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William Z Rymer - One of the best experts on this subject based on the ideXlab platform.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

Julius P A Dewald - One of the best experts on this subject based on the ideXlab platform.

  • modifiability of abnormal isometric elbow and Shoulder joint torque coupling after stroke
    Muscle & Nerve, 2005
    Co-Authors: Michael D Ellis, Bradley G Holubar, A M Acosta, Randall F Beer, Julius P A Dewald
    Abstract:

    Unlike individuals with mild stroke, individuals with severe stroke are constrained to stereotypical movement patterns attributed to abnormal coupling of Shoulder abductors with elbow flexors, and Shoulder Adductors with elbow extensors. Whether abnormal muscle coactivation and associated joint torque patterns can be changed in this population is important to determine given that it bears on the development of effective rehabilitation interventions. Eight subjects participated in a protocol that was designed to reduce abnormal elbow/Shoulder joint torque coupling by training them to generate combinations of isometric elbow and Shoulder joint torques away from the constraining patterns. After training, subjects demonstrated a significant reduction in abnormal torque coupling and a subsequent significant increase in ability to generate torque patterns away from the abnormal pattern. We suggest the rapid time-course of these changes reflects a residual capacity of the central nervous system to adapt to a novel behavioral training environment.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

J D Given - One of the best experts on this subject based on the ideXlab platform.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

Thomas S Buchanan - One of the best experts on this subject based on the ideXlab platform.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

P S Pope - One of the best experts on this subject based on the ideXlab platform.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.

  • abnormal muscle coactivation patterns during isometric torque generation at the elbow and Shoulder in hemiparetic subjects
    Brain, 1995
    Co-Authors: Julius P A Dewald, P S Pope, J D Given, Thomas S Buchanan, William Z Rymer
    Abstract:

    To study abnormal spatial patterns of muscle activation in hemiparetic stroke, we compared EMG activity in paretic and contralateral elbow and Shoulder muscles of 10 hemiparetic subjects during 1.5- s voluntary isometric contractions, against five to eight different loads. Isometric forces were generated in eight directions, referenced to a plane orthogonal to the long axis of the forearm, and were recorded by a three degrees of freedom load cell, mounted at the wrist. Surface and intramuscular EMGs of six elbow and six Shoulder muscles were recorded from both impaired and contralateral upper extremities of each subject. The spatial characteristics of EMG activation of individual muscles were summarized using two measures. The first, called the ‘net resultant EMG vector’ is a new measure which calculated the vector sum of EMG magnitudes for each of the eight directions, and the second, index of EMG focus, is a measure of the range of EMG activation recorded for each load level. Use of these measures permitted us to describe spatial EMG characteristics quantitatively, which has not been done previously. We observed consistent and statistically significant shifts in the resultant EMG vector directions in the impaired limb, especially in Shoulder and other proximal muscles. Significant increases in the angular range of EMG activity were also identified and were most evident at the elbow. Correlation analysis techniques were used to assess the degree of coactivation of different muscle pairs. There were consistent EMG coactivation patterns observed across all subjects (both normal and hemiparetic). However, in spastic-paretic limbs, additional novel coactivational relationships were also recorded, especially between elbow flexors/Shoulder abductors and elbow extensors/Shoulder Adductors. These novel coactivation patterns represent a reduction in the number of possible muscle combinations, or in the number of possible ‘synergies’ in the paretic limb of the stroke subject. This reduction in number of ‘synergies’ could result from a loss of descending command options; from an increased reliance on residual, descending brainstem pathways (such as the reticulospinal and vestibulospinal projections); from changes in spinal interneuronal excitability; or from a combination of several of these factors. The relative merits of these hypotheses are addressed.