Ventilatory adaptation during eccentric cycling in patients ywith 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 f(B) 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, f(B), inspiratory capacity (IC) and oxygen consumption (VO2) were recorded at each workload increment during CPET. Results: At the highest identical minute ventilation (VE) achieved during ECC and CON (28.6 +/- 4.6 L.min(-1)), VT was lower (1010 +/- 218 vs. 1100 +/- 233 mL; p = 0.02), f(B) 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 VO2 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.