Avaliação eletromiografica e força de musculos do membro superior em individuos submetidos a suplementação de creatina / Strenght and elctromyographic evaluation of upper limb muscles in men undergoing creatine supplementation

AUTOR(ES)

Daniela Cristina de Oliveira Silva

DATA DE PUBLICAÇÃO

2009

RESUMO

Surface electromyography is a potential tool for anatomic, clinic and kinesiologic studies of muscle electric activity and it has been employed to identify muscular activation levels associated with force and muscular fatigue. Creatine supplementation has been used to augment the strength and muscular efficiency as well to decrease the onset of muscular fatigue. This study aimed to analyze the force and electromyographic activity of biceps brachii (BB), brachioradialis (BR) and flexor carpi ulnaris (FCU) muscles in subjects submitted to acute and chronic creatine supplementation. Twenty resistance-trained male volunteers, aged 18 to 35 years, were selected for this double-blind, controlled-placebo, randomized study. Volunteers were placed into two groups: creatine (5 g creatine and 5 g maltodextrine, n=10) and placebo (5 g cellulose and 5g maltodextrine, n=10). Oral supplementation was given 4 times per day during the first 7days and once a day in the 49 subsequent days. Volunteers performed maximum isometric voluntary contraction (MIVC) of forearm flexion and with 30% and 60% MIVC, before and after 7 and 56 days of supplementation. Electromyographic signs were captured using passive surface electrodes joined to a pre-amplifier, recorded in a computer-connected electromyography and analyzed by the Myosystem-Br1 software. A load cell was used to measure the maximum isometric strength during the tests. Electromyographic data were calculated by values of amplitude (RMS - root mean square) and median frequency (MF) and analyzed by linear regression curve, generating RMS and MF slopes that were considered muscular efficiency and fatigue indices, respectively. Results showed that creatine group exhibited an increase of strength only after 56 days of supplementation (p <0.05), while no significant difference was found in placebo group. BB and BR muscles showed a decrease of RMS slopes after 7 and 56 days of creatine supplementation with 60% MIVC (p <0.05). No significant difference was observed in MF slopes among times of supplementation for all muscles in both loads and groups. It can be concluded that the chronic creatine supplementation increases the isometric strength of forearm flexion. Also, both acute and chronic creatine supplementation improve the BB and BR muscular efficiency only with high loads, but do not have beneficial effect on reducing muscular fatigue of BB, BR and FCU, whichever the load

ASSUNTO(S)

electromyography eletromiografia flexão do antebraço suplemento ergogenico forearm flexion ergogenic aid

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