Heat cramps are indicators of heat-related attacks, such as heat exhaustion or heat stroke, and are not limited to athletes. Individuals at risk of heat cramps include older people, infants, and children. People living in cities without adequate housing or water supply are also at risk. Heat cramps are common when your body becomes overheated due to prolonged exposure to high temperatures or intense physical activity. Heat cramps are characterised by painful muscle spasms that typically affect the legs, arms, or abdomen. While heat cramps can be uncomfortable, they are usually not serious and can be managed with simple self-care measures.
Humans can regulate their body temperatures within one degree of 37℃ and adjust to temperature changes in their environment (thermoregulation) to aid bodily functions. However, there arefactors that can affect normal thermoregulation and blood flow to the skin, such as extremely hot or cold temperatures, physical exertion activities, skin disorders and certain medications.1, 2, 3
Hot temperatures and dehydration can lead to a heat wave. Chances are high that as a consequence, people are vulnerable to various types of heat-related illnesses. Heat illnesses include heat cramps, heat rash, heat oedema, heat syncope (fainting or dizziness), heatstroke, and heat exhaustion.
When we experience a heat-related illness, we lose electrolytes (salts and minerals) found in the blood, including sodium, potassium, chloride, and bicarbonate. These elements are important for creating an electrochemical gradient, which is used to conduct electrical impulses throughout the body. Hence, they are crucial for maintaining proper muscle contractions.1
Muscle or heat cramps are an early sign of exertional heat illnesses (EHI) and present as painful contractions, muscle spasms or cramps in the arms, abdomen, and legs. There is typically no systemic buildup of heat and core body temperature remains normal.1,3,4
Causes of heat cramps
Heat cramps are primarily caused by excessive sweating, which leads to the loss of essential electrolytes. When the body's electrolyte balance is disrupted, it can result in muscle cramps and spasms. The loss of sodium due to heavy or prolonged sweating is thought to play a significant role in the onset of muscle or heat cramps.1,3,4
Engaging in strenuous activities, especially in hot and humid weather, can increase the risk of developing heat cramps and other heat illnesses. Additionally, inadequate hydration, wearing excessive clothing that hinders sweat evaporation, and being unaccustomed to high temperatures can also contribute to heat cramps, heat exhaustion, or heat stroke.
Signs and symptoms of heat cramps
Heat cramps typically occur during or after physical activity in a hot environment and are often accompanied by profuse sweating and excessive thirst. The most common symptoms of heat cramps include:
- Intense muscle pain or spasms: The affected muscles may feel firm or lumpy to the touch. The pain can be sudden and severe, causing discomfort and limiting movement
- Involuntary jerking movements
- Excessive sweating
- Flushed skin
Heat cramps are typically diagnosed according to a physical exam and evaluation of the symptoms that a patient presents with. Your doctor will ask you about your medical history, recent activities, and exposure to extreme heat. In some cases, they may carry out blood tests to check for electrolyte imbalances or to rule out other possible causes of muscle cramps. If you are suffering from heat-related illnesses, your blood sodium levels can be low and your urine can become very concentrated, indicating dehydration.
Management and treatment for heat cramps
Heat cramps are usually fleeting, but they can last longer. They may also appear and disappear at random. Heat cramps may be self-limiting, but immediate action can reduce their severity. It can also prevent them from progressing to a more serious condition. The best way to manage heat cramps is to prevent them. This can be done by wearing weather-appropriate clothing, staying hydrated and reducing the intensity and frequency of physically exertive activities when it is hot outside.5,6
If you experience heat cramps, taking immediate steps to alleviate the discomfort and prevent further complications is important. Treatment with medications, including diazepam or magnesium and calcium supplements, is not effective for managing heat cramps.1 Research shows that pickle juice helps to reduce the duration of muscle cramp that occurs during exercise.5
- Rest in a cool environment: Move to a shaded or air-conditioned area to cool down and rest. Avoid continuing any strenuous activity until the cramps subside
- Hydrate: Drink plenty of fluids every 15-20 minutes, preferably water or a sports drink that contains electrolytes. Hydration helps replenish the lost minerals and prevents dehydration. It is especially important to stay hydrated during the summer when the temperatures are high
- Stretch and massage: Gently stretch and massage the affected muscles to relieve the cramps, relax the muscles and reduce pain
- Apply cool compresses: A cold compress or ice pack on the affected area can help reduce muscle inflammation and provide relief
Seek medical attention if you:
- Have a heart, respiratory, or kidney disease
- Are following a low-sodium diet
- Have cramps that do not go away after an hour
- High temperatures and humidity
- Engaging in prolonged, strenuous exercise or working in hot conditions without proper hydration and breaks
- Infants, young children, and older adults are more vulnerable to heat cramps due to their bodies' reduced ability to regulate temperature and fluid balance
- Poor adaptation to hot weather, especially after a long period of inactivity or exposure to cooler climates
- Muscular exhaustion
- Wearing extra layers of clothing, protective gear, or equipment
- Consuming a diet chronically deficient in sodium or other electrolytes. This is because sweating causes more electrolytes to be excreted out of the body. Hence, if they are already deficient in the blood, they can drop to dangerously low levels
- Medical conditions, including skin disorders, cardiovascular disease, diabetes mellitus, sickle cell trait, and infections
How can I prevent heat cramps?
