Being fit may slow lung function decline as we age

"While everyone's lung function declines with age, the actual trajectory of this decline varies among individuals, " said Lillian Benck, MD, a medical resident at Northwestern University Feinberg School of Medicine, Chicago, Illinois, and study lead investigator. "What is less known is, beyond smoking, what factors affect this rate of decline."

Dr. Benck added that even though the majority of people will not develop lung disease in their lifetime, "declining lung function is known to increase overall morbidity and mortality even in the absence of overt pulmonary disease."

Dr. Benck and her colleagues analyzed data from the National Heart, Lung, and Blood Institute's CARDIA (Coronary Risk Development in Young Adults Study), which began in 1985-86 with 5,115 healthy black and white men and women, aged 18-30. The study has measured participant's cardiopulmonary fitness periodically over 20 years using a graded treadmill test. At the beginning of the study and at each follow-up assessment, pulmonary function (PF) was also assessed by measuring forced expiratory volume in one second (FEV1) and forced vital capacity (FVC).

After adjusting for age, smoking, body mass index and change in BMI, the association between fitness and lung function remained statistically significant.

Researchers found that participants: • in the top quartile of baseline fitness experienced the least annual decline in PF.

• with the greatest decline in fitness experienced the greatest decline in FEV1and PF over 20 years.

• with sustained or improved fitness experienced the least decline in PF over 20 years.

Dr. Benck said that the last finding is noteworthy because it indicates that fitness matters, not just at a single point in time but over many years. "Fitness early in life and at middle age appears to attenuate this natural decline," she said, noting that the benefit of fitness was even seen among smokers.

Because it is an observational study, researchers cannot claim cause and effect. However, they noted several important strengths, including a large study population and long-term follow-up and objective measurements of fitness and lung health.

Dr. Benck said that CARDIA will continue to follow participants and may eventually provide insights into whether fitness not only preserves lung function, but also reduces the risk of developing lung disease.