Environmental temperature during summertime athletic competitions in Japan

Abstract In this study, we observed the environmental conditions at national athletic competitions between 1997 and 2001 and evaluated the way competitions are held in the summer. The maximal values of wet-bulb globe temperature (WBGT), dry-bulb temperature (DBT), wet-bulb temperature (WBT), globe temperature (GT), and temperature on the track surface (Tgru) were 35.0, 42.8, 32.4, 49.4 and 59.0°C, respectively. Maximal values of GT were above 42.0°C during all ten atheletic competitions, and mean values of daily GT were 35.0°C or higher during nine athletic competitions. The maximal effective radiant heat was 21.3°C. The present data exceeded the ACSM standard (extreme risk when WBGT is above 28°C) in almost all athletic competitions investigated. Moreover, the data also exceeded the JASA standard (suspend exercise in principle when WBGT is above 31°C) in more than 60% of athletic competitions investigated. The air temperature in the stadiums was significantly higher than that in nearby meteorological observatories. Therefore, it may be preferable to use WBGT as an index for predicting the occurrence of heat disorders. It is necessary to set event schedules so that competitive activities occur in the cooler times of day to ensure the safety and optimum performance of the athletes.