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

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

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

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.

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.

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.