Effects of Weather Parameters on Endurance Running Performance: Discipline Specific Analysis of 1258 Races.

Introduction This study evaluated how single or combinations of weather parameters (temperature, humidity, wind speed, solar load) affect peak performance during endurance running events and identify which events are most vulnerable to varying weather conditions. Methods Results for the marathon, 50 km race-walk, 20 km race-walk, 10,000 m, 5,000 m and 3,000 m-steeplechase were obtained from the official websites of large competitions. We identified meteorological data from nearby (8.9 ± 9.3 km) weather stations for 1258 races held between 1936 and 2019 across 42 countries, enabling analysis of 7867 athletes. Results The Wet-Bulb Globe Temperature (WBGT) across races ranged from -7 to 33 °C, with 27% of races taking place in cold/cool, 47% in neutral, 18% in moderate heat, 7% in high heat, and 1% in extreme heat conditions, according to the World Athletics classification. Machine learning decision trees (R2 values: 0.21-0.58) showed that air temperature (importance score: 40%) was the most important weather parameter. But, when used alone, air temperature had lower predictive power (R2 values: 0.04-0.34) than WBGT (R2 values: 0.11-0.47). Conditions of 7.5-15 °C WBGT (or 10-17.5 °C air temperature) increase the likelihood for peak performance. For every degree WBGT outside these optimum conditions, performance declined by 0.3-0.4%. Conclusion More than one-quarter of endurance running events were held in moderate, high, or extreme heat and this number reaches one-half for events other than the marathon. All four weather parameters must be evaluated to mitigate the health and performance implications of exercising at maximal intensities in a hot environment with athletes adopting heat mitigation strategies when possible.