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

10 Citations (Scopus)


BACKGROUND: Progressive threshold loading (PTL) is a common test of respiratory muscle endurance. Healthy naive 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 (>24 h 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 - Jan 2004


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