Impact of Heat and Humidity on Critical Power and Physiological Responses during the Three-Minute All-Out Test in Cyclists

, values under the Ht-wet condition were significantly lower than under Nt-dry and Ht-dry conditions (p < 0.05). During the 3MT, EP, peak power, and average power were significantly higher under the Nt-dry than under Ht-dry and Ht-wet conditions (p < 0.05). In conclusion, high temperature reduced 3MT performance compared with the neutral condition, with no additional decline between Ht-wet and Ht-dry conditions. In contrast, VT and wVT were most reduced under the Ht-wet condition, indicating greater impairment of submaximal physiological responses under hot-humid conditions. These results suggest that humidity mainly affects threshold-related outcomes rather than 3MT performance. Environmental heat should therefore be considered when applying 3MT-derived variables for training prescription.