Leisure-time physical activity is associated with longer life expectancy, even at relatively low levels of activity and regardless of body weight, according to researchers at the National Cancer Institute, part of the National Institutes of Health (NIH).

In order to determine the number of years of life gained from leisure-time physical activity in adulthood, researchers examined data on more than 650,000 adults, mostly aged 40 and older, who took part in 1 of 6 population-based studies that were designed to evaluate various aspects of cancer risk.

After accounting for other factors that could affect life expectancy, the researchers found that life expectancy was 3.4 years longer for people who reported they got the recommend level of physical activity (2.5 hours at moderate intensity/1.25 hours at vigorous intensity each week). People who reported leisure-time physical activity at twice the recommended level gained 4.2 years of life.

The researchers even saw benefit at low levels of activity. For example, people who said they got half of the recommended amount of physical activity still added 1.8 years to their life.

The researchers found that the association between physical activity and life expectancy was similar between men and women, and blacks gained more years of life expectancy than whites. The relationship between life expectancy and physical activity was stronger among people with a history of cancer or heart disease than among those with no history of cancer or heart disease.

The researchers also examined how life expectancy changed with the combination of both activity and obesity. Obesity was associated with a shorter life expectancy, but physical activity helped to mitigate some of the harm. People who were obese and inactive had a life expectancy that was between 5 to 7 years shorter (depending on their level of obesity) than people who were normal weight and moderately active.

The study was published online November 6 in PLoS Medicine.