Effect of pressure and timing of contraction on human rib cage muscle fatigue

Details

Serval ID
serval:BIB_99E017A94A38
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Effect of pressure and timing of contraction on human rib cage muscle fatigue
Journal
American Review of Respiratory Disease
Author(s)
Zocchi  L., Fitting  J. W., Majani  U., Fracchia  C., Rampulla  C., Grassino  A.
ISSN
1073-449X
0003-0805 (Print)
Publication state
Published
Issued date
04/1993
Volume
147
Number
4
Pages
857-64
Notes
Journal Article --- Old month value: Apr
Abstract
Breathing against inspiratory loads can be accomplished with different degrees of coupling between the diaphragm and the other muscles attached to the rib cage (RCM). Thus, the electromyographic signs of fatigue develop separately in each muscle group. While breathing with diaphragm emphasis, the occurrence of diaphragmatic fatigue was found to be related to the tension-time index TTdi (= Pdi/Pdimax x Ti/Ttot). Above the critical range of 0.15 to 0.18, the endurance of the diaphragm is less than 1 h and it is inversely related to the TTdi value. However, in most loaded breathing conditions, the spontaneous pattern of breathing is characterized by predominant activation of RCM. The tension-time conditions at which fatigue develops during breathing with RCM emphasis are not known. We assessed the critical tension-time value in four normal subjects breathing with RCM emphasis against inspiratory threshold loads. RCM predominance was achieved by developing negative abdominal pressure swings during inspiration, and it was characterized by the tension-time index TTrc (Ppl/Pplmax x Tl/Ttot), where Ppl is pleural pressure developed under this condition. Above a critical TTrc value of 0.30, endurance time was inversely related to TTrc, and it resulted from failure of the RCM rather than of the diaphragm. We conclude that the critical threshold, as assessed by TTrc, is higher for breathing patterns with RCM emphasis than previously described by TTdi for diaphragm emphasis. However, when predominantly recruited, as in breathing patterns commonly adopted in loaded conditions, the RCM fatigue earlier than the diaphragm.
Keywords
Adult Humans Male *Muscle Contraction Pressure Respiration/*physiology Respiratory Muscles/*physiology
Pubmed
Web of science
Create date
25/01/2008 9:43
Last modification date
20/08/2019 15:01
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