Fig. 1

Cardiopulmonary parameter-percentages of the \( \Updelta \dot{V} {\text{O}}_{ 2} \) curve of controls and TBsq patients. Cardiopulmonary responses in control subjects and TBsq patients are shown plotted against the percentage of \( \Updelta \dot{V} {\text{O}}_{ 2} \) that occurs during exercise. \( \Updelta \dot{V} {\text{O}}_{ 2} \), the increment in \( \dot{V} {\text{O}}_{ 2} \) between resting and peak exercise; open symbols, control subjects; solid symbols, TBsq patients, V _D /V _T -ratio physiologic dead space/tidal volume-ratio. Square symbols show the dyspnea, lactate, or norepinephrine-break point, with error bars. In all subjects, both the dyspnea and norepinephrine-break points were determined, but in 9 TBsq patients, it was too difficult to determine the lactate break points reliably. Data are mean ± standard error of the mean. ^# p < 0.001, ^¶ p < 0.0001; differences due to the interaction of exercise phase and group on repeated-measures ANOVA