The final pathway that the body uses to produce ATP is the Oxidative Pathway and just as its name implies it utilizes oxygen and why it is called an aerobic process. A much larger quantity of ATP is produced in the Oxidative Pathway, yet it takes a longer time to produce that ATP. The Oxidative Pathway utilizes the Krebs Cycle and the electron transport chain and for simplicity sake we will not go into much detail about those two processes but just understand they are directly involved in the Oxidative Pathway process.
In the glycolytic pathway lactic acid is the by product, in the Oxidative Pathway, Pyruvate is the main substance that is broken down through the Krebs Cycle and the electron transport chain where the energy is created to convert the ADP back into ATP.
Unlike the ATP/CP and the glycolytic pathways the Oxidative Pathway is the only pathway in which fat can be utilized for energy. It is the breaking down of the fat that creates the co-enzymes that power the Kreb’s cycle.
When at rest a large majority of the fuel sources to create power and movement come from fat but when movement intensity increases oxidation process cannot keep up (remember it is a slower process) resulting in a larger percentage of carbohydrates being used instead of fat. A common misconception is that low intensity cardio is primarily fueled from fat. To the contrary, when movement is at the upper end of or the aerobic pathway, almost 100% of that movement is fueled by carbohydrates and not fat. Which means if carbohydrates are not available the body will then turn to breaking down its own muscle tissues to create the energy needed.
Unlike the ATP/CP and Glycolytic Pathways training in the Oxidative Pathway is better suited utilizing continuous exercise compared to interval work. A training regimen in this system could include: working for 60 minutes at 70-75% of Max Heart rate or 20 minutes of tempo work at lactate threshold levels or around 80 to 85% of Max Heart Rate.
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