scholarly journals Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Matteo Beretta-Piccoli ◽  
Gennaro Boccia ◽  
Tessa Ponti ◽  
Ron Clijsen ◽  
Marco Barbero ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Muscle Contraction ◽  
Biceps Brachii ◽  
Isometric Force ◽  
Voluntary Contraction ◽  
Experimental Conditions ◽  
Surface Electromyogram ◽  
Mean Frequency ◽  
Muscle Contraction Intensity ◽  
The Relationship

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.

scholarly journals Computation and Evaluation of Features of Surface Electromyogram to Identify the Force of Muscle Contraction and Muscle Fatigue

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sridhar P. Arjunan ◽  
Dinesh K. Kumar ◽  
Ganesh Naik
Keyword(s):  
Muscle Contraction ◽  
Muscle Fatigue ◽  
Root Mean Square ◽  
Linear Regression Analysis ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Median Frequency ◽  
Mean Square ◽  
Surface Electromyogram ◽  
The Relationship

The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study:normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P<0.01), while NSM5 associated best with level of muscle contraction (%MVC) (P<0.01). Both of these features were not affected by the intersubject variations (P>0.05).

scholarly journals Independence Between Two Channels of Surface Electromyogram Signal to Measure the Loss of Motor Units

2015 ◽  
Vol 15 (3) ◽  
pp. 152-155 ◽  
Author(s):  
Sridhar P. Arjunan ◽  
Dinesh Kumar ◽  
Ganesh Naik
Keyword(s):  
Biceps Brachii ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Frobenius Norm ◽  
Semg Signal ◽  
Surface Electromyogram ◽  
Isometric Muscle Contraction ◽  
Age Range ◽  
The Relationship ◽  
Surface Electromyogram Signal

AbstractThis study has investigated the relationship in the connectivity of motor units in surface electromyogram (sEMG) of biceps brachii muscle. It is hypothesized that with ageing, there is reduction/loss in number of motor units, leading to reduction in the independence between the channels of the recorded muscle activity. Two channels of sEMG were recorded during three levels of isometric muscle contraction: 50 %, 75 % and 100 % maximal voluntary contraction (MVC). 73 subjects (age range 20-70) participated in the experiments. The independence in channel index (ICI) between the two sEMG recording locations was computed using the independent components and Frobenius norm. ANOVA Statistical analysis was performed to test the effect of age (loss of motor units) and level of contraction on ICI. The results show that the ICI among the older cohort was significantly lower compared with the younger adults. This research study has shown that the reduction in number of motor units is reflected by the reduction in the ICI of the sEMG signal.

Intramuscular and surface electromyogram changes during muscle fatigue

1986 ◽  
Vol 60 (4) ◽  
pp. 1179-1185 ◽  
Author(s):  
T. Moritani ◽  
M. Muro ◽  
A. Nagata
Keyword(s):  
Muscle Fatigue ◽  
Biceps Brachii ◽  
Surface Emg ◽  
Firing Frequency ◽  
Voluntary Contraction ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Surface Electromyogram ◽  
Spike Amplitude ◽  
Frequency Power

Twelve male subjects were tested to determine the effects of motor unit (MU) recruitment and firing frequency on the surface electromyogram (EMG) frequency power spectra during sustained maximal voluntary contraction (MVC) and 50% MVC of the biceps brachii muscle. Both the intramuscular MU spikes and surface EMG were recorded simultaneously and analyzed by means of a computer-aided intramuscular spike amplitude-frequency histogram and frequency power spectral analysis, respectively. Results indicated that both mean power frequency (MPF) and amplitude (rmsEMG) of the surface EMG fell significantly (P less than 0.001) together with a progressive reduction in MU spike amplitude and firing frequency during sustained MVC. During 50% MVC there was a significant decline in MPF (P less than 0.001), but this decline was accompanied by a significant increase in rmsEMG (P less than 0.001) and a progressive MU recruitment as evidenced by an increased number of MUs with relatively large spike amplitude. Our data suggest that the surface EMG amplitude could better represent the underlying MU activity during muscle fatigue and the frequency powers spectral shift may or may not reflect changes in MU recruitment and rate-coding patterns.

