Background: Physical training of lower leg skeletal muscle has been shown to increase exercise tolerance in Chronic Obstructive Pulmonary Disease (COPD) patients. The objective of this study was to measure the effect of concurrent aerobic-resistance interval exercise on lower leg muscle function and local muscle tissue oxygenation in the vastus lateralis muscle (VLM) of COPD patients. Methods: Peripheral muscle oxygenation in the VLM was measured using Near Infrared Spectrometry (NIRS) during the six- minute walk test (6MWT) in 15 COPD patients: Experimental (EXP., n = 9) and control (CTL., n = 6). Both groups trained for 3 weeks (1 hour/day and 5 days/week). Training sessions consisted of upper body strength exercises for 20 minutes. Next, the CTL. Group performed 30 minutes of aerobic exercise (motorized treadmill or stationary bike), while the EXP. group completed 30 minutes of aerobic-resistance (concurrent training) interval exercise (non-motorized treadmill). Pre and post-intervention NIRS measurements included oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), hemoglobin difference (HbDif), total hemoglobin (tHb), and tissue saturation index (TSI). Systemic arterial oxygen saturation (SPO2), heart rate and the rating of perceived exertion with the modified Borg scale were also measured pre and post-intervention during the 6MWT. Results: All patients were able to complete three weeks of training. A significant increase in the 6MWT (51.4%, p textless 0.05) distance was noted in the EXP. group and in the VLM HbDiff (69%, p textless 0.05). No significant differences were observed in the other muscle oxygenation variables. Conclusion: Concurrent aerobic-resistance interval exercise increases the total distance covered at the 6MWT (increased functional capacity) and muscle oxygen extraction.