WASHINGTON -- Add blisters, bruises, sprains and even broken bones to the list of things that smokers are more likely to get.
A study of Army basic trainees finds that those who were smokers before entering basic training had a 1.5 times higher rate of injuries related to exercise.
''Our findings make smoking a greater immediate concern to commanders because smoking can affect injury risk and thereby the readiness of soldiers,'' the researchers said. ''Additionally, results should be of interest to the civilian community, because they suggest that youthful smokers will have an immediate reason not to start smoking, or to quit.''
In the study, reported in the April issue of a supplement to the American Journal of Preventive Medicine, researchers followed 1,087 men and 915 women through all eight weeks of basic training.
The recruits were asked, before they started training, about their smoking habits. And the scientists kept track of the new soldiers' clinic visits during training.
Recruits who said they had been smokers had significantly higher risks of injuries, the study found. Forty percent of men who had smoked reported an injury, compared with 29 percent of nonsmokers. Among women, 56 percent of the smoking group reported an injury, compared with 46 percent of nonsmokers.
The study accounted statistically for things that could make the smokers' injury risk appear higher. One such factor is the smokers' lower levels of fitness at the start of training. Other studies have shown that smokers have less endurance than do nonsmokers. Injury rates are higher among people who are less fit, because they get worn out sooner.
And the study indicates that giving up smoking is no quick fix to the injury problem, said Dr. John W. Gardner, an Army colonel and researcher at the Uniformed Services University of the Health Sciences, Bethesda, Md.
Basic training is smoke-free, and recruits are monitored, so it's not easy to sneak a cigarette during training. As a result, the higher injury risk lingered for weeks, even after the smokers had been forced to quit, Gardner said.
The study should give young smokers more reason not to smoke, Gardner said. Trainee-age young adults may not be able to look far enough into the future to imagine themselves developing heart disease or lung cancer in middle age, but they can understand a stress fracture right now, he said.
Other studies have found that smoking reduces the fitness gained from exercise. For instance, research on British officer trainees found smokers trailed nonsmokers in fitness improvements, even when smokers and nonsmokers started at equal fitness levels.
The findings on U.S. basic trainees fit a pattern of research that indicates smoking raises the risks of injury, said Bruce N. Leistikow of the University of California, Davis.
Leistikow had found American smokers in general faced a 1.8 percent higher risk of death from injury. He tracked deaths from 1990 to 1995 among people who had answered questions for the Centers for Disease Control and Prevention's National Health Interview Survey.
Researchers don't know why smokers would face a greater risk of injury, but they have some ideas.
Smokers tend to have impairments in such things as the knee jerk reflex, so smoking seems to affect coordination, Leistikow said. ''If reflexes and coordination are impaired, then people are at a higher risk of injury,'' he said.
Smoking also may impair the body's ability to heal, Gardner said. Exercise is supposed to create microtraumas -- small amounts of damage to tissue that prompt the body to respond by making the healed tissue stronger than it had been before the injury. But recovery from exercise takes time, and smoking may delay recovery, he said.
''Smoking has many different effects, but nicotine is simply poisonous,'' Leistikow said. ''If people are partially poisoned, it lessens their ability to avoid injuries and recover from injuries.''
Another expert thinks the carbon monoxide of smoke may be a big factor, by depriving cells of oxygen. ''We are starving our tissues,'' said Dr. Paul J. Amoroso, a lieutenant colonel at the U.S. Army Research Institute of Environmental Medicine, Natick, Mass.
Amoroso's advice to smokers who are starting exercise is to go easier than nonsmokers on repetitive, impact-creating activities such as running. However, research can't tell yet how much less they should do, on what specific activities, or how long it might take for the higher risk to diminish, he said.
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