Populations in western counties are aging. But this trend is also emerging in developing countries such as China. Keeping people healthy as they age affects not only a country's health services but also its society and economy.

For this study, researchers tracked people such as Naomi Glass who still cleans her home and does volunteer work. "I have never had a day where I have to think about how I'm going to fill it. It's always filled with something or other."

According to the study, the more motion, the longer the life. The study appears in the Journal of the American Medical Association.

Researchers from a number of institutions tracked about 300 older adults between the ages of 70 and 82 for several years. The research was coordinated by the National Institute on Aging under Todd Manini. "Any time we use energy, it's released from the body as carbon dioxide," he says.

Researchers measured the amount of carbon dioxide in the participants' urine. The participants drank special water so the amount of carbon dioxide would be evident.

Daily chores and exercise, such as climbing stairs, is beneficial
The researchers wanted to find out how much energy was used in daily exercise, such as climbing the stairs. "We found that over an eight-year period, that older adults in the low-activity group had three times greater risk of death when compared to older adults in the high-activity group," said Manini.

Naomi Glass is pleased with the news. "I think it's encouraging to people to know that they can maintain their health or maybe improve it by just doing ordinary activities."

This study did not look at the reason why higher activity is associated with lower risk of death. But Manini says activity most likely combats heart disease and cancer. He says for older adults, any movement is better than none, and usual daily activities can provide older adults with enough exercise.