[Introduction] Electrical stimulation is widely used in the field of rehabilitation for purposes such as promoting muscle contraction, enhancing muscle strength, and alleviating pain. In particular, electroacupuncture (EA), a therapy that delivers low-frequency electrical stimulation through acupuncture needles, is commonly used in the acupuncture field and is considered effective for providing direct stimulation to deep tissues. However, detailed evaluations of muscle contraction dynamics induced by EA remain insufficient. The purpose of this study was to quantitatively assess the lateral displacement of muscle and adipose tissues during EA using ultrasound imaging and motion tracking techniques, and to clarify the differences in dynamic behavior among anatomical regions.[Subjects and Methods] Seven healthy young males participated in this study. EA was applied to the medial head of the right gastrocnemius muscle. Longitudinal ultrasound images were obtained, and three 20-second video recordings were collected. Using motion tracking software, lateral displacement was calculated for four regions: fat, gastrocnemius (shallow and deep layers), and soleus. Additionally, gliding distances were defined between fat and the shallow layer (DF), and between the deep layer and soleus (DIF), and their gliding characteristics were compared.[Results] Significant differences were found among the four regions. In particular, the gastrocnemius (both shallow and deep layers) and the soleus showed significantly greater lateral displacement compared to the fat layer. Moreover, a significant difference was observed in gliding distance between DF and DIF, suggesting that EA markedly influences the lateral dynamics of muscle and fascial tissues.[Discussion] This study represents the first objective visualization of muscle contraction dynamics induced by EA. These findings may contribute to the establishment of appropriate application methods and treatment strategies for EA. Future studies involving different muscle groups and stimulation parameters are expected to further expand its clinical applications.