Efeito do direcionamento do foco de atenção interno na ativação muscular em sessões consecutivas de treinamento de força em exercício monoarticular

Abstract

The internal focus of attention (FI) consists of focusing on body movements or the contraction of muscles involved in a particular exercise, which may result in increased activation of the muscle being focused on in a single experimental session. The aim of the present study was to analyze the effect of directing FI on the Pectoralis major (PM) muscle activation during the performance of a strength training protocol in a single-joint exercise over the course of three consecutive sessions. Twenty-four male volunteers with a minimum of six months' continuous experience in strength training were randomly allocated to two groups: control (CON) and experimental (EXP). In one experimental session, both groups performed 3 sets of 8 repetitions at 40% of one repetition maximum, with 1 minute and 30 seconds of rest between sets and free repetition duration, in the peck deck exercise, without focusing direction. In the three subsequent sessions, the EXP group performed the protocol with FI directed to the PM contraction, while the CON group performed the protocol without focusing direction. Data were expressed as mean ± standard deviation. The electromyographic (EMG) signal amplitude of the PM was analyzed using the mean of the root mean square (RMS) of the three sets performed in each session. Normalized EMGRMS was compared using a two-way mixed-design analysis of variance (group x session). In case of statistical significance, LSD post hoc test was conducted to identify differences reported in the analysis of variance. The level of statistical significance adopted for all tests conducted was α = 0.05. The results revealed that the normalized EMGRMS (%) of the PM in the EXP group significantly increased in the first session with FI direction compared to the session without focusing direction (61.35 ± 19.47 vs 91.40 ± 33.16), resulting in a percentage increase of 48.86. Furthermore, the normalized EMGRMS (%) of the PM in the two subsequent sessions with FI in the PM remained higher (86.62 ± 27.61; and 87.73 ± 25.94) compared to the session without focusing direction, but no progressive increase was observed between the three sessions. Although the normalized EMGRMS (%) of the PM in the EXP group increased and that of the CON group did not, no statistically significant difference was found between the two groups. Therefore, focusing on contracting the PM during a single-joint strength training protocol increases its activation, but repeating the FI direction over three consecutive sessions does not result in additional increases.