Key result
Leg blood flow occlusion performed immediately after a ramp-incremental test revealed an O2 extraction reserve that was ~30-45% higher than the plateau reached during exercise, with no significant differences regardless of sex or training status.
Why the study?
Although an O2 extraction reserve has been observed beyond the plateau in NIRS-derived deoxygenated hemoglobin and myoglobin during ramp-incremental testing, whether it is present across populations and exhibits sex- or training-related differences remained unknown.
Does the magnitude of the O2 extraction reserve differ between groups varying in sex and training status?
Cross-Sectional (n=25)
No
Does the magnitude of the O2 extraction reserve differ between groups varying in sex and training status?
An O2 extraction reserve exists at the end of ramp-incremental exercise across different populations, and its amplitude is not affected by sex or training status.
Answers are grounded in this paper and cite their sources.
Supports O2 extraction reserve at ramp-exercise end across populations; leaves open its role in limiting VO2max.
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.
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Inglis et al. (2019) conducted a cross-sectional in Healthy individuals (n=25). Leg blood flow occlusion post-exercise vs. Leg blood flow occlusion at rest and exercise plateau was evaluated on O2 extraction reserve (deoxy[Hb+Mb] amplitude during post-exercise occlusion vs exercise plateau) (p=<0.05). Leg blood flow occlusion performed immediately after a ramp-incremental test revealed an O2 extraction reserve that was ~30-45% higher than the plateau reached during exercise, with no significant differences regardless of sex or training status.
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