CrossFit appealed to me because the approach was trying to find measurable, observable, and repeatable results and chose Olympic Lifters, Olympic Gymnasts, and Olympic Sprinters as the result. Three ways to produce incredible power output wrapped into one package and presented as general fitness.
Metabolism constructs molecules from smaller units or breaks down molecules into smaller units to release energy depending on the needs of the moment within the cellular environment.
With a working model, I was excited to see results. Then I remembered a quote from Bourne Identity when Jason says, "At this altitude, I can run flat out for a half mile before my hands start shaking." I wondered what that referred to. 800m at a dead sprint could be the world record just under 1 min 41 seconds. Hands shaking meant no oxygen getting to his system and energy depletion coming on fast. At least, that was what I thought it meant.
The first 10s is the "stored" energy. The next 2 minutes is the stored glycogen. After about 2 minutes, the fat starts burning. But that would mean after two minutes into a marathon, the body would be burning fat and the runner could go on just fine. How could Jason shake at 800m and a marathoner shake at 20mi? I was missing something...