A Comparison Analysis of Surface EMG on Trunk and Shoulder Stabilizing Muscle according to the Length of the Elastic Bar during Bench Press Exercise

Objectives This study aimed to compare and analyze the activation of stabilization muscles in the trunk and shoulder during the bench press exercise using surface Electromyography (sEMG) based on the length of elastic bars. Methods Fourteen male participants in their 20s (Age: 21.35±0.72 years, Height: 174.42±5.05 cm, Weight: 76.85±9.26 kg) were recruited as participants. Bench press exercises were performed using elastic bars with lengths of 200 cm, 220 cm, and 240 cm. Each participant performed the bench press with a load of 60% of their one-repetition maximum (1RM) for eight repetitions. sEMG was used to measure muscle activation. The selected muscles included the external oblique and rectus abdominis for the trunk, and the anterior and posterior fibers of the deltoid for the shoulder. Statistical analysis was conducted using one-way ANOVA with a significance level of .05. Results The comparison of muscle activation using sEMG across the three elastic bar lengths 200 cm(3.5kg), 220 cm(4kg), and 240 cm(4.5kg) revealed that the 240 cm bar resulted in significantly higher activation of the rectus abdominis, external oblique, and anterior fibers of the deltoid (bilaterally) compared to the 200 cm and 220 cm bars. However, no statistically significant differences were observed in the posterior fibers of the deltoid bilaterally. Conclusions The comparative analysis of three elastic bar lengths during the bench press exercise showed that the 240 cm bar elicited greater activation of the rectus abdominis, external oblique, and anterior fibers of the deltoid (bilaterally) than the 200 cm and 220 cm bars. These findings suggest that the 240 cm bar is more effective in activating stabilization muscles in the trunk and shoulder regions.