This study recruited 20 Māori/Pacific Island (MP; body mass 100.97 kg) and 29 NZ European (NZE; body mass 89.11 kg) elite male athletes and compared the fluid-electrolyte balance by ethnicity. Sweat rates were determined by body mass change during a 1-h spin cycle exercise session. Analyses of sweat samples revealed mean sweat sodium concentrations of 73.4 mmol/L for the MP group and 55.5 mmol/L for the NZE group (p=0.070). The between-group differences were not significant for sweat rates (0.93 L/h for the MP group and 0.89 L/h for the NZE group; p=0.357) or fluid intakes (1.05 L and 0.93 L, respectively; p=0.395). Half of the MP group gained weight during the exercise session compared to 37% of the NZE group. Pre-exercise urine specific gravity was significantly lower amongst the NZE group than the MP group (1.016 g/mL vs 1.024 g/mL; p=0.001). During the exercise session, heart rate did not differ significantly between the groups (p=0.082).
