Self-reported exercise-induced dyspnea and airways obstruction assessed by oscillometry and spirometry in adolescents

Self-reported exercise-induced dyspnea (EID) is common among adolescents. Possible underlying pathologies are exercise-induced bronchoconstriction (EIB) and laryngeal obstruction (EILO). The forced oscillation technique (FOT) may evaluate exercise-induced changes in airway caliber.

To investigate in adolescents the relationship between EID, EIB (post-exercise fall in forced expiratory volume in 1s (FEV₁ )≥10%), EILO, and post-exercise challenge changes in FOT parameters.

One hundred and forty-three subjects (97 with EID) of 13-15 years old underwent a standardized exercise challenge with FOT measurement and spirometry repeatedly performed between 2 and 30 min post-exercise. EILO was studied in a subset of 123 adolescents. Subjects showing greater changes than the healthy subgroup in the modulus of the inspiratory impedance were considered FOT responders.

EID-nonEIB subjects presented similar post-exercise changes in all FOT parameters to nonEID-nonEIB adolescents. Changes in all FOT parameters correlated with FEV₁ fall. 45 of 97 EID subjects responded neither by FEV₁ nor FOT to exercise. 19 and 18 subjects responded only by FEV₁ (onlyFEV₁ responders) or FOT (onlyFOTresponders), respectively. Only a lower baseline forced vital capacity (FVC)%predicted and a higher FEV₁ /FVC distinguished the onlyFEV₁ responders from onlyFOTresponders. FOT parameters did not present specific post-exercise patterns in EILO subjects.

FOT can be used to identify post-exercise changes in lower airway function. However, EID has a modest relation with both FEV₁ and FOT responses, highlighting the need for objective testing. More research is needed to understand whether onlyFEV₁ responders and onlyFOTresponders represent different endotypes.