Muscle Bind

When it comes to muscle metabolism, the phrase “use it or lose it” is more than a cliché. Unused muscles don’t stick around; the body breaks them down and uses their proteins for other purposes. And for those experiencing an environment that makes the physical activity of daily life impossible—a patient confined to a hospital bed, for example, or an astronaut encountering weightlessness for months at a time—the loss of muscle mass can become a major problem.

UTMB metabolism researchers have been working to find a way to fight this predicament with nutritional supplements, testing their ideas on volunteers who spend weeks at a time confined to beds in the university’s General Clinical Research Center. Last September, in a paper published in The Journal of Endocrinology and Metabolism, the investigators reported a dramatic success in a twenty-eight-day bed-rest study with thirteen healthy male volunteers.

“We thought it was the most astounding thing that even though our subjects did no exercise, they were able to maintain muscle mass,” says assistant professor Douglas Paddon-Jones, the lead author on the paper. (Co-authors were Melinda Sheffield-Moore, Randall J. Urban, Arthur B. Sanford, Asle Aarland, Robert R. Wolfe, and Arny A. Ferrando.)

In the experiment, seven of the subjects received drinks containing essential amino acids and carbohydrates three times a day, while six others were given a placebo with no nutritional value. The subjects given supplements retained all of their original leg muscle mass, while the members of the placebo group lost about a pound of leg muscle on average. Those who received the supplements also lost only about half as much leg strength as those given the placebo.

Although the study’s subjects were all between the ages of twenty-six and forty-six, Paddon-Jones believes that its most promising direct application may be in helping hospitalized elderly people.
“The elderly have less muscle to spare than the rest of us,” he says. “When they get sick or injured and wind up in a hospital bed for a prolonged period, many of them lose so much muscle mass and strength that they don’t get back up. For a lot of people, this supplement could make a real difference.”
—Jim Kelly