The relationship between rotator cuff disorders and abdominal muscles: Biomechanical and clinical findings

BackgroundRotator cuff (RC) disorders are common musculoskeletal conditions causing shoulder pain and functional loss. While abdominal muscles aid in core stabilization and force transmission, their strength, endurance, and thickness in RC disorders remain underexplored.ObjectivesThis study aimed to examine the differences in abdominal muscle performance between individuals with RC pathology and healthy controls and to evaluate the relationship of these parameters with pain, disability and quality of life.Materials and MethodThis cross-sectional study evaluated 128 individuals (RC group: 64; control group: 64). The strength of the abdominal muscles was evaluated, and the McGill endurance test was performed. Muscle thickness was measured using ultrasound imaging. Shoulder-related pain, symptoms and functionality were assessed with Shoulder Pain and Disability Index and Western Ontario Rotator Cuff Index.ResultsThe RC group exhibited significantly lower abdominal muscle strength and endurance compared to controls (<i>p</i> < 0.001). A moderate negative correlation was observed between abdominal muscle performance and clinical scores. According to ultrasound evaluations, patients with right-sided shoulder pathology (RSSP) had thinner EO (<i>p</i> < 0.001) and TrA (<i>p</i> = 0.016) muscles on the affected side, while left-sided shoulder pathology (LSSP) showed similar reductions in RA (<i>p</i> = 0.001), EO (<i>p</i> = 0.012), and TrA (<i>p</i> = 0.006) thickness. The RC group showed significantly greater percentage asymmetry in RA muscle thickness compared with controls (<i>p</i> = 0.02), while no statistically significant differences were found for EO, IO, or TrA muscles.ConclusionThis study demonstrates that decreased abdominal muscle function and thickness are associated with RC disorders. We emphasize that core stability exercises should be included in rotator cuff rehabilitation.