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Heat cramps
Last reviewed: 07.07.2025
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Heat cramps are exercise-related muscle contractions that occur during or after physical activity in conditions of elevated ambient temperatures.
Although exertion can cause cramps in cool weather, such cramps are not related to heat and rather reflect a lack of physical fitness. Heat cramps, on the other hand, can develop in physically fit people who sweat profusely and replace fluids but not salts, leading to hyponatremia. Heat cramps are common among heavy-duty workers (especially machine shop workers, metal workers, and miners), military recruits, and athletes.
The cramp occurs suddenly, usually in the muscles of the limbs. Severe pain and spasm in the hands and feet can be temporarily incapacitating. Body temperature remains normal, other changes are minor.
Cramps can be relieved immediately by persistent passive stretching of the involved muscle (e.g. ankle extension in the case of a posterior calf muscle disorder). Fluid and electrolyte deficiencies should be replaced orally [1 L of water with 10 g of salt (two full teaspoons)] or intravenously (1 L of 0.9% sodium chloride solution). Adequate conditioning, acclimatization, and maintenance of fluid and electrolyte balance can prevent cramps.
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