Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions

Beretta-Piccoli, Matteo; D’Antona, Giuseppe; Zampella, Cristian; Barbero, Marco; Clijsen, Ron; Cescon, Corrado

doi:10.1088/1361-6579/aa614c

Cited by 17 publications

(20 citation statements)

References 63 publications

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“…FD, MNF, and ARV showed high intra- and intersession reliability, in accordance with previously published studies [ 28 , 39 , 48 – 51 ]; the intersession reliability of CV at contraction levels higher than 60% MVC was very low. This result might be explained by the fact that the variability of CV between subjects decreases as the level of contraction increases over 60% MVC [ 52 ].…”

Section: Discussionsupporting

confidence: 92%

“…The number of channels used for CV estimation was selected based on visual inspection of single differential signals, between the distal tendon and the innervation zone, along one of the array columns, as previously described [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

“…FD was estimated using the box-counting method, as previously reported [ 28 ]. Data were analyzed by custom-written software in MATLAB R2014b (Mathworks, Natick, USA)…”

Section: Methodsmentioning

confidence: 99%

“…In particular, the FD of the signal is a measure of self-similarity over multiple time scales. Several studies [ 23 – 27 ] have applied box-counting methods to estimate the FD of the sEMG signal and a recent investigation showed a good reliability of FD during isometric contractions in the biceps brachii muscle [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

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Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

Beretta-Piccoli

Boccia

Ponti

et al. 2018

BioMed Research International

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The relationship between fractal dimension of the surface electromyogram (sEMG) and the intensity of muscle contraction is still controversial in simulated and experimental conditions. To support the use of fractal analysis to investigate myoelectric fatigue, it is crucial to establish the interdependence between fractal dimension and muscle contraction intensity. We analyzed the behavior of fractal dimension, conduction velocity, mean frequency, and average rectified value in twenty-eight volunteers at nine levels of isometric force. sEMG was obtained using bidimensional arrays in the biceps brachii muscle. The values of fractal dimension and mean frequency increased with force unless a plateau was reached at 30% maximal voluntary contraction. Overall, our findings suggest that, above a certain level of force, the use of fractal dimension to evaluate the myoelectric manifestations of fatigue may be considered, regardless of muscle contraction intensity.

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Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

“…FD was estimated using the box-counting method, as previously reported [ 28 ]. Data were analyzed by custom-written software in MATLAB R2014b (Mathworks, Natick, USA)…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

Beretta-Piccoli

Boccia

Ponti

et al. 2018

BioMed Research International

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“…We recently reported a decrease of FD during sustained isometric contractions of the quadriceps and biceps muscles, and these changes may be considered as an indicator of progressive MU synchronization [9,35]. Furthermore, FD showed a good reliability during isometric contractions in the biceps brachii muscle [7]. Despite these observations, validation studies to quantify the sensibility of FD to detect MU synchronization are currently lacking.…”

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confidence: 99%

Correlations Between Myoelectric and Hemodynamic Parameters Changes in Biceps Brachii During Sustained Isometric Contraction in Healthy Elderly

Zampella

Barbero

Cescon

et al. 2019

J. of SCI. IN SPORT AND EXERCISE

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Purpose The purpose of the present study was to evaluate the Pearson correlations between hemodynamic parameters obtained with near infrared spectroscopy (NIRS), namely total hemoglobin (tHb) and tissue oxygen index (TOI %), as indicators of blood flow and oxygen extraction, and myoelectric parameters obtained with surface multichannel electromyography (sEMG), namely fractal dimension (FD) and conduction velocity (CV) slopes, as descriptors of central and peripheral fatigue, during sustained high level isometric contractions at 60% maximal voluntary contraction (MVC), in elderly subjects. Methods Ten recreationally healthy elderly subjects (age 67.7 ± 4.6 years), 5 males and 5 females, performed one isometric contraction of the elbow flexors at 120° joint angle at 60% of MVC until exhaustion in two subsequent trials 1 week apart, one for the sEMG and the other one for NIRS recordings from the biceps brachii. Results A negative strong Pearson's correlation between TOI % slope in the functional hyperemic phase (HP) of contraction and a positive correlation between the slope of TOI % recorded during the ischemic phase (IP) and the CV slope were found (r = − 0.76, P < 0.05; r = 0.91, P < 0.01, respectively). A negative strong correlation between tHb IP slope and tHb HP slope and TOI % IP slope and TOI % HP slope (r = − 0.78, P < 0.01; r = − 0.78, P < 0.01, respectively) were also found. No correlation was found between FD slope and hemodynamic parameters (FD slope vs. HP tHb slope, r = − 0.19; FD slope vs. IP tHb slope, r = 0.16; FD slope vs. HP TOI % slope, r = 0.19; FD slope vs. IP TOI % slope, r = 0.27). Conclusion In aged individuals, CV slope correlated with muscle O 2 desaturation (TOI %) rather than reduced muscle blood flow (tHb) in the ischemic phase of isometric contraction to exhaustion. No correlations were found between myoelectric manifestations of central fatigue (FD slope) and data obtained by NIRS.

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Increased resistance towards fatigability in patients with facioscapulohumeral muscular dystrophy

et al. 2021

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Purpose In facioscapulohumeral muscular dystrophy (FSHD) fatigue is a major complaint. We aimed to investigate whether during isometric sustained elbow flexions, performance fatigability indexes differ in patients with FSHD with respect to healthy controls. Methods Seventeen patients with FSHD and seventeen healthy controls performed two isometric flexions of the dominant biceps brachii at 20% of their maximal voluntary contraction (MVC) for 2 min and then at 60% MVC until exhaustion. Muscle weakness was characterized as a percentage of predicted values. Maximal voluntary strength, endurance time and performance fatigability indices (mean frequency of the power spectrum (MNF), muscle fiber conduction velocity (CV) and fractal dimension (FD)), extracted from the surface electromyogram signal (sEMG) were compared between the two groups. Results In patients with FSHD, maximal voluntary strength was 68.7% of predicted value (p < 0.01). Compared to healthy controls, FSHD patients showed reduced MVC (p < 0.001; r = 0.62) and lower levels of performance fatigability, characterized by reduced rate of changes in MNF (p < 0.01; r = 0.56), CV (p < 0.05; 0.37) and FD (p < 0.001; r = 0.51) and increased endurance time (p < 0.001; r = 0.63), during the isometric contraction at 60% MVC. Conclusion A decreased reduction in the slopes of all the considered sEMG parameters during sustained isometric elbow flexions suggests that patients with FSHD experience lower levels of performance fatigability compared to healthy controls.

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Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions

Abstract: Overall, our findings suggest that during isometric fatiguing contractions, CV and FD slopes are reliable variables, with potential application in clinical populations.

Cited by 17 publications

References 63 publications

Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

Correlations Between Myoelectric and Hemodynamic Parameters Changes in Biceps Brachii During Sustained Isometric Contraction in Healthy Elderly

Increased resistance towards fatigability in patients with facioscapulohumeral muscular dystrophy

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