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

OBJECTIVE: 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. METHODS: Eight persons with COPD (forced expiratory volume in one second [FEV(1)] = 1.00 ± 0.27 L) and eight healthy control persons (FEV(1) = 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 (%StO(2)) at rest, during exercise, and recovery. RESULTS: Significantly greater workloads were attained for controls compared with COPD for peak GXT and CON. No significant differences in %StO(2) 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%). CONCLUSION: 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.