title: Sex-related differences in muscle deoxygenation during ramp incremental exercise.
abstract: Sex-specific differences in the temporal profiles of fractional O2 extraction during incremental cycling were examined using changes in near-infrared spectroscopy (NIRS)-derived muscle deoxygenated hemoglobin concentration (Δ[HHb]) and breath-by-breath pulmonary O2 uptake ( .VO2p ) measurements. Subject's (men: n=10; women: n=10) Δ[HHb] data were normalized to 100% of the response, plotted as a function ( .VO2p, % .VO2p), power output (PO), and % PO, and fit with a piecewise double-linear regression model. The slope of the first segment of the double linear model was significantly greater in women compared to men when %Δ[HHb] was plotted as a function of .VO2p, % .VO2p and PO (p<0.05). Both sexes displayed a near-plateau in the %Δ[HHb] which occurred at an exercise intensity near the respiratory compensation point. Thus, young women display a poorer ability to deliver O2 to the exercising tissue compared to men and oxidative demands must be supplemented by a greater fractional O2 extraction.
authors.affiliation: Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada; School of Kinesiology, The University of Western Ontario, London, ON, Canada.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Murias
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Keir
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Spencer
authors.forename: Donald H
authors.initials: DH
authors.lastname: Paterson
mesh_terms: D000204:Activity Cycles / Q000502:physiology*; D000328:Adult; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D016014:Linear Models; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012119:Respiration; D012737:Sex Factors; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D006454:Hemoglobins; C100003:deoxyhemoglobin
keywords: Cycling; Near-infrared spectroscopy; Oxygen extraction