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Travis W Beck - One of the best experts on this subject based on the ideXlab platform.

  • relationship between Innervation Zone width and mean muscle fiber conduction velocity during a sustained isometric contraction
    Journal of Musculoskeletal & Neuronal Interactions, 2015
    Co-Authors: Xin Ye, Travis W Beck, Nathan P Wages
    Abstract:

    OBJECTIVES: To examine the relationship between the biceps brachii muscle Innervation Zone (IZ) width and the mean muscle fiber conduction velocity (MFCV) during a sustained isometric contraction. METHODS: Fifteen healthy men performed a sustained isometric elbow flexion exercise at their 60% maximal voluntary contraction (MVC) until they could not maintain the target force. Mean MFCV was estimated through multichannel surface electromyographic recordings from a linear electrode array. Before exercise, IZ width was quantified. Separate non-parametric one-way analyses of variance (ANOVAs) were used to examine whether there was a difference in each mean MFCV variable among groups with different IZ width. In addition, separate bivariate correlations were also performed to examine the relationships between the IZ width and the mean MFCV variables during the fatiguing exercise. RESULTS: There was a significant difference in the percent decline of mean MFCV (%ΔMFCV) among groups with different IZ width (χ(2) (3)=11.571, p=0.009). In addition, there was also a significant positive relationship between the IZ width and the %ΔMFCV (Kendall's tau= 0.807; p<0.001). CONCLUSIONS: We believe that such relationship is likely influenced by both muscle fiber size and the muscle fiber type composition.

  • Relationship between Innervation Zone width and mean muscle fiber conduction velocity during a sustained isometric contraction.
    Journal of Musculoskeletal & Neuronal Interactions, 2015
    Co-Authors: Xin Ye, Travis W Beck, Nathan P Wages
    Abstract:

    OBJECTIVES: To examine the relationship between the biceps brachii muscle Innervation Zone (IZ) width and the mean muscle fiber conduction velocity (MFCV) during a sustained isometric contraction. METHODS: Fifteen healthy men performed a sustained isometric elbow flexion exercise at their 60% maximal voluntary contraction (MVC) until they could not maintain the target force. Mean MFCV was estimated through multichannel surface electromyographic recordings from a linear electrode array. Before exercise, IZ width was quantified. Separate non-parametric one-way analyses of variance (ANOVAs) were used to examine whether there was a difference in each mean MFCV variable among groups with different IZ width. In addition, separate bivariate correlations were also performed to examine the relationships between the IZ width and the mean MFCV variables during the fatiguing exercise. RESULTS: There was a significant difference in the percent decline of mean MFCV (%ΔMFCV) among groups with different IZ width (χ(2) (3)=11.571, p=0.009). In addition, there was also a significant positive relationship between the IZ width and the %ΔMFCV (Kendall's tau= 0.807; p

  • prolonged passive static stretching induced Innervation Zone shift in biceps brachii
    Applied Physiology Nutrition and Metabolism, 2015
    Co-Authors: Xin Ye, Travis W Beck, Nathan P Wages
    Abstract:

    The purpose of this study was to examine the influence of a bout of repeated and prolonged passive static stretching on the Innervation Zone (IZ) location of the human biceps brachii muscle. Eleven men performed 12 sets of 100-s passive stretches on their biceps brachii. Before (Pre) and immediately after (Post) the stretching intervention, isometric strength was tested during the maximal voluntary contractions (MVCs) of the forearm flexors. The subjects also performed several separate isometric forearm flexion muscle actions at 30%, 50%, and 70% of their predetermined MVCs for examining the locations of the IZ at different contraction intensities. The IZ was identified through multi-channel surface electromyographic (EMG) recordings from a linear electrode array. The stretching intervention induced an average of 10% isometric strength loss for the forearm flexors (mean ± SD: Pre-MVC vs. Post-MVC = 332.12 ± 59.40 N vs. 299.53 ± 70.51 N; p < 0.001). In addition, the average IZ shift was nearly 4.5 mm in average in the proximal direction. However, this shift was not specific to the contraction intensity. We believe that the IZ shift was caused by the elongation of the entire muscle-tendon unit in the proximal direction. Therefore, caution should be taken when using surface EMG technique to examine possible changes in the EMG variables after a stretching protocol, as these variables can be contaminated by the shift of the IZ.

