Associations between physical fitness and lung function in children and young adults

Abstract

Introduction: Although physical activity is important for lung health, the associations between physical activity, fitness, and lung function are unclear. It is unknown whether improving physical fitness during childhood and adolescence enhances adult lung function. Aims: To investigate associations between lung function and aerobic physical fitness in two population-based cohort studies of children and young adults. Methods: Aerobic fitness was measured using a maximal cycle ergometer test at ages 9, 15, 21, and 29 years in Odense, Denmark (n=1369) and using a sub-maximal cycle test at ages 15, 26, 32, and 38 years in Dunedin New Zealand (n=1037). Spirometry, height, and weight were measured, and information about smoking and asthma was collected at each age. Results: Aerobic fitness was associated with greater spirometric volumes (FEV1 and FVC) in both cohorts at all ages, independently of height, weight, sex, asthma, and smoking. In longitudinal analyses, improvements in fitness during adolescence and young adulthood were associated with increases in lung volumes, but these associations were weaker at older ages and were not found after peak adult lung function had been attained. Fitness was not associated with FEV1/FVC ratios in either cross-sectional or longitudinal analyses. Conclusions: Aerobic fitness is associated with greater lung volumes and improvements in fitness during childhood and adolescence are associated with better lung function in young adulthood. There was no evidence of an association with airway calibre. The mechanisms of these associations are not clear but are consistent with the hypothesis that improving children’s fitness will enhance peak adult lung function.