Active seniors may live longer

0 Comments | Deseret News (Salt Lake City), Jul 12, 2006 | by Alice Dembner Boston Globe

The simple activities of daily life, such as washing dishes, walking to the car or even fidgeting, may help older people live longer, according to a study published Wednesday that is the first to measure the energy used for these tasks and its effect on longevity.

Seniors who were most active, regardless of whether they exercised, were nearly 70 percent less likely to die during the six- year study period than those who were most sedentary, the study found. The results shed new light on how much exercise is needed to maintain good health.

"Any movement is better than no movement to lower your risk of death," said Todd M. Manini, a research scientist at the National Institute on Aging, who led the study. "A lot of older adults are intimidated by organized exercise. Our study suggests that it's the accumulation of activity throughout the day that matters."

Previous research on the benefits of exercise found no link between light activities and longer life, indicating instead that moderate to intense activity was needed. Nearly all of that research, however, was based on people's own reports of their activities using questionnaires typically focused on sports or walking. Based on those studies, and others linking exercise to reduction of heart disease, cancer, diabetes and mental sharpness, the government recommends a minimum of 30 minutes a day of moderate activity, such as brisk walking.

Yet, the federal Centers for Disease Control and Prevention says that one in three men and one in two women over age 75 gets no physical activity at all.

The new study, published in the Journal of the American Medical Association, took a fresh look at activity by scientifically measuring the amount of energy a group of 302 men and women ages 70 to 82 used over the course of two weeks. Researchers divided the seniors into three equal groups, based on how much energy they burned and then followed the seniors for an average of six years to see who lived and who died. By the end of the study, 12 percent of those in the highest activity group died compared with 25 percent of those in the least active group. When researchers adjusted for differences in death rates expected based on the individuals' ages, gender, weight and other factors, they found that the least active group was three times as likely to die.

The researchers also found that for every 287 calories per day a senior expended, there was a 32 percent reduction in death rate over the 6-year period. Based on other studies, the researchers estimated that an average older person, weighing about 165 pounds, would burn 287 calories in about 75 minutes of household chores, child care or volunteering in a task that doesn't involve sitting.

The study is the first to provide credible evidence that everyday activities might be beneficial, said William L. Haskell, a professor at the Stanford University School of Medicine who studies the relationship of physical activity and health and was not involved in the new work.

"It looks really attractive, but we need to nail this down" before making any recommendations to seniors about how much activity they need to live longer, he said. "Researchers ask how much activity do we need. But the public approaches it by asking how little can I get away with." He and other researchers are worried that people will use the study to justify giving up on exercise -- a conclusion not supported by the data, he said.

Haskell, who wrote a commentary accompanying the study, said the results do not necessarily apply to healthy younger or middle-aged people either, since they may need to expend far more energy to see positive results. For a sedentary person over 70, "a small amount of activity may have a great benefit," he said.

Haskell said, however, that the study is a milestone because it used an objective method to measure older people's activity.

The researchers gave each participant a dose of special water that contains specific components, called isotopes, that can be measured in urine. These isotopes are released by the body as carbon dioxide with any activity, so, by measuring the change in isotope levels over time, the researchers calculated the energy used. The researchers measured the isotopes in the volunteers' urine a few hours after they drank the water and again after two weeks of normal activities. (They adjusted these numbers for each person's resting metabolism and for the amount of energy he or she typically used to digest food.)

The study did not, however, measure the intensity or type of the seniors' activities, so the researchers had to rely on the seniors' own accounts of what they did. Because of the unreliability of these kinds of reports, the researchers acknowledge that it's possible that the more active group actually was engaging in more intense exercise, and that their added benefit came from the intensity of their activity, as previous studies have suggested. To resolve that problem, the researchers plan to repeat the study using a device that measures intensity of each person's movement.