Abstract
It has been demonstrated that the plateau in the near-infrared spectroscopy (NIRS) derived deoxygenated hemoglobin and myoglobin (deoxy[Hb+Mb]) signal (i.e., deoxy[Hb+Mb]PLATEAU) towards the end of a ramp-incremental (RI) test does not represent the upper-limit in O2 extraction of the vastus lateralis (VL) muscle, given that an O2 extraction reserve has been recently observed. This study aimed to investigate whether this O2 extraction reserve was present in various populations and whether it exhibited sex- and/or training- related differences.Sixteen men- 8 untrained (27±5 years; 83±11 kg; 179±9 cm), 8 trained (27±4 years; 82±10 kg; 182±8 cm) and 9 trained women (27±2 years; 66±10 kg; 172±6 cm) performed a RI cycling test to exhaustion. The NIRS-derived deoxy[Hb+Mb] signal was measured continuously on the VL as a proxy for O2 extraction. A leg blood flow occlusion (i.e., ischemia) was performed at rest (LBFOCC 1) and immediately post the RI test (LBFOCC 2).No significant difference was found between the deoxy[Hb+Mb] amplitude during LBFOCC 1 and the deoxy[Hb+Mb]PLATEAU (p>0.05) nor between baseline (bsln) deoxy[Hb+Mb] values. deoxy[Hb+Mb] amplitude during LBFOCC 2 was significantly greater than LBFOCC 1 and at deoxy[Hb+Mb]PLATEAU (p<0.05) with group means ~30–45% higher than the deoxy[Hb+Mb]PLATEAU and LBFOCC 1 (p<0.05). No significant differences were found between groups in O2 extraction reserve, regardless of sex- or training-statusThe results of this study demonstrated the existence of an O2 extraction reserve in different populations, and that neither sex- nor training-related differences affect the amplitude of the reserve.
Highlights
The examination of muscle metabolism has revealed the presence of a functional reserve in potential energy at the limit of exercise tolerance [1,2]
A difference in absolute VO2peak and peak power output (PO) : was found between all groups (p < 0.05), whereas relative VO2peak was greater in trained men compared to untrained men (p < 0.05) with no difference found between trained women and
The present study investigated whether the magnitude of the O2 extraction reserve following a blood flow occlusion immediately at the end of ramp-incremental exercise was different in trained compared to untrained men and trained women
Summary
The examination of muscle metabolism has revealed the presence of a functional reserve in potential energy at the limit of exercise tolerance [1,2]. Using transient ischemia (i.e., leg blood flow occlusion), the existence of an O2 extraction “reserve” (as measured by the near-infrared spectroscopy (NIRS) derived deoxygenated [hemoglobin and myoglobin]. O2 extraction reserve: Effects of sex and training status decision to publish, or preparation of the manuscript
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