  • accuracy of three different techniques for automatically estimating Innervation Zone location
    Computer Methods and Programs in Biomedicine, 2012
    Co-Authors: Travis W Beck, Jason M Defreitas, Matt S Stock
    Abstract:

    The purpose of this study was to compare the accuracy of the estimated Innervation Zone (IZ) locations obtained from cross-correlation, the minimum amplitude, and maximum center frequency criteria. Eight healthy men (mean+/-SD age=23.0+/-4.3 yrs) performed isometric muscle actions of the leg extensors, and 15 separate bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis. A custom software program was used to estimate the location of the IZ based on: (1) the EMG channel that demonstrated the lowest amplitude, (2) the EMG channel that showed the highest mean frequency, and (3) the EMG channel that demonstrated the lowest peak cross-correlation between the signals from adjacent channels. The IZ location estimates from the lowest amplitude and highest mean frequency criteria were accurate in only 43.75% and 7.5% of the cases, respectively. The accuracy of the cross-correlation-based method was 90%. The cross-correlation-based method was much more accurate for estimating IZ location than were the lowest amplitude and highest mean frequency criteria. Cross-correlation could potentially be used for estimating the location of the IZ without the need for visual inspection of EMG signals.

  • Innervation Zone location of the biceps brachii a comparison between genders and correlation with anthropometric measurements
    Journal of Electromyography and Kinesiology, 2010
    Co-Authors: Jason M Defreitas, Trent J Herda, Eric D Ryan, Joel T Cramer, Pablo B Costa, Travis W Beck
    Abstract:

    Abstract Avoiding the Innervation Zone (IZ) is important when collecting surface electromyographic data. The purposes of this study were threefold: (1) to examine the precision of two different techniques for expressing IZ location for the biceps brachii, (2) to compare these locations between men and women, and (3) to determine if IZ movement with changes in elbow joint angle is related to different anthropometric measures. Twenty-four subjects (mean ± SD ages = 21.8 ± 3.5 yr) performed isometric contractions of the right forearm flexors at each of three separate elbow joint angles (90°, 120°, and 150° between the arm and forearm). During each contraction, the location of the IZ for the biceps brachii was visually identified using a linear electrode array. These IZ locations were expressed in both absolute (i.e. as a distance (mm) from the acromion process) and relative (i.e. as a percentage of humerus length) terms. The results suggested that the estimations of IZ location were more precise when expressed in relative versus absolute terms, and were generally different for men and women. The shift in IZ location with changes in elbow joint angle was not, owever, related to height, weight, or humerus length.

Yingchun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • A Preliminary Study of Effects of Channel Number and Location on the Repeatability of Motor Unit Number Index (MUNIX).
    Frontiers in Neurology, 2020
    Co-Authors: Chuan Zhang, Yingchun Zhang
    Abstract:

    Motor Unit Number Index (MUNIX) is a technique that provides a susceptive biomarker for monitoring Innervation conditions in patients with neurodegenerative diseases. A satisfactory repeatability is essential for the interpretation of MUNIX results. This study aims to examine the effect of channel number and location on the repeatability of MUNIX. In this study, 128 channels of high-density surface electromyography (EMG) signals were recorded from the biceps brachii muscles of eight healthy participants, at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% and 100% of maximal voluntary contraction. The repeatability was defined by the coefficient of variation (CV) of MUNIX estimated from three experiment trials. Single-channel MUNIX (sMUNIX) was calculated on a channel-specific basis and a multi-channel MUNIX (mMUNIX) approach as the weighted average of multiple sMUNIX results. Results have shown 1) significantly improved repeatability with the proposed mMUNIX approach; 2) a higher variability of sMUNIX when the recording channel is positioned away from the Innervation Zone. Our results have demonstrated that 1) increasing the number of EMG channels and 2) placing recording channels close to the Innervation Zone (IZ) are effective methods to improve the repeatability of MUNIX. This study investigated two potential causes of MUNIX variations and provided novel perspectives to improve the repeatability, using high-density surface EMG. The mMUNIX technique proposed can serve as a promising tool for reliable neurodegeneration evaluation.

