Increased physical activity in middle age prolongs life, though it may take five to 10 years before an effect is seen, concludes a study published on bmj.com today. Physical activity is beneficial for health, but about half of all middle aged men in the West do not take part in regular physical activity. It is not yet known whether an increase in exercise later in life reduces death rates.

So researchers in Sweden examined how changes in physical activity levels after middle age influence mortality and compared them with the effect of stopping smoking.

The study involved 2,205 men aged 50 in 1970-3 and living in Uppsala, Sweden. Participants completed a survey on leisure time physical activity and were categorised into low, medium or high activity groups. Participants were re-examined at ages 60, 70, 77, and 82 years and changes in physical activity were recorded. Other information, such as body mass index, blood pressure, cholesterol levels, smoking status and alcohol use, was also collated at each survey.

At age 50, almost half of the men reported a high level of physical activity, corresponding to at least three hours of recreational sports or heavy gardening a week. Just over one third (36%) reported medium activity, corresponding to walks and cycling, and 15% were sedentary.

Overall mortality rates were highest among sedentary men and lowest among the most active men.

However, during the first five years of follow-up, the mortality rate was higher in men who had increased their level of physical activity than in men with unchanged high physical activity. But the number of such deaths was relatively small, so the researchers have not emphasised this finding.

But after 10 years, the mortality rate in these men was reduced to the same level as men with unchanged high physical activity. This reduction in mortality was similar to the effect of stopping smoking.

After adjusting for other risk factors, the researchers estimate that men who reported high levels of physical activity from age 50 were expected to live 2.3 years longer than sedentary men and 1.1 years longer than men who reported medium levels of physical activity.

Increased physical activity prolongs life among middle aged and older men, though there might be a period of 5-10 years before an effect is seen on total mortality, write the authors. This effect is the same as smoking cessation. They suggest further research should investigate whether and to what extent increased physical activity affects mortality in the period soon after the change, while the effects in other age groups and in women also need to be studied.