Comparison of Lower Limb COP and Muscle Activation During Single-Leg Deadlift Using Elastic and Inelastic Barbells

Abstract

Background: This study aimed to investigate how barbell type (elastic vs. inelastic) and lifting speed affect postural stability and lower limb muscle activation during the single-leg deadlift (SLDL), a common unilateral exercise in rehabilitation and performance training. Methods: Twenty-seven healthy adults performed SLDLs using both elastic and inelastic barbells under three lifting speeds (normal, fast, and power). Center of pressure (COP) displacement in the anterior–posterior (AP) and medial–lateral (ML) directions and electromyographic (EMG) activity of eight lower limb muscles were measured. Results: COP displacement was significantly lower when using elastic barbells (AP: F = 6.509, p = 0.017, η2 = 0.200, ω2 = 0.164; ML: F = 9.996, p = 0.004, η2 = 0.278, ω2 = 0.243). EMG activation was significantly higher for the gluteus medius, biceps femoris, semitendinosus, and gastrocnemius (all p < 0.01), especially under power conditions. Significant interactions between barbell type and speed were found for the gluteus medius (F = 13.737, p < 0.001, η2 = 0.346, ω2 = 0.176), semitendinosus (F = 6.757, p = 0.002, η2 = 0.206, ω2 = 0.080), and tibialis anterior (F = 3.617, p = 0.034, η2 = 0.122, ω2 = 0.029). Conclusions: The findings suggest that elastic barbells improve postural control and enhance neuromuscular activation during the SLDL, particularly at higher speeds. These results support the integration of elastic resistance in dynamic balance and injury prevention programs.