Heat acclimation

Heat acclimation is the process of adapting to repeated exposure to hot environments or exercise in the heat so the body can better regulate temperature and maintain performance.

Physiological adaptations and guidelines

Repeated training or work in hot conditions triggers several adjustments. Sweat production starts earlier and increases, and the sweat becomes more dilute because sodium is conserved. Plasma volume expands and the heart pumps more efficiently, which helps deliver blood to the skin for cooling and to the muscles for work. These changes reduce heart rate and core temperature during exertion. Research shows that 10–14 days of heat training can raise sweat rate by roughly 6–17 % and cut sweat sodium concentration by about 30–50 % Thirst mechanisms also recalibrate so that fluid intake better matches loss. To acclimate safely, gradually increase time and intensity in the heat over one to two weeks, stay hydrated, and monitor body weight. Even during acclimation, remember that sweat rates during exercise often range from 0.5–2 litres per hour and can be higher in extreme conditions.

Examples and practical tips

A runner might initially lose 1.5 litres of sweat per hour with a high sodium content; after two weeks of training in hot weather they may sweat slightly more but with lower sodium, allowing them to drink water without risking electrolyte imbalance. When acclimating, drink enough fluids to replace most of the weight you lose and include salty foods or electrolyte tablets during long sessions, but avoid overdrinking. Gradual exposure and mindful fluid and sodium intake help you maintain performance and reduce the risk of heat illness.

A brief wrap‑up: Heat acclimation improves heat tolerance, conserves sodium and supports hydration balance. By exposing yourself gradually to heat and paying attention to your fluid and salt intake, you can maintain performance and reduce the risk of heat-related problems.

Related Terms: Hydration, Sweat rate, Sweat sodium concentration, Hyperhydration, Thirst