In healthy subjects, oxygen consumption and cardiorespiratory responses are lower during eccentric exercise (negative work, W(neg)) than during concentric exercise (positive work, W(pos)) at the same work load. The aim of the present study was to investigate the ventilatory response to W(neg) in patients with chronic obstructive pulmonary disease (COPD). The study population consisted of 12 subjects with COPD [forced expiratory volume in 1 s (FEV1) mean (SD): 1.5 (0.4) 1, 46 (16)% of predicted]. Concentric and eccentric exercise tests (6 min exercise; interval ≤ 1 h) were performed in random order at constant work loads of 25 and 50% of the individual maximal (positive) work capacity. Expired ventilation per minute (V̇E), oxygen consumption (V̇O2) and carbon dioxide production (V̇CO2) were 30% lower during W(neg) than during W(pos) for both work intensities. The-breathing reserve during 25%W(neg) was 11 (8)% and during 50%W(neg) was 18 (14)% higher than during W(pos) at corresponding work loads (P < 0.01). V̇E/V̇O2 and V̇E/V̇CO2 were similar during W(pos) and W(neg). Arterial carbon dioxide tension (PaCO2) increased by 0.1 (0.4) kPa during 50%W(neg) and by 0.7 (0.5) kPa during 50%W(pos) (P < 0.01). During 50%W(neg), perceived leg effort (modified Borg Scale) tended to be higher than perceived breathlessness (2.4 (1.2) vs. 2.0 (1.1). It was concluded that in subjects with COPD, the ventilatory requirements of W(neg) were considerably lower than those of W(pos) at similar work loads up to 50% of maximal work capacity. During W(neg), the ventilatory reserve was higher and gas exchange was less disturbed as a result of a lower V̇O2 and V̇CO2.
Rooyackers, J. M., Dekhuijzen, P. N. R., Van Herwaarden, C. L. A., & Folgering, H. T. M. (1997). Ventilatory response to positive and negative work in patients with chronic obstructive pulmonary disease. Respiratory Medicine, 91(3), 143–149. https://doi.org/10.1016/S0954-6111(97)90050-0