  • transcutaneous Innervation Zone imaging from high density surface electromyography recordings
    Journal of Neural Engineering, 2020
    Co-Authors: Chuan Zhang, Nicholas Dias, Ping Zhou, Sheng Li, Yenting Chen, Yingchun Zhang
    Abstract:

    Objective- It is of great value to accurately localize Innervation Zones (IZs) for better diagnosing and treating neuromuscular diseases, but it is challenging to do so noninvasively from surface electromyography (sEMG) recordings because of the blurring/ distorting effect of the low conductive fat tissues. This study aimed to develop an innovative transcutaneous IZ imaging (TIZI) technique to precisely and efficiently localize the IZ distribution directly over the muscle surface in vivo from high-density sEMG recordings (HD-sEMG). Approach- The TIZI technique was implemented by incorporating HD-sEMG recording, signal decomposition, finite element analysis and inverse calculation. The performance of TIZI was evaluated on the flexor digitorum superficialis (FDS) muscle with simulated sEMG signal and experimental signal recorded from both healthy (n=3) and stroke participants (n=4). The accuracy of imaging was validated by both of the Pearson correlation coefficient (PCC) and localization error (LE) between the TIZI results and the 'true' IZ distribution. Main Results- In the simulation study, results have shown PCCs of 99.85±0.11%, 99.79±0.08%, 99.63±0.22% and 99.31±0.54% at the depth of 10, 15, 20 and 25 mm and SNR of 25 dB. PCCs of 98.74±1.78% and 97.82±1.20% were respectively obtained for experimental signals acquired from the healthy and spastic FDS muscles. The TIZI provided smaller LEs of 1.4±0.92 mm and 2.02 ± 1.3 mm, compared to LEs of 7.42±2.29 mm and 7.8±1.77 mm from skin observations in healthy and spastic FDS, respectively. Significance- Results have demonstrated the high performance of the proposed TIZI technique in transcutaneously imaging the IZ distribution of the skeletal muscles. The performance improvement can be attributed to the elimination of blurring/ distorting effect caused by the low conductive fat and high conductive skin tissues. TIZI may provide an advanced neurological tool for the clinical treatment of neuromuscular diseases, such as guiding botulinum neurotoxin injections in spasticity management.

  • Global Innervation Zone Identification With High-Density Surface Electromyography
    IEEE Transactions on Biomedical Engineering, 2020
    Co-Authors: Chuan Zhang, Jinbao He, Nicholas Dias, Ping Zhou, Sheng Li, Yingchun Zhang
    Abstract:

    Objective: The aim of this study is to compare the performance of three strategies in determining the global Innervation Zone (IZ) distribution. Methods: High-density surface electromyography was recorded from the biceps brachii muscle of seven healthy subjects under isometric voluntary contractions at 20%, 50%, and 100% of the maximal voluntary contraction and supramaximal musculocutaneous nerve stimulations. IZs were detected: first, by visual identification in a column-specific manner (IZ-1D); second, based on decomposed bipolar mapping of motor unit action potentials (IZ-2D); and third, by source imaging in the three-dimensional muscle space (IZ-3D). Results: All three IZ detection approaches have exhibited excellent trial-to-trial repeatability. Consistent IZ results were found in the axial direction of the arm across all three approaches, yet a difference was observed in the mediolateral direction. Conclusions: Among all three approaches, IZ-3D is capable of providing the most comprehensive information regarding the global IZ distribution, while maintaining high consistency with IZ-1D and IZ-2D results. Significance:IZ-3D approach can be a potential tool for global IZ imaging, which is critical to the clinical diagnosis and treatment of neuromuscular disorders.

  • Innervation Zone distribution of the biceps brachii muscle examined using voluntary and electrically evoked high density surface emg
    Journal of Neuroengineering and Rehabilitation, 2019
    Co-Authors: Yingchun Zhang, Ping Zhou, Sheng Li, Chengjun Huang, Cliff S Klein, Zhaojian Meng
    Abstract:

    Background High density surface electromyography (EMG) can be used to estimate muscle Innervation Zones (IZ). The objective of this study was to compare the differences in the distribution of the biceps brachii (BB) IZ derived from voluntary contractions (VC) and electrical stimulation (ES) of the musculocutaneous nerve.

