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