Responses of Motor-Sport Athletes to V8 Supercar Racing in Hot Conditions

Background: Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available. Purpose: To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions. Methods: Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index. Results: Prerace body-core temperatures were (mean +/- SD) 37.7 degrees C +/- 0.4 degrees C (range 37.0 degrees C to 38.2 degrees C), rising to 39.0 degrees C +/- 0.4 degrees C (range 38.4 degrees C to 39.7 degrees C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 +/- 0.12 L/h or 13.4 +/- 1.2 mL . kg(-1) h(-1), and postrace dehydration was 0.6% +/- 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 +/- 0.9), thermal discomfort as uncomfortable (3.1 +/- 1.0), and perceived exertion as very hard to very, very hard (8.7 +/- 1.7) after the races. Overall physiological and perceptual strain were 7.4 +/- 1.0 and 7.1 +/- 1.2, respectively. Conclusions: Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.