Comparison of oxygenation in peripheral muscle during submaximal aerobic exercise, in persons with COPD and healthy, matched-control persons.

The purpose of this study was to compare peripheral muscle oxygenation in persons with chronic obstructive pulmonary disease (COPD) to healthy control persons, during submaximal exercise. Eight persons with COPD (forced expiratory volume in one second [FEV1] = 1.00 +/- 0.27 L) and eight healthy control persons (FEV, = 1.88 +/- 0.55L) performed a submaximal graded exercise test (GXT), and completed 4 min of constant load exercise (CON) at 50% of peak GXT. Measurements included oxygen uptake, heart rate, arterial oxygen saturation and peripheral muscle oxygenation (%StO2) at rest, during exercise, and recovery. Significantly greater workloads were attained for controls compared with COPD for peak GXT and CON. No significant differences in %StO2 were observed between groups at: rest (GXT: 29.5 +/- 22.8 vs 30.4 +/- 17.3%; CON: 33.3 +/- 15.4 vs 35.1 +/- 17.2%); peak GXT (29.4 +/- 19.4 vs 26.5 +/- 15.9%); 4 min of CON (25.9 +/- 13.5 vs 34.5 +/- 21.8%); and recovery (GXT: 46.6 +/- 29.1 vs 44.3 +/- 21.7%; CON: 40.9 +/- 21.5 vs 44.5 +/- 23.2%). These results suggest that peripheral skeletal muscle oxygenation is not compromised in COPD during submaximal exercise, and limitations in exercise capacity are most likely a result of muscle disuse and poor lung function.