Impulse oscillometry reveals subclinical exercise-induced bronchoconstriction undetected by spirometry in healthy...

- Exercise-induced bronchoconstriction (EIB) is the acute constriction of the airways during or after physical exertion. This transient obstruction results in symptoms such as coughing, wheezing, and dyspnea, which can affect exercise performance and overall quality of life. EIB affects a substantial proportion of individuals having asthma; however, it also affects non-asthmatics; nearly 5% to 20% of the general population is affected. Spirometry has been used to assess EIB; however, it has several limitations, including dependence on forced expiratory measurements that reflect large airway function and often overlook small airways. Impulse oscillometry addresses these limitations and enables assessment of small airways without requiring forced expiratory manoeuvres. In this study, we compared the post-exercise physiological responses detected by impulse oscillometry (IOS) and conventional spirometry following cardiopulmonary exercise testing.

Spirometry and impulse oscillometry were performed in healthy young adult males before and at 5, 10,15 and 20 min after completing symptom-limited incremental exercise testing.

FEV₁ decreased significantly 5 min post-exercise compared to baseline. Peak expiratory flow decreased significantly at 5, 10, 15, and 20 min postexercise. A significant increase in peripheral airway resistance (R5-R20) was observed at 5 min post-exercise. X5% pred. increased throughout post-exercise. Resonant frequency was significantly elevated at 5 min post-exercise. Additionally, the reactance area exhibited a significant reduction at 20 min post-exercise.

This study demonstrates that serial IOS parameters detected statistically significant post-exercise peripheral airway changes that were not captured by conventional spirometry.