The effect of core stabilization exercises on lumbar multifidus muscle morphology, pain, functionality, and core stability in individuals with chronic non-specific low back pain

The aim of this study was to investigate the effects of core stabilization exercises on pain intensity, functional disability levels, lumbopelvic core stability, and the lumbar multifidus muscle (LMF) cross-sectional area (CSA) and fat infiltration in individuals with chronic non-specific low back pain (CNSLBP), compared to classic physiotherapy exercises. Thirty-one CNSLBP patients aged 20–61 were randomly assigned to either the Core Exercise Group (CEG, n=15) or Classic Physiotherapy Group (CPG, n=16). Pain intensity (Visual Analog Scale), functional disability (Oswestry Disability Index), lumbopelvic core stability (Sahrmann Core Stability Test), LMF CSA (MRI from L1–2 to L5–S1), and LMF fat infiltration (Goutallier Classification on MRI) were assessed before and after the study. The study was supervised by a physiotherapist five days a week for the first four weeks, followed by home-based exercises three days a week during the subsequent four weeks. After study, both groups showed significant improvements in pain intensity, functional disability, lumbopelvic core stability, LMF CSA, and fat infiltration (p<0.05). These improvements were significantly greater in the CEG compared to the CPG. Specifically, the CEG had larger reductions in all pain measurements, especially activity-induced pain (η²=0.418), and greater enhancements in functional disability and core stability (p<0.05). Additionally, the CEG exhibited more pronounced increases in LMF CSA and decreases in fat infiltration (p<0.05). The results revealed that core stabilization exercises are effective in reducing pain severity, supporting functional recovery, improving lumbopelvic stability, and particularly inducing positive changes in the structural properties of the LMFs in individuals with CNSLBP, all confirmed through objective methods. These results strongly underscore that the restorative effects of core stabilization exercises on muscle structure can facilitate meaningful clinical gains. Consequently, integrating core stabilization exercises into treatment protocols has the potential to enhance therapeutic efficacy by translating these structural improvements into superior clinical outcomes. Key words: Low back pain, physical functional performance, infiltration, lumbar multifidus, core stability.