Characteristic of Spatial Electromyographic Potential Distribution Patterns during Sustained Isometric Contraction of Patients with Parkinson's Disease

Abstract

[Purpose] The purpose of the present study was to investigate the spatial distribution pattern of muscle activation during sustained contraction in Parkinson’s disease (PD) patients using multi-channel surface electromyography (sEMG). [Subjects and Methods] Nine male PD patients and 10 healthy male subjects were enrolled in this study. All subjects performed a sustained isometric knee extension at 10% maximal voluntary contraction for 120 s. Multi-channel sEMG signals were recorded from the vastus lateralis muscle. To evaluate patterns in spatial sEMG potential distribution, absolute root mean square value maps were created at 15, 60, and 120 s from 59 pairs of data. To evaluate temporal changes in the spatial sEMG potential distribution, correlation coefficients for the same electrode locations were calculated at 15, 60 and 120 s. [Results] Correlation coefficients for PD patients were significantly higher than those of the healthy subjects at 120 s. [Conclusion] These results suggest that PD patients might activate limited numbers of the same motor units continuously during sustained contraction.