Trunk muscle activity during the simultaneous performance of two voluntary tasks: A trunk task and a pulsed expiration task

Persistent Link:
http://hdl.handle.net/10150/284038
Title:
Trunk muscle activity during the simultaneous performance of two voluntary tasks: A trunk task and a pulsed expiration task
Author:
Farley, Becky Gwen
Issue Date:
1999
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Trunk control is intriguing because trunk muscles must meet multiple requirements during the performance of everyday tasks (e.g., balancing, locomotion, musical instrument playing, reaching, trunk bending, vocalizing). A unique feature of trunk muscles is that they often participate in simultaneous trunk movement and breathing-related behaviors. This study was designed to test the hypothesis that two voluntary task-specific muscle activity patterns could combine linearly when both tasks activate the same muscles. Surface electromyograms (EMG) were recorded from four trunk sites (upper and lower lateral abdominal, medial and lateral back) during the performance of a trunk task, pulsed expiration task, and combined task (hunk + pulsed expiration task). The trunk task varied across four experiments, and included a static holding task or a uni-directional movement task in both flexion and extension directions. The expiration task was constant. Selected task variables (lung volume, movement amplitude and duration, expiratory target pressure) were consistent across all tasks. For each EMG site, a linear prediction (predicted EMG trace) was calculated from the mathematical addition of the task-specific EMG recorded during the individual trunk and expiration tasks. This linear prediction was compared to the actual muscle activity recorded during the combined task (measured EMG trace) and a point-to-point correlation was performed on the two traces to determine how closely they matched. Findings showed that in just over half the comparisons, the combined muscle activity pattern (measured EMG trace) was the same as a linear addition of each individual muscle activity pattern (predicted EMG trace). Such linear addition implies that two sets of descending command signals reach motoneuron pools essentially unmodified, and that motoneurons supplying trunk muscles may be specially organized to receive dual and simultaneous voluntary neural drive. In the remaining comparisons, the EMG activity for the two individual tasks, were superimposed, but not linearly. This finding suggests that although individual muscles are activated as a unit, selected muscles may be modified by sensory feedback. This flexibility allows the nervous system to take advantage of a muscles mechanical effectiveness and to adapt to environmental constraints without having to reconfigure or construct a new set of instructions.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Neuroscience.; Health Sciences, Rehabilitation and Therapy.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Neurosciences
Degree Grantor:
University of Arizona
Advisor:
Hoit, Jeannette D.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleTrunk muscle activity during the simultaneous performance of two voluntary tasks: A trunk task and a pulsed expiration tasken_US
dc.creatorFarley, Becky Gwenen_US
dc.contributor.authorFarley, Becky Gwenen_US
dc.date.issued1999en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractTrunk control is intriguing because trunk muscles must meet multiple requirements during the performance of everyday tasks (e.g., balancing, locomotion, musical instrument playing, reaching, trunk bending, vocalizing). A unique feature of trunk muscles is that they often participate in simultaneous trunk movement and breathing-related behaviors. This study was designed to test the hypothesis that two voluntary task-specific muscle activity patterns could combine linearly when both tasks activate the same muscles. Surface electromyograms (EMG) were recorded from four trunk sites (upper and lower lateral abdominal, medial and lateral back) during the performance of a trunk task, pulsed expiration task, and combined task (hunk + pulsed expiration task). The trunk task varied across four experiments, and included a static holding task or a uni-directional movement task in both flexion and extension directions. The expiration task was constant. Selected task variables (lung volume, movement amplitude and duration, expiratory target pressure) were consistent across all tasks. For each EMG site, a linear prediction (predicted EMG trace) was calculated from the mathematical addition of the task-specific EMG recorded during the individual trunk and expiration tasks. This linear prediction was compared to the actual muscle activity recorded during the combined task (measured EMG trace) and a point-to-point correlation was performed on the two traces to determine how closely they matched. Findings showed that in just over half the comparisons, the combined muscle activity pattern (measured EMG trace) was the same as a linear addition of each individual muscle activity pattern (predicted EMG trace). Such linear addition implies that two sets of descending command signals reach motoneuron pools essentially unmodified, and that motoneurons supplying trunk muscles may be specially organized to receive dual and simultaneous voluntary neural drive. In the remaining comparisons, the EMG activity for the two individual tasks, were superimposed, but not linearly. This finding suggests that although individual muscles are activated as a unit, selected muscles may be modified by sensory feedback. This flexibility allows the nervous system to take advantage of a muscles mechanical effectiveness and to adapt to environmental constraints without having to reconfigure or construct a new set of instructions.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Neuroscience.en_US
dc.subjectHealth Sciences, Rehabilitation and Therapy.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineNeurosciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorHoit, Jeannette D.en_US
dc.identifier.proquest9927472en_US
dc.identifier.bibrecord.b39560326en_US
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