Effects of caffeine and menthol on cognition and mood during simulated firefighting in the heat

Abstract This study examined the separate effects of caffeine and menthol on cognition and mood during simulated firefighting in the heat. Participants ( N  = 10) performed three trials in a counterbalanced order, either with 400 mg caffeine, menthol lozenges, or placebo. The simulated firefighting consisted of 2 bouts of 20-min treadmill exercise and one bout of 20-min stepping exercise in the heat with two brief 15-min rest periods between each exercise phase. Exercise induced significant dehydration (>3%) and elevated rectal temperature (>38.9 °C), for all three conditions. Neither caffeine nor menthol reduced perceived exertion compared to placebo ( p  > 0.05). Mood ratings (i.e., alertness, hedonic tone, tension) significantly deteriorated over time ( p p