Effect of Creatine Supplementation in Maximal Strength and Electromyogram Amplitude of Physically Active Women

Abstract

Creatine supplementation has shown to enhance muscular strength. However, there is not a consensus on this effect on maximal isometric strength neither on electromyogram (EMG) amplitude. Thus, the aim of this study was to analyze the creatine supplementation effects on maximal isometric strength and EMG amplitude in physically active women. 27 women (age 23.04 ± 1.82 years, body mass 58.37 ± 6.10kg, height 1.63±0.05m and body mass index 21.93 ± 2.02kg/m2) were randomly assigned in creatine (CrG) (n = 13) or placebo group (PLG) (n = 14). The CrG and PLG ingested 20g/day of creatine and 20g/day of maltodextrin during six days, respectively. The strength was measured before and after supplementation using a isometric dynamometer during a maximal isometric voluntary contraction (MIVC) of a unilateral knee extension (3 sets of 6s with 180s rest period), and the EMG was acquired from the vastus lateralis muscle and its amplitude quantified using the root mean square (RMS) values. Two-way ANOVA (2 groups x 2 moments) was used for parametric data and Wilcoxon test for non-parametric analysis (p < 0.05). After supplementation, CrG significantly enhanced strength, with increase of 7.85% (p = 0.002); 7.31% (p = 0.001) and 5.52% (p = 0.000) for the first, second and third trials, respectively. In CrG, the RMS values significantly increased on the third trial (p = 0.026). No changes were found in GPL. Results suggest that creatine supplementation enhance maximal isometric strength and EMG amplitude can be useful to identify these performance modifications.