Changes in operating lung volumes expressed as % of predicted total lung capacity (%TLC predicted) are shown as minute ventilation (V′E) increases during symptom-limited incremental cycle exercise in patients with chronic heart failure following active bive... Changes in operating lung volumes expressed as % of predicted total lung capacity (%TLC predicted) are shown as minute ventilation (V′E) increases during symptom-limited incremental cycle exercise in patients with chronic heart failure following active biventricular pacing (filled circle) and inactive biventricular pacing (open circle). “Restrictive” constraints on tidal volume (VT) expansion during exercise are significantly greater with inactive compared with active biventricular pacing from both below (reduced inspiratory capacity (IC)) and above (inspiratory reserve volume (IRV)). Vertical dotted arrow represents iso-V′E point. Data are presented as mean±se. *: p<0.05 active versus inactive biventricular pacing. Reproduced and adapted from [6] with permission from the publisher. Bruno-Pierre Dubé et al. Eur Respir Rev 2016;25:317-332 ©2016 by European Respiratory Society