  • three dimensional Innervation Zone imaging in spastic muscles of stroke survivors
    Journal of Neural Engineering, 2019
    Co-Authors: Chuan Zhang, Ping Zhou, Sheng Li, Yenting Chen, Yingchun Zhang
    Abstract:

    OBJECTIVE The outcome of botulinum toxin (BTX) therapy of post-stroke spasticity relies largely on accuracy of BTX injection to the proximity of Innervation Zones (IZs). Recently developed three-dimensional IZ imaging (3DIZI) is the only technique currently available to provide 3D distributions of IZs in vivo, yet its performance has not been validated under pathological conditions. APPROACH The performance of 3DIZI was evaluated in the spastic biceps brachii muscles of four chronic stroke subjects. High-density surface electromyography (sEMG) and intramuscular electromyography (iEMG) were simultaneously recorded. The IZ location in the 3D space of the spastic biceps calculated using the 3DIZI technique from sEMG recordings were compared against the IZ location detected using intramuscular wires. MAIN RESULTS 3DIZI successfully reconstructed the IZs in the 3D space of the spastic biceps of all four stroke subjects, with a localization error of 4.7  ±  2.7 mm, and specifically a depth error of 1.8  ±  0.4 mm. SIGNIFICANCE Results have demonstrated the robust performance of 3DIZI under pathological conditions, laying a solid foundation for clinical application of 3D source imaging in leading precise BTX injections for spasticity management.

Terry J Housh - One of the best experts on this subject based on the ideXlab platform.

  • influences of interelectrode distance and Innervation Zone on electromyographic signals
    International Journal of Sports Medicine, 2016
    Co-Authors: Cory M Smith, Jorge M Zuniga, Terry J Housh, Clayton L Camic, Haley C Bergstrom, Trent J Herda, Doug B Smith, Joseph P Weir, Ethan C Hill, Nathaniel D M Jenkins
    Abstract:

    The purpose of the present study was to examine the effects of electrode placements centered over and offset from the Innervation Zone (IZ) with different interelectrode distances (IED) on the time and frequency domain parameters of the electromyographic (EMG) signal during a fatiguing submaximal, isometric workout. 11 adults performed an isometric leg extension muscle action at 50% maximal voluntary isometric contraction (MVIC) to exhaustion. Electromyographic amplitude and frequency parameters were determined from electrode placements with different IED centered over, at proximal offset, at distal offset, and away from the IZ at 10, 50, and 100% of the time to exhaustion using an electrode array. There were greater absolute EMG amplitude and lower absolute EMG frequency for electrode placements over and offset from the IZ, but lower absolute EMG amplitude over than offset from the IZ regardless of IED at each time-point during the time to exhaustion. The absolute EMG frequency values were affected by the location relative to the IZ and IED of the electrode placements, and were greater for distal offset vs. proximal offset electrode placements at each time-point. Normalization of the EMG amplitude and EMG frequency values to MVIC eliminated differences due to IED and electrode placements during the fatiguing workout.

  • effects of the Innervation Zone on the time and frequency domain parameters of the surface electromyographic signal
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Cory M Smith, Jorge M Zuniga, Terry J Housh, Clayton L Camic, Haley C Bergstrom, Trent J Herda, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer
    Abstract:

    Abstract The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the Innervation Zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS ( p >0.05) and greater EMG MPF ( p

  • the influence of electromyographic recording methods and the Innervation Zone on the mean power frequency torque relationships
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    Abstract This study examined the effects of electromyographic (EMG) recording methods and Innervation Zone (IZ) on the mean power frequency (MPF)–torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vastus lateralis. The slopes were calculated from the log-transformed monopolar and bipolar EMG MPF–torque relationships for each channel and subject and 95% confidence intervals (CI) were constructed around the slopes for each relationship and the composite of the slopes. Twenty-two to 55% of the subjects exhibited 95% CIs that did not include a slope of zero for the monopolar EMG MPF–torque relationships while 25–75% of the subjects exhibited 95% CIs that did not include a slope of zero for the bipolar EMG MPF–torque relationships. The composite of the slopes from the EMG MPF–torque relationships were not significantly different from zero for any method or channel, however, the method and IZ location slightly influenced the number of significant slopes on a subject-by-subject basis. The log-transform model indicated that EMG MPF–torque patterns were nonlinear regardless of recording method or distance from the IZ.

