Mitochondrial density
DEMitochondriendichte
Mitochondrial density is how many mitochondria you have per unit of muscle. It also covers how much space they take up. Higher density means more capacity to burn fuel with oxygen. So you can burn more fat and pyruvate aerobically. That improves endurance and metabolic flexibility. Aerobic and Zone 2 training build new mitochondria. They do it via a master regulator called PGC-1α. Age and inactivity reduce density. Keeping yours up is considered central to healthy aging. It also matters for heart-and-lung fitness.
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