Thirteen physically active males; either semi-professional referees (n = 7) or semi-professional soccer players (n = 6) (mean ± SD: age = 20.3 ± 2.2 years; height = 175 ± 7.4 cm; body mass = 70.8 ± 4 kg) volunteered for this study. Sample size of 12 was calculated using computer software (G*Power 3), and was deemed sufficient to observe significant differences in the dependant variable rectal temperature (Tre) based on the previous findings (Drust et al., 2000).