Researchers from Brigham and Women's Hospital (BWH), in collaboration with the National Cancer Institute have quantified how many years of life are gained by being physically active at different levels, among all individuals as well as among various groups with different body mass index (BMI).
"We found that adding low amounts of physical activity to one's daily routine, such as 75 minutes of brisk walking per week, was associated with increased longevity: a gain of 1.8 years of life expectancy after age 40, compared with doing no such activity," explained I-Min Lee, senior author on the study.
"Physical activity above this minimal level was associated with additional gains in longevity. For example, walking briskly for at least 450 minutes a week was associated with a gain of 4.5 years," Lee said.
"Further, physical activity was associated with greater longevity among persons in all BMI groups: those normal weight, overweight, and obese," Lee added.
Researchers analysed data from more than 650,000 subjects and followed them for an average of ten years- analysing over 82,000 deaths.
The large sample size allowed them to estimate years of life gained after the age of 40 among persons with different levels of physical activity and BMI.
The findings show that physical activity was associated with longer life expectancies across a range of activity levels and BMI groups.
Participation in a low level of leisure time physical activity of moderate to vigorous intensity, comparable to up to 75 min of brisk walking per week, was associated with a 19 per cent reduced risk of mortality compared to no such activity.
Assuming a causal relationship, which was not specifically demonstrated in this research, this level of activity would confer a 1.8 year gain in life expectancy after age 40, compared with no activity.
For those who did the equivalent to 150 min of brisk walking per week, the gain in life expectancy was 3.4 years.
Participants faring best were those who were both normal weight and active.
Among normal weight persons who walked for 150 min per week, researchers observed a gain in life expectancy of 7.2 years, compared to those with a BMI of 35 or more who did no leisure time physical activity.
"Our findings reinforce prevailing public health messages promoting both a physically active lifestyle and a normal body weight," Dr Steven C Moore, lead author of this study, said in a statement.
The study was published in journal PLOS Medicine.
