You're lung capacity and fitness (train longer before muscle fatigues from anaerobic), should increase with just training. I don't see much point in taking this unless you are a professional who is racing for money. If you're racing to win endorsements, big contracts and prize money, then maybe consider it. Otherwise why bother?

That was my impression. Increase amount of hemoglobin to increase capacity to feed your muscles with oxygen, more ATP! Same for blood transfusions.