  • quantifying the effects of electrode distance from the Innervation Zone on the electromyographic amplitude versus torque relationships
    Physiological Measurement, 2013
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    The present study applied a log-transformation model to compare the electromyographic (EMG) amplitude versus torque relationships from monopolar EMG signals up to 35 mm proximal and distal from the Innervation Zone (IZ). Seven men (age = 23 ± 2 year; mass = 82 ± 10 kg) and two women (age = 21 ± 1 year; mass = 62 ± 8 kg) performed isometric ramp contractions of the right leg extensors with an eight-channel linear electrode array positioned over the vastus lateralis with the IZ located between channels 4 and 5. Linear regression models were fit to the log-transformed monopolar EMGRMS–torque relationships with the b terms (slope) and the a terms (Y-intercept) calculated for each channel and subject. The b terms for channels 4, 5, and 6 were higher (P ≤ 0.05) than the more distal channels 7 and 8 (P 0.05) among the a terms of the eight channels. Thus, the shapes of the monopolar EMGRMS–torque relationships were altered as a function of distance between the IZ and recording area, which may be helpful for clinicians and researchers who infer changes in motor control strategies based on the shapes of the EMGRMS–torque relationships.

  • the effects of skinfold thicknesses and Innervation Zone on the mechanomyographic signal during cycle ergometry
    Journal of Electromyography and Kinesiology, 2011
    Co-Authors: Jorge M Zuniga, Terry J Housh, Clayton L Camic, Russell C Hendrix, Haley C Bergstrom, Richard J Schmidt, Glen O Johnson
    Abstract:

    Abstract The purpose of this study was to examine the effects of skinfold (SF) thicknesses at four locations on the vastus lateralis (VL) muscle and the placement of accelerometers relative to the Innervation Zone (IZ) on the mechanomyographic (MMG) amplitude and mean power frequency (MPF) responses during incremental cycle ergometry. Twenty adults (age±SD=23.8±3.0years) participated in the investigation. The MMG signals were detected during incremental cycle ergometry using four accelerometers placed on the right VL. Prior to the cycle ergometer test, SF thicknesses were measured. Simple linear regression analyses and one-way repeated measures analyses of variance (ANOVAs) were performed. The present study found that only 10% of the regression analyses and mean comparisons were significant ( p

Joseph P Weir - One of the best experts on this subject based on the ideXlab platform.

  • influences of interelectrode distance and Innervation Zone on electromyographic signals
    International Journal of Sports Medicine, 2016
    Co-Authors: Cory M Smith, Jorge M Zuniga, Terry J Housh, Clayton L Camic, Haley C Bergstrom, Trent J Herda, Doug B Smith, Joseph P Weir, Ethan C Hill, Nathaniel D M Jenkins
    Abstract:

    The purpose of the present study was to examine the effects of electrode placements centered over and offset from the Innervation Zone (IZ) with different interelectrode distances (IED) on the time and frequency domain parameters of the electromyographic (EMG) signal during a fatiguing submaximal, isometric workout. 11 adults performed an isometric leg extension muscle action at 50% maximal voluntary isometric contraction (MVIC) to exhaustion. Electromyographic amplitude and frequency parameters were determined from electrode placements with different IED centered over, at proximal offset, at distal offset, and away from the IZ at 10, 50, and 100% of the time to exhaustion using an electrode array. There were greater absolute EMG amplitude and lower absolute EMG frequency for electrode placements over and offset from the IZ, but lower absolute EMG amplitude over than offset from the IZ regardless of IED at each time-point during the time to exhaustion. The absolute EMG frequency values were affected by the location relative to the IZ and IED of the electrode placements, and were greater for distal offset vs. proximal offset electrode placements at each time-point. Normalization of the EMG amplitude and EMG frequency values to MVIC eliminated differences due to IED and electrode placements during the fatiguing workout.

  • effects of the Innervation Zone on the time and frequency domain parameters of the surface electromyographic signal
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Cory M Smith, Jorge M Zuniga, Terry J Housh, Clayton L Camic, Haley C Bergstrom, Trent J Herda, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer
    Abstract:

    Abstract The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the Innervation Zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS ( p >0.05) and greater EMG MPF ( p

  • the influence of electromyographic recording methods and the Innervation Zone on the mean power frequency torque relationships
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    Abstract This study examined the effects of electromyographic (EMG) recording methods and Innervation Zone (IZ) on the mean power frequency (MPF)–torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vastus lateralis. The slopes were calculated from the log-transformed monopolar and bipolar EMG MPF–torque relationships for each channel and subject and 95% confidence intervals (CI) were constructed around the slopes for each relationship and the composite of the slopes. Twenty-two to 55% of the subjects exhibited 95% CIs that did not include a slope of zero for the monopolar EMG MPF–torque relationships while 25–75% of the subjects exhibited 95% CIs that did not include a slope of zero for the bipolar EMG MPF–torque relationships. The composite of the slopes from the EMG MPF–torque relationships were not significantly different from zero for any method or channel, however, the method and IZ location slightly influenced the number of significant slopes on a subject-by-subject basis. The log-transform model indicated that EMG MPF–torque patterns were nonlinear regardless of recording method or distance from the IZ.

