Effect of electric fan use in isolation or combined with ice slurry/cold water ingestion and lower-leg immersion in young men during intermittent physical activity in hot-humid conditions.

Abstract

Using a randomized crossover protocol, 10 young men completed four 180min exposures (38°C, 60% relative humidity), alternating between 30min of walking and 30min of sitting where fluid or ice slurry were served. Participants underwent four trials: (i) 5mL·kg body mass-1 of 20°C water (CON); (ii) 5mL·kg body mass-1 of 20°C water+fan at 4m·s-1 (FAN); (iii) fan + 3mL·kg body mass-1 of ice slurry + 2mL·kg body mass-1 of 4°C water (FAN+ISCW); and (iv) FAN+ISCW+lower-leg immersion in 20°C water (FAN+ISCW+LLI). Sweat and body mass losses were higher with FAN than CON, FAN+ISCW, and FAN+ISCW+LLI. Mean and peak changes in Δrectal temperature, heart rate, and perceived heat and thirst from baseline were not statistically and practically different between FAN and CON. FAN+ISCW+LLI decreased sweat loss compared with FAN+ISCW and mean and peak changes in Δrectal temperature, heart rate, and perceived thirst compared with CON. FAN+ISCW+LLI also attenuated the changes in Δrectal temperature (peak) and thirst (mean and peak) compared with FAN. In conclusion, FAN slightly exacerbates fluid loss but does not attenuate the changes in Δrectal temperature, heart rate, and perceived heat and thirst during intermittent physical activity in hot-humid conditions. However, coupling ISCW or ISCW+LLI with the use of a fan attenuates the increase in these outcomes compared with no intervention and to a greater extent for rectal temperature and thirst when fan is coupled with ISCW+LLI than when it is used in isolation.