Even in the "oldest old," a little physical activity goes a long way, extending life by at least a few years for people in their mid- to late 80s, Israeli researchers found.
The three-year survival rate was about three times higher for active 85-year-olds compared with those who were inactive. Getting less than four hours of exercise weekly was considered inactive; more than that was active.
The results "clearly support the continued encouragement of physical activity, even among the oldest old. Indeed, it seems that it is never too late to start," the researchers wrote in Monday's Archives of Internal Medicine, which published the study.
They noted that exercise reaped benefits even for previously sedentary 85-year-olds; their three-year survival rate was double that of inactive 85-year-olds.
Oldsters didn't have to be super-athletes to live longer; walking at least four hours weekly counted, even if it was just in 15-minute strolls a few times daily.
"As little as four hours a week was as beneficial as more vigorous or prolonged activity," said study author Dr. Jeremy Jacobs, a geriatric specialist at Hadassah Hebrew University Medical Center in Jerusalem.
Those who exercise less lonely, depressed
Active octogenarians also reported less depression and loneliness and a greater ability to perform daily tasks.
Similar benefits have been shown in people in their 60s and 70s, but there has been little research about exercise benefits in people in their 80s.
The study involved 1,861 Jerusalem residents who were 70 years old in 1990. Participants filled out questionnaires about their health and activity levels through 2008.
At age 85, 64 percent were physically active, a relatively high percentage that reflects the Israeli lifestyle, Jacobs said. But he said similar benefits from exercise likely would be seen among the very old in other countries.
There were 512 deaths. Slightly fewer than 7 percent of the active 85-year-olds died by age 88, versus about 24 percent of those who were inactive.
Jacobs said the researchers took into account factors that also affect survival, including participants' overall health and whether they smoked, and still found that activity levels were strongly related to longevity.
Dr. James Webster, a professor of geriatric medicine at Northwestern University's Feinberg School of Medicine in Chicago, said the study can't completely rule out that participants who were able to exercise were already healthier than the others, and thus likely to live longer.
Still, Webster said the link between octogenarian exercise and longevity appears valid. He was not involved in the study.
Laura Thorp, a researcher at Chicago's Rush University Medical Center, said very old patients who want to increase their activity should do so under a doctor's supervision. Still, Thorp said, "Even those who are not exercisers or athletes can start and still see substantial benefits."