Autonomic and behavioural thermoregulation in tennis.

OBJECTIVES This report describes physiological and behavioural mechanisms behind the control of body temperature and thermal comfort during competitive singles tennis. METHODS Thermoregulatory responses and workload were observed during "best of three sets" tennis matches among 25 players. In total, 94 matches were played in ambient temperatures ranging from 14.5 to 38.4 degrees C. The thermal environment was assessed by dry bulb, wet bulb and natural wet bulb temperatures, globe temperature and wind speed. Core body and skin temperatures were recorded each minute throughout the match, and body mass and fluid intake were measured before the match, after 30 minutes of play and at the completion of the match to determine sweat rate. Subjective ratings of thermal strain included thermal comfort, sweatiness and perceived exertion. Workload observations included match, game and point durations, and the proportion of match time spent in play (effective playing time). RESULTS Change in rectal temperature was positively correlated with point duration (p<0.001) and effective playing time (p<0.05). Sweat rate showed positive associations with air (p<0.0001), rectal (p<0.03) and skin (p<0.0001) temperature. Thermal comfort was reduced with increasing rectal (p<0.03) and skin (p<0.0001) temperature. Point duration and effective playing time were reduced when conditions were rated increasingly difficult (p<0.002 and p<0.0002, respectively). CONCLUSION Autonomic (increase in sweat rate) and behavioural (reduction in workload) thermoregulation are responsible for the control of body temperature and thermal comfort during tennis.