Inactivity in Men Is Linked to Broken Bones, Study Says

By NICHOLAS BAKALAR
Inactive men may have a substantially increased risk for broken bones of all kinds, and especially for hip fractures, a new Swedish study has found.
Even after controlling for health and behavioral variables, researchers reported, sedentary men were more than one and a half times as likely as active ones to suffer a broken bone, and more than two and a half times as likely to break a hip.
Although they are unsure of the mechanism, the authors theorize that exercise may work by increasing skeletal strength and muscle mass, and improving balance. The active men in the study did three or more hours a week of intense physical activity.
The researchers studied health records of 2,205 men beginning at age 49 to 51, and then followed them for up to 35 years, during which 482 men had at least one fracture. The men were interviewed and examined again at ages 60, 70, 77 and 82. At the end of the follow-up period (last Dec. 31), 896 of the men were still living. The study appears online in the June issue of PLoS Medicine.
At each of the five interviews, the scientists posed the same questions about watching television and movies, engaging in other sedentary activities, walking or cycling for pleasure, and engaging in sports. They also administered exercise tests and performed muscle biopsies to measure physical fitness, confirming that the men who reported higher levels of exercise were in fact more fit. By linking records with job titles, they were also able to include information on physical activity at work.
The researchers found that the men who maintained the highest levels of activity had the fewest fractures, and that those with the lowest levels had the most. The association held true for all fractures, but was especially strong for broken hips. Moreover, men who increased their exercise saw a corresponding decrease in the number of fractures.
“It’s never too late to start exercising,” said Dr. Karl Michaelsson, the lead author and a professor of surgery and epidemiology at Uppsala University in Uppsala, Sweden. But he was reluctant to offer specific exercise advice.
“You can’t say to an 85-year-old that he should start vigorous exercise three hours a week,” Dr. Michaelsson said. “Also, we only asked if the men were engaged in physical activity regularly. What kind of physical activity has the greatest effect, we don’t really know.”
The scientists controlled for a large range of variables that might influence physical activity and fracture risk: smoking; marital status; education; alcohol use; body mass index; self-reported chest, joint, or back pain; plus a large number of illnesses including cardiovascular, gastrointestinal, neurological, inflammatory and others.
Dr. Elizabeth Shane, a professor of medicine and osteoporosis specialist at Columbia who was not involved in the study, said she was impressed with the methodology.
“The stress testing and muscle biopsies increase the biological plausibility of the results,” Dr. Shane said. “We always recommend physical activity to our patients, and it’s helpful to know that it does seem to be associated with a decreased risk of fracture.”
The study has other significant strengths, even though it was not a randomized trial. The researchers began monitoring the men before the age when most fractures occur, and the data, gathered from registers using the individual personal registration number given to all Swedish citizens, is highly reliable. Finally, the long follow-up allowed researchers to take health and lifestyle changes over time into account.