Comparison of incremental and constant load tests of inspiratory muscle endurance in COPD

Kylie Hill, S. C. Jenkins, D. L. Philippe, K. L. Shepherd, D. R. Hillman, P. R. Eastwood

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


The aim of the present study was to determine the relative value of incremental and constant load tests in detecting changes in inspiratory muscle endurance following high-intensity inspiratory muscle training (H-IMT) in chronic obstructive pulmonary disease. In total, 16 subjects (11 males; forced expiratory volume in one second (FEV1) 37.4±12.5%) underwent H-IMT. In addition, 17 subjects (11 males; FEV1 36.5±11.5%) underwent sham inspiratory muscle training (S-IMT). Training took place three times a week for 8 weeks. Baseline and post-training measurements were obtained of maximum threshold pressure sustained during an incremental load test (P th,max) and time breathing against a constant load (tlim). Breathing pattern was unconstrained. H-IMT increased Pth,max and tlim relative to baseline and to any change seen following S-IMT. The effect size for Pth,max was greater than for tlim. Post-training tests were accompanied by changes in breathing pattern, including decreased duty cycle, which may have served to decrease inspiratory work and thereby contribute to the increase in Pth,max and tlim in both groups. When assessing inspiratory muscle function in chronic obstructive pulmonary disease via tests in which the pattern of breathing is unconstrained, the current authors recommend incremental load tests be used in preference to constant load tests. However, to attribute changes in these tests to improvements in inspiratory muscle endurance, breathing pattern should be controlled. Copyright

Original languageEnglish
Pages (from-to)479-486
Number of pages8
JournalEuropean Respiratory Journal
Issue number3
Publication statusPublished - Sep 2007
Externally publishedYes

Bibliographical note

Copyright 2008 Elsevier B.V., All rights reserved.


  • Assessment
  • Endurance
  • Lung disease
  • Respiratory muscles


Dive into the research topics of 'Comparison of incremental and constant load tests of inspiratory muscle endurance in COPD'. Together they form a unique fingerprint.

Cite this