“They suggest strongly that people don’t have to

lose muscle mass and function as they grow older.

The changes that we’ve assumed were due to ageing

and therefore were unstoppable seem actually to be caused by inactivity.

And that is something which can be changed.”

 

Aging Well Through Exercise

NYT News Service, January 11, 2012 

 

Is physical frailty inevitable as we grow older? That question preoccupies scientists and the middle-aged. Until recently, the evidence was disheartening. Many studies in the past few years showed that after age 40, people typically lose eight per cent or more of their muscle mass each decade, a process that accelerates significantly after age 70. Less muscle mass generally means less strength, mobility and among the elderly, independence. Moreover, less muscle is also linked with premature mortality.

 

But a growing body of newer science suggests that such decline may not be inexorable. Exercise, the thinking goes, has the potential to change your muscle tone and body composition for the better.

 

The results of a stirring study published last month in the journal The Physician and the Sports medicine is worth considering. For the purpose of the study, researchers at the University of Pittsburgh recruited 40 competitive runners, cyclists and swimmers of various age groups. All were enviably fit.

 

They completed questionnaires that comprised detailing their health and weekly physical activities. Then the researchers measured their muscle mass, leg strength and body composition, determining how much of their body and, more specifically, their muscle tissue was composed of fat. Other studies have found that as people age, they not only lose muscle, but the tissue that remains can become infiltrated with fat.

 

There was little evidence of deterioration in the older athletes’ musculature, however. The athletes in their 70s and 80s had almost as much thigh muscle mass as the athletes in their 40s, with minor if any fat infiltrtation. There was, as scientists noted, a drop-off in leg muscle strength around age 60 in both men and women. They weren’t as strong as the 50 year olds although the difference was not huge. The 70 and 80 year old athletes were about as strong as those in their 60s.

 

“We think these are very encouraging results,” said Dr Vonda Wright, an orthopaedic surgeon and founder of the Performance and Research Initiative for Masters Athletes at the University of Pittsburgh Medical Center, who oversaw the study. “They suggest strongly that people don’t have to lose muscle mass and function as they grow older. The changes that we’ve assumed were due to ageing and therefore were unstoppable seem actually to be caused by inactivity. And that is something which can be changed.”

 

Other recent studies have produced similar findings. Last year, researchers at the Canadian Center for Activity and Ageing, for instance, examined muscle tissue from older competitive runners, checking for the density of their motor units, a measure of muscle health.  The more motor units in a muscle, the stronger it generally is.

 

In multiple earlier studies, people over 50 have been found to possess far fewer muscle motor units than young adults. But that wasn’t true for the sexagenarian runners, whose leg muscles teemed with almost as many motor units as a separate group of active 25 year olds. Of course, the volunteers in both Vonda’s and the Canadian study were, for the most part, lifelong athletes.

 

Whether similar benefits are attainable by people who take up exercise when they are middle-aged or older ‘isn’t yet clear’, Vonda said, In an encouraging animal study from last year, elderly rats that had been sedentary throughout their adult lives were put on a running programme. After 13 weeks, their leg muscle tissues had filled with new satellite cells, a specialised type of stem cell that repairs muscles. Comparable experiments in older people have yet to be done, though.

 

Other questions about the impacts of exercise on ageing muscle also remain unanswered. “We don’t know what kinds of exercise are best,” Vonda said. “In particular, whether endurance exercise is necessary for muscle sparing or whether weight training might be as good or even better.

 

“What we can say with certainty is that any activity is better than none, and more is probably better than less. But the bigger message is that it looks as if how we age can be under our control. Through exercise, you can preserve muscle mass and strength and avoid the decline from vitality to frailty.”

 

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