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Heat Cramps

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Other Names

  • Heat Cramps
  • Sweat Cramps


  • This page refers to heat cramps, a heat related illness


  • Described as early as 1878 in men working in Nevada gold mines
  • First described in the literature by Talbott in 1932[1]


  • Not well described


  • General
    • Occurs from diffuse sweating, loss of sodium chloride, replacing fluid loss with water
    • Most commonly occurs in the hours following exercise
    • Most athletes will have resolution with oral isotonic fluids
  • Climate
    • Typically occurs in warm, humid environments
    • Can be seen in winter months in some sports (hockey goalies, cross country skiing, etc)


  • General[2]
    • Not entirely understood
    • Believed to be due to relative dehydration and loss of sodium from sweating
    • Hyponatremia is likely exacerbated by hypotonic fluid replacement
    • Magnesium, calcium, potassium also lost but are primarily intra-cellular and do not contribute to cramping
  • Hyponatremia
    • Sodium plays a critical electrolyte in the balance of net charges across a neuron's membrane
    • Plays a vital role in maintaining baseline neuro-excitability across neurons
    • Hyponatremia alters the net charge across the cell membrane, increases neuron excitability
    • Increased excitability thought to trigger the sustained, inappropriate skeletal muscle contractions seen in cramping.
  • Dehydration[3]
    • May also be enough to trigger cramping
    • Occurs through alteration in the relative concentration of interstitial sodium and neurotransmitters,
    • Subsequently, athletes develop hyperexcitability and cramping

Associated Conditions

  • Exercise Associated Muscle Cramps (EAMC)
    • Seperate clinical entity
    • Heat cramps ikely represents the extremy end of muscle cramping seen in athletes
  • Heat Exhaustion
    • Some authors consider heat stroke to be a symptom of heat exhaustion rater than a seperate clinical entity[4]

Risk Factors

Differential Diagnosis

Differential Diagnosis of Muscle Cramps

Differential Diagnosis Heat Illness

Clinical Features

  • History
    • Patient will report painful, involuntary, spasmodic muscle contractions
    • Cramps may be brief or sustained (seconds to hours)
    • Typically involves calves, then thighs and shoulders
  • Physical Exam
    • Cramping is often obvious on exam with increased involuntary muscle tone
    • Intense pain is exhibited by the athlete while the contraction is sustained
    • The patient should be neurologically intact


  • Clinical diagnosis
    • Expanded workup may be indicated if clinical picture is not clear


  • Not applicable


  • General
    • Self limited condition
    • Remove athlete from game or practice
    • Rest in a cool environment
  • Stretching and massage
    • Muscle stretching and massage can help
    • Affected muscle should be held at length until the contraction resolves with a slow full stretch
  • Hydration
    • Mild: isotonic sports drinks or electrolyte enhanced drinks
    • Severe: IV isotonic fluids
    • Avoid hypotonic fluids such as water, which can worsen hyponatremia
    • Home remedy: 1 quarter tablespoon of salt, 2 tablespoon of sugar, 500 cc of water[5]
  • Pain/ Muscle relaxant
    • May require enteral or parenteral analgesia
    • In prolonged or refractory cases, benzodiazepines may be indicated
  • The following lack evidence for use
    • Calcium tablets
    • Pickle juice
    • Bananas
    • Dextrose
    • Sodium bicarbonate
    • Quinine


  • General
    • Drink isotonic electrolyte solutions during work, sport or practice[4]
    • Increase dietary salt
    • Add salt to sports drink
    • Become acclimated with training environment
  • Sweat rate
    • All athletes should know their sweat rate (weight lost per hour of exercise + fluid consumed per hour during exercise)
    • Provides rough estimate of how much fluid should be ingested between events, sessions, games, etc

Rehab and Return to Play


  • No specific rehabilitation protocol
    • Passive stretching
    • Massage therapy

Return to Play/ Work

  • General
    • Once cramping has resolved, assess for any injuries or systemic symptoms of hyponatremia
    • Athlete may return to play if exam is reassuring
    • The athlete should be counseled that same day recurrence is very high and may precipitate other injuries
    • If benzodiazepines are administered, the athlete should not return to play the same day

Complications and Prognosis


  • Generally considered a self limited condition with no long term sequalae
  • Lost playing time
    • Common cause


See Also


  1. Talbott J.H., Michelsen J. Heat cramps. A clinical and chemical study. J Clin Invest. 1933; 12: 533-549
  2. Poynter, D. (2010). Heat Cramps: Treatment and Prevention. Athletic Training and Sports Health Care, 205-207.
  3. Schwellnus MP, D. N. (2008). Muscle cramping in athletes–risk factors, clinical assessment, and management. Clinical Sports Medicine, 27(1):183.
  4. 4.0 4.1 Donoghue, A., M.J. Sinclair, and G.P. Bates. Heat exhaustion in a deep underground metalliferous mine. Occup. Environ. Med. 57:165-174, 2000.
  5. Armstrong LE, Casa DJ, Millard-Stafford M, Moran DS, Pyne SW, Roberts WO. American College of Sports Medicine position stand: Exertional heat illness during training and competition. Med Sci Sports Exerc. 2007; 39:556–572.10.1249/MSS.0b013e31802fa199
  6. Waters T. Heat Emergencies In: Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. McGraw Hill Medical. 2011: 1339-1344
Created by:
John Kiel on 30 June 2019 22:49:39
Last edited:
18 September 2022 00:26:04