  • quantifying the effects of electrode distance from the Innervation Zone on the electromyographic amplitude versus torque relationships
    Physiological Measurement, 2013
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    The present study applied a log-transformation model to compare the electromyographic (EMG) amplitude versus torque relationships from monopolar EMG signals up to 35 mm proximal and distal from the Innervation Zone (IZ). Seven men (age = 23 ± 2 year; mass = 82 ± 10 kg) and two women (age = 21 ± 1 year; mass = 62 ± 8 kg) performed isometric ramp contractions of the right leg extensors with an eight-channel linear electrode array positioned over the vastus lateralis with the IZ located between channels 4 and 5. Linear regression models were fit to the log-transformed monopolar EMGRMS–torque relationships with the b terms (slope) and the a terms (Y-intercept) calculated for each channel and subject. The b terms for channels 4, 5, and 6 were higher (P ≤ 0.05) than the more distal channels 7 and 8 (P 0.05) among the a terms of the eight channels. Thus, the shapes of the monopolar EMGRMS–torque relationships were altered as a function of distance between the IZ and recording area, which may be helpful for clinicians and researchers who infer changes in motor control strategies based on the shapes of the EMGRMS–torque relationships.

  • the effects of interelectrode distance over the Innervation Zone and normalization on the electromyographic amplitude and mean power frequency versus concentric eccentric and isometric torque relationships for the vastus lateralis muscle
    Journal of Electromyography and Kinesiology, 2009
    Co-Authors: Travis W Beck, Terry J Housh, Joel T Cramer, Joseph P Weir
    Abstract:

    Abstract The purpose of this study was to examine the influence of interelectrode distance (IED) over the estimated Innervation Zone (IZ) for the vastus lateralis muscle and normalization on the torque-related patterns of responses for electromyographic (EMG) amplitude and mean power frequency (MPF) during concentric isokinetic, eccentric isokinetic, and isometric muscle actions of the leg extensors. Eight men performed submaximal to maximal concentric isokinetic, eccentric isokinetic, and isometric muscle actions of the dominant leg extensors. Surface EMG signals were recorded simultaneously with two bipolar electrode arrangements in single differential configuration (20 and 40mm IEDs) placed over the estimated IZ for the vastus lateralis muscle and a third electrode arrangement in single differential configuration (20mm IED) placed distal to the estimated IZ. The results indicated that there were only a few (six of 90 statistical comparisons) significant ( p

Joel T Cramer - One of the best experts on this subject based on the ideXlab platform.

  • effects of the Innervation Zone on the time and frequency domain parameters of the surface electromyographic signal
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Cory M Smith, Jorge M Zuniga, Terry J Housh, Clayton L Camic, Haley C Bergstrom, Trent J Herda, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer
    Abstract:

    Abstract The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the Innervation Zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS ( p >0.05) and greater EMG MPF ( p

  • the influence of electromyographic recording methods and the Innervation Zone on the mean power frequency torque relationships
    Journal of Electromyography and Kinesiology, 2015
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    Abstract This study examined the effects of electromyographic (EMG) recording methods and Innervation Zone (IZ) on the mean power frequency (MPF)–torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vastus lateralis. The slopes were calculated from the log-transformed monopolar and bipolar EMG MPF–torque relationships for each channel and subject and 95% confidence intervals (CI) were constructed around the slopes for each relationship and the composite of the slopes. Twenty-two to 55% of the subjects exhibited 95% CIs that did not include a slope of zero for the monopolar EMG MPF–torque relationships while 25–75% of the subjects exhibited 95% CIs that did not include a slope of zero for the bipolar EMG MPF–torque relationships. The composite of the slopes from the EMG MPF–torque relationships were not significantly different from zero for any method or channel, however, the method and IZ location slightly influenced the number of significant slopes on a subject-by-subject basis. The log-transform model indicated that EMG MPF–torque patterns were nonlinear regardless of recording method or distance from the IZ.

