Effect of Short-Term Creatine Supplementation on Neuromuscular Function

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The purpose of the present investigation was to determine whether short-term creatine (Cr) supplementation would affect 1) muscle contractile properties assessed by evoked and voluntary contractions, 2) force-velocity relationship, and 3) mean muscle fiber conduction velocity (CV). Using a double-blind random design, 16 moderately trained men (25.2 ± 5.1 yr) were assigned to a Cr (CRE) or a placebo (PLA) group. Subjects supplemented their diet four times a day for 5 d with 5 g of Cr + 15 g maltodextrin (CRE) or 20 g maltodextrin (PLA). Isometric maximal voluntary contraction, maximal twitch, force-velocity relationship, and dynamic fatiguing contractions were assessed in the elbow flexors. Mechanical and EMG signals were recorded and analyzed. CV was estimated from the EMG and used as a parameter of interest. After supplementation, peak torque (PT) of maximal twitch was 33.4% higher, and the time to reach the PT was 54.7% lower in CRE than in PLA (P < 0.05). Torque-angular velocity curve was enhanced after Cr supplementation, especially at the higher velocities. Mean fiber CV was, on average, 8.9% higher in CRE at all angular velocities after supplementation (P < 0.05). EMG and mechanical parameters during the fatiguing exercise protocol did not show significant differences in muscle fatigue between the two groups after supplementation. The present study shows that oral Cr supplementation improves neuromuscular function of the elbow flexor muscle during both voluntary and electrically induced contractions.