Physiological adaptations associated with prolonged exposure to high environmental temperatures. The adaptations that improve heat tolerance include an increase in blood volume, increase in sweating rate with the sweat containing a lower concentration of sodium, decrease in heart rate and lowering of core temperature at a given work load, and a reduction in the perceived intensity of exercise. In addition, heat-acclimatized individuals tend to suffer less from nausea, dizziness, and discomfort in hot temperatures than those who are unacclimatized. Most athletes from temperate regions acclimatize in hot climates very quickly, but a minimum of 7–10 days is advisable. Typically, acclimatization occurs after four to seven sessions of exercising, for 1–4 h per session. The exercise should start gently with periods of about 15 min of work alternated with 15 min rest. The exercise intensity should increase as heat tolerance improves. It is important that athletes take plenty of fluids in a hot climate.
Subjects: Sports and Exercise Medicine.