and easy to follow.

Definitely looks like it supports Lionel's statements that he was a underprepared for the full distance.

I'm curious about how athletes might use this info in training. Perhaps finding their optimum running power for an event? Measuring variability to get an improved sense of pacing?

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Aaron Bales
Lansing Triathlon Team

Interesting looking at the variability between the 2 athletes. But how do you arrive at the power numbers? I'm no scientist, but to me the power difference between them looks no different than their pace difference would. Did their paces vary differently than their power outputs? How does stride length and turnover affect running power? Are there plans to have a foot pod for each foot? ie if I have an injury and have a slight imbalance with my stride it would be cool to see how much of an imbalance is there, and the resulting effect on my power.

Ordered it ;-)
Not sure whether this will reveal more than what I already can sense given I run for several years now but still curious enough to try it out.

Would it detect difference between shoes (weights, running style?)

Cheers
Roberto

Leg spring stiffness is calculated using a validated mathematical model from the scientific literature. There are several inputs, but the model is most sensitive to ground contact time. (Indeed, part of the motivation for moving the sensor from the chest to the foot - which is where Stryd actually started - was to maximize the accuracy of the ground contact time measurements, and the accuracy of the leg spring stiffness estimates.)

I heard Jim Vance talking about running power meters on IM talk. He said that the fastest runners don't have the highest power outputs or the highest W/kg values, rather they are the most efficient. He also said that sometimes when people blow up at the end of a race, they start putting out more power, not less!

That was the point when I decided against getting a running power meter. In cycling W/kg is pretty closely related to speed, if it isn't in running, then I don't really think that a running power meter is a worth while piece of equipment to use.

I am surprised that there aren't bigger power peaks on hills, when I run uphill my heart rate goes up, I would assume that is because my power output is going up, but that isn't really visible in the Kona data.

Pacing (especially on varying terrain) is one place people have reported benefitting by knowing their power.

As I mentioned in the WKO4 article where I introduced the leg spring stiffness calculation (http://home.trainingpeaks.com/...r-running-with-power, though, I think the real benefit to the Stryd (and devices like it) is that it "makes your body a mobile biomechanics laboratory" (to paraphrase SRM). Appl)ying/interpreting the data is more complex than with bike power, though.

How does this compare to the Lumo unit?

How is "ground contact time" established? By GPS? What are the other inputs?

In any one individual at a given point in time just running naturally, speed and power are highly correlated (i.e., R values >0.95). The same is true for VO2 and power. (Indeed, it is because of this close coupling that I previously held that simply knowing your speed was enough.) There can, however, be significant differences between individuals, as well as within the same individual at different points in time. This is not different from cycling, in which the power required to achieve a given speed varies significantly between and even within individuals.

Where cycling and running do differ is how you interpret the data. In cycling, more power is generally better, and so it is relatively easy to use power as the metric to adjust your effort, judge the efficacy of your training, etc. This is not always the case, however - for example, many years ago I did some experiments to determine the fastest way around a particular short loop on my road bike, and learned that I was faster by remaining seated (and hence more aero) up the one climb, vs. standing to generate more power that was simply wasted against additional wind resistance. Similarly, some people find that they are faster in TTs and tris by adopting a very aerodynamic position, even if it compromises their power output.

Analogously, it is possible to run faster by generating more power, but it is also possible to generate more power by not go any faster - the only real difference is the relative frequency with which such circumstances are likely to occur.

Based on the accelerometer measurements.

Is that the one out of Europe that is still sort of under development, in which their web ad highlights the audio feedback it is supposed to provide?

Anyway, the hardware used by all of these devices is fairly simple and standard. Where the product offerings differ is the number of PhD faculty members behind their development. ;) (In the case of Stryd, n=4.)

Thanks for the reply Andrew. The address is Mountain View, CA, so I think it's US. Looks like they have a pod that goes on the waist to measure rotation as well.

https://www.lumobodytech.com

Andrew,
I have the chest strap version of stryd, can you get LSS from this?

At least at present, only in WKO4, which calculates it from the other data.

The new Stryd footpod uses the same formula, but calculates it internally and stores the result as a data channel in the .ft file.

Note that although both approaches use the same formula, they may not (or may) yield comparable values for leg spring stiffness, due to the relative (in)accuracy with which ground contact time is measured, (In fact, as soon as I post this, I'm off to do a treadmill test using my Pioneer, so that I compare the leg spring stiffness values it provides to those the footpod reports when mine arrives in the next couple of days.)

Speaking of leg spring stiffness:

https://www.facebook.com/.../?type=3&theater

Gadget overload.

Efficiency is the key to IM running rather than focussing on data. Jan had a shit day but his form was maintained and this carried him through not what power output he was doing.

Focus on what you can control on the day which is generally form. If your form is shit you are leaking energy.

Don't over complicate things.

In regards to Sanders he went in under trained so with or without the stryd you know he was under trained.

Mark Allen and Dave Scott two very different runners in style but great IM runners why? Maintaining their form from start to finish. Cadence/Staying tall not leaking energy

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Andrew Garwood
http://www.2xu.com
http://www.newtonrunning.com
http://www.ascendsport.com.au

Hi Andrew

Im a sceptic of this product and didnt get a chance to have a look in Kona.

Can you please explain to me how this works better than if someone had a foot pod on their bike to measure power?

Thanks

Brett

Yeah, don't buy stryd if you're not a wko4 user and you expect to get easy access to interesting metrics!

So it seems relatively straight forward to me that running performance (at a very high level) is a result of output (power) and how efficiently that output is translated into forward motion (which I'm guessing LSS is the most accurate measure?)

If the above is true, I guess the big question from me is - increasing power is fairly straight forward and down to training response. What have you seen that can influence LSS in a meaningful way? Has LSS been measured when athletes attempt to vary their normal form? I.e what have you seen from data that is a definite 'win' in terms of form/technique with regard to LSS?