title: Influence of priming exercise on muscle deoxy[Hb + Mb] during ramp cycle exercise.
abstract: The aim of the present study was to gain better insight into the mechanisms underpinning the sigmoid pattern of deoxy[Hb + Mb] during incremental exercise by assessing the changes in the profile following prior high-intensity exercise. Ten physically active students performed two incremental ramp (25 W min(-1)) exercises (AL and LL, respectively) preceded on one occasion by incremental arm (10 W min(-1)) and on another occasion by incremental leg exercise (25 W min(-1)), which served as the reference test (RT). Deoxy[Hb + Mb] was measured by means of near-infrared spectroscopy and surface EMG was recorded at the Vastus Lateralis throughout the exercises. Deoxy[Hb + Mb], integrated EMG and Median Power Frequency (MdPF) were expressed as a function of work rate (W) and compared between the exercises. During RT and AL deoxy[Hb + Mb] followed a sigmoid increase as a function of work rate. However, during LL deoxy[Hb + Mb] increased immediately from the onset of the ramp exercise and thus no longer followed a sigmoid pattern. This different pattern in deoxy[Hb + Mb] was accompanied by a steeper slope of the iEMG/W-relationship below the GET (LL: 0.89 ± 0.11% W(-1); RT: 0.74 ± 0.08% W(-1); AL: 0.72 ± 0.10% W(-1)) and a more pronounced decrease in MdPF in LL (17.2 ± 4.5%) compared to RT (5.0 ± 2.1%) and AL (3.9 ± 3.2%). It was observed that the sigmoid pattern of deoxy[Hb + Mb] was disturbed when the ramp exercise was preceded by priming leg exercise. Since the differences in deoxy[Hb + Mb] were accompanied by differences in EMG it can be suggested that muscle fibre recruitment is an important underlying mechanism for the pattern of deoxy[Hb + Mb] during ramp exercise.
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: Jacques
authors.initials: J
authors.lastname: Bouckaert
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Barstow
authors.forename: Jan
authors.initials: J
authors.lastname: Bourgois
mesh_terms: D000328:Adult; D001107:Architectural Accessibility / Q000295:instrumentation; D001642:Bicycling / Q000502:physiology*; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation; D006454:Hemoglobins / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D009211:Myoglobin / Q000032:analysis / Q000378:metabolism*; D009994:Osmolar Concentration; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D013997:Time Factors; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; C055547:deoxymyoglobin; C100003:deoxyhemoglobin