Effect of short-term creatine supplementation on neuromuscular function.

PURPOSE: 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).

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: The present study shows that oral Cr supplementation improves neuromuscular function of the elbow flexor muscle during both voluntary and electrically induced contractions.