08.04.2015
15 minutes a day may be enough for people ages 60 and up
by Parker Brown
Staff Writer, MedPage Today
Even a little exercise was associated with reduced mortality for adults over 60, according to a meta-analysis of nine cohort studies.
In about 122,000 patients with an average follow-up period of 9.8 years, only 15 minutes of moderate to vigorous physical activity was associated with a 22% reduction in mortality (risk ratio 0.78, 95% CI 0.71-0.87, P<0.0001) when compared with those who did no activity. Participants who exercised for 150 minutes a week at a moderate intensity or for 75 minutes at vigorous intensity, the amounts recommended by the Physical Activity Guidelines Advisory Committee Report, had a risk reduction of 28% (RR 0.72, 95% CI 0.65-0.80, P<0.0001), reported David Hupin, MD, at CHU Saint-Etienne in France, and colleagues.
The group that exercised the most (>1000 MET-min per week) had a 35% reduction (RR 0.65, 95% CI 0.61-0.70, P<0.0001), they wrote in the British Journal of Sports Medicine.
The meta-analysis showed a curvilinear relationship between physical activity and all-cause mortality: those who initially do little to no physical activity derived benefit from doing more. The authors added that much of the benefit seemed to be from a lowered risk of dying of cardiovascular disease. The relationship between activity and lower cancer mortality was less strong, but the decrease in risk was still significantly significant.
“These findings may help convince general practitioners that a lower dose of moderate to vigorous physical activity… (>3 METs) than currently recommended has health benefits,” Hupin wrote in an e-mail to MedPage Today. “General practitioners who play an essential role in promoting MVPA should encourage older adults to include even low doses of MVPA in their daily lives.”
The reduction in all-cause mortality was stronger for men than for women, Hupin’s group noted, adding that there was a possibility that men may have overestimated their activity, or that women might have underestimated theirs.
“This protective effect appears dose-dependent and is already significant for a low dose of moderate to vigorous physical activity (or about 15 min per day), which is below current recommendations for older adults,” they stated. “These results can guide future recommendations for older adults and may improve adherence to regular physical activity programs and thus their global health.”
Exercise has previously been shown to offer a wide array of benefits to older adults. Astudy last year found that exercise may shield post-menopausal women from atrial fibrillation. Another 2014 study found that regular aerobic exercise for older womenappeared to enlarge an area of the brain that is often associated with memory, and a 2011 study found that aerobic exercise was linked to larger brain volume.
All of the studies examined in this analysis were prospective cohort studies in which all participants were 60 or older. Additionally, in all of the studies, the participants had no known neurodegenerative condition at the beginning of the study, there was an evaluation of moderate to vigorous physical activity, deaths were reported, there was a follow-up of at least 3 years, and relative risks were calculated. Studies that had more than 15% loss to follow-up or evaluated low-intensity physical activity were not included.
Four of the cohorts included women only, two included men only, and three included both men and women.
Researchers used the metabolic equivalent of task (MET) to measure the energy expenditure, or “dose,” of an activity. Resting energy expenditure was assumed to be 1 MET; vigorous exercise was more than 6 METs. Brisk walking fell into the moderate exercise category (3-5.9 METs). The low physical activity group had 1-499 MET-min, the medium group 500-999 MET-min, and the highest group more than 1,000 MET-min.
The authors pointed out that the targets for physical activity might be too high, discouraging some adults from exercising at all for fear they won’t hit the target. “The fact that any effort will be worthwhile may help convince those 60% of participants over 60 years of age, who do not practice any regular physical activity, to become active,” they wrote.
Limitations of the study included a risk of bias due to the uncertainty of doses in some of the studies. In addition, two of the larger studies in the analysis contributed to 61% of the results, and the cohorts evaluated were not geographically diverse.
Hupin told MedPage Today that he is interested in looking at the benefits of replacing sitting with light-intensity activities.
“Our future studies using objective measures of moderate- and vigorous-intensity and light-intensity physical activity will be helpful to add clarity,” he wrote.
Hupin and co-authors disclosed no relevant relationships with industry.
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