Benefits of heat re-acclimation in the lead-up to the Tokyo Olympics

As presented in the first editorial from this series, the Tokyo Olympics are expected to be the hottest in modern history.1 While the postponing from 2020 to 2021 will not change the period of the year, it will allow more time for athletes to plan for multiple heat acclimation camps. Indeed, heat acclimation is the most important countermeasure athletes can adopt to protect their health and enhance performance.2 Heat acclimation develops following repeated training in hot conditions in response to marked increases in core and skin temperature, skin blood flow and sweat rate.2 It is commonly accepted that daily training in the heat for 60–90 min for 2 weeks allows for adaptations to occur, including plasma volume expansion and enhanced heat dissipation.3 These adaptations contribute to lower the cardiovascular response associated with exercising in the heat and thus improve performance.