Detecting Musculoskeletal Co-contraction for Ankle Rehabilitation through Variational Mode Decomposition in sEMG

Abstract

The ankle joint plays important role in performing fundamental activities such as walking and other essential daily tasks. Muscular co-contraction improves joint quality as impaired ankle joint causes gait issues, induces pain and sometimes inflammation. The need is to characterize the ankle muscle co-contraction in sEMG signal by using an efficient technique i.e. Variational Mode Decomposition (VMD) to make sure that it could be a non-pharmacological treatment for persons having ankle joint issues. VMD approach analyzes surface electromyographic signals from antagonist muscles of the lower limb during walking of 20 healthy individuals and assesses muscular co-contraction using the coscalogram function. In this research, the novel combination of the scalogram visualization technique with Variational Mode Decomposition (VMD) is employed for the first time. The present study compares VMD with the Continuous Wavelet Transform (CWT) approach and shows that VMD outperforms CWT in terms of both SNR and RMSE. On average, the increase in SNR in case of VMD (-17.65 ± 8.1dB to 2.98 ±2.2dB, p<0.05) was greater than that of CWT (-17.65 ±3.7dB to 1.34±1.5dB). Similarly, the reduction in RMSE with VMD (0.023 ±0.0029 to 0.017 ±0.0015, p<0.05) surpassed that achieved with CWT (0.023±0.0027to 0.020±0.0025). This study aims to introduce a method that would be helpful for clinical and rehabilitation purposes to improve joint quality by identifying ankle muscle co-contraction