Rib cage distortion and dynamic hyperinflation during two exercise intensities in people with COPD

Abstract

Background: The relationship between rib cage (RC) motion abnormalities, dynamic hyperinflation (DH), and exercise capacity in people with COPD is controversial.

Aim: To investigate RC distortion and operational chest wall volumes during moderate and high constant-rate exercises in people with COPD.

Methods: Seven male participants [median(Q1-Q3) age: 63(60.0-66.0) years; FEV₁: 39.0(38.0-63.0)% of predicted] performed a symptom-limited incremental exercise testing on cycle ergometer, followed by constant-rate tests (60 % and 80 % of peak work rate). Optoelectronic plethysmography was used to evaluate RC distortion: phase angle-PhAng, inspiratory phase ratio-PhRIB, expiratory phase ratio-PhREB; and chest wall volumes: end-inspiratory volume-Vei and end-expiratory volume-Vee.

Results: PhRIB and PhREB significantly increased during both constant-rate exercise tests, without difference between them. In general, Vei of the chest wall significantly increased in both exercise intensities while Vee did not change.

Conclusions: The occurrence of RC distortion seemed not to limit the exercise capacity in people with COPD evaluated, and it was present even in the absence of DH.

Keywords: Chronic pulmonary obstructive disease; Constant-load exercise test; Optoelectronic plethysmography.