Muscle cramps happen when your muscles contract without you wanting them to. Muscles contract when they get messages from motor neurons (nerve cells that talk to muscles). These neurons fire because of sodium going into the cell. Potassium has to leave in order to stop the message and let the muscle relax again. The entire process is fairly complicated and has to do with the concentrations of sodium and potassium and their charges.

You need the right balance of sodium, potassium, and water for all of this to work right. Your body is good at keeping things in balance as long as you get enough water. Most muscle cramps are caused by dehydration (lack of water). Americans usually get way more sodium than they need. Bananas and potatoes can help if you are low on potassium.

Low calcium and magnesium can also cause cramps. Your muscles need calcium in order to relax.

Great question!I like to run a lot, and I have often wondered the same thing about potassium and cramping. Potassium is an electrolyte, along with sodium, magnesium, calcium, and other minerals. If you ever drink Gatorade or another sports drink, you will probably see the term electrolyte somewhere on the bottle. Electrolytes are charged ions, which are really important to help muscle cells work properly. When you exercise you can lose both water and electrolytes when you sweat, and this messes up how well your muscles will function leading to the contractions we know as cramps.

Other things besides potassium and electrolytes can affect cramping. Sometimes something as simple as stretching will help cure a cramp. But is it definitely a good thing to keep a healthy diet that includes potassium, and taking both water and electrolytes when you exercise can help prevent cramping.

Potassium works with sodium to help your body maintain a proper water and electrolyte balance. Potassium helps cells uptake certain molecules and if potassium is lacking then the cells cannot work properly. When exercising, you sweat and with that sweat you lose water, sodium and potassium. Muscles need water, sodium and potassium in the correct concentrations in order to work properly. If there is excessive perspiration, then dehydration occurs and the muscles cannot perform properly, thus a cramp. Potassium on its own does not prevent cramping, but is a key component of the electrolyte balance.