title: Skeletal muscle metabolism during short duration high-intensity exercise: influence of creatine supplementation.
abstract: Seven male subjects performed repeated bouts of high-intensity exercise, on a cycle ergometer, before and after 6 d of creatine supplementation (20 g Cr H2O day-1). The exercise protocol consisted of five 6-s exercise periods performed at a fixed exercise intensity, interspersed with 30-s recovery periods (Part I), followed (40 s later) by one 10 s exercise period (Part II) where the ability to maintain power output was evaluated. Muscle biopsies were taken from m. vastus lateralis at rest, and immediately after (i) the fifth 6 s exercise period in Part I and (ii) the 10 s exercise period in Part II. In addition, a series of counter movement (CMJ) and squat (SJ) jumps were performed before and after the administration period. As a result of the creatine supplementation, total muscle creatine [creatine (Cr) + phosphocreatine (PCr)] concentration at rest increased from (mean +/- SEM) 128.7 (4.3) to 151.5 (5.5) mmol kg-1 dry wt (P < 0.05). This was accompanied by a 1.1 (0.5) kg increase in body mass (P < 0.05). After the fifth exercise bout in Part I of the exercise protocol, PCr concentration was higher [69.7 (2.3) vs. 45.6 (7.5) mmol kg-1 dry wt, P < 0.05], and muscle lactate was lower [26.2 (5.5) vs. 44.3 (9.9) mmol kg-1 dry wt, P < 0.05] after vs. before supplementation. In Part II, after creatinine supplementation, subjects were better able to maintain power output during the 10-s exercise period (P < 0.05). There was no change in jump performance as a result of the creatine supplementation (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Karolinska Institute, Department of Physiology and Pharmacology, Physiology III, Stockholm, Sweden.
authors.forename: P D
authors.initials: PD
authors.lastname: Balsom
authors.forename: K
authors.initials: K
authors.lastname: Söderlund
authors.forename: B
authors.initials: B
authors.lastname: Sjödin
authors.forename: B
authors.initials: B
authors.lastname: Ekblom
mesh_terms: D000255:Adenosine Triphosphate / Q000097:blood / Q000378:metabolism; D000328:Adult; D001835:Body Weight / Q000502:physiology; D003401:Creatine / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000097:blood; D007773:Lactates / Q000097:blood / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010725:Phosphocreatine / Q000097:blood / Q000378:metabolism
chemical_list: D007042:Hypoxanthines; D007773:Lactates; D010725:Phosphocreatine; D019271:Hypoxanthine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D003401:Creatine