Tufts Medicine

Anyone who plays sports, whether as a weekend warrior or a pro, has likely encountered the pain of a muscle cramp. Veteran marathoner Paula Radcliffe cramped up so badly at the 2004 Olympics in Athens that she had to withdraw from the race.

But what underlies the condition, exactly? For a long time now, sports medicine experts have theorized that muscle dehydration or a muscle starved for electrolytes caused the cramp, and treated it accordingly with water and electrolytes.

Rod MacKinnon, M82, H02, winner of the 2003 Nobel Prize in Chemistry, has a different idea. “The primary origin of the cramp is the nerve, not the muscle,” he told the Wall Street Journal last summer. The backstory has the tang of salt air. MacKinnon was kayaking with a friend off Cape Cod a decade ago when his hands and arms cramped up badly. Once back on shore, MacKinnon and his friend, Bruce Bean, a Harvard neurobiologist, hypothesized that the condition might be linked to something gone awry with impulses in the nervous system.

MacKinnon had an edge when it came to understanding nerves; after all, he won the Nobel Prize for uncovering the first atomic structure of protein molecules that generate electrical signals in living organisms. Now he had the idea that he could modify the nervous system—distract it, in a way—by overloading the nervous system through pungent flavors in a person’s mouth. In MacKinnon’s more precise, scientific phrasing, “The strong sensory input causes inhibition of the motor output.”

He has spent the past decade tinkering in his kitchen at home to test his theory, cooking up spicy drinks with varying amount of ginger and cinnamon while also trying to induce cramps using electrical stimulation. He found that his drinks did indeed have the effect of deterring muscle cramps. The results of more controlled subsequent studies done in the laboratory, which he presented last year at meetings of the American Academy of Neurology and the American College of Sports Medicine, further confirmed his hypothesis.

Word has gotten around, and a number of endurance athletes have already started drinking something spicy before their events. In 2015, MacKinnon launched his own concentrated beverage, called “Hotshot,” distributed nationwide. Nobody, not even the inventor, pretends the peppery mix of flavors tastes good. But it apparently delivers such a shock to the body that the body has no time for muscle cramps.