Effect of Gluteus Medius Strengthening on Pain, Function, and Muscle Macromorphology in Nonspecific Chronic Low Back Pain: Randomized Controlled Trial

Background and purpose. Low back pain (LBP) is a common health problem that hinders patients’ daily activities. During hip physical examination on LBP patients, gluteus medius (GMed) weakness and tenderness were found. Therefore, in patients with non-specific chronic low back pain (NSCLBP), this study examined the effect of adding specific GMed strengthening to the APTA-guided program on pain, back disability, GMed macromorphology, strength, and functional performance. Methods. This study is a randomized controlled trial involving 58 patients with NSCLBP aged between 20 and 45 years. The pain was measured by a numerical pain rating scale, functional disability was estimated by the Oswestry disability index, and Ultrasonography evaluated GMed thickness. A hand-held dynamometer measured GMed strength, and its functional performance was assessed by a single-leg squat test (SLST). Patients were randomly assigned to group A received the APTA program and group B received the same program plus selected GMed strengthening. Results. For groups A and B, the percentage of change in pain was 40%, and 66.67% and that of disability level was 45.24 %, and 61.5 %, in favor of group B. The between-group comparison revealed significant differences for pain (p = 0.001) but not for functional disability (p = 0.12). There was a significant difference in GMed thickness for average relaxed (p = 0.009), and average contracted (p = 0.043) in both groups post-treatment but not for activation (p = 0.063). GMed strength changed by 13.1% and 21.8% in groups A and B respectively but no significant differences were observed between groups (p = 0.44). The percentage of change in the SLST was 20.6% and 58.8% for Groups A and B respectively, with a significant between-group comparison (p = 0.04). Conclusions. GMed strengthening exercises improved GMed macromorphology, reduced disability, and pain, and enhanced functional performance. It may therefore be advised that patients with NSCLBP incorporate strengthening of the GMed muscle in their treatment program. Study registration. This study was registered in ClinicalTrials.gov (NCT05521165).