Winter 2015

Thwarted Strength

Tiny molecule appears to impede older people's ability to build new muscle tissue

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Photo: Istockphoto

In trying to understand why older people have a harder time building new muscle, Tufts researchers may have found a molecular culprit.

For a study published in The FASEB Journal, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts recruited 16 healthy but sedentary men—half in their 20s and half in their 70s—to perform a single bout of resistance exercise that would trigger muscle growth. When the scientists examined tissue samples taken before and six hours after the exercise, they found that the older men had lower levels of microRNAs, small molecules that have a prominent role in regulating the genes that program muscle protein production.

“One of the steps in building muscle seems to be missing in the older men, preventing them from responding to the exercise as strongly as the younger men did,” said lead author Donato Rivas, Ph.D., a scientist in the Nutrition, Exercise Physiology and Sarcopenia Laboratory at the HNRCA.

The authors, including senior author and laboratory director Professor Roger A. Fielding, Ph.D., note the small size of the study necessitates conducting more research, particularly in men and women who have sarcopenia, the age-related loss of muscle mass, strength and function.

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