A Novel Multidimensional Approach to Motor Function Assessment Under Functional Electrical Stimulation: Integration of Electromyography and Inertial Information

Functional electrical stimulation (FES) has emerged as a promising technique for motor rehabilitation, yet quantifying its effects remains challenging. While current assessment methods utilizing clinical scales, kinematic parameters, and biomarkers offer comprehensive evaluations, they fail to delineate the specific motor function domains influenced by FES, and quantify both therapeutic outcomes and functional improvements. To address these limitations, we introduced multi-objective decision analysis method to propose a novel multidimensional evaluation framework for assessing FES-driven motor performance under varying stimulation parameters. This study represents the first systematic analysis of the effects of different FES parameters on motor function from three dimensions: movement execution completeness, dynamic movement stability, and muscle fatigue. For this, we collected surface electromyogram (EMG) and inertial signals under different parameters of FES-driven wrist movements. As a result, we found a relationship between the FES stimulus parameters and different movement level features. Our findings demonstrate that completion indicators generally increased with increasing stimulus amplitude, while movement stability indicators showed an inverse relationship with stimulus frequency. Notably, fatigue indicators exhibited dual trends, reflecting different aspects of motor unit performance. Further analysis showed revealed that our proposed model was sensitive to changes in stimulus parameter conditions while maintaining consistent evaluation rankings as sample sizes increase. This work establishes a novel, cost-effective model and methodology to quantify motor function and stimulus effects during FES application, providing a crucial foundation for subsequent precise modulation of FES parameters and timely evaluation of rehabilitation progress.