Fatigue May Be Prime Cause of Muscle Cramps

From the WebMD Archives

Nov. 23, 1999 (Cleveland) -- Muscle cramps associated with exercise may not be caused by failing to drink enough Gatorade, according to a new theory. Instead, muscle fatigue and inadequate stretching may be the two most important factors contributing to muscle cramps in endurance athletes.

"The thing is that we all see muscle cramps, but no one is sure what is happening with them," Kara H. Browning, MD, tells WebMD. Browning is a staff physician in the department of orthopedic surgery, sports medicine section, at the Cleveland Clinic Foundation.

In the current issue of The Physician and Sportsmedicine, Martin P. Schwellnus, MSc, MD, who originated the muscle fatigue theory in 1997, discusses the theory and the available evidence that supports it. Schwellnus is with the University of Cape Town Medical School in South Africa.

Schwellnus has published other articles supporting the same theory, according to Browning. In this most recent article, he "is going into more detail and attempting to bring some basic science research to bear on the question to support his theory," she says. "He actually has been more rigorous than most of us, since most of what we know is based on anecdotal evidence."

Browning says that Schwellnus' theory of muscle fatigue is actually supported by the experience of her department in treating the Cleveland Indians, Cleveland Browns, Cleveland Cavaliers, and Cleveland Rockers. "Cramps are more common in the preseason when the athlete is not as well conditioned and is more subject to fatigue," she says. She adds, however, that at least in football the preseason games are often played in conditions of extreme heat. "Whether it is the heat or athletes who are not as well conditioned is still unknown." She says, too, that Schwellnus concentrates on endurance athletes, but "we're not sure if a muscle cramp in a marathon runner and a muscle cramp in a linebacker are the same."

Schwellnus writes that inadequate stretching also contributes to muscle cramps, and Browning agrees with that premise.

But Browning adds that she and most of her colleagues also think that dehydration or electrolyte imbalance is a factor. "With high school teams, you always have one kid every year who cramps. In some cases we do a medical work-up, checking kidneys, electrolytes, and so on. Usually we find nothing medical, and so we just advise him to drink lots of Gatorade," she says. She adds that in her experience, cramps rarely require a physician's intervention.

Based on his theory, Schwellnus advises treating acute cramps by passive stretching of the affected muscles, holding the muscle in a stretched position until twitching ceases, and general supportive care such as oral fluids and making the athlete comfortable.

Some orthopedists have suggested intravenous infusion of electrolytes, but Browning does not recommend that strategy. Others have found that calcium supplements are helpful. However, competitive athletes who are taking herbal substances and other supplements need to recognize that "many of these ... may contribute to muscle cramps," Browning says.

Vital Information:

  • For endurance athletes, the two most important factors contributing to muscle cramps are muscle fatigue and inadequate stretching, according to a new theory.
  • Some experts disagree, adding that dehydration or electrolyte imbalance are also contributing factors.
  • For relief, athletes should hold the affected muscle in a stretched position until twitching subsides.