Still have unanswered questions on oxygen depletion:

Sorry, this has been debated before. I've been all over the Net, all over books and haven't been able to get a short answer, an understandable answer in plain English. The question is in two parts: When swimming all out, a hundred yards or meters in a short or long course, what gives out? What slows you down? When doing flip turns with or without dolphin kicks, what makes you gasp for air if you stay too long under, and what makes you maybe go for open turn instead of flip turn when doing long distance, such as a 400 or 800. What part of your body will gain experience or endurance if you do the Tennessee Turns? Why is it that if you hold your breath instead of blowing out air to keep air out of nose, you will last more in your kick-off? Is this all related to C02 retention or is it an oxygen problem or is it a metabolic problem, going even deeper into the lactic acid buildup? Thanks again for your answers....billy fanstone