July 8, 2011 -- The older you get, the more you may have to work to maintain your muscles, according to a new study.
Researchers report that men and women over the age of 60 have to lift weights more often than younger adults to maintain muscle mass and muscle size.
"Our data are the first to suggest that older adults require greater weekly maintenance dosing than younger individuals to maintain resistance-training-induced increases in muscle mass," study co-researcher and physiologist Marcas Bamman, PhD, of the University of Alabama, Birmingham, says in a press release.
The study is published in Medicine & Science in Sports & Exercise.
The researchers write that preventing sarcopenia -- muscle loss that occurs as we get older -- is "one of the most pressing challenges of biomedicine in our aging society." And resistance training, such as lifting weights, is the best means of prevention.
However, life often gets in the way of regular exercise. "A major limiting factor of RT [resistance training] as a therapeutic approach to sarcopenia is the second key ingredient that defines efficacy -- sustainability," the researchers write.
So they set out to determine the impact that scaling back a weight-lifting regimen would have on muscles and strength.
Seventy adults were recruited for the 48-week study, which was sponsored in part by the National Institute on Aging. Thirty-nine of the study participants were aged 60 to 75; the remainder ranged in age from 20 to 35.
For the first four months, everybody did the same exercises three times a week: three sets of knee extensions, leg presses, and squats. Each participant steadily increased the amount of resistance over that period. By the end of this first part of the study, everyone -- young and old -- had gained muscle.
The second phase was designed to reveal how much of that muscle would be lost to inactivity or reduced exercise. To start, the researchers randomly divided the participants into three groups. Then, for the next 32 weeks, one group did no exercise at all, another group did the same exercises as before but only one day per week, while the third group reduced their regimen to one set of exercises once a week.
By the end of the study, the differences between the young and old groups were striking. The younger participants who continued to exercise showed little or no reduction in the muscle gains they had made during the previous phase of the study, despite the less frequent and less intense workouts.
Members of the older group, by contrast, lost muscle mass when they scaled back their training regimen, indicating that they need to lift weights more often than young people to keep their muscles buff. Their strength, however, remained the same.
"Among the old," the researchers write, "neither prescription was sufficient to maintain the gains in muscle size."
And maintaining muscle mass, the researchers conclude, is essential to healthy aging. "The positive health benefits of increased muscle mass among older adults extend well beyond muscle performance," they write.
Those benefits include increased aerobic capacity, better fatty acid metabolism, and improved bone and joint health.
"Therefore, we recommend progressive RT continue indefinitely for the health and functional status of all individuals," the researchers write.
