If everyone in the study had gotten enough activity, decline in physical function could have been as much as 32% lower, the researchers estimate.
"Older persons with chronic conditions need to be encouraged to participate in physical activities, regardless of their current capabilities," they write.
Arthritis and other rheumatic conditions are the leading causes of disability in the U.S., says the study. Nearly 60% of U.S. adults aged 65 and older have arthritis, and 10% of them say their daily activities are limited, the researchers note.
Trouble With Daily Life
Arthritis can be painful, and that may understandably make some patients want to avoid physical activity. But the new study says that's not always a great idea.
More than 5,700 people with arthritis participated. All were at least 65 years old.
At the study's start, nearly one in five said their physical function was limited, and some 13% had trouble with activities of daily life. Almost 6% said they had trouble with two or more activities, while twice as many reported problems with three or more daily tasks.
Men, Whites More Active
Many participants said they weren't very active, but women and minorities were more likely to fall into that category.
Women were more likely than men to say they had a hard time with daily activities.
About 68% of women said they didn't get regular, vigorous activity, compared to 57% of men. Among minorities of either sex, the rates were 73% for blacks, 70% for Hispanics, and 63% for whites or people of other races.
After two years, 14% of at-risk participants reported declines in physical function. That included 15% of all women in the study, 18% of Hispanics, and nearly 19% of black participants.
After evaluating various potentially unhealthy behaviors, the researchers found that lack of regular, vigorous physical activity nearly doubled the risk of functional decline. Almost two-thirds of the participants did not get regular physical activity.
More Problems 2 Years Later
The biggest predictor of limitations in daily activities was lack of regular vigorous physical activity. A decline in mental skills also predicted physical limitations in daily activity.
"Function declined less frequently in persons who engaged in regular, vigorous physical activity, regardless of their baseline ability," write the researchers, who included Dorothy Dunlop, PhD, of Northwestern University's medical school.
In other words, being as active as possible was beneficial. Health care providers can help design a plan to do that safely.
Lack of regular physical activity is a potentially modifiable risk factor which could substantially reduce functional decline and health care cost, they conclude.