Field study on the effect of space type, exercise intensity, and wet bulb globe temperature on thermal responses of exercisers

The aim of this study is to analyse the effect of three variables, i.e., space type, exercise intensity, and wet bulb globe temperature (WBGT), on the thermophysiological and subjective response of exercisers in hot and humid areas. A field survey was conducted in two types of exercise space, i.e., a semi-outdoor space and an indoor space with natural ventilation in Guangzhou, China, during the summer of 2019. The subjective responses of 36 subjects were collected through questionnaires. Three exercise intensities were evaluated at a WBGT of 27-30 degrees C: shooting (3.7 +/- 1.4 MET), layup (5.2 +/- 1.4 MET), and full-court dribbling shuttle run (7.2 +/- 1.4 MET). The environmental and physiological data were recorded. The findings suggest that people should exercise in a semi -outdoor space rather than in an indoor space with natural ventilation in summer. Among the three variables, exercise intensity had the strongest influence on the thermal sensation vote and thermal acceptability vote, even the sweat feeling index only affected by exercise intensity. The WBGT significantly influenced the mean skin temperature. Thus, it is recommended that people exercise when the WBGT <= 29.4 degrees C. The WBGT was the op-timum indicator of the thermal responses of exercisers compared with operative temperature and heat index. This study improves our understanding of the steady-state thermal responses of exercisers with high metabolic rates and indicates that semi-outdoor spaces are preferable when exercising in hot and humid areas compared with the naturally ventilated indoor spaces.