WASHINGTON — Exercise, and to a lesser extent even daily activity, appears to be key to maintaining mobility in older adults, according to data presented at the annual meeting of the Gerontological Society of America.
“It's very clear that in these people—well-functioning people at baseline—physical inactivity increases the risk of functional mobility limitation about twofold versus those who exercise,” said Marjolein Visser, M.D., of Vrije University Medical Center, Amsterdam. There is an intermediate risk for those who are active in daily living but do not regularly participate in structured exercise. “There is some benefit but not as great a benefit as for exercise.”
In a study including 2,987 individuals aged 70–79 years, physical activity during the last 7 days was assessed using a questionnaire that addressed duration and intensity of exercise, as well as daily living activity.
The data came from the Health, Aging, and Body Composition study, sponsored by the National Institute on Aging. To be included in this study, volunteers had to be free of disabilities affecting daily living and free of functional limitations. “This is important because it indicates that they were very likely to be physically capable of being physically active,” Dr. Visser said.
Participants were categorized according to activity level. The exercise group (474 men, 251 women) got at least 1,000 kcal/wk of structured exercise. The active lifestyle group (666 men, 899 women) got about the same amount of total physical activity as those in the exercise group, but less than 1,000 kcal/wk came from structured exercise. The inactive group (303 men, 394 women) got little or no structured exercise and were not active in terms of daily living.
Patients were followed for an average of 4.5 years through an annual clinical exam and self-reports of level of difficulty walking a quarter of a mile and walking up 10 steps. Difficulty had to persist over at least two reports to result in a change of status. Mobility limitation was reported by 34% of men and 47% of women.
The inactive group had the most mobility limitation during follow-up, with the intermediate group showing greater mobility, and the exercise group had the greatest mobility.
After adjusting for demographic, lifestyle, and health factors, inactive men and women had twice the risk of mobility limitation during follow-up, compared with those who exercised. Those with an active lifestyle had an intermittent risk.
The researchers also looked at associations between walking and mobility limitation among only the subjects who got little or no exercise
In this walking subgroup analysis, those who rarely walked (440 men, 649 women) had the highest risk of mobility limitation. Occasional walkers (247 men, 378 women) had an intermediate risk, while frequent walkers (282 men, 266 women) had the lowest risk.
The researchers also wanted to examine the relationship between activity and mobility is mediated muscle parameters. by muscle mass (at midthigh), strength (knee extension), and muscle fat (midthigh attenuation on a CT scan).
Those who recieved structured exercise had more muscle mass, less fat in their muscle, and more muscle strength than those with an active lifestyle. Inactive participants had the least muscle mass, the most fat in their muscle, and the least muscle strength. There was no association between walking activity and the muscle parameters.