Short-term endurance training in the cold with layered clothing mitigates perceptual strain during exercise in the heat

PURPOSE: We examined whether short-term endurance training in the cold combined with layered clothing enhances cardiovascular, thermoregulatory, and performance adaptations. METHODS: Sixteen healthy males completed five consecutive days of endurance cycling in the cold (10 °C, 50% relative humidity [rH]) while wearing either thermal layered clothing (WEAR) or light clothing (CON). Before and after training, participants performed a graded exercise test, a time-to-exhaustion test, and a heat stress test (30 min at 35 °C, 50% rH). RESULTS: During training, heart rate, skin temperature, and sweat rate were higher in WEAR than CON (P < 0.05). Maximal power output increased similarly in both groups (WEAR: + 7.2 ± 9.5%; CON: + 8.4 ± 7.1%, P < 0.05), while maximal oxygen uptake improved only in WEAR (52.4 ± 7.3 to 55.2 ± 7.1 mL/kg/min, P < 0.05). During the heat stress test, ratings of perceived exertion and thermal sensation decreased after training in WEAR only (P < 0.05), with no changes in sweat rate, skin temperature, or rectal temperature in either group. CONCLUSION: Short-term endurance training in the cold combined with layered clothing attenuated perceptual strain during subsequent exercise in the heat, implying a practical alternative approach to traditional heat acclimation strategies.