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Recently, 10 healthy male college students filed into an exercise laboratory at Brigham Young University in Utah to drink pickle juice. Many people involved in sports are convinced that the briny fluid combats muscle cramping. In a 2008 survey, a quarter of the athletic trainers interviewed said that they regularly dispense pickle juice to cramp-stricken athletes. Many also report that, in their experiences, the stuff quickly brakes the cramping. The athletic trainers have told researchers that they believe the pickle juice must be replenishing the salt and fluids the athletes had lost to sweat. But no laboratory science had verified that theory.

The Utah volunteers began with a series of 30-minute bicycling sessions, using a semi-recumbent bicycle, configured so that only leg pedaled. The laboratory was warm, increasing the amount the exercising men sweated. Each cycled in 30-minute bouts (with five minutes of rest between) until each had lost 3 percent of his body weight through perspiration, a widely accepted definition of mild dehydration.

The young men were then fitted with a contraption on the big toe of their unexercised leg, and the tibial nerve in the men’s ankles was electrically stimulated, causing a muscle in the big toe to cramp. (The procedure causes some discomfort, making it too painful to use on larger muscles, like the hamstrings or the quadriceps.) The volunteers were told to relax and let the cramps run their course. The average duration of the cramps was about two and a half minutes.

The volunteers rested and did not drink any fluids. Then their tibial nerve was zapped again. This time, though, as soon as the toe cramps began, each man downed about 2.5 ounces of either deionized water or pickle juice, strained from a jar of ordinary Vlasic dills. The reaction, for some, was rapid. Within about 85 seconds, the men drinking pickle juice stopped cramping. But the cramps continued unabated in the men drinking water. Pickle juice had “relieved a cramp 45 percent faster” than drinking no fluids and about 37 percent faster than water, concluded the authors of the study, which was published last month on the Web site of the journal of the American College of Sports Medicine.

Exercise-induced muscle cramps are one of the continuing mysteries of physiology. Extremely pervasive, they afflict most active people at some point. But scientists remain deeply divided about what causes the cramping. For years, most people, inside and outside academia, believed that cramping was caused by sweating-induced dehydration and the accompanying loss of sodium and potassium. Sufferers were advised to load up on potassium-rich bananas or chug large amounts of salty sports drinks.

But a number of laboratory and field studies in recent years have undermined the dehydration theory. The most recent, completed by the same group of scientists who studied pickle juice, employed a similar study design. A group of college students had cramps induced in their toes. They then pedaled with one leg until dehydration set in. Their toes were made to cramp again, Presumably if dehydration were the underlying cause of the cramping, the scientists should have been able to induce a cramp with less electrical stimulation when the men were dehydrated; their muscles should have been primed to cramp. But the experiment didn’t work out that way. As detailed last month in the journal Medicine and Science in Sports and Exercise, the scientists had to use the same amount of stimulation to induce a cramp after dehydration as they had before. Their conclusion? “Exercise-induced cramps occurring to athletes” who are mildly dehydrated “were likely not caused by dehydration,” says Kevin C. Miller, Ph.D., ATC, the lead author of both studies and now an assistant professor in the Athletic Training Education Program at North Dakota State University in Fargo.

What, then, does probably cause athletes to cramp? The pickle-juice experiment provides some intriguing clues. “The pickle juice did not have time” to leave the men’s stomachs during the experiment, Mr. Miller points out. So the liquid itself could not have been replenishing lost fluids and salt in the affected muscles. Instead some other mechanism must have initiated the cramps and been stymied by the pickle juice.

Mr. Miller suspects that that mechanism is exhaustion, either directly or through biochemical processes the accompany fatigue. Certain mechanisms within muscles have been found, in animal and limited human studies, he says, to start misfiring when a muscle is extremely tired. Small nerves that should keep the muscle from overcontracting malfunction and the muscle bunches when it should relax. Pickle juice may work, Mr. Miller says, by countermanding the malfunction. Something in the acidic juice, perhaps even a specific molecule of some kind, may be lighting up specialized nervous-system receptors in the throat or stomach, he says, which, in turn, send out nerve signals that somehow disrupt the reflex melee in the muscles. Mr. Miller suspects that, ultimately, it’s the vinegar in the pickle juice that activates the receptors. In a recent case report by other researchers, a single athlete’s cramping was relieved more quickly when he drank pure vinegar (without much pleasure, I’m sure) than when he drank pickle juice.

At the moment, speculation about the powers of pickle juice remains just that, speculative. “It’s extremely challenging” to induce realistic sports cramps in the lab, Mr. Miller says. His technique, of causing the big toe to spasm, while useful, can’t fully replicate what happens in larger, stronger leg muscles during a cramp. Still, the work is suggestive and, perhaps most important, implies methods for finding relief. “If muscle fatigue is the cause,” he says, then training properly, building up your mileage slowly and perhaps adding strength training that focuses specifically on muscles that have cramped in the past, may help. In the meantime, if your calf or other muscle suddenly, painfully catches, “try stretching it,” Mr. Miller says. Doing so has been found in laboratory studies to significantly shorten the duration of a muscle cramp, most likely by shaking up and resetting the misfiring muscle and nerve reflexes. And perhaps, if you can stomach the idea, pack a few ounces of pickle juice on your next training session. It’s not as palatable as bananas, but unlike them, “it seems to work,” Mr. Miller says.