Why Do Humans Get Cramps When Exercising?

When you run or jump, your muscles work really hard. Sometimes they get so tired that they tighten up and hurt, that's a cramp! It feels like your leg is stuck in the middle of a hug it doesn't want to finish.

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Examples

A runner's legs seize up like they're stuck in a tight hug.
Swimming for too long causes a cramp in your calf that feels like it’s being squeezed by a giant hand.
During a bike ride, your thigh muscles suddenly tighten and hurt like they’re holding on to something they don’t want to let go of.

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Categories: Health · exercise· cramps· muscles· science· health