title: Greater V˙O2peak is correlated with greater skeletal muscle deoxygenation amplitude and hemoglobin concentration within individual muscles during ramp-incremental cycle exercise.
abstract: It is axiomatic that greater aerobic fitness (V˙O2peak) derives from enhanced perfusive and diffusive O2conductances across active muscles. However, it remains unknown how these conductances might be reflected by regional differences in fractional O2extraction (i.e., deoxy [Hb+Mb] and tissue O2saturation [StO2]) and diffusive O2potential (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˙O2peakrange: ~37.4-66.4 mL kg-1min-1), we tested the hypotheses that (1) deoxy[Hb+Mb] and total[Hb+Mb] at V˙O2peakwould be positively correlated with V˙O2peakin 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˙O2peakPeak deoxy [Hb+Mb] and StO2correlated with V˙O2peakfor 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 StO2correlated with V˙O2peakonly 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 O2extraction) correlated significantly with V˙O2peakin both RF and VL muscles. However, only in the RF did total[Hb+Mb] (index of diffusive O2potential) relate to fitness.
authors.affiliation: Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Okushima
authors.affiliation: Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas.
authors.forename: David C
authors.initials: DC
authors.lastname: Poole
authors.affiliation: Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Barstow
authors.affiliation: Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.
authors.forename: Harry B
authors.initials: HB
authors.lastname: Rossiter
authors.affiliation: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment Kobe University, Kobe, Japan.
authors.forename: Narihiko
authors.initials: N
authors.lastname: Kondo
authors.affiliation: Department of Internal Medicine & Cardiology, Heart Center, Leipzig University, Leipzig, Germany.
authors.forename: T Scott
authors.initials: TS
authors.lastname: Bowen
authors.affiliation: Faculty of Education Niigata University, Niigata, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Amano
authors.affiliation: Applied Physiology Laboratory, Kobe Design University, Kobe, Japan s-koga@kobe-du.ac.jp.
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Koga
mesh_terms: D006454:Hemoglobins / Q000378:metabolism*; D000072696:High-Intensity Interval Training; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption; D010809:Physical Fitness; D055815:Young Adult
chemical_list: D006454:Hemoglobins
keywords: Diffusive oxygen potential; fractional oxygen extraction; peak oxygen uptake; time‐resolved NIRS