Effects Of A Portable Fan On Physiological And Cognitive Responses During Exercise In The Heat

Heat stress during physical activity can impair performance and cognitive function, particularly for individuals working outdoors. A new portable fan has been designed to be worn on a cap or hardhat to help alleviate the effects of heat stress for outdoor active individuals. PURPOSE: To examine the impact of the portable fan on physiological responses, perceived heat stress, and cognitive function during exercise in hot and humid conditions. METHOD: In this randomized, counter-balanced cross-over study, 10 participants completed two trials, with (WF) and without the fan (WOF), cycling at 50% of HRR in a temperature- and humidity-controlled chamber (30 °C and 70% RH). Skin temperature was continuously measured on the forehead, neck, chest, thigh, and tympanic membrane at 1 Hz. Heart rate (HR) and breathing rate (BR) were monitored using a chest-worn telemetric device. Cognitive function and subjective heat stress were assessed pre- and post-trial using a computerized Stroop Test and visual analog scales (VAS). Two-way RM-ANOVA was used to analyze differences between treatments over time. RESULTS: HR responses were not different between WF and WOF (p = 0.48). Forehead temperature responses were lower at 15 and after 30 min of exercise in WF (32.4 ± 0.8 °C; 32.2 ± 0.8 °C, resp; mean ± 95% CI) compared to WOF (34.2 ± 0.8 °C; 33.8 ± 0.8 °C; all p < 0.05). Chest temperature was also lower at 30 min in WF (34.9 ± 0.6 °C) compared to WOF (35.2 ± 0.6 °C), with no differences for neck, thigh, or tympanic skin temperatures. BR was lower after 30 min of exercise in the WF (24.6 ± 2.8) compared to WOF (26.6 ± 2.8; treatment p < 0.05). Post-exercise response times in the Stroop test were faster than pre-exercise for both the congruent (715 ms vs. 628 ms, p < 0.05) and incongruent tests (841 ms vs. 720 ms, p < 0.05), with no effects from trial condition or their interaction. CONCLUSION: Heart rate showed no difference between treatments, indicating well-controlled exercise intensity and environmental conditions. The portable fan effectively lowered upper body temperatures for skin exposed to the fan (forehead and chest), but had no effect on tympanic temperature, felt heat stress, or cognitive function. These data suggest the fan may help alleviate upper body heat stress and offering potential benefits for outdoor physical activity and sport.