Forget jumping jacks and treadmills. Just doing household chores and other mundane activities of daily living is enough to help older adults live longer, new research suggests.

Elderly couch potatoes were much more likely to die within about six years than those whose lives included regular activity no more strenuous than washing dishes, vacuuming, gardening and climbing stairs, according to the study of adults aged 72 to 80.

About 12 percent of people with the highest amount of daily activity died during the six-year follow-up, compared with nearly 25 percent of the least active participants. The government-funded study appears in Wednesday's Journal of the American Medical Association.

"This is a monumental study," said Dr. Andrew Goldberg, a geriatrics expert who was not involved in the research. "They used state-of-the-art methodology to answer a very important question, which is how important is it to remain physically active."

The highest activity level studied "translates into a 50 percent reduction in mortality. That's really big," said Goldberg, a University of Maryland professor and director of geriatric research at the Baltimore Veterans Affairs Medical Center.

The most active among the 302 adults studied didn't even do much, if any, rigorous exercise. But they did burn about 1,000 calories daily through activity, or about 600 more than the least active.

For someone weighing 170 pounds, roughly the study's average body weight, that would equal about 3 1/2 hours of daily activity including yard work and household chores, versus less than two hours of similar activity for the least active.

The groups had similar amounts of age-related illness including diabetes, arthritis and cardiovascular disease, which affected more than half the study participants.

The most active were more likely to work for pay and to climb two or more flights of stairs daily, but surprisingly didn't do higher amounts of traditional exercise, said lead author Todd Manini, a scientist at the National Institute on Aging.

Jean Serpico, 75, of Arlington Heights, Ill., wasn't part of the research but has habits similar to the most active participants in the study. She climbs stairs daily to her second-floor condo, does frequent volunteer work, enjoys household chores, baking, shopping and helping her elderly neighbors.

"I do all that to keep busy. I just can't sit and look out the window," Serpico said. "I just keep active. I think it keeps me going."

The study results don't mean that older adults who engage in a more intense fitness regimen should stop, or that they won't gain perhaps even greater health benefits from it, the researchers said. Rather, they said, the study should be encouraging for those intimidated by traditional exercise, illustrating that activity doesn't have to be strenuous to be beneficial.

Manini said it is uncertain whether the results would apply to younger people.

The researchers used a laboratory technique that some consider the gold standard of measuring expended energy and more reliable than self-reported activity levels, although they also questioned participants about their habits.

Participants drank specially formulated water that is expelled from the body as carbon dioxide, which is a direct measure of energy use. For the next two weeks, they went about their usual activities. Fourteen days later, researchers measured the amount of special water remaining in the body. The difference between the levels on the first and 14th day, factoring in resting metabolic rate, determined how much energy had been expended through activity.

Participants were then followed for up to about eight years.

Improved activity-related cardiac fitness and well-being from feeling socially connected through work or volunteering might explain why active people lived longer, although the study didn't measure those effects, said co-author Dr. James Everhart of the National Institute of Diabetes and Digestive and Kidney Diseases.

Dr. Sandra Selikson, a geriatrics specialist at Montefiore Medical Center in New York, said the results would help her encourage her older patients.

"You don't have to be motivated to do a mini-triathalon or a 10K. Just being active ... even benefited people who had medical problems," Selikson said. "Even doing something is better than nothing."