Although exercise-associated muscle cramps (EAMC) are common in ultradistance runners and athletes in general, their etiology remains unclear. EAMC are painful, sudden, involuntary contractions of skeletal muscle occurring during or after exercise and are recognized by visible bulging or knotting of the whole, or part of, a muscle. Many clinicians believe EAMC occur after an imbalance in electrolyte concentrations, specifically serum sodium concentration ([Na+]s) and serum potassium concentration ([K+]s). Studies that have established a link between EAMC occurrence and serum electrolyte concentrations after an athletic event are unhelpful.
Focused Clinical Question:
Are [Na+]s and [K+]s different in athletes who experience EAMC than noncrampers?
Murray is with the Dept of Rehabilitation Science, George Mason University, Fairfax, VA. Miller is with the Dept of Rehabilitation and Medical Sciences, and Edwards, the Exercise and Health Sciences Div, Central Michigan University, Mount Pleasant, MI.