Cooling Between Exercise Bouts and Post-exercise With the Fan Cooling Jacket on Thermal Strain in Hot-Humid Environments

Abstract

This study investigated the effects of cooling between exercise bouts and post-exercise with a commercially available fan cooling jacket on thermal and perceptual responses during and following exercise in hot-humid environments. Ten male athletes completed two 30 min cycling bouts at a constant workload (1.4 watts⋅kg^-1 of body mass) with a 5 min recovery period in between. Exercise was followed by a 10 min recovery period. In an environmental chamber (33°C, 65% relative humidity), participants performed two trials with (FCJ) or without (CON) the fan cooling jacket on a T-shirt during the 5 min inter-exercise and 10 min post-exercise recovery periods. Mean, chest and upper arm skin temperatures, and thermal sensation and comfort were lower in FCJ than CON trial during and following exercise (P < 0.05). Thigh and calf skin temperatures, infrared tympanic temperature and heart rate were lower in FCJ than CON trial during the experimental trials (P < 0.05). The rates of fall in mean, chest and upper arm skin temperatures, infrared tympanic temperature and thermal sensation and comfort were faster in FCJ than CON trial during both recovery periods (P < 0.05). There were faster rates of fall in thigh and calf skin temperatures and heart rate in FCJ than CON trial during the post-exercise recovery period (P < 0.05). No difference was observed between trials in the rating of perceived exertion (P > 0.05). This study indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would effectively mitigate thermal strain and perception/discomfort during and following exercise in hot-humid environments. This garment would reduce whole-body skin temperature quickly while promoting falls in lower-body as well as upper-body skin temperatures.

Keywords: body temperature; cooling garment; exercise; fan cooling; heat stress.

FIGURE 1

The fan cooling jacket. (A) anterior aspect. (B) posterior aspect. (C) anterior opening aspect. The black arrow indicates the fan (B,C). The silver arrow indicates a battery box (C).

FIGURE 2

Schematic representation of the experimental protocol. T_ty, infrared tympanic temperature; HR, heart rate; TS, thermal sensation; TC, thermal comfort; RPE, rating of perceived exertion.

FIGURE 3

Responses of mean (A), T_sk; chest (B), T_che; upper arm (C), T_upp; thigh (D), T_thi; and calf (E), T_cal; skin temperatures and infrared tympanic temperature (F) T_ty. EX1, the first exercise bout; C, the inter-exercise recovery; EX2, the second exercise bout; PC, the post-exercise recovery. *P < 0.001 denotes significant differences between FCJ and CON trials at particular time points. ^†P < 0.05 denotes a significant two-way interaction of trial × time between FCJ and CON trials during the experimental trials.

FIGURE 4

Changes in heart rate (HR). EX1, the first exercise bout; C, the inter-exercise recovery; EX2, the second exercise bout; PC, the post-exercise recovery. *P < 0.05 denotes a significant two-way interaction of trial × time between FCJ and CON trials during the experimental trials.

FIGURE 5

Responses of thermal sensation (A) TS (–4 extremely cold to 4 extremely hot); and comfort (B) TC (1 comfortable to 4 very uncomfortable); and rating of perceived exertion (C) RPE (6 no exertion at all to 20 maximal exertion). EX1, the first exercise bout; C, the inter-exercise recovery; EX2, the second exercise bout; PC, the post-exercise recovery. *P < 0.05 denotes significant differences between FCJ and CON trials at particular time points.