  • quantifying the effects of electrode distance from the Innervation Zone on the electromyographic amplitude versus torque relationships
    Physiological Measurement, 2013
    Co-Authors: Trent J Herda, Jorge M Zuniga, Clayton L Camic, Haley C Bergstrom, Eric D Ryan, Doug B Smith, Joseph P Weir, Joel T Cramer, Terry J Housh
    Abstract:

    The present study applied a log-transformation model to compare the electromyographic (EMG) amplitude versus torque relationships from monopolar EMG signals up to 35 mm proximal and distal from the Innervation Zone (IZ). Seven men (age = 23 ± 2 year; mass = 82 ± 10 kg) and two women (age = 21 ± 1 year; mass = 62 ± 8 kg) performed isometric ramp contractions of the right leg extensors with an eight-channel linear electrode array positioned over the vastus lateralis with the IZ located between channels 4 and 5. Linear regression models were fit to the log-transformed monopolar EMGRMS–torque relationships with the b terms (slope) and the a terms (Y-intercept) calculated for each channel and subject. The b terms for channels 4, 5, and 6 were higher (P ≤ 0.05) than the more distal channels 7 and 8 (P 0.05) among the a terms of the eight channels. Thus, the shapes of the monopolar EMGRMS–torque relationships were altered as a function of distance between the IZ and recording area, which may be helpful for clinicians and researchers who infer changes in motor control strategies based on the shapes of the EMGRMS–torque relationships.

  • Innervation Zone location of the biceps brachii a comparison between genders and correlation with anthropometric measurements
    Journal of Electromyography and Kinesiology, 2010
    Co-Authors: Jason M Defreitas, Trent J Herda, Eric D Ryan, Joel T Cramer, Pablo B Costa, Travis W Beck
    Abstract:

    Abstract Avoiding the Innervation Zone (IZ) is important when collecting surface electromyographic data. The purposes of this study were threefold: (1) to examine the precision of two different techniques for expressing IZ location for the biceps brachii, (2) to compare these locations between men and women, and (3) to determine if IZ movement with changes in elbow joint angle is related to different anthropometric measures. Twenty-four subjects (mean ± SD ages = 21.8 ± 3.5 yr) performed isometric contractions of the right forearm flexors at each of three separate elbow joint angles (90°, 120°, and 150° between the arm and forearm). During each contraction, the location of the IZ for the biceps brachii was visually identified using a linear electrode array. These IZ locations were expressed in both absolute (i.e. as a distance (mm) from the acromion process) and relative (i.e. as a percentage of humerus length) terms. The results suggested that the estimations of IZ location were more precise when expressed in relative versus absolute terms, and were generally different for men and women. The shift in IZ location with changes in elbow joint angle was not, owever, related to height, weight, or humerus length.

  • electrode placement over the Innervation Zone affects the low not the high frequency portion of the emg frequency spectrum
    Journal of Electromyography and Kinesiology, 2009
    Co-Authors: Travis W Beck, Terry J Housh, Trent J Herda, Eric D Ryan, Joel T Cramer, Pablo B Costa, Jeffrey R Stout, Jason M Defreitas
    Abstract:

    Abstract The purpose of this study was to use a wavelet-based signal processing technique to examine the influence of electrode placement over the Innervation Zone (IZ) on the shape of the electromyographic (EMG) frequency spectrum. Ten healthy males (mean±SD age=23.6±3.0years) performed isometric muscle actions of the dominant leg extensors at 10%, 40%, 70%, and 100% of the maximum voluntary contraction (MVC). Surface EMG signals were detected simultaneously from the vastus lateralis with two bipolar electrode arrangements. One of the electrode arrangements had its center point located directly over the IZ, while the other arrangement had its center point distal to the IZ (i.e., 20mm away). All EMG signals were processed with a wavelet-based procedure. The results showed that for all isometric torque levels, the EMG signals from the distal electrode arrangement demonstrated greater total intensity values than those for the IZ arrangement for frequencies ranging from approximately 2 to 110Hz. There were no consistent differences, however, between the IZ and distal electrode arrangements for total EMG intensity values above 110Hz. Thus, these findings indicated that electrode placement over the IZ affected primarily the low-, rather than the high-frequency portion of the EMG frequency spectrum.