Exploring Back Muscle Activities in Chronic Low Back Pain Patients Using a Large-Area Stretchable Electrode Array...

Exploring the back muscle activity in chronic low back pain (CLBP) patients is crucial for the quantitative assessment of their neuromuscular function. However, hindered by the lack of stretchable, large-area electrode arrays capable of spanning the entire back, existing studies have primarily focused on the erector spinae and multifidus muscles in the lower back. Here, we report a large-area, stretchable high-density surface electromyography (HD-sEMG) electrode array designed to cover both lower and upper back regions, enabling comprehensive characterization of back muscle activity in CLBP patients. The array comprises 64 channels arranged in a half-dumbbell configuration, inspired by the anatomical distribution of the erector spinae and multifidus muscles. Notably, this array demonstrates unprecedented operability, scalability for mass production, and reliable data acquisition capabilities. 128-channel HD-sEMG signals were acquired from both healthy controls and CLBP patients during the Biering-Sørensen test, a standardized lumbar endurance protocol. Statistical analyses of sEMG-derived metrics and topographic maps revealed significant intergroup differences in muscle activity, as well as regional variations between the lower back, upper back, and full-back segments, particularly in contraction time and fatigue-related metric changes. These findings offer novel insights into the neuromuscular dysfunction in CLBP, potentially illuminating the underlying physiological adaptations associated with CLBP.