Inspiratory muscles do not limit maximal incremental exercise performance in healthy subjects

Lee M. Romer, Jordan D. Miller, Hans C. Haverkamp, David F. Pegelow, Jerome A. Dempsey

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We investigated whether the inspiratory muscles affect maximal incremental exercise performance using a placebo-controlled, crossover design. Six cyclists each performed six incremental exercise tests. For three trials, subjects exercised with proportional assist ventilation (PAV). For the remaining three trials, subjects underwent sham respiratory muscle unloading (placebo). Inspiratory muscle pressure (Pmus) was reduced with PAV (-35.9 ± 2.3% versus placebo; P < 0.05). Furthermore, over(V, ̇)O2 and perceptions of dyspnea and limb discomfort at submaximal exercise intensities were significantly reduced with PAV. Peak power output, however, was not different between placebo and PAV (324 ± 4 W versus 326 ± 4 W; P > 0.05). Diaphragm fatigue (bilateral phrenic nerve stimulation) did not occur in placebo. In conclusion, substantially unloading the inspiratory muscles did not affect maximal incremental exercise performance. Therefore, our data do not support a role for either inspiratory muscle work or fatigue per se in the limitation of maximal incremental exercise.

Original languageEnglish (US)
Pages (from-to)353-361
Number of pages9
JournalRespiratory Physiology and Neurobiology
Issue number3
StatePublished - Jun 15 2007


  • Diaphragm
  • Dyspnea
  • Fatigue
  • Respiratory muscles

ASJC Scopus subject areas

  • General Neuroscience
  • Physiology
  • Pulmonary and Respiratory Medicine


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