Today’s Wonder of the Day was inspired by Skylar. Skylar Wonders, “Why do people get cramps?” Thanks for WONDERing with us, Skylar!

Sometimes they happen when you least expect them. You're jogging around the track during gym class or you're doing drills at volleyball practice and…BAM!...your leg muscle seizes up. The pain can be so intense that it takes your breath away.

What just happened? Does your leg hate you? Is your leg going to fall off? Nope! It's probably just a muscle cramp.

Muscle cramps can occur in just about any of the muscles in your body. While cramps in the legs are quite common, it's not unusual to get cramps in your arms or sides. The most common areas for muscle cramps are the calves, thighs, feet, hands, arms, and abdomen.

Muscle cramps often occur when you're exercising. However, as anyone who has ever had growing pains can tell you, they can also occur at night when you're sleeping.

A muscle cramp is an involuntary contraction of a muscle. This means that it happens without your control. The muscle contracts — gets smaller — and hardens. It often stays that way for several seconds to several minutes, causing pain that can sometimes be severe.

Muscle cramps often won't go away on their own. You may need to stretch and massage the muscle to get it to relax and go back to normal. Sometimes when you move immediately after a muscle cramp, the muscle will cramp again. You may have to stretch and massage it repeatedly before the cramp goes away for good.

Even though muscles have been around for as long as animals have existed, doctors still don't know exactly what causes muscle cramps. Doctors now believe some of the main factors causing muscle cramps include dehydration, low levels of electrolytes, being out of shape, and muscle fatigue.

Muscle cramps often occur when exercising in extreme heat. When you exercise in really hot weather, you sweat a lot. That sweat contains fluid and electrolytes, so your body becomes dehydrated while your muscles lose needed electrolytes. That's why it's important to stay hydrated when you're exercising. If you're going to be sweating a lot, you might also want to consider a sports drink that replenishes needed electrolytes!

Wonder What's Next?

Join us in Wonderopolis tomorrow for a look at a famous female factory worker!