Muscle cramps are sudden, involuntary contractions that occur in various muscles. These contractions are often painful and can affect different muscle groups.

Commonly affected muscles include those in the back of your lower leg, the back of your thigh, and the front of your thigh.

You may also experience cramps in your:

• abdominal wall
• arms
• hands
• feet

The intense pain of a cramp can awaken you at night or make it difficult to walk.

Causes of muscle cramps

Muscle cramps have several causes. Some cramps result from overuse of your muscles. This typically occurs while you’re exercising.

Muscle injuries and dehydration can also trigger cramps. Dehydration is the excessive loss of fluids in the body.

Low levels of any of the following minerals that contribute to healthy muscle function may also cause muscle cramps:

• calcium
• potassium
• sodium
• magnesium

Low blood supply to your legs and feet can cause cramping in those areas when you exercise, walk, or participate in physical activities.

In some cases, a medical condition can cause muscle cramps. These conditions include:

• spinal nerve compression, which can cause muscle cramps in your legs when walking or standing
• alcoholism
• pregnancy
• kidney failure
• hypothyroidism, or low thyroid gland function

Other times, the cause of muscle cramps is unknown.