Here are the theories:
http://www.nytimes.com/2008/02/14/he...on/14BEST.html
Cramping is still pretty much a mystery; mostly because no one has really studied the issue.
There are three leading hypotheses about how to treat cramps and how to prevent them.There’s the dehydration proposal: you just need more fluid. But, Dr. Schwellnus said, he studied athletes who cramped and found that they were no more dehydrated before or after a race than those who did not have cramps.
Then there’s the electrolyte hypothesis: what you really need is sodium and potassium.
Michael F. Bergeron, who directs the environmental physiology laboratory at the Medical College of Georgia, said the electrolyte hypothesis applies to a specific type of cramp that is related to excessive sweating. It occurs, he said, when the fluid that bathes the connection between muscle and nerve is depleted of sodium and potassium, which was lost through sweat. The nerve then becomes hypersensitive, Dr. Bergeron said.
“Usually you feel little twitches first,” he explained. “They last for 20 to 30 minutes and if you don’t do anything you can be in full-blown cramps.” Those cramps, he continued can move from place to place on your body, from one leg to the next, to your arms, stomach, even your fingers or your face.
The solution, Dr. Bergeron said, is to drink salty fluids like Gatorade (the company sponsors his research). He said he had prevented cramps in tennis players this way.
But asked whether there are any rigorous studies to confirm this hypothesis, he said no. “We haven’t done the study yet,” he said. “We’re at the point of kind of connecting the dots.”
The third hypothesis is advanced by Dr. Schwellnus. He questions the electrolyte hypothesis because his studies of Ironman-distance triathletes as well as other studies of endurance athletes found no difference in electrolyte levels between those who suffered cramps and those who did not.
DR. SCHWELLNUS proposes that the real cause of cramping is an imbalance between nerve signals that excite a muscle and those that inhibit its contractions. And that imbalance, he said, occurs when a muscle is growing fatigued.
His solutions for cramps are to exercise less intensely and for shorter times, to be sure you had enough carbohydrates to fuel your muscles, to train sufficiently and to regularly stretch the muscles that give you problems. These recommendations are based on his recent study of Ironman triathletes, Dr. Schwellnus said.
But while he advocates those practices, he said, they have not been proved in a rigorous study.