Mitochondrial function decreases with age, shown by fewer and smaller mitochondria per gram of muscle in biopsies.

“how do you quantify this in animals so if you if you were to take a four month old mouse versus a two and a half year old mouse and you did muscle biopsies obviously there's a quantitative assessment that you would do you would say per gram of muscle there's this many mitochondria versus this they're this big versus that big”