Heat cramps, also known as heat cramps, are caused by sweating profusely during strenuous exercise in a hot environment. Muscle cramps often occur after the activity stops, mainly involving skeletal muscles, lasting for about a few minutes and then relieving without obvious temperature rise. Muscle cramps may be related to severe body sodium loss (excessive sweating and drinking hypotonic fluids) and hyperventilation. Heat cramps can also be an early manifestation of heat stroke. Skeletal muscle spasms induced by physical activity due to excessive fluid intake without sodium supplementation. In a high temperature (>38°C) environment, when excessive fluid loss occurs due to sweating and only water is supplemented, heat cramps may occur after physical activity. The result is due to the relative loss of sodium, occasionally potassium and magnesium. Heat cramps are common in manual laborers (such as machine room personnel, steel workers, miners), climbers or skiers who wear excessive cold-weather clothing, tennis players and other weekend athletes, and people who are not adapted to hot and dry climates, the latter of which evaporates quickly and makes excessive sweating almost unnoticeable.