WET-BULB GLOBE TEMPERATURE INDEX AND PERFORMANCE IN COMPETITIVE DISTANCE RUNNERS

In 1974 two sets of heat stress guidelines, each based on the wet bulb globe temperature (WBGT) index, were designed for men's National Coll egiate Athletic Association (NCAA) Championship Division I distance ru nning competitions. One set of guidelines was established to minimize the chance of heat injury during distance running events. A second set was designed to predict heat stress related performance decrements. D uring the time the heat injury guidelines were used (1974-1993), no he at injuries were reported. The purpose of this study was to assess the accuracy of the performance decrement guidelines and determine whethe r the WBGT indices were linearly related to men's championship distanc e running performance. WBGT index data were collected during the 1500- , 3000-steeplechase (SC), 5000-, and 10,000-m events at men's NCAA Div ision I Track and Field Championships held from 1974 to 1981 (excludin g 1975). These data were compared to the average running performance o f the top six finishers in each event. Analysis of the accuracy of the NCAA performance decrement guidelines revealed four unexpected perfor mances out of 28 predictions. Pearson product-moment correlation and l inear regression analyses between the WBGT indices and performance rev ealed statistically significant linear relationships for the 3000-SC a nd 10,000-m events (P < 0.05). A significant linear relationship was a lso found when the 1500-, 3000-SC, 5000-, and 10,000-m results were po oled (P < 0.05). In conclusion, the NCAA guidelines were effective in preventing heal injury and fairly successful in predicting performance . However, a linear relationship between WBGT indices and distance run ning performance did not exist for all running events.