Doing household chores such as washing dishes and climbing stairs can help older adults to live longer, a new study shows.

Researchers in the U.S. studied a group of 302 adults aged 70 to 82 who lived independently. Participants were followed for an average of six years.

About 12 per cent of those who were the most active died during the study, compared to nearly 25 per cent among the least active.

"The message here is that for older adults, any movement is better than no movement and that this can come from usual daily activities," said lead author Todd Manini of the National Institute on Aging.

People in the high-activity group tended to climb two more flights of stairs a day compared to those in the low-activity group.

The most active participants weren't doing traditional exercises, yet they burned about 1,000 calories daily, about 600 more than the least active, the researchers report in Wednesday's issue of the Journal of the American Medical Association.
 
Unlike previous studies that relied on self-reports of physical activity levels, the team measured how much energy participants burned, which is considered the best way of measuring energy expended.

Manini and his team gave participants specially formulated water, which made it possible to measure carbon dioxide in urine after two weeks of usual activities.

The conclusion that "'simply expending energy through any activity may influence survival in older adults' is provocative and if documented by future research would have major implications for physical activity recommendations," Steven Blair of the Cooper Institute in Dallas and William Haskell of Stanford University School of Medicine in California wrote in a journal commentary.

To find out how the findings could translate into recommendations, the conclusions need to be verified in studies combining the water technique with technologies to measure the intensity of activity, the pair said.