THE WET BULB GLOBE TEMPERATURE INDEX AND PERFORMANCE IN COMPETITIVE DISTANCE RUNNERS 1195

Abstract

Preliminary wet bulb globe temperature (WBGT) index guidelines were designed in 1974 for National Collegiate Athletic Association (NCAA) Championship Division I distance running competition that would minimize the chance of heat injury during championship distance running events and predict when environmental conditions would cause performance decrements. The purpose of this study was to test the validity of the NCAA guidelines and the utility of the WBGT index for predicting the effects of environmental heat stress on running performance. WBGT index data obtained during the 1500 m, 3000 m steeplechase (SC), 5000 m and 10000 m events at NCAA Division I Track and Field championship track meets held between 1974 and 1981 (excluding 1975) were compared to the average running performance of the top six finishers in each event. Evaluation of the effectiveness of these guidelines showed no occurrence of heat injury reported between 1974 and 1981. Pearson-product moment correlation revealed significant relationships between the WBGT index and performance when all event data were pooled (r = -0.52) and for the 10000 m (r = -0.91) and 3000 m SC (r = -0.83) when each event was analyzed separately (P < 0.05). The results for the 1500 and 5000 m events were not significant. Also, the 1500 and 5000 m events showed a wide range of running performance (approximately -2.0 to + 1.0%) could occur very close to the threshold for performance decrement guidelines of 29.2°C for the 1500 m and 25.0°C for the 5000 m. However, errors in predicted decrements in performance for all events based on the WBGT guidelines were rare. In conclusion, the WBGT index heat injury guidelines were effective in preventing heat injury. Also, performance decrement guidelines were significantly related to running performance in the 3000 m SC and 10000 m but not for the 1500 and 5000 m events.