The Effect of Fatigue on Wheelchair Users' Upper Limb Muscle Coordination Patterns in Time-Frequency and Principal Component Analysis.

Liping Qi,Shuo Guan,Hai-Long Liu,Martin Ferguson-Pell,Li Zhang,Chang-Kai Sun

doi:10.1109/tnsre.2021.3119359

Abstract

An assessment of shoulder muscle coordination patterns is important to gain insight into muscle fatigue during wheelchair propulsion. The objective of the present study was to quantify muscle coordination changes over time during fatiguing wheelchair propulsion, as the muscles go through distinct levels of fatigue, a) non-fatigued, b) transiting to fatigue and c) fatigued to exhaustion. We recorded surface electromyography (sEMG) signals of the anterior deltoid (AD), middle deltoid (MD), posterior deltoid (PD), infraspinatus (IS), upper trapezius (UT), sternal head of the pectoralis major (PM), biceps brachii (BB), and triceps brachii (TB) during a wheelchair incremental exercise test. Nine wheelchair users with a diagnosis of spina bifida or T6-T12 spinal cord injury volunteered for the study. Oxygen uptake and SmartWheel kinetic parameters were also recorded during the test. EMG signals were processed by wavelet and principal component analysis (PCA), allowing for an assessment of how wheelchair users modify their muscle coordination patterns over time. Analyses of covariance (ANCOVA) were conducted to identify the main effect of fatigue levels on muscle coordination patterns by controlling for the effect of increased workload as covariate. A significant effect of fatigue levels on the PC1 and PC3 loading scores was found after controlling for the effect of increasing workloads (with both cases). In addition, PC3 reflects the most dominant fatigue effect on muscle coordination patterns which are not affected by increased ergometer workload. PC3 indicates muscle imbalance when muscles are fully fatigued and muscle co-contraction when muscles are beginning to fatigue. We conclude that fatigue-related changes in neuromuscular activity during wheelchair propulsion contribute to muscle imbalance and reflect a strategy of stiffening the shoulder joint.

Highlights

MUSCLE fatigue is defined as a decline in a muscle’s capacity to generate force that is induced by maximal and submaximal exercise [1,2,3]
In order to control the effect of the progressively increased workload during the incremental test, we used the analysis of covariance to determine the effect of fatigue level on EMG, kinetic and oxygen uptake variables with ergometer workload as covariate because the ergometer workload is linearly related to the level of the fatigue
EMG signals were first decomposed by a well-defined wavelet analysis, which allowed us to identify the timing and level of individual muscle activity during each propulsion cycle, and principal components analysis (PCA) analysis was used to capture the most relevant features of the coordination patterns associated with muscle fatigue in the present study

Summary

Introduction

MUSCLE fatigue is defined as a decline in a muscle’s capacity to generate force that is induced by maximal and submaximal exercise [1,2,3]. Wheelchair users may compensate for muscle fatigue by changing the movement patterns. These fatigue-induced changes can bring about a redistribution of muscle activity level among muscles and change inter-joint and inter-muscular coordination [6, 7]. Previous studies have reported alternating levels of muscle activity between push muscles (anterior deltoid and pectoralis major) and recovery muscles (posterior deltoid and upper trapezius) during fatiguing wheelchair propulsion [7]. Several studies have reported stroke pattern changes associated with muscle fatigue during prolonged wheelchair propulsion [8, 9]

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Conclusion