Patients with chronic airflow obstruction (CAO) often develop impairment of respiratory muscle function. We hypothesized that inspiratory muscle strength, as assessed by resting, peak inspiratory pressure (PIP) may be an important determinant of maximum exercise capacity in patients with CAO. Twenty ambulatory male patients (mean age, 56 ± 3 years [± SE]) with CAO (FEV1, 1.72 ± 0.21 L) comprised the studied population. Oxygen consumption at incremental cycle ergometry to tolerance (V̇O2max, 1.80 ± 0.20 L/min) served as the dependent variable for regression vs measures of resting pulmonary function. Significant correlations with V̇O2max included power output in watts (r = 0.951), V̇Emax (r = 0.858), Dsb (r = 0.841), PIP (r = 0.816), age (r = -0.809), FEV1 (r = 0.763), and FVC (r = 0.663). The FEV1, Dsb, and PIP each entered into a multiple linear regression relationship describing V̇O2max. Also, when paired with V̇Emax as independent variables in multiple regression, PIP and Dsb each improved description of V̇O2max over V̇Emax alone (p < 0.05), whereas FEV1 and FVC did not (p > 0.05). We conclude that factors other than ventilatory capacity also have a quantitative effect on V̇O2max and that PIP constitutes a determinant of maximum exercise capacity in patients with CAO.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine
- Cardiology and Cardiovascular Medicine