Heat acclimatization does not improve VO2max or cycling performance in a cool climate in trained cyclists

Abstract

This study investigated if well-trained cyclists improve V ˙ O 2 m a x and performance in cool conditions following heat acclimatization through natural outdoor training in hot conditions. Eighteen trained male cyclists were tested for physiological adaptations, V ˙ O 2 m a x , peak aerobic power output, exercise efficiency, and outdoor time trial (TT) performance (43.4km in cool environment, ∼5-13°C) before and after 2 weeks of training in a cool (CON, n=9) or hot (∼35°C, HA, n=9) environment. After heat acclimatization, TT performance in the heat was improved by 16%; however, there was no change in the HA group in V ˙ O 2 m a x (4.79±0.21L/min vs 4.82±0.35L/min), peak aerobic power output (417±16W vs 422±17W), and outdoor TT performance in cool conditions (300±14W/69±3min vs 302±9W/69±4min). The present study shows that 2 weeks of heat acclimatization was associated with marked improvements in TT performance in the heat. However, for the well-trained endurance athletes, this did not transfer to an improved aerobic exercise capacity or outdoor TT performance in cool conditions.