Investigation of thermal stress in racing kart athletes

Motor racing drivers may be exposed to thermal stress, which can influence their performance and put them at risk of heat stroke. The aim of the work described here was to monitor core body temperature and other physiological and environmental variables continuously in racing kart drivers and to investigate the relationship between core body temperature and lap-time/lap-time-variability, the latter being an indication of driver performance. As an indication of core temperature we used the eardrum temperature, T_eardrum, measured with a modified, extremely-compact radiation thermometer. We also measured instantaneous heart rate, the vector magnitude of acceleration, G, sweat weight, ambient temperature and relative humidity in the racing suit and full-face helmet, T_a(suit)/RH_suit/T_a(met)/RH_met, road temperature, and lap-time. The measuring instruments functioned satisfactorily during karting performed on a racing circuit. In all participants (n= 15: 30.9 ±6.4 S.D. yrs) during driving, we found that T_eardrum gradually increased from 36.8°C to 38.2°C It is suggested that the observed rise in T_eardrum could be due to the G stresses to which the driver's were subjected, as heat production of the body was increased due to the increased muscle activity against G during driving. In addition, we found that the degradation of the local environment around the body (T_a(suit)/max= 41.0°C,RH_suit/max=96.6%,T_a(met)/max= 41.0 °C, RH_met/max=93.5%) could be also be one of the major factors. We also found a statistically significant correlation between Teardrum and lap-time/lap-time-variability. These results suggest that monitoring of Teardrum could be of considerable importance in protecting racing drivers from heat stroke and assessing their performance during motor racing.