Why do slow twitch fibers have more mitochondria

Slow twitch fibers have more mitochondria because they aerobic oxidation basically oxidative phosphorylation to resist muscle fatigue by generation of ATP molecules.

Explanation:

Slow twitch fibers are also called red muscle fibers that contain large amount of mitochondria and Myoglobin pigment which gives them red coloration.

     Slow twitch  fibers uses oxygen to carry out oxidative phosphorylation of aerobic respiration to generate energy rich compound called adenosine tri phosphate or ATP.Thus the slow twitch muscle fibers can resist muscle fatigue.

      That"s why slow twitch muscle contain more mitochondria

it marks things for degradation via the proteasome. it alters there celluar location.