Effect of voluntary electric fan use on autonomic and perceptual responses to lower leg passive heating in humans

This study investigated the efficacy of voluntary fan utilization on autonomic thermoeffector responses and thermal perceptions during passive heating by lower leg immersion (42 °C) in a 27 °C ambient temperature, 50% relative humidity. Fourteen young healthy adults (8 females) were recruited for this study where they underwent two trials with (Fan) and without an electric fan (No fan) during 50 min of passive heat stress. The skin temperature on forearm and abdomen was lower in Fan than in No fan (all p < 0.02), and the local skin temperature on the chest, and mean skin temperature were significantly lower in Fan than in No fan in the final 20 min (mean value of mean skin temperature: 34.77(0.15) °C vs 35.11(0.12) °C, respectively, all p < 0.03), whilst the rectal temperature was not different between trials (37.11(0.23) °C vs 37.08(0.27) °C, p = 0.78). The sensitivity of local sweat rate (LSR) with the increase of mean body temperature on the chest and forearm was significantly lower in Fan than No fan trials (all p < 0.02). The sum value of thermal sensation was lower and wetness was higher in Fan than in No fan in the final 25 min (thermal sensation: 7.50 (1.25) vs 5.00 (3.06), wetness: -6.57 (2.31) vs -5.21 (2.46), all p<0.03) whilst thermal discomfort did not differ significantly between trials (p = 0.12). The voluntary use of an electric fan attenuates the autonomic thermoeffector response, such as sweating, and influences thermal sensation and wetness but did not affect core temperature and thermal discomfort during lower leg immersion.