A short recovery period between same-day competitions is common practice in organized youth sports. We hypothesized that young athletes will experience an increase in physiological strain and perceptual discomfort during a second identical exercise bout in the heat, with one hour (21°C) between bouts, even with ample hydration. Twenty-four athletes (6 boys, 6 girls 12-13 y, 47.7±8.3 kg; 6 boys, 6 girls 16-17 y, 61.0±8.6 kg) completed two 80-min intermittent exercise (treadmill 60%, cycle 40% VO_2peak) bouts in the heat (33°C, 48.9±6.1% rh). Sweat loss during each bout (B) was similar within each age group (12-13 y B1: 943.6±237.1 ml, B2: 955.5±250.3 ml; 16-17 y B1: 1382.2±480.7 ml, B2: 1373.1±472.2 ml). Area under the curve (AUC) was not statistically different (p>0.05) between bouts for core body temperature (T_C) (12-13 y B1 peak: 38.6±0.4°C, B2: 38.4±0.2°C; 16-17 y B1 peak: 38.8±0.7°C, B2: 38.7±0.6°C), physiological strain index (PSI) (12-13 y B1 peak: 7.9±0.9, B2: 7.5±0.7; 16-17 y B1 peak: 8.1±1.5, B2: 7.9±1.4), or thermal sensation for any age/sex sub-group or for all subjects combined. However, rating of perceived exertion AUC and peak were higher (p=0.0090 and 0.0004, respectively) during B2 in the older age group. Notably, 4 subjects experienced consistently higher responses throughout B2. With these healthy, fit, young athletes, one hour of complete rest, cool-down, and rehydration, following 80 min of strenuous exercise in the heat, was generally effective in eliminating any apparent carry-over effects that would have resulted in greater thermal and cardiovascular strain during a subsequent identical exercise bout.