(CNN) - Losing the ability to move and perform the activities of daily life can lead to a loss of independence and even be deadly, so researchers are focusing on preventing conditions that can lead to disability.
Being physically active can help prevent disability in those who have or who are at risk of joint conditions. According to a new study, adults with lower-extremity joint symptoms like aching, pain or stiffness who get at least one hour of moderate to vigorous exercise every week are more likely to be free of disability after four years than those who do not meet this exercise goal.
The study, published Monday in the American Journal of Preventive Medicine, looked at participants in the Osteoarthritis Initiative, a large, multisite study on knee osteoarthritis, who were at increased risk of disability because of lower-extremity symptoms, from 2008 to 2014.
Arthritis is the inflammation of joints, the location where bones come together in the body, and can lead to disability. Osteoarthritis is a type of arthritis that occurs with aging and excessive use of joints.
"People who start to experience occasional pain, stiffness and weakness may have early osteoarthritis, the most common type of arthritis impacting more than 30 million Americans," said Cindy McDaniel, senior vice president of consumer health at the nonprofit Arthritis Foundation.
As cartilage, the tissue that covers the bone between joints, is gradually worn down, the bones can rub against each other and cause pain. Because of this, osteoarthritis is sometimes called degenerative joint disease or "wear and tear" arthritis, McDaniel explained.
Dorothy D. Dunlop, lead author of the study and professor of rheumatology medicine and preventive medicine at Northwestern's Feinberg School of Medicine, said the researchers "focused on adults with pain, aching or stiffness in lower [hip, knee, ankle, foot] joints because they are at elevated risk for developing disability."
Although these patients, ages 49 to 83, had lower-extremity joint problems, they were considered disability-free at the beginning of the study, defined as having a gait, or walking, speed of at least 1 meter per second and not reporting any limitations on their activities of daily living, such as getting dressed or walking across a room.
To measure their levels of activity, the patients were monitored with accelerometers.
"After monitoring physical activity, participants were interviewed every other year over four years," Dunlop said. The results showed that people who got at least 56 minutes of moderate to vigorous exercise per week had an 86% decreased risk of being mobility-disabled compared with those who got less exercise.
"One hour per week of brisk activity is simple to remember and at the same time is almost as strong a predictor of maintaining basic abilities as the optimal thresholds," Dunlop said.
The US Centers for Disease Control and Prevention recommends 150 minutes per week of moderate exercise for people with arthritis. These guidelines help set expectations, but they are not always followed. Nearly half of American adults exercise less than recommended, according to the CDC's National Health Interview Survey.
Previous research has shown that physical activity prevents disability, but this is the first systematic study to look at the minimum time commitment required to maintain the ability to live independently.
"Identifying an evidence-based physical activity goal which supports these basic abilities may motivate inactive older adults to begin their path towards health benefits from a physically active lifestyle," Dunlop said. "If future work shows one hour a week of moderate activity is beneficially related to other health outcomes, this threshold could provide an intermediate physical activity goal."
The study authors acknowledge some limitations: Because they looked at adults with symptomatic lower extremity joint conditions, as opposed to general joint conditions, the results are less generalizable. Also, the accelerometers were not able to record activities in water and may underestimate cycling activity.
There is an increasing need for preventing disability. "As osteoarthritis prevalence and impact have grown," McDaniel noted, "so has the attention focused on improving diagnostic techniques, treatment options and patient outcomes."
One of the ways to improve patient outcomes is encouraging an active lifestyle, which is key to maintaining independence. The bottom line is to stay as active as possible, Dunlop emphasized.
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