The effect of learning on ventilatory responses to inspiratory threshold loading in COPD

Gavin A. Sturdy, David R. Hillman, Daniel J. Green, Sue C. Jenkins, Nola M. Cecins, Peter R. Eastwood

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Background: Progressive threshold loading (PTL) is a common test of respiratory muscle endurance. Healthy naïve subjects improve endurance with successive exposures to PTL by altering their breathing responses, thus necessitating a familiarization period before reproducible measures can be obtained. This study sought to determine whether a similar "learning effect" is evident in patients with COPD, and what the mechanism of any such effect may be. Methods: Ten subjects with COPD (FEV1 34±13% predicted underwent PTL on four occasions (>24h apart). During PTL measurements were obtained of breathing pattern and maximum threshold pressure (Pthmax) achieved. Maximum inspiratory pressure (PImax) was measured on each occasion. Results: Over the four tests PImax improved by 21±16% (SD) (P<0.05) and Pthmax by 32±21% (P<0.05) with a plateau in these measures achieved by test three. Pthmax/ PImax was unchanged, being 61±11% at test one and 67±12% at test four. In contrast to healthy subjects, PTL was not associated with increased expiratory time or decreased end-expiratory lung volume. Conclusions: In contrast to PImax and Pthmax, which changed with successive tests, a single measure of the ratio Pthmax/PImax may present a useful guide to the endurance capacity of the respiratory muscles in patients with COPD.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalRespiratory Medicine
Issue number1
Publication statusPublished - 1 Jan 2004
Externally publishedYes

Bibliographical note

Funding Information:
This work was funded in part by National Health and Medical Research Council (Australia) Grant 212016.

Copyright 2017 Elsevier B.V., All rights reserved.


  • Inspiratory muscles
  • Respiratory muscle endurance
  • Respiratory muscle strength


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