Study proves physical activity helps maintain mobility in older adults

May 27, 2014

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Andrea Grossman

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GAINESVILLE, Fla/BOSTON (May 27, 2014) — It’s something we’ve all heard for years: Exercise can help keep older adults healthy. But now a study, the first of its kind to look at frail, older adults, proves that physical activity can help these people maintain their mobility and dodge physical disability.

A new University of Florida study, for which the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University served as a field center, shows daily moderate physical activity may mean the difference between seniors being able to keep up everyday activities or becoming housebound. In fact, moderate physical activity helped aging adults maintain their ability to walk at a rate 18 percent higher than older adults who did not exercise.
“The very purpose of the study is to provide definitive evidence that physical activity can truly improve the independence of older adults,” said principal investigator Marco Pahor, director of the UF’s Institute on Aging.

What’s more, moderate physical activity not only helped older adults maintain mobility but also helped prevent the occurrence of long-term mobility loss. Co-principal investigator Jack Guralnik, a professor of epidemiology and public health at the University of Maryland School of Medicine, said there was a 28 percent reduction in people permanently losing the ability to walk easily.

“The fact that we had an even bigger impact on persistent disability is very good,” said Guralnik, who also holds a faculty position at UF. “It implies that a greater percentage of the adults who had physical activity intervention recovered when they did develop mobility disability.”

The results will be published in the May issue of the Journal of the American Medical Association, and will be presented at 1 p.m. May 27 at the annual meeting of the American College of Sports Medicine in Orlando.

Researchers showed that prescribed daily physical activity would prevent older adults’ loss of mobility, defined in the study as the ability to walk 400 meters, or about a quarter of a mile. Although 400 meters might sound like an arbitrary number, it’s an important figure for older adults, researchers said. “Four hundred meters is once around the track, or from the parking lot to the store, or two or three blocks around your neighborhood,” Guralnik said.

At the field site at the USDA HNRCA at Tufts University, Roger A. Fielding, Ph.D., director of the Nutrition, Exercise Physiology and Sarcopenia Laboratory, led a team that successfully enrolled more than 200 men and women and he co-chaired the committee that led the design of the study’s interventions. “It’s very exciting to be a part of study where the results could have far-reaching public health implications,” said Fielding, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts University and at Tufts University School of Medicine. “We know that an individual’s ability to maintain their independence is really linked to their walking ability. So when someone loses their ability to walk a short distance, we see that as a major life event for that older person.”

Called the Lifestyle Interventions and Independence for Elders, or LIFE, study, the study also took place at field centers at Northwestern University, Pennington Biomedical Research Center, University of Pittsburgh, Stanford University, Wake Forest School of Medicine, Yale University and the Jacksonville Brooks Rehabilitation in Florida.

The researchers recruited 1,635 sedentary men and women aged 70-89 for the study at the eight field centers. The participants could walk a quarter mile within 15 minutes but were at risk for losing that ability. Low physical performance can be a predictor of early death and higher hospitalization and institutionalization rates, and patients with low physical performance are not often recruited to large studies, Pahor said.

“These are people who are patients we see every day. This is why this study is so important: It includes a population that is typically understudied,” Pahor said.

The participants were randomly separated into two groups and followed for an average of 2.6 years. The first group of 818 walked 150 minutes per week and did strength, flexibility and balance training. They were monitored by two visits to field centers per week. The second group of 817 attended health education classes and performed stretching exercises. This phase of the study occurred between February 2010 and December 2013.

Staff members assessed study participants every six months, checking their ability to walk, their body weight, blood pressure and pulse rate, among other measurements. The staff was not told which participants were assigned to physical activity or to the education classes.

The study did turn up one unanticipated result: The number of people reporting hospitalizations in the physical activity group was slightly higher than in the education group, though the number was not statistically significant. The researchers think this is in part because the physical activity group had more frequent contact with research staff, possibly resulting in a higher reporting of hospitalizations. The physical activity could also have triggered underlying heart trouble and other health problems. Researchers plan to study this occurrence more closely, Pahor said.

“It’s quite a vulnerable and high-risk population,” Pahor said. “Both age and poor health were factors. We selected people who had low physical performance, which is a strong predictor for future morbidity, hospitalization, institutionalization and mortality.”

Wendy Kohrt, professor of medicine in the division of geriatric medicine at the University of Colorado, helped review the scientific merit of the study before the launch of the main LIFE trial. She said the information produced by this study fills gaps in researchers’ knowledge of the types of people enrolled in the study.

“As an exercise scientist, I believe this type of research is absolutely critical to establish scientific evidence on which to make recommendations for how lifestyle can beneficially influence health status,” Kohrt said. “There is a general belief among the public and the scientific and medical communities that we know exercise is good for you, so why do we need to do more research in this area? However, we still do not know whether certain types or doses of exercise are better than others, particularly for specific health conditions or diseases. The LIFE trial demonstrated that a modest increase in physical activity has the potential to help older adults maintain functional independence.”

Pahor and Guralnik said there is still a vast amount of data to unpack from the study, including looking at the effects of physical activity on the participants’ emotional well-being. Fielding’s laboratory will use the LIFE data to try to evaluate whether the varying levels of the amount of physical activity performed among the participants has an impact on changes in the ability to walk short distances.

 A National Institutes of Health and National Institute on Aging Cooperative Agreement funded the study. The National Heart, Lung and Blood Institute provided additional support.

Pahor, M. et al. “Effect of Structured Physical Activity on Prevention of Major Mobility Disability in Older Adults: The LIFE Study Randomized Clinical Trial.” Journal of the American Medical Association. Published online ahead of print May 27, 2014.

For three decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations.  Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies. The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight degree programs, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy.

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