Multimodal Assessment of Back Performance Scale Tasks in Low Back Pain and Healthy Subjects

Low back pain (LBP) represents a leading cause of disability worldwide, with its prevalence and incidence rising significantly as life expectancy increases. In recent years, inertial measurement unit (IMU) and electromyography (EMG)-based methods for monitoring spinal kinematics and back muscle activity have proven effective in enhancing LBP diagnostic accuracy. Studies investigating body kinematics, muscular activation and trunk muscles co-activation, have identified key alterations in LBP patients compared to healthy individuals. However, accurately quantifying LBP intensity remains an open challenge. In this context, the Back Performance Scale (BPS) was developed to assess functional limitations in LBP patients. However, it has never been validated with sensor-based measurements, nor has its test redundancy been systematically analyzed. This study aims to refine and optimize the BPS by integrating quantitative EMG and IMU data while assessing its redundancy, ultimately providing a clinically validated, efficient, and practical tool for functional assessment and diagnosis in clinical and rehabilitation settings.