How do pain-related cognitions relate to lifting techniques in people with lifting-related chronic low back pain? A replicated single-case design study

BACKGROUND: Chronic low back pain (CLBP) frequently involves lifting as a pain-provoking activity. Pain-related cognitions, such as pain-related fear, pain catastrophizing, and pain self-efficacy, are suggested to influence lifting behavior. However, the longitudinal relationship between changes in lifting kinematics and pain-related cognitions within individuals remains unexplored. OBJECTIVE: To investigate longitudinal within-person relationships between changes in lifting kinematics and changes in pain-related cognitions in people with lifting-related CLBP. METHODS: Five adults (2 females, aged 26-47 years) with lifting-related CLBP participated in a single-case design study. Weekly assessments were conducted during a 4-6-week baseline period, a 12-week Cognitive Functional Therapy intervention (up to 10 sessions), and a 3-month follow-up. Sagittal plane lifting kinematics of the spine and lower extremities were measured using wearable sensors, and pain-related cognitions (pain-related fear, pain catastrophizing, pain self-efficacy) were assessed via online questionnaires. Cross-correlation analyses examined within-person relationships between changes in lifting kinematics and changes in pain-related cognitions. RESULTS: Relationships between changes in lifting kinematics and pain-related cognitions were individual-specific. Changes in lifting techniques were frequently associated with reduced pain-related fear (15/25 relationships, 60%) and pain catastrophizing (16/25 relationships, 64%), and occasionally with improved pain self-efficacy (12/25 relationships, 48%). Where relationships were observed, reduced pain-related fear and pain catastrophizing, along with improved pain self-efficacy, were usually (39/43 relationships, 91%) associated with increased trunk flexion and velocity, decreased knee flexion and velocity, and faster lifting speed. CONCLUSIONS: For individuals with lifting-related CLBP, reduced pain-related fear and pain catastrophizing, along with improved pain self-efficacy, often occurred alongside a transition from squat-like to more semi-squat or stoop-like lifting techniques, accompanied by faster movement speed.