Respiratory muscle pressure development during breath holding in apnea divers

Troy J. Cross, Toni Breskovic, Surendran Sabapathy, Petra Zubin Maslov, Bruce D. Johnson, Zeljko Dujic

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)93-101
Number of pages9
JournalMedicine and science in sports and exercise
Issue number1
StatePublished - Jan 2013


  • Respiratory
  • apnea
  • mechanics
  • pressures

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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