Immediate effects of spinal manipulation, exercise therapy, and open-label placebo on lifting performance and pain in individuals with chronic non-specific back pain: a motion laboratory-based crossover randomized controlled trial

BACKGROUND: Chronic non-specific back pain (CBP) is a leading cause of disability worldwide and is commonly associated with limitations in movements such as lifting. Although spinal manipulation (SMT) and exercise therapy (ET) are recommended treatments for CBP, their effects on objectively measured movement performance remain insufficiently explored. Open-label placebo (OLP) has gained attention for engaging placebo-related mechanisms ethically. This study aimed to investigate the immediate effects of SMT, ET, and OLP on lifting performance and pain in individuals with CBP, and to evaluate the add-on effects of OLP. METHODS: A motion laboratory-based crossover randomized controlled trial included 50 individuals with CBP. Participants were recruited between April and July 2025 and attended a single laboratory session between September and October 2025. Participants performed lifting tasks using light and heavy loads before and after SMT, ET, and OLP interventions in randomized order. Three-dimensional motion capture was used to assess temporal, spatial, and spatiotemporal aspects of lifting performance. Subjective outcomes included pain intensity, perceived effectiveness, willingness to undergo each treatment, and treatment preference. Data were analyzed using linear mixed-effects models and functional data analysis. RESULTS: Overall lifting performance changed to a small degree following the interventions. No significant between-group differences were observed at the primary endpoint. Significant within-group changes were observed following SMT, including altered intersegmental coordination during the light lift, characterized by a greater relative contribution of back movement early in the lifting phase, reduced thorax-pelvis tilt during the heavy lift, and reduced pain. OLP was associated with reduced thorax-pelvis tilt and increased hip and knee flexion during the light lift. Subjective evaluations did not consistently correspond to objective biomechanical changes. CONCLUSION: SMT, ET, and OLP demonstrated limited immediate effects on overall lifting performance in individuals with CBP. However, some within-group changes in thorax-pelvis movement and intersegmental coordination suggest that certain aspects of movement quality may respond to short-term interventions even when conventional biomechanical outcomes remain largely unchanged. The findings suggest the value of integrating subjective and objective outcomes, while advanced biomechanical analyses may provide insight into subtle movement changes in CBP. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov (ID NCT06891625).