The contribution of FEV1 and airflow limitation on the intensity of dyspnea and leg effort during exercise. Insights from a real‐world cohort

Abstract Rationale The effort required to cycle and breathe intensify as power increases during incremental exercise. It is currently unclear how changes in FEV1 in the presence or absence of airflow limitation) impacts the intensity of dyspnea and leg effort. This is clinically important as the improvement in FEV1 is often the target for improving dyspnea. Objectives To investigate the relationship between dyspnea (D), leg effort, power (P), and FEV1 with and without airflow limitation using direct psychophysical scaling performed during incremental exercise testing to symptom limited capacity. Methods Retrospective analysis of consecutive patients over the age of 35 referred for cardio‐pulmonary exercise testing at McMaster University Medical Centre from 1988–2012.The modified Borg scale was used to measure dyspnea throughout incremental exercise testing. Measurements and results 38,788 patients were included in the analysis [Mean Age 58.6 years (SD ±11.8), Males 61%, BMI 28.1 kg/m2 (SD ±5.1), FEV1 was 2.7 L (SD ±0.85), 95% predicted (SD ±20.4), FVC 3.4 L (SD ± 1.0), 94% predicted (SD ±17.0)], and 10.9% had airflow limitation (AL, FEV1/FVC