Figure 1.

Diagram of cardiopulmonary exercise testing. BF, breathing frequency; CO₂, carbon dioxide; HR, heart rate; LV, left ventricle; O₂, oxygen; ${\dot{\mathrm{Q}}}_{{\text{CO}}_2}$, elimination rate for carbon dioxide; ${\dot{\mathrm{Q}}}_{{\mathrm{O}}_2}$, consumption rate for oxygen; RV, right ventricle; SV, stroke volume; ${\dot{\mathrm{V}}}_{\mathrm{A}}$, alveolar ventilation; ${\dot{\mathrm{V}}}_{\mathrm{D}}$, dead space ventilation; ${\dot{\mathrm{V}}}_{\mathrm{E}}$, minute ventilation; ${\dot{\mathrm{V}}}_{{\text{CO}}_2}$, carbon dioxide elimination; ${\dot{\mathrm{V}}}_{{\mathrm{O}}_2}$,oxygen consumption; V_T, tidal volume. Reprinted from Wasserman et al.¹⁹ with permission.