Responses to V8 Supercar driving in hot conditions

Abstract

Two male V8 Supercar drivers (age: 28.4, 31.3 yrs; peak VO2: 60.0, 47.3 mL.kg-1.min-1; height: 1.77, 1.79 m; body mass: 71.0, 78.7 kg) were studied during the Darwin round of the 2002 V8 Supercar championship to examine thermal, cardiovascular and perceptual responses to competitive driving in hot conditions. Urine specific gravity (USG) and colour was determined prior to each race. Body mass, thermal strain and thermal discomfort were measured pre- and post-race. An ingestible telemetric pill (CorTemp, HTI Technologies, USA) permitted continuous measurement of core body temperature while driving. Race 1 was contested over 52km while races 2 and 3 were 100km. A peak core temperature of 39.7oC was observed following race 2 (cabin temperature 52.1oC, WBGT Index 30.7oC). Although both drivers used cooling interventions, they generally perceived their post-race body temperature as very hot causing them to feel uncomfortable. While body mass loss was limited to 1% during the races, 3% was lost throughout the 30 hours spanning practice to race 3 completion. One driver was well hydrated prior to races (Usg 1.004, 1.007, 1.007), while the hydration status of the other varied (1.023, 1.007, 1.028). The data demonstrates that V8 Supercar drivers can attain core body temperatures approaching hyperthermic values which induce high levels of perceived thermal strain from short driving bouts in hot conditions.