Repeated Sprint Training in Heat Improves Repeated Sprint Ability Under Temperate Conditions Similarly in Active...

The aim of this study was to compare the adaptive responses to repeated sprint training in heat (RSHT) on exercise performance under temperate conditions between males and females. Active males and females completed 7 weeks of repeated sprint training twice a week in temperate (CON, 20°C, 55% relative humidity (RH), males: n = 12, females: n = 13) or hot (HEAT, 30°C, 60% RH, males: n = 12, females: n = 14) conditions. Before and after training, a repeated sprint ability test (RSA) was performed (10-s cycle sprints with 20-s recovery between sprints, until exhaustion), and aerobic and anaerobic qualities were evaluated in temperate conditions. Thermoregulatory responses were measured on Training 1 and 12 (TR1 and TR12). Sprint number during RSA increased after HEAT from 15 to 21 in males and from 8 to 13 in females (p < 0.001), without significant changes after CON. VO₂peak during an incremental exercise test (+3 ± 1 mL·kg^-1·min^-1, p = 0.032) and mean power output during a Wingate test (+0.41 ± 0.15 W·kg^-1, p = 0.007) increased in all groups. No changes were observed in hematological parameters. In HEAT group only, the change in core temperature (-0.16 ± 0.07°C, p = 0.015), but not skin, and thermal sensation (-1 ± 0, p < 0.001) were lower at TR12 than TR1 in both sexes. No changes were observed in sweat rate or whole-body sweat sodium concentration. Seven weeks of RSHT induced partial heat acclimation and increased the number of repeated sprints performed under temperate conditions in females, to the same extent as in males.