Examining Changes in Electromyography during Swing Performance in Various Strike Zone Locations of Collegiate Baseball Players

Swinging a bat is considered a sequential movement requiring coordinated muscle activation during each movement phase. There are a limited number of studies investigating swing performance as it relates to electromyography. The purpose of this study was to investigate the muscle activation pattern of the stride leg in respect to the phases within the swing and throughout the various locations within the strike zone in collegiate baseball players. Surface electromyography (EMG) examined the muscle activation patterns of the stride leg gluteus maximus (GM), vastus medialis (VMO), semitendinosus (H), medial gastrocnemius (MG), and tibilais anterior (TA) in 13 Division I college baseball players. The swing was broken down into three distinct phases for analysis (stride, transition, swing) determined by the use of a motion capture system. Participants completed counterbalanced swing trials in various locations of their respective strike zone. Repeated measures ANOVA were used to examine possible differences in EMG over the strike zone independent of each phase of the swing. Significant main effect differences in percent activation and mean muscle activity of the lower extremity were seen in trials completed at various tee heights and tee placements within their respective strike zone independent of swing phase (p<.05). Significant main effect differences in percent activation were also seen in the phases of the swing for the VMO, H, MG and TA (p<0.05). This information can provide insight to strength and conditioning professionals to focus on sport specific exercises within these distinct phases of the swing.