EFFECT OF ORAL CREATINE AND CAFFEINE ON MUSCLE PHOSPHOCREATINE RESYNTHESIS IN COMPETITIVE SWIMMERS

Abstract

1283 The purpose of this investigation was to examine the effects of creatine (Cr) + caffeine (Ca) on the resynthesis of muscle phosphocreatine and on performance characteristics associated with swimming. Six highly trained female swimmers were randomly selected and tested for baseline measurements prior to supplementation. Each subject consumed Cr(0.4 g/kg/d) for 5d + a gelatin placebo (200 mg/d) for the final 3d. Following a brief washout period each subject consumed Cr(0.4 g/kg/d) for 5d + Ca(200 mg/d) for the final 3d (Treatment: randomized, double blind). 31P NMRs of the forearm flexors and a maximal intermittent exercise fatigue test of a wrist curl were performed. The exercise test consisted of 3×30s maximal wrist curls on a 3min rest interval. Also, a 6×8s tethered resistance swim to measure force generated and a 6×50y repeat swim on a 3min rest interval to measure performance time were also conducted. Muscle PCr resynthesis was not changed across the treatment conditions. Total force produced was increased by Cr + Ca (P<0.05) but was not changed by Cr alone. Performance time was significantly faster after Cr(P<0.05), but was not altered following Cr + Ca. The data show that Cr supplementation markedly improves swim performance when a 3min recovery is provided between repeat swims. Conversely, Cr + Ca significantly improved force generation when a 30s recovery is provided between repeat swims. Finally, 31P NMRs is not an appropriate measuring device for PCr resynthesis. These results await further confirmation in a subsequent study utilizing a larger number of subjects.