scholarly journals Model analysis of the relationship between intracellular Po2 and energy demand in skeletal muscle

2012 ◽  
Vol 303 (11) ◽  
pp. R1110-R1126 ◽  
Author(s):  
Jessica Spires ◽  
L. Bruce Gladden ◽  
Bruno Grassi ◽  
Gerald M. Saidel ◽  
Nicola Lai
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Contraction ◽  
Energy Demand ◽  
Experimental Studies ◽  
Experimental Conditions ◽  
Permeability Surface ◽  
The Relationship ◽  
And Diffusion ◽  
Main Factor

On the basis of experimental studies, the intracellular O2 (iPo2)-work rate (WR) relationship in skeletal muscle is not unique. One study found that iPo2 reached a plateau at 60% of maximal WR, while another found that iPo2 decreased linearly at higher WR, inferring capillary permeability-surface area ( PS) and blood-tissue O2 gradient, respectively, as alternative dominant factors for determining O2 diffusion changes during exercise. This relationship is affected by several factors, including O2 delivery and oxidative and glycolytic capacities of the muscle. In this study, these factors are examined using a mechanistic, mathematical model to analyze experimental data from contracting skeletal muscle and predict the effects of muscle contraction on O2 transport, glycogenolysis, and iPo2. The model describes convection, O2 diffusion, and cellular metabolism, including anaerobic glycogenolysis. Consequently, the model simulates iPo2 in response to muscle contraction under a variety of experimental conditions. The model was validated by comparison of simulations of O2 uptake with corresponding experimental responses of electrically stimulated canine muscle under different O2 content, blood flow, and contraction intensities. The model allows hypothetical variation of PS, glycogenolytic capacity, and blood flow and predictions of the distinctive effects of these factors on the iPo2-contraction intensity relationship in canine muscle. Although PS is the main factor regulating O2 diffusion rate, model simulations indicate that PS and O2 gradient have essential roles, depending on the specific conditions. Furthermore, the model predicts that different convection and diffusion patterns and metabolic factors may be responsible for different iPo2-WR relationships in humans.

Dynamic imaging of skeletal muscle contraction in three orthogonal directions

2010 ◽  
Vol 109 (3) ◽  
pp. 906-915 ◽  
Author(s):  
Richard G. P. Lopata ◽  
Johannes P. van Dijk ◽  
Sigrid Pillen ◽  
Maartje M. Nillesen ◽  
Huub Maas ◽  
...  
Keyword(s):  
Muscle Contraction ◽  
Biceps Brachii ◽  
Estimation Method ◽  
Vertical Direction ◽  
Local Strain ◽  
Local Deformation ◽  
Voluntary Contraction ◽  
Dynamic Imaging ◽  
Relative Deformation ◽  
Voluntary Contractions

In this study, a multidimensional strain estimation method using biplane ultrasound is presented to assess local relative deformation (i.e., local strain) in three orthogonal directions in skeletal muscles during induced and voluntary contractions. The method was tested in the musculus biceps brachii of five healthy subjects for three different types of muscle contraction: 1) excitation of the muscle with a single electrical pulse via the musculocutaneous nerve, resulting in a so-called “twitch” contraction; 2) a train of five pulses at 10 Hz and 20 Hz, respectively, to obtain a submaximum tetanic contraction; and 3) voluntary contractions at 30, 60, and 100% of maximum contraction force. Results show that biplane ultrasound strain imaging is feasible. The method yielded adequate performance using the radio frequency data in tracking the tissue motion and enabled the measurement of local deformation in both the vertical direction (orthogonal to the arm) and in the horizontal directions (parallel and perpendicular to direction of the arm) in two orthogonal cross sections of the muscle. The twitch experiments appeared to be reproducible in all three directions, and high strains in vertical (25 to 30%) and horizontal (−20% to −10%) directions were measured. Visual inspection of both the ultrasound data, as well as the strain data, revealed a relaxation that was significantly slower than the force decay. The pulse train experiments nicely illustrated the performance of our technique: 1) similar patterns of force and strain waveforms were found; and 2) each stimulation frequency yielded a different strain pattern, e.g., peak vertical strain was 40% during 10-Hz stimulation and 60% during 20-Hz stimulation. The voluntary contraction patterns were found to be both practically feasible and reproducible, which will enable muscles and more natural contraction patterns to be examined without the need of electrical stimulation.

