Prevent a 'Charley Horse'

A 'charley horse' is a painful muscle spasm that occurs most often in the legs. It begins suddenly and may cause severe pain when the muscle won't relax.

Proper preparation before exercise can help prevent charley horses. The U.S. National Library of Medicine offers these suggestions:
Stretch properly and thoroughly before any exercise.
Stay hydrated by drinking plenty of fluids before and after exercise.
Include plenty of potassium in your diet. Orange juice and bananas are excellent sources.
Don't overexert yourself and strain your muscles, which could cause spasms.