Purpose: We examined fluid intake, the relation between body mass (BM) loss and performance, and core temperature in young triathletes during a competition in tropical climate.
Methods: Fluid intake and pre and post BM were measured in 35 adolescent athletes, and core temperature was measured in one female and one male.
Results: Mean urine specific gravity (1.024 [0.007]) indicated that athletes were in suboptimal state of hydration upon waking. Race time was 73.2 (8.0) minutes. BM decreased by 0.6 (0.3) kg (P < .05). Fluid intake (528.5 [221.6] mL) replaced 47% of the fluid loss (1184.9 [256.4] mL) and was higher during run (11.5 [6.6] mL·min-1) compared to bike (7.3 [3.1] mL·min-1), P < .01. Loss in BM was ≥1.0% in 66% and ≥1.5% in 29% of the athletes. Males showed a moderate association between percentage loss in BM and finishing time (r = -.52), higher sweat rates (1.0 [0.3] L·h-1), and faster times (69.4 [7.5] min; P < .05). Core temperature rose to 40.1 °C in the female and 39.6 °C in the male.
Conclusion: Young triathletes competing in a hot/humid climate became mildly to moderately dehydrated and hyperthermic even when water and sports drinks were available but did not show symptoms of heat illness.
Keywords: core temperature; sports; sweating; tropics.