Stryd uses data from your last 90 days of training to estimate different race predictions. By combining the user's personal fatigue factor and their Power-Duration Curve, a model can predict how they might perform in a race in ideal circumstances (a flat course, with the same environmental conditions that the user trains with). The prediction will be based on how quickly they become fatigued and how their power output decreases over time.
Details on the features that contribute to the Stryd Race Predictions are as follows:
Fatigue Factor: When you exercise, your body uses energy, and as you continue to exert yourself, you become tired, or "fatigued." The fatigue factor is a measure of how quickly you tire out. A higher fatigue factor means you get tired faster.
Power-Duration Curve (PDC): This is a graph that shows the relationship between the power (energy) you can exert and how long you can maintain that exertion. Imagine sprinting versus jogging. You can sprint at full speed for a short time, but you can jog at a slower pace for a much longer time. If you plot your maximum power at different time lengths (for example, 1 minute, 5 minutes, 10 minutes, etc.), you will get a curve that generally goes down as time increases. This is the Power-Duration Curve. The "slope" of this curve essentially describes how quickly your power decreases as time goes on.
In simpler terms, think of running a race like driving a car with a certain amount of gas. The fatigue factor is how quickly your car uses gas, and the Power-Duration Curve is how fast you can drive at different gas levels. Given the ideal circumstances, you can predict how far and how fast the car (or runner) can go before it runs out of gas (or gets too tired to continue at the same speed).