Muscular activity of hamstrings under attentional focus instructions: an electromyography based study

Abstract Objectives The effect of attentional focusing on muscular activities and motor skills has been well established. It is known that internal focusing (on body movement or the action itself) results in increased muscular activity. However, external focusing (on apparatus or the effect of action) results in decreased motor responses. In this study, the impact of attentional focusing has been investigated by exploring the three major components of hamstrings: the semitendinosus, the semimembranosus and the biceps femoris via EMG activity on 20 amateur football players during leg curl exercises. Methods To measure muscle activities of the participants, Integrated EMG (IEMG) was calculated on the data’s MVC values. Paired sampled t-tests with Bonferroni correction (α=0.0167) were performed on the average IEMG values to determine if there is a significant difference between participants’ muscles activities under various attentional focus conditions. Results The results showed that the semimembranosus exhibited significantly reduced activity under both external (p=0.0124) and internal focus (p=0.0008), while the semitendinosus displayed a small but non-significant reduction under external focus (p=0.0355 > 0.0167). The biceps femoris showed no significant motor response regarding change between attentional focus instructions. Conclusions This study improves understanding of the mind-muscle connection by showing muscle-specific differences in attentional focus effects, with semimembranosus being most responsive.