title: Influence of blood flow occlusion on muscle oxygenation characteristics and the parameters of the power-duration relationship.
abstract: It was previously (Monod H, Scherrer J. Ergonomics 8: 329-338, 1965) postulated that blood flow occlusion during exercise would reduce critical power (CP) to 0 Watts (W), while not altering the curvature constant (W'). We empirically assessed the influence of blood flow occlusion on CP, W', and muscle oxygenation characteristics. Ten healthy men (age: 24.8 ± 2.6 yr; height: 180 ± 5 cm; weight: 84.6 ± 10.1 kg) completed four constant-power handgrip exercise tests during both control blood flow (control) and blood flow occlusion (occlusion) for the determination of the power-duration relationship. Occlusion CP (-0.7 ± 0.4 W) was significantly (P < 0.001) lower than control CP (4.1 ± 0.7 W) and significantly (P < 0.001) lower than 0 W. Occlusion W' (808 ± 155 J) was significantly (P < 0.001) different from control W' (558 ± 129 J), and all 10 subjects demonstrated an increased occlusion W' with a mean increase of ∼49%. The present findings support the aerobic nature of CP. The findings also demonstrate that the amount of work that can be performed above CP is constant for a given condition, but can vary across conditions. Moreover, this amount of work that can be performed above CP does not appear to be the determinant of W', but rather a consequence of the depletion of intramuscular energy stores and/or the accumulation of fatigue-inducing metabolites, which limit exercise tolerance and determine W'.
authors: Department of Kinesiology, Kansas State University, Manhattan, Kansas; Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and rbrox@ksu.edu.
authors: R M
authors: RM
authors: Broxterman
authors: Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma.
authors: C J
authors: CJ
authors: Ade
authors: Department of Kinesiology, Kansas State University, Manhattan, Kansas;
authors: J C
authors: JC
authors: Craig
authors: Department of Kinesiology, Kansas State University, Manhattan, Kansas;
authors: S L
authors: SL
authors: Wilcox
authors: Department of Kinesiology, Kansas State University, Manhattan, Kansas;
authors: S J
authors: SJ
authors: Schlup
authors: Department of Kinesiology, Kansas State University, Manhattan, Kansas;
authors: T J
authors: TJ
authors: Barstow
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: critical power; curvature constant; muscle ischemia; oxygen delivery