Abstract des Autors

31P NMR was used to assess the influence of two weeks creatine supplementation (21 g/d) on resting muscle PCr concentration, on the rate of PCr depletion (Rdepl), PCr repletion (Rrepl) and on the halftime of PCr repletion (t1/2). Body mass (BM) and volume of body water compartments were also estimated by impedance spectroscopy. Fourteen healthy male subjects (20.8+/-1.9 y) participated in this double-blind study. PCr was measured using a surface coil placed under the calf muscle, at rest and during two exercise bout the duration of which was 1 min. They were interspaced by a recovery of 10 min. The exercises comprised of 50 plantar flexions-extensions against weights corresponding to 40% and 70% of maximal voluntary contraction (MVC), respectively. Creatine supplementation increased resting muscle PCr content by ca. 20% (P=0.002). Rdepl was also increased by ca. 15% (P<0.001) and ca. 10% (P=0.026) during 40% and 70% MVC exercises, respectively. No change was observed in Rrepl and t1/2. BM and body water compartments were not influenced. These results indicate that during a standardized exercise more ATP is synthesized by the CK reaction when the pre-exercise level in PCr is higher, giving some support to the positive effects recorded on muscle performance. Verf.-Referat