If everyone in the United States population was as active as the top 25 per cent, individuals over the age of 40 could add five years to their life, according to a new study led by Griffith University researchers.
Physical activity has long been known to be good for health, however estimates have varied regarding how much benefit could be gained from a defined amount of activity, both for individuals and for populations.
This latest study used accelerometry to gain an accurate view of the population's physical activity levels instead of relying on survey responses as per other studies, and found the benefits were around twice as strong as previous estimates.
It found the most active quarter of people in the community had a 73 per cent lower risk of death than their least active counterparts.
For that least active quartile, a single one-hour walk could potentially return a benefit of around six additional hours of life.
Lead researcher Professor Lennert Veerman said this least-active cohort had the greatest potential for health gains.
"If you're already very active or in that top quartile, an extra hour's walk may not make much difference as you've, in a sense, already 'maxxed out' your benefit," he said.
"If the least active quartile of the population over age 40 were to increase their activity level to that of the most active quartile however, they might live, on average, about 11 years longer.
"This is not an unreasonable prospect, as 25 per cent of the population is already doing it.
"It can be any type of exercise but would roughly be the equivalent of just under three hours of walking per day."
The research team suggested low levels of physical activity could even rival the negative effects of smoking, with other research finding each cigarette could take 11 minutes from a smoker's life.
By extension, a more active lifestyle could also offer protective effects against heart disease, stroke, certain cancers and other chronic illnesses, with the study's findings highlighting a need for national physical activity guidelines to be revisited using these methods.
Dr Veerman said physical activity had been vastly underestimated in its capacity to improve health outcomes, suggesting even modest increases in movement could lead to significant life-extension benefits.
"If there's something you could do to more than halve your risk of death, physical activity is enormously powerful," he said.
"If we could increase investment in promoting physical activity and creating living environments that promote it such as walkable or cyclable neighbourhoods and convenient, affordable public transport systems, we could not only increase longevity but also reduce pressure on our health systems and the environment."
