Just exercising for 15 minutes daily may lower the risk of death in the elderly, a new study has claimed.

“Age is not an excuse to do no exercise. It is well established that regular physical activity has a better overall effect on health than any medical treatment,” said David Hupin from University Hospital of Saint-Etienne in France.

“But less than half of older adults achieve the recommended minimum of 150 minutes moderate intensity or 75 minutes vigorous intensity exercise each week,” said Hupin.

Researchers studied two cohorts. A French cohort of 1,011 subjects aged 65 in 2001 was followed over a period of 12 years. An international cohort of 122,417 subjects aged 60 was included from a systematic review and meta-analysis, with a mean follow up of 10 years.

Physical activity was measured in Metabolic Equivalent of Task (MET) minutes per week, which refers to the amount of energy (calories) expended per minute of physical activity.

One MET minute per week is equal to the amount of energy expended just sitting. The number of MET minutes an individual clocks up every week depends on the intensity of physical activity, researchers said.

For example, moderate intensity activity ranges between 3 and 5.9 MET minutes while vigorous intensity activity is classified as 6 or more, they said.

The recommended levels of exercise equate to between 500 and 1000 MET minutes every week. Researchers looked at the associated risk of death for four categories of weekly physical activity in MET minutes, defined as inactive (reference for comparison), low (1-499), medium (500- 999) or high (1000).

During the follow up there were 88 (9%) and 18,122 (15%) deaths in the French and international cohorts, respectively, researchers said.

The risk of death reduced in a dose response relationship as the level of exercise increased. Compared to those who were inactive, older adults with low, medium and high activity levels had a 22%, 28% and 35% lower risk of death, respectively, they said.

“These two studies show that the more physical activity older adults do, the greater the health benefit they have. The biggest jump in benefit was achieved at the low level of exercise, with the medium and high levels bringing smaller increments of benefit,” said Hupin.

“We found that the low level of activity, which is half the recommended amount, was associated with a 22% reduced risk of death in older adults compared with those who were inactive,” he said. This level of activity equates to a 15 minute brisk walk every day.