Air temperature and physiological and subjective responses during competitive singles tennis.

OBJECTIVES: This report describes the thermal stresses and strains during competitive singles tennis.
METHODS: Thermoregulatory responses were investigated during best of three set tennis matches among 25 players. A total of 86 observations were made from 43 matches played, covering each season, with ambient temperatures ranging from 14.5 to 38.4 degrees C. Core body temperature and skin temperature were recorded each minute throughout the match, whilst heart rate was logged every 15 s. Body mass and fluid intake were measured before the match, after 30 min 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. The thermal environment was assessed by dry bulb, wet bulb and natural wet bulb temperatures, globe temperature and wind speed.
RESULTS: Mean (SD) core temperature after 30 min of play was 38.4 degrees C (0.4 degrees C), and demonstrated no association with air temperature or wet bulb globe temperature. Mean skin temperature was 31.8 degrees C (2.3 degrees C) ranging from 25.7 to 36.5 degrees C, and showed a positive association with air temperature (p<0.001). Heart rate varied widely during play, resulting in a mean (SD) response of 136.1 (13.7) beats/min and no association with air temperature. Sweat rate averaged 1.0 (0.4) litres/h (0.2-2.4 litres/h) or 12.8 (5.5) ml/kg/h (2.7-26.0 ml/kg/h), and demonstrated a positive relationship with air temperature (p<0.001). All subjective responses showed positive correlations with air temperature (p<0.001).
CONCLUSIONS: Stressful environmental conditions produce a high skin temperature and rating of thermal discomfort. However, overall thermoregulatory strain during tennis is moderate, with core temperature remaining within safe levels.