Science Questions

Why does one get cramp?

Sun, 11th Jan 2009

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Question

Ian asked:

Why does one get cramp?

Answer

Chris - Cramp is a muscle spasm and we donít actually know what cramp is.  We just know that if people have regular cramps Ė and it tends to happen quite often at night and it tends to happen in younger people more often than older people and it tends to be relieved with quinine, the same stuff that makes tonic water taste nice. A muscle spasm is when some of the muscle fibres Ė because a muscle isnít just one homogeneous giant thing. Itís actually made up of lots of individual little muscle fibres. Some of those muscle fibres go into a spasm. In other words, the contract more than they should and they lock in a contracted state. Surprisingly, muscle actually takes energy to relax, not to contract. When a body of a person dies, they go into rigor mortis because the cells in their muscles run out of energy and their muscles canít relax and they stay rigid. Thatís why a person gets rigor mortis. If you leave them a bit longer then the rigor mortis goes away again when the muscle breaks down and starts to relax. What cramp could be is for some reason that clutch of muscle fibres donít have enough energy in them, perhaps because thereís been a reduction in blood flow thatís insufficient for the muscles needs. Therefore the muscle runs a little bit short of energy and this trips its inability to relax properly and you get a cramp. Rubbing a muscle and massaging it to get the blood through it can make it better.

Zanzibar Rothschild, in Second Life - Bananas are good for cramps. Could it be down to potassium?

Chris - could be but I donít know for sure. I know that if you donít have enough potassium then you can end up with excitable cells in that way and this can lead to muscle spasms so thatís a possibility.

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