Ventilatory adaptation during eccentric cycling in patients with severe COPD: potential implications for exercise training.

INTRODUCTION: Eccentric (ECC) cycling is viewed as an alternative to concentric (CON) cycling for exercise training in patients with severe COPD as it induces a much lower ventilatory demand for a given mechanical load than CON cycling. However, a more hyperpneic breathing pattern (i.e., higher fB and lower tidal volume (VT)) during ECC than during CON has been reported in healthy subjects.

RESEARCH QUESTION: Do patients with severe COPD develop a more hyperpneic breathing pattern during ECC than during CON cycling, and is it associated with differences in dynamic hyperinflation, ventilatory efficiency and cardiometabolic adaptation?

METHODS: Fourteen patients with severe COPD performed incremental CON and ECC cardiopulmonary exercise tests (CPET). Several physiological parameters including VT, fB , inspiratory capacity (IC) and oxygen consumption (V̇O2 ) were recorded at each workload increment during CPET.

RESULTS: At the highest identical minute ventilation (V̇E) achieved during ECC and CON (28.6 ± 4.6 L.min-1 ), VT was lower (1010 ± 218 vs. 1100 ± 233 mL; p = 0.02), fB was higher (29.0 ± 5.1 vs. 27.0 ± 5.5 min-1 ; p = 0.03), IC(% baseline) was lower (84 ± 10 vs. 78 ± 9; p < 0.01) and markers of ventilatory efficiency were poorer during ECC than during CON. Similar results were found at the highest identical V̇O2 achieved during ECC and CON.

CONCLUSION: The finding of a more hyperpneic ventilatory pattern during ECC cycling together with a lower IC and a poorer ventilatory efficiency suggests that ECC exercise training should be decided with caution in patients with severe COPD.