BUFFALO, N.Y. -- Regular exercise helps aging muscles retain their flexibility and protects them from injury, one of the few studies of the effect of exercise training on muscle function in aging animals has found.
Results of the University at Buffalo study appeared in the April issue of the Journal of Applied Physiology.
Luc E. Gosselin, assistant professor in the Department of Physical Therapy, Exercise and Nutrition Sciences in the UB School of Health Related Professions who authored the study, said the results have important implications for aging human populations.
"The amount of money spent on maintaining the elderly in nursing homes is enormous, and many elderly end up there because of frailty. We can postpone frailty by getting seniors involved in exercise programs," Gosselin said.
"Seniors have two problems to contend with: They are more susceptible to muscle injury during exercise, and once injured, they need more time to repair. However, if seniors stay active, they are less susceptible to injury than if they are sedentary."
Gosselin's study, which used rats as an animal model, concentrated on the soleus, a small muscle beneath the calf. His purpose was two-fold: to determine to what extent endurance training improves function, and whether young and old rats training at a comparable, relative exercise intensity would derive similar protection from injury.
"Aging affects muscles used for locomotion in a number of ways," Gosselin stated. "These include reduced work capacity, loss of muscle mass, increase in connective tissue and muscle stiffness, and increased healing time after injury.
"Endurance exercise training has been shown to ameliorate oxidative capacity and muscle stiffness due to age. However, the extent to which long-term endurance training protects muscle from injury was not previously known, especially with aging," he noted.
Both young and old study animals were assigned to either an exercise group or a sedentary control group. The exercise group trained five days a week for 45 minutes a day for 10 weeks on a treadmill set at a 15 percent incline. The old animals trained at a slower speed but at the same relative intensity as the young animals.
By the end of 10 weeks, the young rats were running at the rate of 27 meters per minute and the old rats at 15 meters per minute, or at about 70 percent of their maximal oxygen intake.
Following the training period, Gosselin injured the soleus muscles of all animals by inducing repeated contractions, and then compared their residual strength. Results showed that the trained muscles were more resistant to injury than those from sedentary animals, and surprisingly, that old muscles benefited as much from the training as young muscles.
Gosselin said the study needs to be repeated in humans, but he expects similar results.
The research was funded by grants from the American Federation for Aging Research and the National Institute of Child Health and Human Development.
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