Analyzing Origin of Multifractality of Surface Electromyography Signals in Dynamic Contractions
01 Aug 2015-Journal of Nanotechnology in Engineering and Medicine (American Society of Mechanical Engineers)-Vol. 6, Iss: 3, pp 031002
TL;DR: In this paper, the origin of multifractality of surface electromyography (sEMG) signals during dynamic contraction in nonfatigue and fatigue conditions was analyzed and the results indicated that sEMG signals exhibit multifractal behavior.
Abstract: The aim of this study is analyze the origin of multifractality of surface electromyography (sEMG) signals during dynamic contraction in nonfatigue and fatigue conditions. sEMG signals are recorded from triceps brachii muscles of twenty two normal healthy subjects. The signals are divided into six equal segments on time scale for normalization. The first and sixth segments are considered as nonfatigue and fatigue condition respectively. The source of multifractality can be due to correlation and probability distribution. The original sEMG series are transformed into shuffled and surrogate series. These three series namely, original, shuffled and surrogate series in nonfatigue and fatigue conditions are subjected to multifractal detrended fluctuation analysis (MFDFA) and features are extracted. The results indicate that sEMG signals exhibit multifractal behavior. Further investigation revealed that origin of multifractality is primarily due to correlation. The origin of multifractality due to correlation is quantified as 80% in nonfatigue and 86% in fatigue conditions. This method of multifractal analysis may be useful for analyzing progressive changes in muscle contraction in varied neuromuscular studies.
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TL;DR: The investigated parameters reveal that the three heads of TB act independently before fatigue onset and appear to work in union after fatigue, and spectral parameters to be more specific predictors of fatigue.
Abstract: OBJECTIVE The objective of this study was to investigate fatigue in the three heads of the triceps brachii (TB) muscle using surface electromyography (sEMG) obtained at 30%, 45% and 60% of maximal voluntary contraction (MVC). METHODS Twenty-five subjects performed isometric elbow extension until failure, and the rate of fatigue (ROF), time to fatigue (TTF) and normalized TTF (NTTF) were statistically analysed. Subsequently, the behaviour of root-mean-square (RMS), mean-power frequency (MPF) and median-power frequency (MDF) under pre-, onset- and post-fatigue conditions were compared. RESULTS The findings indicated that, among the heads, ROF was statistically significant at 30% and 45% MVC (P 0.05). For every head, only TTF was statistically significant (P<0.05) at different intensities. MPF and MDF under pre-, onset- and post-fatigue conditions were statistically significant (P<0.05) among the heads at all intensities, whereas RMS showed no such behaviour. CONCLUSION The investigated parameters reveal that the three heads of TB act independently before fatigue onset and appear to work in union after fatigue. Synergist head pairs exhibit similar spectral and temporal behaviour in contrast to the non-synergist TB head pair. We find spectral parameters to be more specific predictors of fatigue.
6 citations
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01 Jan 2019
TL;DR: The contents of the chapter deal with the details of a rigorous and robust non-linear technique, namely, multifractal detrended fluctuation analysis, to assess the multifractional property of EMG signals of patients with neuromuscular disorders.
Abstract: Myopathies (MYO) are a group of disorders where malfunction of muscle fibers occurs for a number of reasons which results in a muscular dysfunction manifesting weakness of muscles. Neuropathies are also disorders of the peripheral nervous system for which information transmission from brain and spinal cord to every other part of the body is disturbed. For diagnosis and characterization of motor neuron disease (MND), myopathy, and neuropathy, the electromyography (EMG) is extensively used since EMG signal can be analyzed to obtain information in regard to degree of disorder. The contents of the chapter deal with the details of a rigorous and robust non-linear technique, namely, multifractal detrended fluctuation analysis, to assess the multifractal property of EMG signals of patients with neuromuscular disorders and also use of two quantitative parameters, the multifractal width, and the auto-correlation exponent as biomarker for diagnosis and prognosis of both MYO and NEURO and even for early detection of MND.
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28 May 2019TL;DR: To investigate whether kinesiology tape effects postural control, participants were assessed performing a dynamic balance task, whereby center of mass data would be analyzed using multifractal analysis in a repeated measures design.
Abstract: Postural analysis has been traditionally assessed using linear methods such as standard deviation to track postural variability, however postural adjustment during dynamic movement is a function of nonlinear interactions of multiple systems including sensorimotor and vestibular systems that require nonlinear analysis. Kinesiology tape promoted as a means of improving physical performance by enhancing proprioception rather than providing support to joints such as the ankle and knee. In order to investigate whether kinesiology tape effects postural control, participants were assessed performing a dynamic balance task, whereby center of mass data would be analyzed using multifractal analysis in a repeated measures design. To gauge the potential influence of different neurophysiological or mechanical adaptations to the adhesion of tape to skin, and not necessarily the properties of a specific type of tape, static tape was also assessed. Four individuals, free of injury, performed the Y Balance Test without tape, and with the application of static tape and kinesiology tape applied at the quadriceps, triceps surae and ankle. Both tapes were applied to the lower limb during separate testing sessions. All participants completed the Y Balance Test. Using the Y Balance test as a surrogate measure of proprioception influences postural control, multifractal dimension analysis was used to quantify the dynamic changes in the center of mass whilst undertaking the Y Balance Test. Statistical analysis included the Kruskal Wallis test to allow for non-normally distributed data and a Bonferroni corrected pairwise T test as a post hoc test to ascertain pairwise differences between the three conditions. Significance was set at 0.05. The fractal analysis of the dynamic changes in center of mass showed a typical multifractal, nonlinear spectrum with significant differences between the control and both taping conditions (static and kinesiology tape conditions, p = 0.021 and 0.09 respectively). Proprioception as part of postural stability is a nonlinear mechanism that plays a role in postural control. Both kinesiology tape can potentially improve proprioception at the ankle joint.
Additional excerpts
...For instance, multifractal analysis of EMG has been shown to be useful in differentiating signals as part of concentric and eccentric muscle contractions indicated changes associated with fatigue using multiscale detrended fluctuation analysis [21]....
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