Effect of Stabilization Exercises Added to Routine Physiotherapy on Trunk Muscle Dimensions, Pain, Disability, and Lumbar Range of Motion in Patients With Unilateral Lumbar Disc Protrusion: A Randomized Controlled Trial

ABSTRACT Background and Aims To investigate the effects of stabilization exercises added to routine physiotherapy on trunk muscle dimensions, pain intensity, functional disability, and lumbar spine range of motion (ROM) in patients with unilateral lumbar disc protrusion. Methods This randomized assessor‐blinded controlled clinical trial was conducted in an outpatient physiotherapy clinic. Sixty patients diagnosed with unilateral lumbar disc protrusion were randomly allocated to an experimental or control group. The control group received routine physiotherapy, while the experimental group received routine physiotherapy combined with supervised stabilization exercises. Trunk muscle dimensions, including thickness of the deep abdominal muscles (transversus abdominis, internal oblique, and external oblique), psoas major, and lumbar multifidus, were assessed using ultrasonography at rest and during contraction. Pain intensity, functional disability, and lumbar spine ROM were also evaluated before and after the intervention. Changes in muscle thickness during contraction were evaluated as indicators of muscle performance. Results Both groups showed significant improvements in pain intensity, functional disability, and lumbar spine ROM ( p < 0.05). However, the experimental group demonstrated significantly greater improvements in pain intensity and lumbar spine ROM. In addition, muscle thickness during contraction changed significantly in the experimental group ( p < 0.05). These changes are interpreted as indirect indicators of potential functional or neuromuscular activation changes rather than definitive structural adaptations. Conclusion Adding stabilization exercises to routine physiotherapy was associated with improvements in pain, lumbar mobility, and trunk muscle thickness in patients with unilateral lumbar disc protrusion, with potential clinical implications for optimizing conservative physiotherapy programs.