Winter 2019

Warning: Falling Strength Ahead

Researchers take a crucial step in the fight against muscle loss.

By Elizabeth Gehrman

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llustration: Sébastien Thibault

We have long known that the older people get, the less robust their muscles become until, for many, disability begins to set in. But it wasn’t until 1989 that the study of muscle wasting had advanced enough that Irwin Rosenberg, then the director of the Jean Mayer USDA Human Nutrition Center on Aging (HNRCA) at Tufts, realized it was time to put a name to the condition. He chose “sarcopenia,” rooted in the ancient Greek sarx, for flesh, and penia, for loss. The disorder is more debilitating than its Greek roots alone suggest.

“The loss of muscle mass and concurrent muscle weakness is really associated with the loss of some critical functions we as human beings need to be able to perform to live safe, happy, independent lives,” said Roger Fielding, associate director of the HNRCA and director of its Nutrition, Exercise Physiology, and Sarcopenia Laboratory. Fielding, a Friedman School professor, likens sarcopenia to osteoporosis in terms of clinical recognition. “Maybe forty years ago people were talking about bone loss as a normal consequence of aging,” he said. “But it wasn’t considered a disease until it became linked to fractures.”

Similarly, sarcopenia isn’t a problem until it begins to affect older adults’ ability to function. “We see muscle loss across the whole animal kingdom,” Fielding said. “It’s a progressive, normal change, but not all people reach the threshold where it limits their ability to get out of a chair or perform other tasks.”

For more than thirty years, researchers at Tufts have been investigating the causes of sarcopenia and how to prevent or reverse it. Now they are calling for a crucial next step in the fight: a formal definition. Not having one has been a “major roadblock” to developing therapies to target sarcopenia, said Shalender Bhasin, director of the Boston Claude D. Pepper Older Americans Independence Center at Brigham and Women’s Hospital. “It’s crucial for patients who need to be treated, for doctors to diagnose correctly and get reimbursed, for pharmaceutical companies and researchers to identify individuals for studies, and for regulatory agencies to approve treatments.”

So on November 13, Tufts cohosted, with the Brigham and the University of California, San Francisco, a conference in Boston. Cochaired by Bhasin and Peggy Cawthon, a senior scientist at the California Pacific Medical Center, the conference brought together researchers from around the world to work toward an evidence-based consensus. How much muscle loss does it take before sarcopenia is called a disease? What tests should doctors use to diagnose it? And what are some of the biomarkers?

At the conference, an international panel of experts presented and voted on position statements, which were generally in agreement but differed on a few key points. “Doing science is hard, but it’s easy compared to generating a consensus,” Bhasin said. “This conference is a very big deal. Defining this condition will have enormous societal, academic, and economic impact.”

 

Milestones in Tufts’ Sarcopenia Research

As the population ages, properly diagnosing and treating sarcopenia will become even more important. “Part of the reason people lose their ability to walk and perform other physical tasks is they have a problem with their muscles,” Fielding said. Many studies—“some done for the first time at Tufts”—have shown that strength training can have potent ameliorating effects.

“Strength conditioning in older men” (1988)
This groundbreaking study showed for the first time that a systematic strength-training program could help older adults build muscle. Researchers put the knees of a dozen healthy men sixty to seventy-two years old through their paces. At the end of twelve weeks, C.T. scans showed increases in total thigh area, total muscle area, and quadriceps area; biopses showed significant growth in muscle fiber.

“Exercise training and nutritional supplementation for physical frailty in very elderly people” (1994)
This trial, led by researchers at Tufts, compared exercise training with micronutrient supplementation in one hundred frail nursing home residents with a mean age of eighty-seven. Among the exercisers, muscle strength improved by 113 percent in just ten weeks (the supplement alone had no effect). The pivotal study showed exercise could work, even in a very old population with limited mobility and multiple comorbidities.

“Effect of structured physical activity on prevention of major mobility disability in older adults” (2014)
Tufts was one of eight clinical field centers in this randomized trial that tested a key hypothesis: that a long-term structured physical activity program is more effective than health education alone in increasing mobility. The study was important because it began to show scalability—elderly participants worked out at a center twice a week but also at home nearly twice as often over the course of nearly four years.

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