Key result
During incremental cycling, muscle deoxygenation in the deep rectus femoris was significantly less than the superficial vastus lateralis at 70% (67.2 vs 75.5 μM) and 80% of peak work rate.
Observational (n=8)
Absolute Event Rate: 67.2% vs 75.5%
Deep quadriceps muscle exhibits a divergent deoxygenation pattern compared to superficial muscle during incremental cycling, likely due to different fiber populations and recruitment profiles.
Divergent quadriceps deoxygenation warrants layered NIRS assessment in exercise studies; leaves open fiber-specific recruitment effects on performance.
Muscle deoxygenation (i.e., deoxy[Hb + Mb]) during exercise assesses the matching of oxygen delivery (Q̇O2) to oxygen utilization (V̇O2). Until now limitations in near-infrared spectroscopy (NIRS) technology did not permit discrimination of deoxy[Hb + Mb] between superficial and deep muscles. In humans, the deep quadriceps is more highly vascularized and oxidative than the superficial quadriceps. Using high-power time-resolved NIRS, we tested the hypothesis that deoxygenation of the deep quadriceps would be less than in superficial muscle during incremental cycling exercise in eight males. Pulmonary V̇O2 was measured and muscle deoxy[Hb + Mb] was determined in the superficial vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF-s) and the deep rectus femoris (RF-d). deoxy[Hb + Mb] in RF-d was significantly less than VL at 70% (67.2 ± 7.0 vs. 75.5 ± 10.7 μM) and 80% (71.4 ± 11.0 vs. 79.0 ± 15.4 μM) of peak work rate (WR(peak)), but greater than VL and VM at WR(peak) (87.7 ± 32.5 vs. 76.6 ± 17.5 and 75.1 ± 19.9 μM). RF-s was intermediate at WR(peak) (82.6 ± 18.7 μM). Total hemoglobin and myoglobin concentration and tissue oxygen saturation were significantly greater in RF-d than RF-s throughout exercise. The slope of deoxy[Hb + Mb] increase (proportional to Q̇O2/V̇O2) in VL and VM slowed markedly above 70% WR(peak), whereas it became greater in RF-d. This divergent deoxygenation pattern may be due to a greater population of slow-twitch muscle fibers in the RF-d muscle and the differential recruitment profiles and vascular and metabolic control properties of specific fiber populations within superficial and deeper muscle regions.
No takes yet. Share an insight, caveat, or question.
Okushima et al. (2015) reported an observational. Deep quadriceps (RF-d) measurement vs. Superficial quadriceps (VL, VM, RF-s) was evaluated on Muscle deoxygenation (deoxy[Hb + Mb]) at 70% of peak work rate. During incremental cycling, muscle deoxygenation in the deep rectus femoris was significantly less than the superficial vastus lateralis at 70% (67.2 vs 75.5 μM) and 80% of peak work rate.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: