Arm position matters: Changes in vastus medialis activation during the single-leg squat in recreational athletes

Abstract

The single-leg squat (SLS) is commonly used to assess lower-extremity neuromuscular performance. However, the effect of arm position on vastus medialis activation during the SLS remains unclear. This study aimed to investigate the effect of different arm positions on vastus medialis activation during the SLS in recreational athletes. Twenty recreational athletes (10 males, 10 females; age 25.15 ± 3.39 years) performed the SLS in four arm-position conditions: arms free, arms flexed at 90°, hands on hips, and arms crossed over the chest. Surface electromyography was used to assess mean and peak vastus medialis activation (%MVIC). Differences among conditions were analyzed using the Friedman test and Bonferroni-corrected Wilcoxon signed-rank tests. Mean vastus medialis activation differed significantly among arm positions ( p < 0.001). Activation was greater with the arms crossed over the chest than with the arms free ( p < 0.001), arms flexed at 90° ( p = 0.005), or hands on hips ( p = 0.006). Peak activation was greater with the arms crossed over the chest than with the arms free ( p = 0.002). Arm position influences vastus medialis activation during the SLS. These findings suggest that arm position should be considered when using the SLS for assessment and exercise progression.