The results, published on Tuesday in the journal JAMA, reinforce the necessity of frequent physical activity for our aging parents, grandparents and, of course, ourselves.
While everyone knows that exercise is a good idea, whatever your age, the hard, scientific evidence about its benefits in the old and infirm has been surprisingly limited.
For the first time, we have directly shown that exercise can effectively lessen or prevent the development of physical disability in a population of extremely vulnerable elderly people, said Dr Marco Pahor, the director of the Institute on Aging at the University of Florida in Gainesville and the lead author of the study.
For this latest study, the Lifestyle Interventions and Independence for Elders, or LIFE, trial, scientists at eight universities and research centres around the country began recruiting volunteers in 2010, using an unusual set of selection criteria. Unlike many exercise studies, which tend to be filled with people in relatively robust health who can easily exercise, this trial used volunteers who were sedentary and infirm, and on the cusp of frailty.
Ultimately, they recruited 1,635 sedentary men and women aged 70 to 89 who scored below a nine on a 12-point scale of physical functioning often used to assess older people. Almost half scored an eight or lower, but all were able to walk on their own for 400 meters, or a quarter-mile, the researchers cutoff point for being physically disabled.
Then the men and women were randomly assigned to either an exercise or an education group.
Those in the education assignment were asked to visit the research centre once a month or so to learn about nutrition, health care and other topics related to ageing.
The exercise group received information about ageing but also started a programme of walking and light, lower-body weight training with ankle weights, going to the research center twice a week for supervised group walks on a track, with the walks growing progressively longer. They were also asked to complete three or four more exercise sessions at home, aiming for a total of 150 minutes of walking and about three 10-minute sessions of weight-training exercises each week.
Every six months, researchers checked the physical functioning of all of the volunteers, with particular attention to if they could still walk 400 metres by themselves.
The experiment continued for an average of 2.6 years.
By the end of that time, the exercising volunteers were about 18 per cent less likely to have experienced any episode of physical disability during the experiment. They were also about 28 per cent less likely to have become persistently, possibly permanently disabled, defined as being unable to walk those 400 metres by themselves.
Most of the volunteers tolerated the exercise programme very well, Dr Pahor said, but the results did raise some flags. More volunteers in the exercise group wound up hospitalised during the study than did the participants in the education group, possibly because their vital signs were checked far more often, the researchers say. The exercise regimen may also have unmasked underlying medical conditions, Dr Pahor said.
- Gretchen Reynolds