Why is it advised to avoid distances over 200m when testing for speed?

Avoiding distances over 200 meters when testing for speed is recommended primarily because of two main factors: anaerobic capacity and the peak speed that athletes can typically achieve.

Testing distances beyond 200 meters can shift the focus away from pure speed and more towards endurance, as athletes may begin to engage energy systems that are not purely anaerobic. Specifically, longer distances require contributions from aerobic metabolism, which can obscure the measurement of pure sprinting speed that is the goal of speed tests.

Additionally, most athletes reach their top speed within the first 100 meters. Beyond this distance, there is usually a significant decrease in speed output, which could lead to misleading results regarding an athlete's maximum speed capability. Consequently, by focusing on shorter distances, evaluators can ensure they are accurately capturing peak speed performance without the confounding effects of endurance contributions.

Thus, the advice to limit testing distances to under 200 meters effectively aligns with the principles of assessing speed in a manner that yields valid and reliable results.