Multichannel Neuromuscular Electrical Stimulation With Core Exercise for Chronic Low Back Pain

Inclusion Criteria: * Aged 18 to 55 years. * Chronic non-specific low back pain lasting at least three months. * Low back pain not attributable to a specific trauma, infection, tumor, fracture, rheumatologic disease, or serious neurological disorder. * Pain intensity meeting the protocol threshold stated as VAS \>=3. \[TEYIT - because the outcome VAS is a 100-mm scale, clarify whether the intended eligibility threshold is \>=30 mm (equivalent to 3/10) rather than \>=3 mm.\] * Physical and cognitive ability to perform the core exercise program. * Willingness to attend two treatment sessions per week for six weeks (12 sessions total). * Voluntary participation and provision of written informed consent. Exclusion Criteria: * Age younger than 18 years or older than 55 years. * Low back pain due to disc herniation, spinal stenosis, fracture, tumor, infection, or inflammatory disease. * Nerve root involvement, marked sensory loss, or muscle weakness. * Previous lumbar spine surgery. * Pacemaker or other electronic implant; pregnancy; epilepsy; or active cancer. * Open wound or skin disease in the treatment area. * Physical therapy for low back pain within the previous month or continuation of another low back pain treatment during the study period.