According to a recent study, if you're a smoker, moderate to high levels of exercise may help slow the decline of your lung function and reduce your risk of developing chronic obstructive pulmonary disease or COPD. Here's what the research shows.

Findings from a large trial, called the Lung Health Study, showed that people with early-stage COPD who had no symptoms and who quit smoking after taking part in an intensive smoking cessation program were less likely to die of any cause (including lung cancer and heart disease) nearly 15 years after stopping than were those who had not given up smoking.

But what if you can't – or haven't yet -- quit smoking? A study reported in the American Journal of Respiratory and Critical Care Medicine (Volume 175, page 458) suggests that moderate exercise may reduce the risk on COPD in smokers.

Researchers assessed the physical activity, smoking history, and lung function of 6,790 people for 11 years. At the beginning of the study, they excluded people with COPD. Over the course of the study, 928 people developed COPD. However, smokers with moderate to high levels of physical activity (equal to walking about one mile or more per day) were 23% less likely to develop COPD than smokers who were less physically active.

The researchers speculate that exercise suppresses the production of inflammatory markers in the lungs caused by smoking, which reduces the development of COPD. People who had never smoked fared the best, with a slower lung function decline and reduced risk of developing COPD over the course of the study compared with current and former smokers.

Bottom Line: Of course the best way to reduce your risk of COPD is to quit smoking. But if you haven't achieved that milestone yet, make sure you're keeping physically active in the meantime to help protect your lungs.