The pathophysiology arises from structural and biochemical degeneration within the intervertebral disc rather than direct nerve root compression alone. When radicular symptoms are present, patients frequently experience a combination of localized lumbar pain, radiating leg pain, reduced spinal mobility, and impaired daily function. Non-surgical spinal decompression therapy is frequently employed as a conservative treatment for lumbar disc pathology due to its capacity to reduce intradiscal pressure, increase disc height, and unload compressed neural structures. Nevertheless, decompression alone does not fully restore neuromuscular control or spinal stability; it is consequently commonly paired with an active exercise approach. Two of the most widely utilized adjunct approaches are the McKenzie Extension Protocol, which employs directional-preference movements and repeated end-range loading to promote symptom centralization, and Core Stability Exercises, which target the deep trunk stabilizers to improve segmental control of the lumbar spine. Although each approach is independently supported by evidence, no recent trial has directly compared their effectiveness when each is combined with spinal decompression therapy in patients with MRI-confirmed discogenic low back pain accompanied by radiculopathy. This evidence gap consequently leaves clinicians without clear guidance on which combined strategy to select.

The present study is a single-blind randomized controlled trial designed to determine and compare the effects of the McKenzie Extension Protocol versus Core Stability Exercises, each combined with spinal decompression therapy, on pain intensity, functional disability, and lumbar range of motion in adults with MRI-confirmed discogenic low back pain and radiculopathy. Forty-two participants aged 25-45 years, with a posterolateral disc bulge confirmed on MRI, a Numeric Pain Rating Scale (NPRS) score greater than 3, and a positive Straight Leg Raise test, will be recruited using purposive sampling and randomly allocated by lottery method into two equal groups of 21. Group A will receive spinal decompression therapy followed by McKenzie extension-based exercises, while Group B will receive the same decompression protocol followed by core stabilization exercises such as abdominal drawing-in, bridging, bird-dog, and side-plank variations. Both groups will also receive standardized adjunct modalities, including moist heat and interferential current therapy, and will attend three sessions per week for four consecutive weeks, totaling 12 sessions.

Outcomes will be assessed at baseline and immediately after the four-week intervention period by a blinded assessor to minimize bias. The primary outcome measures include pain intensity (NPRS), functional disability (Oswestry Disability Index), lumbar range of motion (inclinometer), and lower-limb neural mobility (Straight Leg Raise angle). Data will be analyzed using SPSS to compare within-group and between-group changes across the two interventions.

This trial is anticipated to generate direct comparative evidence on which combined rehabilitation strategy, either decompression with McKenzie exercises or decompression with core stability exercises, produces superior clinical outcomes for this patient population. Given that current clinical guidelines do not specify a preferred adjunct approach for discogenic radiculopathy managed with decompression, the findings are intended to assist physiotherapists in selecting more targeted, evidence-based rehabilitation protocols. Such evidence may potentially improve pain relief, functional recovery, and cost-effectiveness of care, while simultaneously reducing the long-term burden associated with chronic low back pain.