A muscle cramp is a sudden, involuntary, painful contraction of a muscle. They are usually self-extinguishing within seconds to minutes. ¹

Cramps can sometimes be the symptom of a nervous system or metabolic disorder, however, they often occur in healthy subjects with no history of such disorders.¹ The latter are what we may call “benign cramps'' and these will be the focus of this article.  Benign cramps often occur during sleep, pregnancy, and strenuous physical exercise. 

Muscle cramping during or immediately after physical exercise was first reported more than 100 yr ago in miners working in hot and humid conditions. Dehydration (and/or electrolyte depletion) often is given as an explanation for muscle cramps occurring in workers and athletes, although this claim is not supported by scientific evidence.¹

The main risk factors for exercise-associated muscle cramps include family history of cramping, previous occurrence of cramps during or after exercise, increased...