Document Detail


Activation of the human diaphragm during a repetitive postural task.
MedLine Citation:
PMID:  10618161     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The co-ordination between respiratory and postural functions of the diaphragm was investigated during repetitive upper limb movement. It was hypothesised that diaphragm activity would occur either tonically or phasically in association with the forces from each movement and that this activity would combine with phasic respiratory activity. Movements of the upper limb and ribcage were measured while standing subjects performed repetitive upper limb movements 'as fast as possible'. Electromyographic (EMG) recordings of the costal diaphragm were made using intramuscular electrodes in four subjects. Surface electrodes were placed over the deltoid and erector spinae muscles. In contrast to standing at rest, diaphragm activity was present throughout expiration at 78 +/- 17% (mean +/- s.d.) of its peak inspiratory magnitude during repeated upper limb movement. Bursts of deltoid and erector spinae EMG activity occurred at the limb movement frequency (approximately 2.9 Hz). Although the majority of diaphragm EMG power was at the respiratory frequency (approximately 0.4 Hz), a peak was also present at the movement frequency. This finding was corroborated by averaged EMG activity triggered from upper limb movement. In addition, diaphragm EMG activity was coherent with ribcage motion at the respiratory frequency and with upper limb movement at the movement frequency. The diaphragm response was similar when movement was performed while sitting. In addition, when subjects moved with increasing frequency the peak upper limb acceleration correlated with diaphragm EMG amplitude. These findings support the argument that diaphragm contraction is related to trunk control. The results indicate that activity of human phrenic motoneurones is organised such that it contributes to both posture and respiration during a task which repetitively challenges trunk posture.
Authors:
P W Hodges; S C Gandevia
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  522 Pt 1     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2000 Jan 
Date Detail:
Created Date:  2000-02-18     Completed Date:  2000-02-18     Revised Date:  2013-06-11    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  165-75     Citation Subset:  IM; S    
Affiliation:
Prince of Wales Medical Research Institute, High Street, Randwick, NSW 2031, Australia. p.hodges@unsw.edu.au
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MeSH Terms
Descriptor/Qualifier:
Adult
Arm / physiology*
Diaphragm / physiology*
Electromyography
Humans
Male
Movement / physiology*
Posture / physiology*
Respiratory Physiological Phenomena*
Ribs / physiology
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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