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Human Energy Systems 3, The Aerobic or Oxygen System

By July 17, 2009 October 20th, 2011 No Comments

My 2 previous blogs have looked at the CP (rocket fuel) and Lactate (petrol) energy systems, today we’ll have a look at the third and final one, the aerobic or oxygen system, which in our car fuel comparison is more like diesel.. Aerobic simply means “with oxygen” and refers to the energy system that produces ATP (the source of all our energy, see the blog on CP energy systems) from the complete breakdown of carbohydrate and fat in the presence of O2. The aerobic energy system is dominant when there is sufficient O2 in the cells to meet the energy production requirements. This is especially true if the body is at rest, and the oxygen system is the dominant one up to about 60% of maximum exertion.. The fuel sources for this energy system are fatty acids (fat!) and carbohydrate, stored in their blood as glucose, and they supply the body with ATP during aerobic metabolism. Whether the body is at rest or exercising aerobically, both carbohydrate and fat are required, just in varying proportions. Fat is commonly said to burn in a carbohydrate flame, meaning that fat cannot be broken down without the presence of carbohydrate. The production of energy from the oxygen system produces only ATP (where the energy actually comes from), CO2, water and heat, so there is no nasty waste product like in the lactate system (lactic acid), and thus the oxygen system is only limited by time taken to refuel during exercise. The complete breakdown of 1 glucose molecule will regenerate 36 moles of ATP or 263Kcals. 1 molecule of fat will yield 460 moles of ATP, making it a far more concentrated energy supply; however carbohydrate remains the preferred source of energy since it will realse it’s energy a lot faster, even though it has less of it per molecule to release.

Now that we have looked at the three diferent energy systems we can begin to see why understanding them is important, not just from a scientific view but for anyone who wants to begin training these energy systems to improve-an athlete, fitness enthusiast and of course a personal trainer. In the next blog we will look at the impact these energy systems have on training and how the energy systems are the key not only in getting fitter but also in personal training for weight loss. Remember that all these systems operate simultaneousle, but one of them will be dominant at a given time depending on the level of exertion. The CP system takes us from 95-100%, the lactate system from 60-95%, and the oxygen system from 0-60%.

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