Most people have experienced a cramp (also known as a charley horse). It occurs when, out of the blue, a muscle contracts violently and will not let go until it is good and ready.

A cramp usually comes as a surprise and can drop even the strongest athlete to their knees. Cramps can happen during or after exercise – up to six hours later – and during sleep (called night cramps). A cramp can last mere seconds or up to 10 minutes, and the muscle can be sore up to 24 hours later.

What Causes Cramps?

Who knows?! The cause is often unknown, but overusing a muscle is one of the most common causes. One theory that seems reasonable to me is that we need more fluid – simple dehydration. We also really need sodium and potassium.

When we sweat too much, the fluid that bathes the connection between the muscle and nerve is depleted of sodium and potassium, so the nerve becomes hypersensitive.

There are medical reasons cramps occur, particularly in adults, so they should not be brushed off – especially if they are recurring.

Narrowed blood vessels, usually from atherosclerosis (hardening of the arteries), and compression of a nerve – possibly from spinal stenosis, hypothyroidism or potassium deficiency – can cause cramps, as can medications like diuretics used to lower blood pressure.

What Can You do About Cramps?

Finding out what you can do is more important than finding out the cause of the cramp. Everyone seems to have an answer about how to take care of your cramp. Here are a few:

• Drink plenty of water.
• Stretch before and after exercise.
• Massage the cramped muscle.
• Apply heat, like a warm towel, to tighten muscles, and something cold to sore muscles.

Who Can Get Cramps?

Preteens and teens who are growing a lot seem to get more cramps, which is not really explained by any of the common explanations. Cramps are not worrisome unless they happen frequently. Ask your doctor if you're worried.

If they happen at night, try stretching your legs before bed – particularly the calf muscles. Keep your blankets loose around your feet. Don't sleep with your knees bent and your toes pointed down – which shortens the calf muscles.

Written by: Adolescent Interest Group

Reviewed by: Jen Hawkins, MPH

Last reviewed: September 2019