1. Greater V˙O2peak is correlated with greater skeletal muscle deoxygenation amplitude and hemoglobin concentration within individual muscles during ramp-incremental cycle exercise
- Author
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Okushima, Dai, Poole, David C, Barstow, Thomas J, Rossiter, Harry B, Kondo, Narihiko, Bowen, T Scott, Amano, Tatsuro, and Koga, Shunsaku
- Subjects
Male ,Physiology ,Prevention ,time‐resolved NIRS ,Clinical Sciences ,Medical Physiology ,Skeletal ,High-Intensity Interval Training ,Hemoglobins ,Young Adult ,Oxygen Consumption ,Clinical Research ,Physical Fitness ,time-resolved NIRS ,fractional oxygen extraction ,Muscle ,Humans ,peak oxygen uptake ,Diffusive oxygen potential - Abstract
It is axiomatic that greater aerobic fitness (V˙O2peak) derives from enhanced perfusive and diffusive O2 conductances across active muscles. However, it remains unknown how these conductances might be reflected by regional differences in fractional O2 extraction (i.e., deoxy [Hb+Mb] and tissue O2 saturation [StO2]) and diffusive O2 potential (i.e., total[Hb+Mb]) among muscles spatially heterogeneous in blood flow, fiber type, and recruitment (vastus lateralis, VL; rectus femoris, RF). Using quantitative time-resolved near-infrared spectroscopy during ramp cycling in 24 young participants (V˙O2peak range: ~37.4-66.4mLkg-1min-1), we tested the hypotheses that (1) deoxy[Hb+Mb] and total[Hb+Mb] at V˙O2peak would be positively correlated with V˙O2peak in both VL and RF muscles; (2) the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) during submaximal exercise would not differ among subjects differing in V˙O2peak Peak deoxy [Hb+Mb] and StO2 correlated with V˙O2peak for both VL (r=0.44 and -0.51) and RF (r=0.49 and -0.49), whereas for total[Hb+Mb] this was true only for RF (r=0.45). Baseline deoxy[Hb+Mb] and StO2 correlated with V˙O2peak only for RF (r=-0.50 and 0.54). In addition, the deoxy[Hb+Mb] slopes were not affected by aerobic fitness. In conclusion, while the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) did not differ between fitness groups the capacity to deoxygenate [Hb+Mb] (index of maximal fractional O2 extraction) correlated significantly with V˙O2peak in both RF and VL muscles. However, only in the RF did total[Hb+Mb] (index of diffusive O2 potential) relate to fitness.
- Published
- 2016