title: Pattern of deoxy[Hb+Mb] during ramp cycle exercise: influence of aerobic fitness status.
abstract: During ramp exercise the deoxy[Hb + Mb] pattern follows a sigmoid model [f(x) = f (0) + A/(1 + exp(-(-c +dx))], indicating a non-linear muscle blood flow (Qm)/oxygen uptake (VO25)-relationship. We hypothesised that in trained cyclists the sigmoid would display a rightward shift, due to an increased oxidative capacity and/or higher percentage of slow-twitch fibres. A total of 10 cyclists and 11 physically active students (PA students) performed a relative ramp exercise (+/-12 min) and a ramp25-exercise (25 W min(-1)). Deoxy[Hb + Mb] was measured at the M. Vastus Lateralis by NIRS, normalized to the total amplitude of the response and expressed as a function of absolute and relative (%peakP) work rate. The work rate corresponding to c/d (i.e.50% of the amplitude of the deoxy[Hb + Mb] response) was the only parameter of the sigmoid that differed significantly between cyclists (57.9 +/- 4.4% and 60.1 +/- 4.1%peakP in the relative and ramp25, respectively) and PAstudents (49.6 +/- 4.2% and 48.2 +/- 5.1%peakP, respectively), indicating a rightward shift of the sigmoid in the cyclists. These results suggest a change in the time course of C((a-v))O(2) as a function of aerobic fitness status.
authors.affiliation: Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium. Jan.boone@ugent.be
authors.forename: Jan
authors.initials: J
authors.lastname: Boone
authors.forename: Katrien
authors.initials: K
authors.lastname: Koppo
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Barstow
authors.forename: Jacques
authors.initials: J
authors.lastname: Bouckaert
mesh_terms: D000293:Adolescent; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D009211:Myoglobin / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; C055547:deoxymyoglobin; C100003:deoxyhemoglobin