Effect of acute heat exposure on the determination of critical power and W' in women and men

Purpose: The goal of this study was to investigate to what extent acute heat exposure would affect the parameters of the power-duration relationship, i.e. CP and W', using multiple constant workload tests to exhaustion, in women and men. Methods: 24 young physically active participants (12 men, 12 women) performed 3 to 5 constant load tests to determine CP and W', both in temperate (TEMP; 18°C) and hot (HOT; 36°C) environmental conditions. A repeated-measures ANOVA was executed to find differences between TEMP and HOT, and between women and men. Results: In HOT, CP was reduced by 6.5% (227 ± 50 vs. 212 ± 47 W), while W' increased 12.4% (16.4 ± 4.4 vs. 18.5 ± 5.6 kJ). No significant two-way sex × temperature interactions were observed, indicating that the environmental conditions did not have a different effect in men compared with women. The intersection of the average curvatures in TEMP and HOT occurred at 137 s and 280 W in women, and 153 s and 397 W in men. Conclusion: Acute heat exposure had an impact on the parameters CP and W', i.e., CP decreased whereas W' increased. The increase in W' might be a consequence of the mathematical modelling for the used test methodology, rather than a physiological accurate value of W' in HOT. No differences induced by heat exposure were observed between women and men.