scholarly journals Comparison of Endurance Time Prediction of Biceps Brachii Using Logarithmic Parameters of a Surface Electromyogram during Low-Moderate Level Isotonic Contractions

2021 ◽  
Vol 11 (6) ◽  
pp. 2861
Author(s):  
Chang-ok Cho ◽  
Jin-Hyoung Jeong ◽  
Yun-jeong Kim ◽  
Jee Hun Jang ◽  
Sang-Sik Lee ◽  
...  
Keyword(s):  
Biceps Brachii ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Endurance Capacity ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Spectral Parameters ◽  
Endurance Time ◽  
Surface Electromyogram ◽  
Isotonic Contractions

At relatively low effort level tasks, surface electromyogram (sEMG) spectral parameters have demonstrated an inconsistent ability to monitor localized muscle fatigue and predict endurance capacity. The main purpose of this study was to assess the potential of the endurance time (Tend) prediction using logarithmic parameters compared to raw data. Ten healthy subjects performed five sets of voluntary isotonic contractions until their exhaustion at 20% of their maximum voluntary contraction (MVC) level. We extracted five sEMG spectral parameters namely the power in the low frequency band (LFB), the mean power frequency (MPF), the high-to-low ratio between two frequency bands (H/L-FB), the Dimitrov spectral index (DSI), and the high-to-low ratio between two spectral moments (H/L-SM), and then converted them to logarithms. Changes in these ten parameters were monitored using area ratio and linear regressive slope as statistical predictors and estimating from onset at every 10% of Tend. Significant correlations (r > 0.5) were found between log(Tend) and the linear regressive slopes in the logarithmic H/L-SM at every 10% of Tend. In conclusion, logarithmic parameters can be used to describe changes in the fatigue content of sEMG and can be employed as a better predictor of Tend in comparison to the raw parameters.

scholarly journals Biceps brachii muscle hardness assessed by a push-in meter in comparison to ultrasound strain elastography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mitsuyoshi Murayama ◽  
Kazunori Nosaka ◽  
Takayuki Inami ◽  
Norihiro Shima ◽  
Tsugutake Yoneda
Keyword(s):  
Biceps Brachii ◽  
Elbow Flexion ◽  
Strain Ratio ◽  
Voluntary Contraction ◽  
Strain Elastography ◽  
Muscle Hardness ◽  
The Relationship ◽  
Force Displacement ◽  
Resting Muscle ◽  
Hardness Values

AbstractThis study investigated the relationship between push-in meter (PM) and ultrasound strain elastography (USE) for biceps brachii (BB) muscle hardness. BB hardness of 21 young men was assessed by PM and USE during rest and isometric contractions of six different intensities (15, 30, 45, 60, 75, 90% of maximal voluntary contraction: MVC) at 30°, 60° and 90° elbow flexion. Muscle hardness (E) was calculated from the force–displacement relationship in PM, and strain ratio (SR) between an acoustic coupler (elastic modulus: 22.6 kPa) and different regions of interest (ROIs) in BB was calculated and converted to Young’s modulus (YM) in USE. In resting muscle, E was 26.1 ± 6.4 kPa, and SR and YM for the whole BB was 0.88 ± 0.4 and 30.8 ± 12.8 kPa, respectively. A significant (p < 0.01) correlation was evident between E and logarithmical transformed SR (LTSR) for the ROI of whole BB (r = − 0.626), and E and converted YM (r = 0.615). E increased approximately ninefold from resting to 90% MVC, and E and LTSR (r = − 0.732 to − 0.880), and E and converted YM for the SR above 0.1 were correlated (r = 0.599–0.768, p < 0.01). These results suggest that muscle hardness values obtained by PM and USE are comparable.

