Motor control exercises with and without the McKenzie method of mechanical diagnosis and therapy for fear-avoidance beliefs in chronic low back pain: a two-arm, parallel-group superiority randomized controlled trial protocol

Chronic low back pain (CLBP) is a major cause of disability and is commonly associated with psychological factors such as fear-avoidance beliefs and reduced pain self-efficacy. Motor control exercises aim to improve spinal stability, while the McKenzie method of mechanical diagnosis and therapy (MDT) emphasizes directional preference and self-management. Evidence regarding the combined effects of these approaches on psychological outcomes in CLBP is limited. This study aims to compare the effects of motor control exercises alone and in combination with the MDT on fear-avoidance beliefs and pain self-efficacy in individuals with CLBP. This single-blind, parallel randomized controlled trial will recruit adults aged 20–50 years with CLBP, moderate to severe fear-avoidance beliefs, pain intensity > 3, and a directional preference identified using the McKenzie assessment. Participants will be randomly allocated to receive either motor control exercises or motor control exercises combined with MDT. A total of 48 participants (24 per group) will be randomly allocated to receive either motor control exercises or motor control exercises combined with MDT. Interventions will be delivered three times per week for ten sessions. The primary outcome is fear-avoidance beliefs, with pain self-efficacy, pain intensity, and functional disability as secondary outcomes. Post-intervention outcomes will be compared between groups using analysis of covariance (ANCOVA) adjusted for baseline values. Psychological factors such as fear of movement and low pain self-efficacy play a critical role in the persistence of CLBP and may limit the effectiveness of exercise-based rehabilitation. While motor control exercises target neuromuscular impairments, the MDT incorporates cognitive and behavioral elements through symptom-guided movement and patient education. This trial is designed to clarify whether adding MDT to motor control exercises provides additional benefits for psychological outcomes in individuals with CLBP. The findings may inform clinical decision-making by supporting a more integrated, biopsychosocial approach to exercise prescription for CLBP. Iranian Registry of Clinical Trials: IRCT20251029067812N1. Registered on 5 November 2025, https://irct.behdasht.gov.ir/trial/87148 .