Participants in this arm received a McKenzie-based extension exercise program focusing on repeated lumbar extension movements. The exercises were performed under the supervision of a physical therapist according to standardized McKenzie principles. The program was designed to reduce pain, improve lumbar range of motion, and decrease functional disability in individuals with chronic non-specific low back pain.

Participants in this arm received a motor control exercise program designed to improve activation, coordination, and endurance of deep trunk muscles, including the transversus abdominis and multifidus. The exercises were supervised by a physical therapist and were progressed according to patient tolerance. The intervention aimed to improve spinal stability, reduce pain, and enhance functional ability.

Participants in this arm received a combined intervention consisting of McKenzie extension exercises and motor control exercises. The program integrated repeated lumbar extension movements with trunk stabilization and motor control training. The intervention was supervised by a physical therapist and aimed to improve pain intensity, lumbar range of motion, muscle endurance, and functional disability.

Participants received a McKenzie-based extension exercise program consisting of repeated lumbar extension movements performed in lying and standing positions. The exercises were prescribed and supervised by a physical therapist according to standardized McKenzie principles. The intervention focused on symptom centralization, pain reduction, and improvement in lumbar range of motion and functional ability in individuals with chronic non-specific low back pain.

Pain intensity was assessed using the Numeric Pain Rating Scale (NPRS), an 11-point scale ranging from 0 (no pain) to 10 (worst imaginable pain). Participants reported their average pain intensity, with higher scores indicating greater pain severity.

Trunk extensor muscle endurance was measured using the Biering-Sorensen test. Participants maintained the horizontal prone position with the upper body unsupported for as long as possible, and the duration was recorded in seconds as a measure of trunk muscle endurance.

Lumbar range of motion was assessed using a goniometer to measure flexion and extension movements of the lumbar spine. Measurements were recorded in degrees, with higher values indicating greater spinal mobility.

Functional disability was evaluated using the Oswestry Disability Index (ODI), a validated self-reported questionnaire assessing disability related to low back pain. Scores were calculated as percentages, with higher scores indicating greater disability.