Document Detail


Loads on spinal tissues during simultaneous lifting and ventilatory challenge.
MedLine Citation:
PMID:  7671856     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Muscles of the torso have been implicated to play a role in stabilization of the low back, and to assist in ventilation. This motivated an investigation to combine a load challenge to the low back with a breathing challenge, similar to that which a worker might experience when shovelling snow. Perhaps modulation of muscle activity needed to facilitate breathing may compromise the margin of safety of tissues that depend on constant muscle activity for support. Eight young healthy males dynamically lifted, and isometrically held, large loads (73-95 kg) and breathed a 10% CO2 gas mixture to elevate breathing (both with and without hand-held loads). Individual tissue forces were calculated using an anatomically detailed, dynamic model of the torso that was sensitive to individual variation by utilizing myoelectric signals, intra-abdominal pressure, ventilation rate and spine kinematics, obtained from each subject, as input. For large loads in the hands, most subjects appeared to stabilize the trunk with large muscle forces relegating the responsibility of creating lung air flow to the diaphragm. When reasonably small low-back demands were coupled with a breathing challenge and higher ventilation rates two out of eight subjects demonstrated entrainment of abdominal activity to breathing that resulted in additional cyclic low-back compressive loading of the order of 1000 N. Ergonomists should consider the additional tissue loading from physiologically demanding tasks and the related ventilation challenge, together with the tissue loads required to support external objects and maintain body posture.
Authors:
S M McGill; M T Sharratt; J P Seguin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ergonomics     Volume:  38     ISSN:  0014-0139     ISO Abbreviation:  Ergonomics     Publication Date:  1995 Sep 
Date Detail:
Created Date:  1995-10-19     Completed Date:  1995-10-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0373220     Medline TA:  Ergonomics     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1772-92     Citation Subset:  IM; S    
Affiliation:
Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adult
Analysis of Variance
Biomechanics
Electromyography
Humans
Isometric Contraction / physiology
Lifting*
Male
Models, Biological
Muscle, Skeletal / physiology*
Posture
Pulmonary Ventilation / physiology*
Spine / physiology*

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


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