The Nuance

Everything You Know About Muscle Cramps Is Wrong

And eating a banana won’t help

Photo by rawpixel on Unsplash

Every week, the Nuance will go beyond the basics, offering a deep and researched look at the latest science and expert insights on a buzzed-about health topic.

You’re wrapping up a morning run when one of your hamstring muscles balls into an angry fist of pain. Or it’s the middle of the night, and a sudden spasm grips your calf and forces you out of bed.

While they’re common—affecting roughly 37 percent of the population — muscle cramps have long been shrouded in mystery. For a long time, experts believed that muscle fatigue or some sort of fluid imbalance — brought on either by dehydration or inadequate amounts of electrolytes in the blood — could disrupt muscle homeostasis in ways that triggered involuntary activity. This theory was based on some well-established muscle cramp trends, including the fact that intense exercise can produce a cramp, and that cramps are more common in summer than in winter.

But new research complicates these old theories. “Marathon runners who cramp in competition do not differ in their serum electrolytes from those who do not,” explains Michael Behringer, MD, PhD, a professor of sports science at Goethe University in Frankfurt, Germany. Behringer says it’s…