# Variability of power output metric

Has anyone looked at variability of power output and how that can impact lots of different things (not the only or main variable) and can be very different from outside to inside riding

• comfort
• ftp different between indoor and outdoor

I’m not talking about the metric some power meters have that look at individual pedal strokes or normalized power which looks at a longer time frame. I’m more thinking in-between like 10 seconds or around that (not sure on exact numbers). So instead of using a rolling 30 second average like normalized power it would be a rolling 30 second standard deviation. Maybe include the linear slope of that 30 seconds do you can throw out data points where the slope is far away from 0 (i.e. when your trying to go harder or easier)

Seems like there are people good at holding steady power and those who aren’t and this could better show that. Seems like holding x watts with a smaller variability would be a significant different load on the body than if they have a large variability.

In my experience, there are factors outside of the athlete’s control. E. g. when you have variable wind conditions, in my experience, power can fluctuate by 50 W (e. g. 200 W one second, 250 W a few moments later).

Moreover, one essential aspect of pacing outdoors is maintaining one’s momentum. That means, assuming you are not changing gears, you only change your cadence very slowly. You want to avoid sudden changes in cadence (= sudden changes in force).

There is VI, “variability index”, which is the ratio of normalised power to average power. Usually you’d calculate that for a longer duration, like for the full ride. But you could maybe have a rolling VI, but it shouldn’t be shorter than 30s (because normalised power needs that).

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