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 humans 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!

44 Join the Discussion

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    • Hi there, yoseph! We’re glad you learned something new about cramps and how to prevent them! It’s about the science of our bodies– salt is necessary, as well as water, to keep our muscles cramp-free! Thanks for WONDERing with us today! :-)

  1. Hi there. I am in Mrs. Hess’ class and I wonder why some old people have been cramp on their muscles. I wish people exercise to make their muscles strong!

    I think tomorrow’s Wonder is about rules in the world! I CAN’T WAIT TOMORROW’S WONDER!

    • Hi there, Kathy! Thanks for visiting us today! We learned that exercise and stretching help those muscle cramps, but age has a lot to do with it, too! Drinking water and eating healthy can also help! Thanks for joining us today– we’ll see you tomorrow! :)

    • Thanks for WONDERing with us, Isaiah! We bet you can find out how to prevent cramps and keep your body nice and healthy by checking out today’s Wonder content! Keep up the great work! :-)

    • We’re so very glad you learned something new with us, Kathy! We hope your muscles don’t cramp… but if you do, you’ll know what to do! :)

  2. That is always happened to me when I’m sleeping, such a PAIN :( Maybe I should do some exercise!
    I think tomorrow’s wonder will be about food rules :-)

  3. Hi wonderopolis I read that the place that receives the most cramps is the leg, but I get my cramps mostly in my abdomen when I run or do many movements like dancing. Why does this happen?

    • We get cramps in all different muscles, depending on what we do, Emily! Keep stretching, and drinking lots of water, too! Thanks for WONDERing about muscles with us today! :)

  4. I do not really drink pickle juice yuck! But it is good that you do not have to drink too much of it. I enjoy wondering with you. Thanks for evrything!

    • That’s okay, Blakeleigh! While pickle juice may not be your favorite thing to drink (it’s not ours, either), it can help in the case of muscle cramps. You can prevent muscle cramps in other ways, too! Thanks so very much for WONDERing with us– we enjoy your company! :)

    • Hi there, James! We’re sorry to hear that our cramping Wonder wasn’t one of your favorites, but we’re glad you’re here! Do you have a favorite new fact you learned today? :)

    • Cramps are no fun at all, we agree, Jusin! That’s why it’s important to drink lots of water and stretch after exercising! We are glad you asked about our picture! You can get an avatar, or picture, with the help of an adult or computer teacher. We bet you can find some more information about it on the Internet! :)

    • Oh no, Wonder Friend Jon! We’re sorry to hear that! We hope you continue to drink lots of fluids and stretch after you exercise or play a sport! The next time you are feeling cramped, try talking to an adult or parent about those cramps. Perhaps a trip to the doctor will help you understand why your body is cramping up! :)

    • Great question, Reagan! Cramps can be caused from many different things, but usually muscle cramps can be eased with some salty and water (like pickle juice)! Thanks for sharing your comment! :)

  5. I’ve never had a muscle cramp and wonderopolis I thought these videos would be more educational but I still love when will pigs fly thanks wonderopolis by the way what are your names so I can thank you all?

    • Hey there, Wonder Friend Chamani! We’re glad you haven’t been cramping– your muscles are in great shape and you have been drinking enough water! Good for you! :) There are LOTS of Wonder Friends who read all these awesome comments we receive, and lots of us respond to you! We are so very glad you have visited us today, and we look forward to WONDERing with you again soon! :)

  6. We would like to know, what is it in the pickle juice that relieves muscle cramps? Are there other drinks that you can drink to make your cramps go away as fast as pickle juice?

    • Hello Wonder Friends in Mrs. Higgins’ Class! Thanks for visiting Wonderopolis today, we are so glad you’re here! Pickle juice is a way to combat dehydration. When your body doesn’t have enough sodium in it (perhaps you’ve been sweating a lot and you’ve sweat out the sodium), pickle juice can help! Some athletes eat chips after a big race. The saltiness of the chips helps them retain water! :)

  7. I get cramps just putting a shirt on. Found out I had celiac disease. It prevents your body from absorbing nutrients from your food. Explains why I get tired, can’t focus, and I dehydrate a lot faster than most.

    • Hi there, John, we’re so glad that you and your doctors have discovered why you have been feeling tired often! We bet you have certain foods that are important to eat, and some that you should stay away from. It’s good to know that you are on the road to feeling better and living a healthy lifestyle! Many kids and adults have found out they have celiac disease and are doing a great job taking care of their bodies. We are proud of you for sharing your comment John, and we have a Wonder just for you: Wonder #676– What is Gluten? :)

  8. Hi, I get muscle cramps even though I drink alot of Powerade, and I’m very healthy.
    I also play travel soccer so I’m always running. What do you think?

    • Hi Graham! Muscle cramps will especially happen if you’re using your muscles in sports like you are! It’s definitely not a bad thing to get them as long as you’re hydrated! Thanks for WONDERing with us! :)

    • That’s right, Caiden! Overworked, and strained muscles can also cramp. However, be sure to drink lots of water and stretch before exercising to help prevent muscle cramps. Thanks for WONDERing with us today! :-)

  9. Wow! I didn’t know that you can get cramps from being dehydrated, Its amazing what the human body can do these days, I also didn’t know that the body can also get cramps when its in need of electrolytes! If you gets cramps like that then…. Does that mean that thing you’re parents tell you like “Wait at least 30 minutes before you go in the water!” is a myth? Or does that mean you’re in need of electrolytes? Also i have a question, I’ve been getting a sharp pain in my spine from time to time It doesn’t happen like 24/7 it sometimes just strikes me, what do you think that means? Thanks for the fascinating facts!

    • Thanks for WONDERing with us, Isabella! If you have a sharp pain in your spine, it’s best to see a doctor about it. A doctor can get to the bottom of the situation and help ensure you stay in tip-top shape! :)

    • Ouch! That’s no good, Brook! We hope this Wonder of the Day has given you some tips for preventing and alleviating muscle cramps! :)

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Have you ever wondered…

  • Why do your muscles cramp?
  • How should you treat muscle cramps?
  • Can you prevent muscle cramps?

Wonder Gallery

CrampsVimeo Video

Try It Out

Ready to learn more about your muscles? Find a friend or family member and enjoy one or more of the following activities:

  • Do you know where your main muscles are? Do you know their names? Check out this online muscle map and learn where your muscles are and what they’re called. For fun, use a washable marker to write the names of muscles on your body!
  • Do you ever get muscle cramps? If so, it can be helpful to know what to do when you get them. It’s also good to know how to prevent them from happening in the first place. Cramps will eventually go away on their own, but there are a few things you can do to help them go away faster. First, stop whatever you were doing that led to the cramp. Take some time to stretch the muscle that is cramping. Massaging the muscle while you stretch it can help, too. To prevent cramps from occurring in the first place, improve your overall level of fitness. When you’re more fit, your muscles don’t get as tired and you’ll have fewer problems with cramps. It will also help if you warm up and stretch before you exercise. Getting your muscles ready for exercise will help them perform better and cramp less. You should also drink plenty of water. Staying properly hydrated will help your entire body perform to the best of its ability.
  • Older children, especially those who are active in sports, may want to begin building bigger muscles to increase performance and decrease the chance of muscle cramps. Take some time to think about the activities or sports you engage in regularly. Which muscles need to be in tip-top shape? Check out these basic strength-building exercises you can do at home without weights to work on various muscle groups. Create a basic plan consisting of a few exercises you can use to work on the muscle groups you want to make stronger!

Still Wondering

Check out Science NetLinks’ Muscles interactive to learn all about the human muscular system, including a review of muscle location and a visual interactive of how the muscle moves a body area.

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