The potential efficacy of continuous plantar foot cooling during relatively mild simulated occupational heat stress-a...

To identify the effect size regarding glabrous skin foot cooling on core temperature, cognitive performance, and physical work capacity (PWC) during mild simulated occupational heat stress.

A pilot sample of twelve healthy adults (5 women) completed experimental visits in a 38.7 ± 0.7 ℃ and 46 ± 9% relative humidity environment that consisted of 60-minutes of steady-state upper body ergometry exercise followed by a 60-minute PWC test involving upper body ergometry while maintaining a rating of perceived exertion of 13 ("somewhat hard"). In one trial, participants stood with bare feet on cooled plates (17.7 ± 0.5 ℃) and in the other they were on noncooled plates (36.5 ± 0.1 ℃), with the order assigned in a block randomized manner.

Core temperature increased during steady-state exercise (from 37.5 ± 0.3 to 37.6 ± 0.3 ℃, p < 0.003) and the PWC test (from 37.6 ± 0.3 to 37.9 ± 0.3 ℃, p < 0.001), but there was no difference between conditions (mean difference 0.03±0.18 ℃, p ≥ 0.592, d_z=0.112). During the PWC test, there was no difference between conditions for mean power output (p = 0.213, d_z=0.184), with the final power outputs of 28 ± 9 W and 30 ± 9 W for control and cooling conditions, respectively. There were no condition effects for cognitive performance on any measure (p ≥ 0.207, d_z≤0.405). However, foot cooling (+ 15 ± 9 bpm) reduced increases of heart rate during the PWC test compared to control (+ 21 ± 11 bpm, p = 0.013, d_z=0.425).

Glabrous skin foot cooling has a relatively small effect on core temperature and PWC, but moderate effects on cognitive performance and heart rate during short duration (~ 3 h) mild heat stress.