Preventing heat cramps involves adopting certain measures to keep your body cool and well-hydrated. Drink plenty of fluids before, during, and after physical activity. Aim to consume electrolyte-rich beverages to replace the minerals lost through sweat. Additionally, if you're working or exercising in the heat, take regular breaks in shaded or air-conditioned places to cool down and wear loose-fitting, lightweight clothing that allows for better air circulation and evaporation of sweat. Furthermore, If you're not accustomed to hot weather, gradually increase your exposure to higher temperatures over several days to allow your body to adapt.
How common are heat cramps?
Heat cramps are common in people who engage in physical activity in hot environments.
When should I see a doctor?
Although heat cramps themselves are not fatal, they can also present in a more serious condition called exertional sickling. Seek immediate medical attention if you experience severe heat cramps, prolonged muscle spasms, dizziness, confusion, or a rapid heart rate as severe heat cramps can lead to heat exhaustion or heat stroke, which may be life-threatening.
Heat cramps are a common heat-related illness caused by physical exertion in hot environments. Symptoms include muscle pain, weakness, and excessive sweating. Infants, children and elderly people are more likely to suffer from heat cramps due to their limited ability to regulate body temperature and fluid levels. Individuals who lead a low-sodium diet, regularly engage in physical activity in the heat and who wear weather-inappropriate clothing are also at a high risk of experiencing heat cramps. Moving to a cool, shaded area, rehydrating with cool fluids, and gently stretching and massaging the cramped muscles are ways to manage heat cramps. Staying hydrated, taking frequent breaks in a cool place, and avoiding strenuous activity in hot weather help to prevent heat cramps. Seeking immediate medical attention may be necessary if the symptoms persist or worsen as this can be a sign of a more serious heat-related condition, like heat exhaustion or heat stroke.
- Leiva DF, Church B. Heat Illness. [Updated 2023 Apr 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553117/
- Périard, Julien D., et al. “Exercise under Heat Stress: Thermoregulation, Hydration, Performance Implications, and Mitigation Strategies.” Physiological Reviews, vol. 101, no. 4, Oct. 2021, pp. 1873–979. DOI.org (Crossref), https://doi.org/10.1152/physrev.00038.2020.
- Cheshire, William P. “Thermoregulatory Disorders and Illness Related to Heat and Cold Stress.” Autonomic Neuroscience, vol. 196, Apr. 2016, pp. 91–104. DOI.org (Crossref), https://doi.org/10.1016/j.autneu.2016.01.001
- Leyk, Dieter. “Health Risks and Interventions in Exertional Heat Stress.” Deutsches Ärzteblatt International, Aug. 2019. DOI.org (Crossref), https://doi.org/10.3238/arztebl.2019.0537.
- Maughan, Ronald J., and Susan M. Shirreffs. “Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining.” Sports Medicine, vol. 49, no. S2, Dec. 2019, pp. 115–24. DO.org (Crossref), https://doi.org/10.1007/s40279-019-01162-1.
- Sorensen, Cecilia, and Jeremy Hess. “Treatment and Prevention of Heat-Related Illness.” New England Journal of Medicine, edited by Caren G. Solomon, vol. 387, no. 15, Oct. 2022, pp. 1404–13. DOI.org (Crossref), https://doi.org/10.1056/NEJMcp2210623.