Have you ever turned over in the middle of the night and suddenly felt a painful cramp in your leg?

Night cramps can strike almost anyone; particularly susceptible are those who have spent the day exercising strenuously or those who have engaged in some unusual outdoor activity such as hiking or cycling.

Their most common cause is an exaggeration of a normal body reflex. When you turn during sleep, the tendons attached to your muscles stretch. Then the muscle contracts. If it stays contracted, you'll have a painful cramp.

When you get a cramp, you should immediately stretch, knead and heat the cramped muscle. Stretching will exhaust the tendon reflex while kneading and heating will increase the flow of blood to the muscle, helping it to relax.

Prevent night cramps by exhausting the stretch reflex before you go to bed. For the calf muscle, stand facing wall from a few feet away. Place both hands on the wall at shoulder height. Keeping heels on the ground, slowly bend elbows to lean closer to the wall. Repeat 20 times.

Night cramps also can be caused by pinched nerves and blocked blood flow. If they happen frequently, see a doctor.

Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.