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Exercise-induced bronchoconstriction (EIBc) and exercise-induced bronchodilation (EIBd) occur following exercise, both of which are affected by increasing age and lower forced expiratory volume in 1 second (FEV1) percent predicted. Further, female sex influences EIBc, but not EIBd, whereas airflow limitation affects EIBd but not EIBc. Researchers conducted a retrospective study based on data obtained from sequential patients referred for clinical exercise testing at McMaster University Medical Center (MMUMC) in Hamilton, Ontario, Canada. Results of the analysis were published in the European Respiratory Journal.
Investigators sought to examine the effects of age, sex, FEV1, and airflow limitation (FEV1/forced vital capacity [FVC] <0.7) on the prevalence of EIBc and EIBd. Between 1988 and 2012, incremental cardiopulmonary exercise tests (CPETs) on cycle ergometry to symptom limitation was performed at MMUMC. The most common reasons for exercise testing was the evaluation of exercise-induced symptoms of chest pain (25%), dyspnea (12%), precardiac rehabilitation (10%), post myocardial infarction (MI; 7%), suspected exercise-induced asthma (3%), congenital heart disease (3%), cystic fibrosis (2%), and chronic obstructive pulmonary disease (COPD; 2%).
A total of 35,258 participants between 6 and 95 years of age (mean age, 53 years) were included in the study. Overall, 60% of the participants were male, and 10.3% experienced airflow limitation. A total of 1771 participants were classified as EIBc and 1861 as EIBd. Individuals with EIBc and EIBd had a lower FEV1 and a greater proportion of participants with airflow limitation at baseline, with 34% considered to be normal in both groups (no history of MI, COPD, asthma, normal spirometry, and a normal exercise capacity).
Female participants had a significantly increased likelihood of EIBc compared with male participants (odds ratio [OR], 1.76; 95% CI, 1.60-1.94; P <.0001). With respect to age, the likelihood of EIBc in both males and females was lowest in the 40- to 50-year-old age-group (males: 3.2%; females: 4.7%) and increased, reaching a peak of 10.3% in females and 7.5% in males. Other than participants who were younger than 10 years of age, the probabilities were always greater in females than in males.
Further, females had no increased probability of EIBd compared with males over the entire age range (OR, 1.04; 95% CI, 0.95-1.15; P =.38). The likelihood of EIBd was the lowest in the 10- to 20-year-old age-group for males (3.2%) and in the 30- to 40-year-old age-group for females (3.2%). The greatest likelihood of EIBd in females was reported among those younger than 10 years of age.
The likelihood of EIBc increased as the FEV1 percent predicted decreased (<40%; OR, 4.38; 95% CI, 3.04-6.31; P <.0001), with a greater than 2-fold increased likelihood in females (OR, 2.31; 95% CI, 1.71-3.113; P <.0001). The effect of the presence of airflow limitation, however, did not reach statistical significance (OR, 1.34; 95% CI, 0.99-1.81; P =.06).
The researchers concluded that the current study findings of EIBc should not be considered synonymous with those in patients with asthma. Additional prospective studies on the sensitivity and specificity of CPET in the diagnosis of exercise-induced asthma based on EIBc, or reversibility based on EIBd, are thus warranted.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Reference
Satia I, Priel E, Al-Khazraji BK, et al. Exercise induced bronchoconstriction and bronchodilation; investigating the effects of age, sex, airflow limitation and the FEV1. Eur Respir J. Published online January 14, 2021. doi:10.1183/13993003.04026-2020
