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VIDEO: The Cramping Myth

Posted by: on October, 20 2015

Found on Competitor.com by Matt Fitzgerald


In 1932, John Talbott, a physician with the Fatigue Laboratory at Harvard University, traveled to Nevada in hopes of figuring out why some of the workers involved in building the Hoover Dam suffered from muscle cramps. In historic accounts of his work, Talbott observed that cramping workers had lost high levels of body fluid and electrolyte minerals through sweat. He noted also that the cramps seemed to abate when the workers were given intravenous saline and salted milk to drink. On the basis of these observations, Talbott concluded that working in the heat caused muscle cramps due to dehydration and electrolyte loss.

It was a reasonable assumption. For decades, Talbott’s theory of muscle cramps helped form the basis of treatment. Generations of athletes were taught to prevent muscle cramps by ingesting plenty of fluid and electrolytes during exercise. But for many, these measures brought little relief.

Cathy Harris, a trail runner and mother from northern California, is a typical case. About 15 miles into almost every race, she experiences debilitating muscle cramps in her calves. “I feel like I’ve tried everything to prevent or cure them,” she says. “I run with a hydration pack and drink plenty. I use salt tablets liberally during races, as well as homeopathic leg cramp tablets. I apply magnesium cream to my legs before and during runs.”

Recent science explains why. In a 2005 study, for example, researchers at the University of North Carolina supplied volunteers who had a history of muscle cramps with plenty of fluid and electrolytes in an effort to prevent cramps from occurring during a prolonged workout in a hot environment. Despite these measures, 69 percent of the volunteers cramped anyway.

What was the story here? Dr. Rod MacKinnon, a Nobel Prize-winning neuroscientist, began to ask the question after an event that occurred off the coast of Cape Cod in 2010. He was enjoying a long-distance sea kayaking excursion when his arms seized up. MacKinnon was surprised by the cramps because he had taken pains to stay well-hydrated and topped up on electrolytes. Upon returning home, he dug into the literature on muscle cramps.

As MacKinnon well knew, muscles run on electricity. In order for muscles to contract and relax effectively during exercise, the electrical signals that the brain sends to the muscles through motor nerves must maintain a smooth, steady rhythm. But when a muscle becomes fatigued or otherwise stressed, the motor nerve feeding into it may become hyperexcited, triggering a constant, painful contraction.

Support for this explanation of muscle cramps comes from experiments in which electrodes are used to replicate the job that motor nerves perform during exercise. In one such experiment, the results of which were published in 2009, researchers at Brigham Young University attached electrodes to the muscles of 19 volunteers with a history of cramping and 12 athletes with no such history. The frequency of the electrical impulses delivered into the muscle was increased until each volunteer cramped. The results showed that the volunteers with a history of suffering cramping episodes cramped at a significantly lower frequency. This finding, in addition to supplying evidence that cramping is caused by a kind of electrical overload from the motor nerve, suggests that some athletes—athletes like Cathy Harris —are more susceptible to cramping than others.

As MacKinnon learned more about muscle cramps, he reasoned that the nervous system could be called upon as a solution. It so happened that MacKinnon’s 2003 Nobel Prize was awarded for work he had done on ion channels, which play a key role in transmitting movement commands sent through the nervous system into actual muscle contractions. Based on his knowledge of ion channels, MacKinnon suspected that a nutritional intervention designed to stimulate sensory fibers in just the right way could prevent the motor nerves from becoming hyperexcited and greatly reduce the risk of cramping.

Fortunately, a number of compounds that occur naturally in some foods are known to provide this type of stimulation. In collaboration with Bruce Bean, a neurobiologist at Harvard University and fellow kayaker, MacKinnon developed a formulation—billed as the first nutritional beverage for neuromuscular performance—and began testing it.

These early tests have been encouraging. In one of them, the formulation was found to slash the occurrence of exercise-associated muscle cramps in half. In 2016, biotech company Flex Pharma will bring the product to market in the form of a spicy 2-ounce shot to be taken before exercise. Cathy Harris —and many other athletes—are counting the days until they can get their hands on it, and the cramping myth is finally laid to rest.