Differences in Muscle O 2 Dynamics During Treadmill Exercise Between Aerobic Capacity-Matched Overweight and Normal-Weight Adults.

The aim of this study was to compare muscle O-2 dynamics during exercise between aerobic capacity-matched overweight and normal-weight adults. Overweight women (OW, n = 9) and normal-weight women (NW, n = 14) performed graded treadmill exercise until exhaustion. Muscle O-2 saturation (SmO2) and relative changes from rest in deoxygenated hemoglobin concentration (Delta deoxy-Hb) and total hemoglobin concentration (Atotal-Hb) were monitored continuously at gastrocnemius medians muscle by near infrared spatial resolved spectroscopy. Significantly higher SmO2 and lower Delta deoxy-Hb and Delta total-Hb were observed in OW compared with NW. Pulmonary O-2 uptake (VO2) normalized by fat-free mass was matched between groups. In both groups, peak VO2 was significantly correlated with change in SmO2 and Delta deoxy-Hb. Our findings suggest that both muscle blood volume and deoxygenation were lower in overweight adults, compared to aerobic capacity-matched normal-weight adults. Moreover, lowered muscle O-2 extraction was related to peak VO2 in overweight adults, as well as in normal-weight adults.