Mitigation of heat strain by wearing a long-sleeve fan-attached jacket in a hot or humid environment

Abstract

Objectives This study examined whether a fan‐attached jacket (FAJ) may mitigate the heat strain in hot or humid environment. Methods Nine healthy men engaged in 60‐min sessions on a bicycle ergometer (4 metabolic equivalents [METs] workload) in hot‐dry (40°C and 30% relative humidity) and warm‐humid (30°C and 85% relative humidity) environments. Both are equivalent to an approximately 29°C wet‐bulb globe temperature. The experiment was repeated—once wearing an ordinal jacket (control condition) and once wearing a long‐sleeve FAJ that transfers ambient air at a flow rate of 12 L/s (FAJ condition)—in both environments. Results Increases in core temperatures in hot‐dry environment were not statistically different between control and FAJ; however, that in the warm‐humid environment were significantly different between control and FAJ (0.96 ± 0.10°C and 0.71 ± 0.11°C in rectal temperature, P < .0001; and 0.94 ± 0.09°C and 0.61 ± 0.09°C in esophageal temperature, P < .0001). Changes in heart rate were different between control and FAJ in both environments (62 ± 3 bpm and 47 ± 7 bpm, P < .0001 in hot‐dry environment; and 61 ± 3 bpm and 46 ± 5 bpm, P < .0001 in the warm‐humid environment) and decrease of %weight change was different in hot‐dry environment (1.59 ± 0.12% and 1.25 ± 0.05%, P = .0039), but not in the warm‐humid environment. Conclusions Wearing a FAJ may mitigate heat strain both in hot or humid environments.

Recovery with a fan-cooling jacket after exposure to high solar radiation during exercise in hot outdoor environments

“…Participants repeatedly performed the cycling exercise protocol, which consisted of one set of 5 min at a load of 1.5 watt/kgBM and 15 min at a load of 2.0 watt/kgBM at 60 rpm. This exercise was repeated until the Tre reached 38.50°C ( 16 ) ( Figure 1 ).…”

“…Post-exercise fanning in compensable heat stress has been proven to be an effective method to reduce the increased Tc and Tsk, accompanied by greater evaporative heat loss (15). Several previous studies have observed that fan-cooling jackets suppress the increased in both Tc and Tsk in hot indoor environments (16,17). However, its application has not been studied during recovery from hyperthermia in postexercise, and it is unclear whether it reduces Tc and Tsk more rapidly, which are elevated by exercise under high solar radiation.…”