March 22, 2000 (Atlanta) -- Smokers may be at higher risk for exercise-related injury, according to a report in the April issue of the American Journal ofPreventive Medicine. Experts say new data suggest that smoking has an adverse effect on the repair of muscle, bone, and connective tissue.
Because smoking has been identified as a risk factor for physical injury, researchers explored its effect on exercise-related injury during basic military training. More than 2,000 male and female recruits completed a questionnaire about smoking, exercise, and injury. Body mass and physical fitness were also assessed before the training program started.
The data showed that those recruits with a history of smoking, prior to smoke-free basic training, suffered significantly more injuries than nonsmokers. Even when the researchers controlled for age, weight, and fitness level, those with a smoking history were 1.5 times more likely to be injured than those who didn't smoke.
Some of the detrimental effects of smoking are immediate. "Soldiers and others don't have to wait 10 to 30 years to experience the effects of smoking," says lead study author John Gardner, MD, DrPH, a medical epidemiologist and professor of preventive medicine at the Uniformed Service University of the Health Sciences in Bethesda, Md. "Some effects occur at an early age, have immediate consequences, and last at least several weeks after smoking cessation.
"Subjects with a smoking history were less active, less fit, and had more previous injuries. And so behavioral differences explain the findings in part," Gardner tells WebMD. "But it's also likely that smoking interferes with the process of tissue repair, making musculoskeletal tissue more susceptible to trauma and overuse."
Research supports this theory. "There's evidence that smoking interferes with both wound healing and tissue repair," says Bruce Jones, MD, MPH, a medical epidemiologist with the division of unintentional injury at the CDC. "It's also been shown that bone union is delayed in smokers with leg fractures and that middle-aged smokers have less bone density." Jones, who provided WebMD with an objective assessment of this study, says that many studies link smoking and injury, but the biological mechanism behind this link is unclear.