Figure 4. Skeletal muscle mitochondrial volume density in untrained healthy controls and patients with chronic heart failure with reduced ejection fraction (HFrEF) before (pre) and after (post) knee‐extensor exercise (KE) training.

Inset, the relationship between capillarity and mitochondrial volume density content before and after KE training in the patients with HFrEF. Data are presented as mean ± SE. ^* P < 0.05 post vs. pre; ^# P < 0.05 HFrEF vs. controls.