Comparison of Gluteus Medius and Quadratus Lumborum Muscle Activity During Hip Abduction Exercises in Individuals With Gluteus Medius Weakness

Background:The purpose of this study was to compare gluteus medius (Gmed) and quadratus lumborum (QL) muscle activities and the Gmed/QL activity ratio, during five hip abduction exercises in individuals with Gmed weakness.Objects: Nineteen participants with clinically identified Gmed weakness performed five hip abduction exercises: side-lying hip abduction (SHA), side-bridge (SB), SB using sling (SB-sling), SB with hip abduction (SB-HA), and SB-HA using sling (SB-HA-sling).Surface electromyography recorded Gmed and QL, normalized to %maximum voluntary isometric contraction (%MVIC).A repeated-measures ANOVA was used to assess differences across conditions.Results: Significant differences were found in Gmed (F = 68.980,p = 0.001) and QL (F = 10.676,p = 0.001) activation across exercises.Gmed activity was highest in SB-HA (61.77 14.46 %MVIC), while SHA produced the highest Gmed/QL activity ratio (1.70 0.26), indicating more selective Gmed activation.SB and SB-sling showed lower Gmed activity and higher QL activation.SB-HA-sling resulted in moderate Gmed activation without significantly increasing QL activation. Conclusion:The SB-HA exercise is effective for co-activating Gmed and QL, while SHA and SB-HA-sling are better suited for selectively targeting Gmed with minimal QL compensation.These findings support exercise selection based on specific rehabilitation goals.