Muscle deoxygenation and oxygen uptake plateau occurrence in children with obesity

Abstract

Background: In children with obesity, the imbalance between O2 delivery and extraction might be related to the inability to achieve VO2max during treadmill tests. The aim of the study is to characterize the changes in muscle deoxyhemoglobin (BPdeoxy[heme]) in the gastrocnemius medialis of children with obesity. 26 children with obesity (11.6±1.7 y) performed a treadmill walking test to exhaustion during which pulmonary gas exchanges and gastrocnemius medialis deoxy[heme] responses were measured continuously. BPdeoxy[heme] was determined for each participant using piecewise double-linear regressions. VO2peak and deoxy[heme] responses were compared between participants who achieved the criteria for verifying VO2max (VO2 plateau or both heart rate >95% and respiratory exchange ratio >1.0) and those not. Results: BPdeoxy[heme] was detected in 25 out of 26 participants at 77±9% VO2peak and occurred at a similar relative intensity both subgroups. There was no relationship between BPdeoxy[heme] and VO2peak. Conclusion: The imbalance between O2 delivery and extraction occur at high intensites during a treadmill walking test in youth with obesity, that may partly explain their difficulty to further continue the test regardless of the achievement of the criteria for verifying VO2max.