title: Inspiratory loading and limb locomotor and respiratory muscle deoxygenation during cycling exercise.
abstract: The aim of this study was to determine the effect of inspiratory loading on limb locomotor (LM) and respiratory muscle (RM) deoxygenation ([deoxy (Hb+Mb)]) using NIRS during constant-power cycling exercise. Sixteen, male cyclists completed three, 6-min trials. The intensity of the first 3-min of each trial was equivalent to ~80% V(O(2max)) (EX(80%)); during the final 3-min, subjects received an intervention consisting of either moderate inspiratory loading (Load(mod)), heavy inspiratory loading (Load(heavy)), or maximal exercise (Load(EX)). Load(heavy) significantly increased LM [deoxy(Hb+Mb)] from 12.2±9.0 μm during EX(80%) to 15.3±11.7 μm, and RM [deoxy(Hb+Mb)] from 5.9±3.6 μm to 9.5±6.6 μm. LM and RM [deoxy(Hb+Mb)] were significantly increased from EX(80%) to Load(EX); 12.8±9.1 μm to 16.4±10.3 μm and 5.9±2.9 μm to 11.0±6.4 μm, respectively. These data suggest an increase in respiratory muscle load increases muscle deoxy(Hb+Mb) and thus may indicate a reduction in oxygen delivery and/or increased oxygen extraction by the active muscles.
authors.affiliation: Human Performance Laboratory, Department of Kinesiology, Indiana University, Bloomington, IN 47401, USA.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Turner
authors.forename: Sandra
authors.initials: S
authors.lastname: Tecklenburg-Lund
authors.forename: Robert F
authors.initials: RF
authors.lastname: Chapman
authors.forename: Joel M
authors.initials: JM
authors.lastname: Stager
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Duke
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Mickleborough
mesh_terms: D001642:Bicycling / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D010100:Oxygen