Washington: Indulging in physical activities for 30 minutes 6 days a week could slash death risk from any cause in elderly men by 40 percent, claims a new study.

The researchers base their findings on people taking part in the Oslo Study, which invited almost 26,000 men born between 1923 and 1932 for a health check in 1972-3 (Oslo I).

The analysis indicated that less than an hour a week of light physical activity was not associated with any meaningful reduction in risk of death from any cause. But more than an hour was linked to a 32 percent to 56 percent lower risk.

Less than an hour of vigorous physical activity, on the other hand, was linked to a reduction in risk of between 23 percent and 37 percent for cardiovascular disease and death from any cause.

The more time spent doing vigorous exercise the lower the risk seemed to be, falling by between 36 percent and 49 percent.

And men who regularly engaged in moderate to vigorous physical activity during their leisure time lived five years longer, on average, than those who were classified as sedentary.

Factoring in that the risk of death from heart disease/stroke rises with age, made only a slight difference to the results.

The impact would seem to be as good for health as quitting smoking among this age group, suggest the researchers.

This is an observational study so no definitive conclusions can be drawn about cause and effect, and the researchers point out that only the healthiest participants in the first wave of the study took part in the second wave, which may have lowered overall absolute risk.

But the differences in risk of death between those who were inactive and active were striking, even at the age of 73, they suggest.

The research published online in the British Journal of Sports Medicine.