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A Little Exercise Might Lengthen Life

A little physical activity can go a long way toward extending your life, regardless of your weight, a new study found. People who walked briskly or did other activity at only half the recommended amount gained nearly 2 years in life expectancy compared to inactive people. Those who exercised even more gained up to 4.5 years of life.

Researchers have long known that physical activity can enhance health. Exercise can help with weight control; strengthen bones, muscles and joints; and reduce the risk for heart disease and other disorders. Despite these known benefits, most Americans are sitting or inactive for more than half of each day, and about one-third of U.S. adults are obese.

Earlier studies identified a relationship between longevity and both physical activity and body mass index (BMI, a ratio of weight to height). But it was unclear how different levels of activity and BMI might affect life expectancy.

To take a closer look, an international team of scientists led by Dr. Steven C. Moore at NIH’s National Cancer Institute (NCI) analyzed data on more than 650,000 adults who were followed for about 10 years. These people, mostly age 40 and older, were drawn from 6 studies originally designed to assess cancer risk. The studies relied on self-reported activity levels and BMIs. The work was funded in part by NCI, along with NIH’s National Institute on Aging (NIA) and National Heart, Lung and Blood Institute (NHLBI).

As reported in the November 2012 issue of PLoS Medicine, the researchers found that people who said they exercised at recommended levels gained 3.4 years of life compared to those who were inactive. The U.S. Department of Health and Human Services recommends that adults engage in physical activity for 2.5 hours at moderate intensity—or 75 minutes at vigorous intensity—each week.

Participants who were physically active at twice the recommended level gained 4.2 years in life expectancy. Those who said they got half the recommended amount of physical activity added 1.8 years to their lives.

The researchers also found that obesity was linked to a shorter lifespan. However, physical activity across all BMI levels helped to lengthen life. People who were active and moderately obese gained about 3 years of life expectancy compared to those who were normal weight but inactive.

The combination of obesity and inactivity led to the worst outcomes. People who were obese and inactive had a life expectancy that was between 5 and 7 years shorter than those who were normal weight and moderately active.

“In this study we saw that if you don't do any activity, doing some will give you a benefit in terms of life expectancy. And if you currently do some activity, doing more will probably give you even greater benefits,” says Moore. “Regular exercise extended the lives in every group that we examined in our study—normal weight, overweight, or obese.”