An environment can be defined as hot , when air temperature exceeds 30oC. At approximately 30oC, the air and skin temperature are in equilibrium, and conductive heat loss from the skin to the environment ceases. From this point on, athletes must rely primarily on sweating to reduce the body s heat load and avoid fatigue and overheating. As air temperature increases above 30oC, the body absorbs heat from the environment, further increasing the heat load and the demands placed on sweating. In these circumstances, body temperature can increase rapidly to impose considerable circulatory strain on the athlete, resulting in fatigue or in the worst cases, heat stress or heat illness. A 7-14 day acclimatisation period is the best way to ensure optimal performance during exercise in the heat.
Acclimatisation evokes several physiological adaptations that benefit performance.
These include an increase in blood volume, a reduced heart rate, increased perfusion of the working muscles with blood, and an improved sweating response. If arriving one to two weeks early to acclimatise is impractical, athletes should consider other options. To simulate acclimatisation by exercising in warmer conditions, athletes could train indoors, or during the hottest part of the day. Accordingly, elite athletes are capable of losing two to three litres of sweat per hour, which can seriously impact on blood volume and impair cardiovascular function. Therefore, it is essential that athletes are well hydrated.