Reliability difference between spectral and entropic measures of erector spinae muscle fatigability

Sung, Paul S.; Zürcher, Ulrich; Kaufman, Miron

doi:10.1016/j.jelekin.2008.11.005

Cited by 29 publications

(26 citation statements)

References 30 publications

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“…The study of gender differences with respect to for instance pain and motor control has higher entropy values for males than for females (Sung et al, 2008). This calls for further 2 studies describing the structural changes of force variability in task-related and tangential 3 forces in relation with respect to gender difference during short and continuous force 4 production.…”

mentioning

confidence: 99%

Amount and structure of force variability during short, ramp and sustained contractions in males and females

Svendsen

Madeleine

2010

Human Movement Science

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mentioning

confidence: 99%

Amount and structure of force variability during short, ramp and sustained contractions in males and females

Svendsen

Madeleine

2010

Human Movement Science

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“…A previous study confirmed that the entropy measurement for characterizing neuromuscular alterations is reliable [6]. As a result, Shannon entropy, which measures complexity and the degree of uncertainty of information, could be widely utilized to assess localized muscle fatigability.…”

Section: Introductionmentioning

confidence: 69%

Spectral and entropy changes for back muscle fatigability following spinal stabilization exercises

Lee¹,

Kim²,

Sung³

2010

JRRD

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Abstract-The entropy of electromyography (EMG) signals suggests a possible tool for the clinical assessment of low back pain (LBP). However, a general physiological mechanism for entropy and pain and/or dysfunction following exercise intervention is still unknown. This comparative study investigated the differences between entropy levels of the EMG signals and the slope of median frequency (MF) based on power spectrum analysis in chronic LBP subjects after 4 weeks of spinal stabilization exercises (SSEs). In total, 46 subjects (24 female and 22 male) participated in the exercise program; the EMG signals of their thoracic and lumbar erector spinae muscles were measured. Following the SSEs, the level of pain as measured by the Million Visual Analog Scale decreased significantly from 3.80 to 2.81 (T = 3.42, p = 0.001). The Shannon entropy levels of the EMG signals were not different based on the back muscles (F = 2.86, p = 0.09) but demonstrated a significant interaction with pain level (F = 7.17, p = 0.01). The slope of MF differed among the muscles (F = 12.06, p = 0.01); however, no interaction with the level of pain was found (F = 0.19, p = 0.66). Therefore, the Shannon entropy of the EMG signals might be a useful and valuable clinical tool to measure pain following intervention.

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“…This connection led to the notion of homeostasis, namely that the normal function of physiologic systems operates in a steady state and that fluctuations are suppressed. However, contradictory results have subsequently been reported without clear understanding of the reliability of entropy measures (Humphrey et al, 2005;Sung et al, 2008b). Our previous studies indicated that the plateau entropy value was consistently higher for the healthy individual than for the LBP individual.…”

Section: Reliability Of Surface Electromyography Analysismentioning

confidence: 93%

“…Our previous study results indicated that the measurement of back muscle fatigability, especially the erector spinae muscle, indicated that the entropy analysis was a more reliable measure than the power spectral analysis (Sung et al, 2008b). It is well known that the observed EMG signal depends on anatomical factors, such as muscle geometry, subcutaneous fat, gender, and other confounding factors (Lindstrom et al, 1974;Mannion et al, 1997c;Pullman et al, 2000;Roy et al, 1997;Solomonow et al, 1990).…”

Section: Reliability Of Surface Electromyography Analysismentioning

confidence: 96%

“…Nonlinear analysis using fractal geometry and random walks theory proved to be useful in the analysis of a variety of time series such as correlations between global temperatures and solar activity (Scafetta & West, 2003), earthquake statistics (Scafetta & West, 2004), human heartbeat (Ivanov et al, 1999), and shapes of red cells under flow stress (Korol & Rasia, 2003). Recently, nonlinear time series generated by the back muscles' electrical activity was investigated between subjects with and without LBP motivated by the need to develop an evaluation tool for LBP (Lee et al, 2010;Sung et al, 2005;Sung et al, 2007a;Sung et al, 2010). Using random walk concepts, Collins and De Luca have studied the erratic motion of the center of pressure of a standing human body (Collins & De Luca, 1994;Collins & De Luca, 1995).…”

Section: Entropy Of Electromyographymentioning

confidence: 99%

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Nonlinear Analysis of Surface Electromyography

Sung¹

2012

EMG Methods for Evaluating Muscle and Nerve Function

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EMG Methods for Evaluating Muscle and Nerve Function 134that the signal must be interpreted as "noise." The noise is due to the interaction between a particular muscle and all other biomechanical "units" of the body. In many cases, the power spectrum follows an algebraic dependence P(f) ~ 1/f. The case =0 corresponds to "white noise" while =2 characterizes diffusive Brownian motion. Therefore, the MF of the EMG power spectrum is sensitive to physiological manifestations of muscular dysfunction as an alternative assessment tool to identify muscle fatigue (Mannion et al., 1997b;Roy et al., 1997). H o w e v e r , t h e r e i s a l a c k o f r e s e a r c h t h a t c o m p a r e s t h i s t o o l w i t h o t h e r n o n l i n e a r measurements based on pain level or dysfunction. During a fatiguing contraction, a compression of the power spectrum of the EMG signal to lower frequencies is typically observed (Lindstrom et al., 1974). This phenomenon is measured during a contraction as a decrease in the MF of the EMG signal. Individuals with better endurance than others exhibit a less precipitous decay rate of the MF (Mannion et al., 1997b). Thus, it would be necessary to compare the results between Shannon entropy levels of the EMG and MF of the spectral quantities following intervention to enhance outcome measurements.Other results indicated that subjects with LBP show less fatigue than healthy subjects (Humphrey et al., 2005;Mannion et al., 2001). Thus, despite considerable efforts by many researchers, a link between MF and musculoskeletal pain/dysfunction remains elusive. Moreover, the surface EMG is not a scientifically acceptable tool for the diagnosis of pain/dysfunction, and further studies are recommended to assess the specificity and sensitivity of surface EMG (Pullman et al., 2000). Therefore, a clinical diagnosis and evaluation of LBP is still elusive, and the efficacy of therapeutic intervention and assessment for LBP cannot be tested reliably. The power spectrum analysis provides an objective and noninvasive assessment of muscle function since EMG changes are associated with fatigue (De Luca, 1984;Mannion et al., 1997a). However, contradictory results have been reported in studies using EMG as an outcome measure. The power spectrum has a limited dynamic range, and the change of the MF does not reflect such long-time correlations. New methods must be designed to capture biologically important characteristics from noisy time series. Researchers using nonlinear time series analysis have developed several mathematical tools to reveal the presence of power-law time correlations. Investigations of physiologic time series have led to the understanding that some degree of noise is necessary for the proper functioning of biological systems (Belair et al., 1995b;Glass, 2001;Strogatz, 2001). These systems must respond to external stimuli that may vary both in strength and time scale by many orders of magnitude. The "degree of irregularity" of time series can be quantified by computing the (information) entropy of...

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Reliability difference between spectral and entropic measures of erector spinae muscle fatigability

Cited by 29 publications

References 30 publications

Amount and structure of force variability during short, ramp and sustained contractions in males and females

Amount and structure of force variability during short, ramp and sustained contractions in males and females

Spectral and entropy changes for back muscle fatigability following spinal stabilization exercises

Nonlinear Analysis of Surface Electromyography

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