\*\*Brief Summary\*\* Lumbar radicular pain arising from intervertebral disc herniation is commonly managed with a caudal epidural steroid injection (CESI), a minimally invasive procedure that delivers anti-inflammatory medication to the sacral hiatus. Although CESI affords short-term analgesia, a sizable proportion of patients continue to experience pain-related disability and diminished quality of life, underscoring the need for optimised post-injection rehabilitation. This single-centre, three-arm, parallel-group randomised controlled trial will evaluate the comparative efficacy of two evidence-informed exercise paradigms-moderate-intensity aerobic training and progressive lumbopelvic stabilisation-when each is superimposed upon a standard physiotherapy package of heat, therapeutic ultrasound and transcutaneous electrical nerve stimulation (TENS). Forty-two adults (18-70 years) with MRI-confirmed lumbar disc herniation who have undergone CESI at Çankırı State Hospital will be randomly allocated (1:1:1) to one of the following six-week interventions, initiated two weeks post-injection and delivered thrice weekly under physiotherapist supervision: 1. Conventional physiotherapy alone (heat + ultrasound + TENS). 2. Conventional physiotherapy plus aerobic exercise (treadmill walking at 55-80 % of age-predicted maximal heart rate with structured warm-up/cool-down). 3. Conventional physiotherapy plus core-stabilisation exercise (phased activation of deep trunk musculature progressing to dynamic tasks on unstable surfaces). Primary end-points are pain intensity (10 cm Visual Analogue Scale) and back-specific disability (Oswestry Disability Index). Secondary end-points include generic health-related quality of life (SF-12) and lumbar proprioceptive body awareness (Fremantle Back Awareness Questionnaire). Outcomes will be captured at baseline, post-intervention (6 weeks) and at 3- and 6-month follow-up to ascertain both immediate and sustained effects. Study Question Does adjunctive aerobic or core-stabilisation exercise confer superior reductions in pain and disability, and greater gains in quality of life and body awareness, compared with conventional physiotherapy alone in adults following CESI for lumbar disc herniation? It is hypothesised that both exercise approaches will yield clinically and statistically superior outcomes relative to standard care, with stabilisation training providing the most durable functional benefits. Findings are expected to refine post-CESI rehabilitation algorithms and inform evidence-based clinical guidance for physiotherapists managing lumbar disc pathology.