Middle-aged people who do poorly on simple tests of physical ability may be at increased risk of early death, according to a new study.
Another study found that light-intensity physical activity every day may reduce the chance of disability in adults with -- or at risk of developing -- knee arthritis.
Both studies were published online April 29 in the journal bmj.com.
In the first study, researchers looked at data from more than 5,000 people in Britain who at age 53 underwent tests of their grip strength, how fast they could stand from sitting in a chair and their balance while standing.
The participants were followed up to age 66. During that time, 88 died from cancer, 47 from heart disease and 42 from other causes. Those who did worse on the tests of physical ability at age 53 had a higher risk of dying over the following 13 years, according to a journal news release.
The researchers also found that people who could not complete any of the physical ability tests at age 53 were 12 times more likely to die during the follow-up period than those who completed all three tests.
The findings suggest that these simple physical ability tests could be used to identify middle-aged people who are less likely to achieve a "long and healthy life," concluded Dr. Rachel Cooper at the Medical Research Council Unit for Lifelong Health and Ageing at University College London, and colleagues.
The second study, by U.S. researchers, included nearly 1,700 people, aged 49 to 83, who had or were at high risk for knee osteoarthritis. At the start of the study, all of the participants could do normal daily activities such as dressing, bathing, preparing meals or grocery shopping.
Over two years of follow-up, those who did light physical activity were less likely to become disabled due to knee osteoarthritis.
"Our findings provide encouragement for adults who may not be candidates to increase physical activity intensity due to health limitations. Greater daily physical activity time may reduce the risk of disability, even if the intensity of that additional activity is not increased," the researchers concluded.
A journal editorial accompanying both studies noted that "little attention has been given to the question of how much activity is needed to make a difference," wrote Dr. Elizabeth Badley, at the University of Toronto.
Lack of physical activity in people with knee osteoarthritis increases their risk of disability and reductions in physical ability, and "reduced physical capability in turn compromises life expectancy," she wrote.
The underlying message in both studies is that "even a little helps -- at least as far as physical activity is concerned," Badley concluded.
While the studies tied physical activity and ability in middle age to future risk of death and arthritis disability, they did not establish cause-and-effect relationships.