A painful, involuntary skeletal muscle contraction. This may occur at rest or during exercise, is asymmetrical, and usually affects the gastrocnemius muscle and small muscles of the foot. Ordinary muscle cramps are not due to fluid or electrolyte abnormality. These cramps begin when a muscle already in its most shortened position involuntarily contracts.
Painful involuntary contractions of muscles. They may be due to ischemia of the muscle(s), dehydration, or electrolyte imbalance.