Perceptual Responses to Submaximal and High-Intensity Cycling Exercise in Moderate and Hot Environments

This randomized, counterbalanced crossover study examined the effects of ambient heat on thermal sensation (TS), thermal comfort (TC), and rating of perceived exertion (RPE) during submaximal and high-intensity cycling. Eleven recreationally active men completed 60 min of cycling at a workload prescribed from 60% of VO2max, followed by 15 min of seated recovery and a time to exhaustion (TTE) test at a workload prescribed from 90% of VO2max, in moderate (MT: 22 °C, 45% RH) and hot (HT: 35 °C, 45% RH) conditions. During submaximal exercise, condition by time interactions were observed for TS, TC, and RPE (all p ≤ 0.05), with greater heat sensation, discomfort, and exertion in HT. Achieved oxygen uptake during TTE corresponded to 78.7 ± 1.9% and 85.3 ± 3.8% of VO2max in HT and MT, respectively. At exhaustion, TS, TC, and RPE did not differ significantly between conditions. Perceptual ratings differentiated the environments during prolonged submaximal exercise but not at the end of the high-intensity TTE test. This convergence should be interpreted cautiously because ceiling effects, the small sample, unequal TTE duration, and differences in achieved metabolic intensity may have contributed.