How to prevent muscle cramps?

Activity: Authorities recommend stretching before and after cramps that are caused by vigorous physical activity, along with an adequate warm-up and cool down. Good hydration before, during, and after the activity is important, especially if the duration exceeds one hour, and replacement of lost electrolytes (especially sodium and potassium, which are major components of perspiration) can also be helpful. Excessive fatigue, especially in warm weather, should be avoided.
Drinking water

Pre-exercise
1. 0.5 liters per hour for a 180-pound person several hours (three to four hours) prior to exercise.

2. Consuming beverages with sodium and/or small amounts of salted snacks or sodium-containing foods at meals will help to stimulate thirst and retain the consumed fluids.

During exercise:
1. Suggested starting points for marathon runners is 0.4 to 0.8 liters per hour, but again, it should be individualized based on body weight loss.

2. There should be no more than 10% carbohydrate in the beverage, and 7% has generally been considered close to optimal. Carbohydrate consumption is generally recommended only after one hour of exertion.

Post-exercise:
1. Drink approximately 0.5 liters of water for every pound of body weight lost.

2. Consuming beverages and snacks with sodium will help expedite rapid and complete recovery by stimulating thirst and fluid retention.