Final answer:
Type I (slow-twitch) and Type IIa (fast-twitch oxidative) skeletal muscle fibers both have a high blood supply due to their richness in mitochondria and myoglobin, which helps them carry oxygen and sustain aerobic activity.
Step-by-step explanation:
The types of skeletal muscle fibers that contain a high blood supply are Type I (slow-twitch) fibers and Type IIa (fast-twitch oxidative) fibers. Type I fibers, also known as slow oxidative or 'red' muscle, are dense with capillaries and rich in mitochondria and myoglobin, enabling them to carry oxygen and sustain aerobic activity. Type IIa fibers are fast-twitch muscles that are also rich in mitochondria and myoglobin; they primarily use aerobic respiration but can switch to anaerobic respiration, making them slightly less resistant to fatigue than Type I fibers. On the other hand, Type IIb or fast-twitch glycolytic fibers, which are anaerobic and 'white' muscle, have fewer mitochondria and myoglobin, indicating a lower blood supply.