Address for correspondence: Dr. Ioannis Vogiatzis,

The present study investigated how end-expiratory rib cage and abdominal volume regulation during exercise is related to the degree of dynamic chest wall hyperinflation in patients with different spirometric severity of COPD based on the GOLD classification. Forty-two COPD patients and eleven healthy age-matched subjects were studied during a ramp-incremental cycling test to the limit of tolerance (Wpeak). Volume variations of the chest wall [at end-expiration (EEVcw) and end-inspiration] and its compartments [rib cage (Vrc) and abdominal (Vab)] were computed by Optoelectronic Plethysmography. At Wpeak only patients in GOLD stages III and IV exhibited a significant increase in EEVcw (by 454±509 and 562±363 ml, respectively). These patients did not significantly reduce end-expiratory Vab, whereas patients in GOLD stage II resembled healthy subjects in that they significantly reduced end-expiratory Vab (by 287±350 ml). In patients, the greater the increase in EEVcw at Wpeak, the smaller were the reductions in end-expiratory Vab (r=0.76; p=0.0001) and the greater was the increase in end-expiratory Vrc (r=0.62; p=0.001)