Increasing activity levels in middle age can prolong life as much as giving up smoking, a study suggests.
Swedish researchers from Uppsala University monitored more than 2,200 men from the age of 50.
They found those who increased activity levels from 50 to 60 ended up living as long as those who were already exercising regularly by middle age.
Public health experts said the findings showed it was never too late to start exercising.
The team asked the men about their activity levels at the start of the study in the early 1970s, when they were aged 50.
It shows that it is never too late to start exercising
Karl Michaelsson, lead researcher
The men were put into three groups - high levels of activity, moderate levels and sedentary.
High levels was classed as those who did at least three hours of sports or heavy gardening each week.
Moderate was said to be the equivalent of several hours of walking or cycling, while people who were classed as sedentary spent most of their free time watching TV.
Their exercise habits were then reassessed at the age of 60.
The team found that those who were doing high levels of activity at the age of 50 lived 2.3 years longer than sedentary men and 1.1 years longer than those who reported medium levels of activity - once a range of factors such as weight, alcohol intake and smoking was taken into account.
But interestingly the researchers found that those who increased their activity level to high - whether they were in the moderate or low group - from the age of 50 to 60 also lived the longest.
It was not clear what effect reducing activity levels during this period had, the British Medical Journal report said.
Allotment holder Mike Reeves explains his approach to exercise
Lead researcher Karl Michaelsson said the study showed it was essential to encourage men to become active, although he said more research would be needed to see if the effect was replicated in women.
He said the impact on lifespan was the same as for someone who gave up smoking during this period.
"Efforts for promotion of physical activity, even among middle aged and older men are important."
Professor Alan Maryon-Davis, president of the Faculty of Public Health, said: "These results are very interesting.
"It shows that it is never too late to start exercising. I think this period is very important for men and what is probably happening here is that the exercise during these years is strengthening their cardiovascular system.
"But, of course, other factors such as diet will play an important role."
Cathy Ross, cardiac nurse at the British Heart Foundation, said: "The study adds support to what we already know, which is that people who are physically active are half as likely to get cardiovascular disease as those that are inactive.
"Being active at any age helps control your weight, reduce blood pressure and cholesterol and will provide long term benefits for your heart health and general health."
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