It’s not clear from the study if women were born with extra-flexible joints or obtained them through a lifetime of exercise and stretching, according to Tim Spector, a professor of rheumatology at St. Thomas’ Hospital in London.
However, the findings suggest the retaining flexibility in old age can ward off arthritis, he says.
“Our research suggests that both the innate or the exercise route (to flexibility) both seem to help prevent arthritis — so exercise and stretching should be encouraged,” said Spector.
“In our study we only tested the women once and can’t really separate hypermobile women who remained flexible from normal women who exercised and stretched to become more flexible than their sedentary peers,” said Spector.
People with hypermobile joints, as it’s known medically, have an expanded range of motion. They can often pull their thumbs down to touch their wrists and have elbows that hyper-extend when they stretch out their arms. And the knees of double-jointed people may bow backwards when they stand up straight.
Spector and his colleagues found that bone mineral density was three percent higher in the hips of the hypermobile group compared with other women. There was no difference in spine bone mineral density between the two groups of women, according to the study in the current issue of the Journal of Rheumatology.
The researchers also looked for osteoarthritis in the hands, knees, spine and hips of hypermobile women. Compared to their normal-jointed counterparts, hypermobile women showed a reduced risk for arthritis in the knees only.
People born with looser joints may be drawn to physical activity, which may also play a role in arthritis risk, according to Spector.
This means that hypermobility in an aging population may be an advantage and a marker of fitness when it persists later in life.
Spector recommends that all postmenopausal women concentrate on flexibility, exercise regularly and keep their body mass index — a ratio of weight to height — below 25. He says all these can help prevent osteoarthritis.
The American Academy of Orthopedic Surgeons and the American Geriatrics Society recommend that adults engage in 30 minutes of moderate physical activity every day. In addition to the cardiovascular benefits, they say exercise strengthens bones and reduces joint and muscle pain.