Use of facemask and mouthpiece to assess constant-workrate exercise capacity in COPD.

Purpose: To compare the response to constant-workrate cycling exercise between the mouthpiece and the facemask in patients with chronic obstructive pulmonary disease (COPD).

Methods: Ten patients with COPD (FEV1: 48 +/- 14% pred, mean +/- SD) performed two symptom-limited constant-workrate cycling exercise tests at 80% of their predetermined peak exercise capacity. One test was performed using a mouthpiece and the other with a facemask, in a random order.