Correlation between spectral and temporal mechanomyography features during functional electrical stimulation

Abstract

Introduction: Signal analysis involves time and/or frequency domains, and correlations are described in the literature for voluntary contractions. However, there are few studies about those correlations using mechanomyography (MMG) response during functional electrical stimulation (FES) elicited contractions in spinal cord injured subjects. This study aimed to determine the correlation between spectral and temporal MMG features during FES application to healthy (HV) and spinal cord injured volunteers (SCIV). Methods: Twenty volunteers participated in the research divided in two groups: HV (N=10) and SCIV (N=10). The protocol consisted of four FES profiles transcutaneously applied to quadriceps femoris muscle via femoral nerve. Each application produced a sustained knee extension greater than 65º up to 2 min without adjusting FES intensity. The investigation involved the correlation between MMG signal root mean square (RMS) and mean frequency (MF). Results: HV and SCIV indicated that MMG RMS and MMG MF variations were inversely related with -0.12 ≥ r ≥ -0.82. The dispersion between MMG MF and MMG RMS reached 0.50 ≤ r 2 ≤ 0.64. Conclusion: The increase in MMG RMS and the decrease in MMG MF may be explained by the motor units coherence during fatigue state or by motor neuron adaptation (habituation) along FES application (without modification on parameters).

Influence of subcutaneous fat on mechanomyographic signals at three levels of voluntary effort

“…In applications with comparisons between the MMG signal and the force response the biceps brachii (Orizio et al, 1989) and rectus femoris (Krueger et al, 2016;Shin et al, 2016) are the muscles more used due its easy accessibility and comparison capability.…”

“…However, those researchers did not show if there is a trend related to different force levels or if this influence occurs in all (three) accelerometers axes. With the force increase, new motor units located in different places of the muscle are recruited influencing the vibration pattern of each axis (Herda et al, 2010) once the amplitude of MMG for the rectus femoris muscle contraction represents a mechanical 3-axis signal (Shin et al, 2016) and it is generated by the motor units coherence increasing the mechanical wave amplitude (Krueger et al, 2016).…”

Assessment of muscle activity using electrical stimulation and mechanomyography: a systematic review

“…Four studies [ 58 – 61 ] have been identified to discuss the physiological behaviors after fatigue administration. In one of these studies [ 58 ], the authors evaluated the correlation between the temporal and spectral features of MMG from 10 SCI and 10 health volunteers undergoing recovery by NMES. and from the analysis of window length were examined.…”

Impact of Skinfold Thickness on Wavelet-Based Mechanomyographic Signal

“…Mechanomyography (MMG) is a noninvasive technique that can be also used for monitoring muscle biofeedback as, for instance, can be apply in the control of myoelectrical [1][2][3] and neural prostheses [4] and to support physical therapy sessions [5,6]. The MMG records vibrations [7] of detectable muscle fibers on the surface of the skin.…”