Those who just can't quit smoking may have a teeny, tiny bit of added protection from a possible onset of lung cancer -- if they are willing to get out there and sweat.

In a study of older women, researchers found that physically active smokers have a 35 percent lower risk of developing lung cancer than their sedentary counterparts.

This doesn't mean that women who exercise have a free pass to smoke, but the study does reveal the lowest risk of lung cancer among study participants was found in those who had moderate workouts more than four times per week, or vigorous workouts two or more times per week.

It is unclear why physical activity might have a preventive effect on lung cancer. Perhaps the improved pulmonary function resulting from exercise reduces the concentration of carcinogenic particles that deposit in the lungs. Or maybe becoming more physically active increases smokers' awareness of the damage they have caused their lungs, motivating them to smoke less or quit.

One thing is clear, however. The single most important step a smoker can take to prevent lung cancer is quitting the nasty habit -- because those who stop smoking are 10 times less likely to develop lung cancer than those who smoke.

Dr. Norman Edelman, chief medical officer for the American Lung Association does not want smokers to gain a false sense of security from this study.

"We don't want people to get the wrong message," Edelman said. "A regular smoker has a risk of lung cancer 10 times that of a nonsmoker, and 35 percent reduction in that risk is trivial."

Edelman also states that the study does not address the effect of exercise on other smoking-related health problems, such as emphysema and heart disease. And because the active women in the study were less likely to be overweight, it is unclear if the lower lung cancer rate is a result of their exercising or their weight.