Measurement and Analysis of Surface Electromyogram and Handgrip Force

2011 ◽  
Vol 225-226 ◽  
pp. 1318-1322
Author(s):  
Dong Mei Hao ◽  
Yan Zhang ◽  
Dong Ye Zhang ◽  
Zheng Wan ◽  
Yi Yang
Keyword(s):  
Voluntary Contraction ◽  
Median Frequency ◽  
Force Level ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Surface Electromyogram ◽  
Static Contraction ◽  
Power Frequency ◽  
Relationship Of ◽  
The Relationship

To investigate the relationship of surface electromyogram (sEMG) and handgrip force, a measurement system was developed. Ten healthy subjects were required to perform a series of static contraction trials by maintaining the force level with maximal voluntary contraction (MVC), 75%MVC, 50%MVC and 25%MVC respectively. Then they sustained MVC as long as possible until fatigue. The handgrip force and sEMG on the forearm muscles were recorded. Root mean square (RMS), mean power frequency (MPF) and median frequency (MF) of the sEMG were calculated with LabVIEW. The results show that RMS increased with force level during voluntary contraction, while MPF and MF shift to lower frequency during fatigue condition. These findings suggested that the designed system can be used to study forearm function.

Functional difference in short- and long-latency interhemispheric inhibitions from active to resting hemisphere during a unilateral muscle contraction

2014 ◽  
Vol 111 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Kazumasa Uehara ◽  
Takuya Morishita ◽  
Shinji Kubota ◽  
Masato Hirano ◽  
Kozo Funase
Keyword(s):  
Muscle Contraction ◽  
Primary Motor Cortex ◽  
Maximum Voluntary Contraction ◽  
Conditioning Stimulus ◽  
Voluntary Contraction ◽  
Muscle Contractions ◽  
Functional Difference ◽  
Experimental Conditions ◽  
Long Latency ◽  
Significant Difference

The aim of the present study was to investigate whether there is a functional difference in short-latency (SIHI) and long-latency (LIHI) interhemispheric inhibition from the active to the resting primary motor cortex (M1) with paired-pulse transcranial magnetic stimulation during a unilateral muscle contraction. In nine healthy right-handed participants, IHI was tested from the dominant to the nondominant M1 and vice versa under resting conditions or during performance of a sustained unilateral muscle contraction with the right or left first dorsal interosseous muscle at 10% and 30% maximum voluntary contraction. To obtain measurements of SIHI and LIHI, a conditioning stimulus (CS) was applied over the M1 contralateral to the muscle contraction, followed by a test stimulus over the M1 ipsilateral to the muscle contraction at short (10 ms) and long (40 ms) interstimulus intervals. We used four CS intensities to investigate SIHI and LIHI from the active to the resting M1 systematically. The amount of IHI during the unilateral muscle contractions showed a significant difference between SIHI and LIHI, but the amount of IHI during the resting condition did not. In particular, SIHI during the muscle contractions, but not LIHI, significantly increased with increase in CS intensity compared with the resting condition. Laterality of IHI was not detected in any of the experimental conditions. The present study provides novel evidence that a functional difference between SIHI and LIHI from the active to the resting M1 exists during unilateral muscle contractions.

Myoelectrical and mechanical changes linked to length specificity during isometric training

1988 ◽  
Vol 64 (4) ◽  
pp. 1500-1505 ◽  
Author(s):  
C. Thepaut-Mathieu ◽  
J. Van Hoecke ◽  
B. Maton
Keyword(s):  
Maximal Voluntary Contraction ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Voluntary Contraction ◽  
The Other ◽  
Neural Activation ◽  
Surface Electromyogram ◽  
Isometric Training ◽  
Integrated Emg ◽  
Experimental Group

Mechanical and neural activation changes that accompanied muscle isometric training were studied in males. Training and testing sessions consisted of right elbow isometric flexions. Each experimental group was trained during 5 wk at one of the following angles: 25, 80, and 120 degrees. Bipolar surface electromyogram (EMG) was recorded from the biceps brachii and brachioradialis muscles. An improvement of maximal voluntary contraction (MVC) was always found at the training angle and was systematically greater than at the other angles. Moreover, the shorter the muscle length at which the training has been carried out, the more the gain was limited to the training angle. An increase of the maximal integrated EMG of both biceps brachii and brachioradialis frequently accompanied the improvement of MVC at the training angle.

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