Exercise-induced bronchoconstriction and bronchodilation: investigating the effects of age, sex, airflow limitation and FEV1.

ABSTRACT

Exercise-induced bronchoconstriction (EIBc) is a recognised response to exercise in asthmatic subjects and athletes but is less well understood in an unselected broad population. Exercise-induced bronchodilation (EIBd) has received even less attention. The objective of this study was to investigate the effects of age, sex, forced expiratory volume in 1 s (FEV1) and airflow limitation (FEV1/forced vital capacity (FVC) <0.7) on the prevalence of EIBc and EIBd.This was a retrospective study based on incremental cardiopulmonary exercise testing on cycle ergometry to symptom limitation performed between 1988 and 2012. FEV1 was measured before and 10 min after exercise. EIBc was defined as a percentage fall in FEV1 post-exercise below the 5th percentile, while EIBd was defined as a percentage increase in FEV1 above the 95th percentile.35 258 subjects aged 6-95 years were included in the study (mean age 53 years, 60% male) and 10.3% had airflow limitation (FEV1/FVC <0.7). The lowest 5% of subjects demonstrated a ≥7.6% fall in FEV1 post-exercise (EIBc), while the highest 5% demonstrated a >11% increase in FEV1 post-exercise (EIBd). The probability of both EIBc and EIBd increased with age and was highest in females across all ages (OR 1.76, 95% CI 1.60-1.94; p<0.0001). The probability of EIBc increased as FEV1 % pred declined (<40% OR 4.38, 95% CI 3.04-6.31; p<0.0001), with a >2-fold increased likelihood in females (OR 2.31, 95% CI 1.71-3.11; p<0.0001), with a trend with airflow limitation (p=0.06). The probability of EIBd increased as FEV1 % pred declined, in the presence of airflow limitation (OR 1.55, 95% CI 1.24-1.95; p=0.0001), but sex had no effect.EIBc and EIBd can be demonstrated at the population level, and are influenced by age, sex, FEV1 % pred and airflow limitation.