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