The Stryd platform will calculate your Critical Power automatically based on your running data. Critical Power (threshold power) represents the highest power that a runner can maintain in a quasi-steady state without fatiguing, where the duration may range from 30-70 minutes, depending on the individual.
The Stryd system evaluates your Critical Power each time a new run is uploaded into your account. Stryd only uses your actual run data to calculate your Critical Power. We do not make any estimations or guesses.
Your Critical Power will change in two scenarios:
1. Your Critical Power can be adjusted downward if 90-day old runs are dropped as they no longer contribute to your fitness.
2. Your Critical Power can only be adjusted upward if you ran at a higher power level for a certain duration than you have done previously. Not all hard runs make a difference. For example, you may run a 3-minute interval slightly harder than previously, but the extra effort may not be enough to adjust your Critical Power.
If you think your fitness has improved, but your Critical Power has not been adjusted, you can improve your Critical Power by doing a time trail between 20 and 40 minutes. You can use your Power Duration Curve to get an exact power target. In the example below, you see a Power Duration Curve with the Modeled Ability switched on. To improve Critical Power, this runner could attempt to exceed the highest power for a duration of 20 minutes. If the runner averages 305 watts for 20 minutes, Critical Power will be adjusted upward (as the previous highest average power for 20 minutes was 301 watts):
If you feel your auto-calculated Critical Power is incorrect, you can reset your auto-calculated Critical Power calculation and start anew (it will take 3 runs for the system to give you a new Critical Power number). And you can also switch to manual Critical Power and do a Critical Power test.