II. Epidemiology
- Acclimatized athletes and laborers at end of work
III. Pathophysiology
- Hyponatremia and volume depletion from profuse sweating and replacement with hypotonic fluids
- Provoked by Muscle overload or Fatigue, Dehydration or Electrolyte disturbance
IV. Risk Factors
- See Heat Illness Risk Factors
- See Medications Predisposing to Heat Illness
- Athletes
- Field workers
- Roofers
- Steel Workers
- Coal Miners
V. Symptoms
- Symptom onset during or after exertion
- Brief, intermittent painful Muscle Contractions or cramps (esp. larger Muscle groups)
- Abdominal Muscles
- Gastrocnemius (Calves)
- Quadriceps
- Hamstrings
- Associated symptoms
- Increased thirst
- Excessive sweating
- Sinus Tachycardia
VI. Signs
- Distinguish from Heat Exhaustion
- Findings of Heat Stroke are absent
- Normal mentation and
- Core Temperature <104 F
VII. Labs
- Labs are not indicated in most cases of isolated Heat Cramps
- Consider lab testing if systemic symptoms suggest associated Heat Exhaustion
- Basic chemistry panel (chem8)
- Creatinine phosphokinase (CPK)
VIII. Management
- Rest
- Oral hydration with Electrolyte replacement (salt containing solution)
- Stretching and massage of cramping Muscles
IX. Prevention
- See Heat Illness Prevention
- Prior to work or Exercise:
- Adequate Stretching
- Adequate water intake
- With Exercise (especially longer than 1 hour)
X. References
- Czerkawski (1996) Your Patient Fitness 10(4): 13-20
- Salinas and Ruttan (2017) Crit Dec Emerg Med 31(9): 3-10
- Sandor (1997) Physician SportsMed, 25(6):35-40
- Zink (2020) Crit Dec Emerg Med 34(3): 19-27
- Barrow (1998) Am Fam Physician 58(3):749-56 [PubMed]
- Gauer (2019) Am Fam Physician 99(8):482-9 [PubMed]
- Hett (1998) Postgrad Med 103(6):107-20 [PubMed]
- Wexler (2002) Am Fam Physician 65(11):2307-20 [PubMed]