Exercise Capacity and Ventilatory, Circulatory, and Symptom Limitation in Patients with Chronic Airflow Limitation

TLDR

The study measured dyspnea, leg effort, ventilation, and heart rate at maximal cycle‑ergometer exercise in 97 chronic airflow limitation patients and 320 matched controls, reporting values as mean ± SD. CAL patients achieved only 60 % of predicted peak power, had higher dyspnea and leg effort ratings, and displayed lower ventilation and heart‑rate reserve compared with controls, indicating that dyspnea and peripheral muscle effort disproportionately limit their exercise capacity.

Abstract

Dyspnea, leg effort (Borg 0 to 10 scale), ventilation, and heart rate (emax/ecap; HRmax/HRcap expressed as a percentage of capacity) were measured at maximal exercise (cycle ergometer) in 97 patients with chronic airflow limitation (CAL) (FEV1 46.6 ± 14.23% of predicted) and compared with 320 matched control subjects. Patients with CAL achieved a maximum power output of 86 ± 39.5 W (60 ± 23.2% of predicted) compared with 140 ± 37.5 W (98 ± 14.5% of predicted) in controls (p < 0.0001), emax/ecap was 72 ± 19.3% compared with 53 ± 18.6% (p < 0.0001), and HRmax/HRcap was 76 ± 13.5% compared with 82 ± 13% (p < 0.001). These findings were expected. The median intensity of dyspnea was 6 (severe to very severe) and leg effort was 7 (very severe) in both groups, and these findings were unexpected. The patients with CAL were handicapped by an increase in both dyspnea and peripheral muscular effort relative to the actual power output. The rating of dyspnea exceeded leg effort in 25 (26%) of CAL versus 69 (22%) control subjects: the rating of leg effort exceeded dyspnea in 42 (43%) CAL and 117 (36%) control subjects; both were rated equally in 30 (31%) CAL and 134 (42%) control subjects, respectively (NS). emax/ecap and HRmax/HRcap were not significantly different in those limited by dyspnea, leg fatigue, or a combination of both. All values are expressed ± SD.