Effect of exercise training and detraining on gas exchange kinetics in patients with chronic obstructive pulmonary disease

Symptom-limited incremental exercise tests are used to estimate the training effect on patients with chronic obstructive pulmonary disease (COPD). However, there is a need for objective parameters for measurement on submaximal exercise testing. The purpose of this study was to assess the usefulness of measurement of oxygen uptake ((V)over dot O-2) kinetics during a constant work rate exercise test of patients with COPD after exercise training. Eleven patients with COPD performed exercise tests before and after cycle ergometer training on 3 days per week for 8 weeks; they then went without training for 5 months and performed the same tests. They performed an incremental exercise test to symptom-limited maximum and a constant work rate exercise test for 6 min on a cycle ergometer. The time constant of (V)over dot O-2 during the onset of constant work rate exercise was significantly decreased (from 63.5+/-7.8 s to 53.2+/-8.0 s) after exercise training (P=0.021), but was significantly increased (to 73.4+/-14.9 s) after 5 months without training (P=0.001). The oxygen pulse at steady state during constant work rate exercise testing was significantly increased after exercise training but decreased 5 months later. The change in blood lactate from rest to steady state during constant work rate exercise was significantly decreased after exercise training, but increased 5 months later. Measurement of the time constant of (V)over dot O-2 and oxygen pulse during constant work rate exercise are useful for the objective evaluation of the training effect of patients with COPD.