TY - JOUR
T1 - Respiratory muscle pressure development during breath holding in apnea divers
AU - Cross, Troy J.
AU - Breskovic, Toni
AU - Sabapathy, Surendran
AU - Maslov, Petra Zubin
AU - Johnson, Bruce D.
AU - Dujic, Zeljko
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/1
Y1 - 2013/1
N2 - Introduction: We sought to characterize the patterns of active pressure development of the inspiratory and expiratory rib cage muscles (P rcm,i and Prcm,e), the diaphragm (Pdi,i), and the expiratory abdominal muscles (Pabm,e) during maximal dry breath holding in trained apnea divers (n = 8). Methods: Respiratory contractions were assessed via esophageal and gastric manometry. It was expected that inspiratory/expiratory pressures would progressively increase in both magnitude and frequency during the struggle phase, and that inspiratory rib cage muscle pressures would rise at a rate exceeding that of the diaphragm by the break point. Results: Prcm,i, Pdi,i, Prcm,e, and Pabm,e significantly increased from the beginning until the end of the struggle phase (P < 0.05). Moreover, Pdi,i/Prcm,i and Pabm,e/Prcm,e ratios had declined by the break point (P < 0.05), indicating that rib cage muscles increased their contribution to net inspiratory/expiratory pressure development by the end of the breath hold, relative to that contributed by the diaphragm and abdominal muscles. The pressure-time indices of the diaphragm and inspiratory rib cage muscles continuously increased over the struggle phase (P < 0.05). Conclusions: The extradiaphragmatic shift in inspiratory muscle recruitment, commensurate with increasing Prcm,e and Pabm,e, may reflect an extreme loading response to breathing against a heavy elastance (i.e., closed glottis). In addition, the relative intensity of diaphragmatic and inspiratory rib cage muscle contractions approaches potentially fatiguing levels by the break point of maximal breath holding.
AB - Introduction: We sought to characterize the patterns of active pressure development of the inspiratory and expiratory rib cage muscles (P rcm,i and Prcm,e), the diaphragm (Pdi,i), and the expiratory abdominal muscles (Pabm,e) during maximal dry breath holding in trained apnea divers (n = 8). Methods: Respiratory contractions were assessed via esophageal and gastric manometry. It was expected that inspiratory/expiratory pressures would progressively increase in both magnitude and frequency during the struggle phase, and that inspiratory rib cage muscle pressures would rise at a rate exceeding that of the diaphragm by the break point. Results: Prcm,i, Pdi,i, Prcm,e, and Pabm,e significantly increased from the beginning until the end of the struggle phase (P < 0.05). Moreover, Pdi,i/Prcm,i and Pabm,e/Prcm,e ratios had declined by the break point (P < 0.05), indicating that rib cage muscles increased their contribution to net inspiratory/expiratory pressure development by the end of the breath hold, relative to that contributed by the diaphragm and abdominal muscles. The pressure-time indices of the diaphragm and inspiratory rib cage muscles continuously increased over the struggle phase (P < 0.05). Conclusions: The extradiaphragmatic shift in inspiratory muscle recruitment, commensurate with increasing Prcm,e and Pabm,e, may reflect an extreme loading response to breathing against a heavy elastance (i.e., closed glottis). In addition, the relative intensity of diaphragmatic and inspiratory rib cage muscle contractions approaches potentially fatiguing levels by the break point of maximal breath holding.
KW - Respiratory
KW - apnea
KW - mechanics
KW - pressures
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U2 - 10.1249/MSS.0b013e3182690e6a
DO - 10.1249/MSS.0b013e3182690e6a
M3 - Article
C2 - 22811036
AN - SCOPUS:84871616346
SN - 0195-9131
VL - 45
SP - 93
EP - 101
JO - Medicine and science in sports and exercise
JF - Medicine and science in sports and exercise
IS - 1
ER -