Figure 2.

Tissue deoxygenation (HHb, row (A)), oxygenation (HbO₂, row (B)), total blood capacity (TOT, row (C)), and saturation (S_mO₂, row (D)) of leg muscles (solid symbol) and ventilatory muscles (open symbol) in response to incremental exercise in healthy subjects (Normal) and subjects with chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF). Paired t tests were used for comparison between two muscles at three stages of the exercise test, respectively: ^a p < 0.05, ^b p < 0.01, ^c p < 0.001, ^d p < 0.0001; paired t tests were used for comparisons of changes in variables between rest and unloaded exercise and between unloaded exercise and at peak (or nadir) exercise, respectively: ^# p < 0.1, * p < 0.05, ** p < 0.01, *** p < 0.001, ⁺ p < 0.0001.