title: Muscle phosphocreatine repletion following single and repeated short sprint efforts.
abstract: Phosphocreatine (PCr) repletion following either single (1x6 s, n=7) or repeated (5x6 s, departing every 30 s, n=8) maximal short sprint cycling efforts was measured in separate groups of trained subjects. Muscle biopsies (vastus lateralis) were taken pre-exercise before warming up, and then at 10 s, 30 s and 3 min post-exercise. After the 1 x 6 s sprint PCr concentration was respectively, 55% (10 s; P<0.01), 69% (30 s; P<0.01) and 90% (3 min; NS) of the pre-exercise value (mean+/-SD) (81.1+/-7.4 mmol x kg(-1) DM), whereas after the 5x6 s sprints, PCr concentration was, respectively, 27% (10 s; P<0.01), 45% (30 s; P<0.01) and 84% (3 min; P<0.01) of the pre-exercise value (77.1+/-4.9 mmol x kg(-1) DM). PCr concentration was correlated with muscle lactate at 30 s (r=-0.82; P<0.05) and 3 min of recovery (r=-0.94; P<0.01) for the 1x6 s sprint, but not for the 5x6 s sprints. The extent of PCr repletion was significantly greater after the 5x6 s sprints than the 1x6 s sprint between both 10 s and 30 s and 30 s and 3 min, despite lower PCr levels at 10 s, 30 s and 3 min following the 5x6 s sprints. Full repletion of PCr is likely to take longer after repeated sprints than single short sprints because of a greater degree of PCr depletion, such that replenishment must commence from lower PCr levels rather than because of slower rates of repletion.
authors.affiliation: Department of Human Movement, The University of Western Australia, Nedlands.
authors.forename: B
authors.initials: B
authors.lastname: Dawson
authors.forename: C
authors.initials: C
authors.lastname: Goodman
authors.forename: S
authors.initials: S
authors.lastname: Lawrence
authors.forename: D
authors.initials: D
authors.lastname: Preen
authors.forename: T
authors.initials: T
authors.lastname: Polglaze
authors.forename: M
authors.initials: M
authors.lastname: Fitzsimons
authors.forename: P
authors.initials: P
authors.lastname: Fournier
mesh_terms: D000328:Adult; D001706:Biopsy; D015444:Exercise / Q000502:physiology*; D006801:Humans; D019344:Lactic Acid / Q000032:analysis; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D010725:Phosphocreatine / Q000378:metabolism*
chemical_list: D010725:Phosphocreatine; D019344:Lactic Acid