Key Point

Smokers can potentially attenuate the deleterious effects of their habit by regularly engaging in moderate to high levels of physical activity.

BARCELONA—The benefits of physical exercise to strengthen the lungs and increase breathing capacity are well-known, and new research by Garcia-Aymerich and colleagues published in the American Journal of Respiratory Critical Care Medicine takes the concept one step further. After analyzing data from the ongoing Copenhagen City Heart Study, they found that smokers who engage in moderate to high levels of regular physical activity have slower declines in lung function and less risk for COPD than do smokers who engage in low levels of activity. “Beyond the importance of reinforcing anti­smoking initiatives at all levels of the health care process, the recommendation of increasing the level of physical activity may be especially important in active smokers,” the researchers said.

Data for 6,790 subjects with a mean of 11 years of follow-up were included in the analysis. Never smokers, former smokers, and active smokers comprised 23%, 22%, and 55% of participants, respectively; during the study period, 86% of subjects did not change their smoking status, 10% quit smoking, 2% started smoking, and 2% resumed smoking. The researchers determined that, respectively, 12%, 50%, and 38% of subjects participated in low (mean expenditure of 82 kcal/d), moderate (99 kcal/d), and high (123 kcal/d) levels of regular physical activity at baseline.

As per the definition of FEV1/FVC of 70% or less, 12% of subjects had COPD at baseline, and nearly 930 subjects developed COPD during follow-up. Overall, active smokers had a higher risk of COPD than did never smokers and former smokers; however, the odds ratios for COPD, based on levels of physical activity, were as follows:

• 1.00 for any subject with low physical activity

• 0.80 for all subjects with moderate to high physical activity

• 0.80 for never smokers with moderate to high physical activity

• 1.11 for former smokers with moderate to high physical activity

• 0.77 for active smokers with moderate to high physical activity.

The benefit of physical activity was greater among persons with asthma than among those without asthma.

“Results for FEV1 decline, FVC decline, and COPD risk remained very similar after stratification according to sex, baseline chronic mucus hypersecretion, and baseline BMI,” the study authors noted. Furthermore, there was a trend toward increased decline in lung function among subjects who decreased their usual amount of physical activity during the course of the study and decreased decline among those who increased their physical activity levels during the course of the study.

The authors suggested that inflammation might be the link that ties physical activity to smoking. “Inflammation relates smoking with lung function decline and pathogenesis of COPD,” they noted, and regular exercise suppresses the production of inflammatory markers such as interleukin-6 and C-reactive protein and enhances anti-inflammatory markers (eg, interleukin-10, adiponectin). “It is plausible that regular physical activity could counteract the smoking effects through an anti-inflammatory and antioxidant mechanism,” they added.            

—Adriene Marshall

Suggested Reading
Garcia-Aymerich J, Lange P, Benet M, et al. Regular physical activity modifies smoking-related lung function decline and reduces risk of chronic obstructive pulmonary disease: a population-based cohort study. Am J Respir Crit Care Med. 2007;175:458-463.

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