Figure 3.

Correlations related to exercise tolerance and ventilatory efficiency. Difference: between before and after pulmonary rehabilitation; ΔFO₂: difference between inspired and expired O₂ concentration; V’_E: minute ventilation; V’_E/V’_CO2-nadir: lowest value of the ratio between minute ventilation and carbon dioxide output during exercise (see the Methods section for details); V’_E–V’_CO2-slope: the slope was determined by linear regression analysis of minute ventilation to carbon dioxide output observed during exercise (see the Methods section for details); V’_O2: oxygen uptake. Black arrows mean the up and down differences obtained from pulmonary rehabilitation.