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Ventilatory responses to inspiratory threshold loading in humans.

Authors
  • Yanos, J
  • Banner, A
  • Stanko, R
  • Gentry, S
  • Greenawalt, K
Type
Published Article
Journal
Journal of applied physiology (Bethesda, Md. : 1985)
Publication Date
Jun 01, 1990
Volume
68
Issue
6
Pages
2511–2520
Identifiers
PMID: 2117008
Source
Medline
License
Unknown

Abstract

Normal alveolar ventilation tends to be maintained during external mechanical loading. The precise manner by which this occurs is unclear but may involve intrinsic mechanisms related to the muscular pump, neural influences, and chemoreceptor control. Recent observations suggest that submaximal threshold loads may result in hyperventilation. In this study we explicitly examined the respiratory effects of sustained threshold loading in normal subjects. We found that sustained threshold loading resulted in hyperventilation associated with high P100's (mouth pressure 100 ms after the start of an occluded breath) and increased tidal volumes but with little effect on duty cycle or respiratory rate. In addition, this increased respiratory motor output was sustained for 30-60 s after the load was removed. At very high threshold loads, hyperventilation failed to occur, despite increased P100's. We conclude that threshold loading results in increased respiratory motor output and hyperventilation, a response that is different from that observed with either resistive or elastic loads, and that the failure to hyperventilate at the higher loads may be the result of mechanical limitation.

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