Final answer:
Type IIA muscle fibers are rich in mitochondria, red in color due to myoglobin, and adapted for prolonged contractions, leveraging aerobic metabolism for ATP production.
Step-by-step explanation:
Among the characteristics of fast oxidative Type IIA muscle fibers, they are known for being rich in mitochondria, which are integral to their aerobic metabolism. Due to the presence of a significant amount of myoglobin and a dense network of capillaries, these fibers appear red in color. Moreover, these characteristics facilitate their adaptation to perform well in activities requiring prolonged contractions, as they are capable of using oxygen efficiently to generate ATP, supporting sustained muscle activity. It is not correct to say that they predominantly rely on anaerobic metabolism, as Type IIA fibers are indeed oxidative.