How does my body get energy to swim and why do my muscles hurt sometimes?
ATP (adenosine triphosphate, means an adenine molecule connected to three phosphate molecules) is the body's main energy carrier. It releases energy when it loses one phosphate molecule, becoming ADP (adenosine diphosphate, an adenine molecule connected to two phosphate molecules). Your body uses the energy that is released to do most everything.
Muscle cells contain very little ATP, but have a lot of creatine phosphate (a creatine molecule + a phosphate molecule). Creatine phosphate makes extra ATP by giving one of its phosphates to ADP, making it back into an ATP so the body can have energy that powers muscle contractions, cutting down on the need to breathe as much (like when we go a lap without breathing).
However, the oxygen supply eventually is too little and not enough for the body. Something called lactate begins to gather in your muscles, and this creates pain and fatigue in your muscles.
When you stop swimming fast, you usually breathe really fast. This gives your body extra oxygen, which helps lactate diffuse (leave) the muscle and go to the liver, where it turns into glucose, a sugar, which your body can use to make more ATP sometime later.
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