Cycling efficiency is not compromised for moderate exercise in moderately severe COPD.

Introduction/purpose: Hyperpnea and hyperinflation have been proposed as contributors to exaggerated energy demands in chronic obstructive pulmonary disease (COPD), yet there are incomplete data on exercise requirements. This study compared total-body energy demands of the internal (unloaded) and external work of cycling and delta mechanical efficiency in 40 patients (FEV1: 36+/-14% predicted) with COPD and 28 healthy age-matched controls while characterizing dynamic hyperinflation.

Methods: Steady-state V O2 was obtained at rest, during unloaded and 20-W cycling, and at 20, 50, and 65% peak cycling power.