1. Is the limiting factor in staying "aerobic" having enough oxygen in the blood stream? or in the muscle cells?
2. When you run slower than Aerobic Threshold pace are you working only your slow twitch muscle fibers or are your type IIA's being recruited as well?
3. When you use fast twitch muscle fibers do you always use slow twitch fibers in addition? Or does your body completely switch once the fast twitch fibers are recruited?
4. If type IIA's aren't being used then does long runs below AT have any effect on endurance or "aerobic strength" in an 800m or 1500m?
5. If no to #4, how do you explain the success of Arthur Lydiard in the shorter races?