Answer: Fast and slow oxidative fibers.
Explanation:
Addition of more mitochondria to a muscle fiber will have the greatest effect on FAST and SLOW oxidative fibers.
Mitochondria are interesting organelles which are involved in controlling many critical cellular processes for the physiology of the skeletal muscle. They take part in central roles in the area of muscle cell metabolism, energy supply, the regulation of energy-sensitive signaling pathways, reactive oxygen and species production.
