Figure 2.

A–P: physiologic responses to constant work rate exercise testing in patients with COPD receiving LAMA/LAMA therapy (closed circles) vs. Placebo (open circles). Description of visits is given in text. All data points are for 48 subjects, except the 4.5 minute time point, in which only 22 subjects completed this duration in both tests. *P < 0.05, **P = 0.01, ***P ≤ 0.001 by rmANOVA. V̇_E (L/min), pulmonary ventilation; V_T (L), tidal volume; RR (breaths/min), respiratory rate; V̇_E/MVV (%), pulmonary ventilation divided by maximum voluntary ventilation; V̇o₂ (L/min), oxygen uptake; V̇co₂ (L/min), carbon dioxide output; HR (beats/min), heart rate; V̇o₂/HR (mL/beat), oxygen pulse; V̇E/V̇co₂, pulmonary ventilation divided by carbon dioxide output; $\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_2}$ (mmHg), end-tidal carbon dioxide partial pressure; Tc${\mathrm{P}}_{{\mathrm{C}\mathrm{O}}_2}$ (mmHg), transcutaneous carbon dioxide partial pressure; V_D/V_T, dead space to tidal volume ratio; IRV (L), inspiratory reserve volume; IC (L), inspiratory capacity; $\mathrm{S}{\mathrm{p}}_{{\mathrm{O}}_2}$ (%), oxygen saturation by pulse oximetry. COPD, chronic obstructive pulmonary disease; LAMA, long-acting muscarinic antagonists.