Histological and morphological changes of multifidus muscle have been reported in lumbar disc herniation (LDH), but there is scarce research comparing the efficacy of different treatment programs that can correct multifidus dysfunction in chronic low back pain (LBP) with LDH. The purpose: this study will be to investigate and compare the effect of lumbar stabilization exercises and manipulation on multifidus muscle in chronic LBP patients with LDH. Subjects: sixty patients aged ranged from 45 - 65 years suffering from chronic LBP with LDH will be randomly assigned into three groups, each group includes 20 patients. Method: group (A) (control group) will receive general exercises for back muscles, group (B) will receive general exercises and lumbar stabilization exercises, and group (C) will receive general exercises and lumbar manipulation (B and C experimental groups). The outcome measurements pre and post 6 weeks of treatment will be pain intensity by visual analogue scale (VAS), functional disabilities by Oswestry disability index (ODI), lumbar repositioning by Biodex system (LR), cross sectional area (CSA) and the asymmetry of both sides of multifidus muscle at the fourth and fifth lumbar vertebrae by ultrasonography.

Inclusion Criteria:

• The selected subjects had chronic LBP with magnetic resonance imaging (MRI) evidence of disc herniation at levels of L4-L5 and/or L5-S1 diagnosed by physician (orthopedist, neurosurgeon).
• A period of continuous complaints of pain for more than 12 weeks.
• All patients reported an average pain level of at least 5 on a scale of 0 to 10.

Exclusion Criteria:

• Acute inflammatory diseases of musculoskeletal system.
• Pathology or deformities of hip, knee and ankle joints.
• History of surgical approach to their back or had special pathology or non spinal condition causing referred back symptoms.
• Patient who indicated for surgery to treat lumbar disc herniation (i.e. sever intolerable pain, motor weakness, and cannot control urine and stool).
• Cardiopulmonary diseases which decrease the patient's tolerance and activities.
• Spondylolisthesis.
• Diabetic neuropathy.
• Osteoporosis.
• A recent history of vestibular disorder or inner ear infection with associated balance and coordination problems.
• A history of cerebral trauma with unresolved neurosensory symptoms or neurological deficits.