Give an example of an exercise routine utilizing each of the three major energy pathways. How long does the body utilize each pathway as its main energy source? Are the examples you gave specifically designed to utilize that particular pathway or is it just the nature of the exercise?

There are three energy pathways that the body uses to obtain energy for exercise. (1, 2, 3) In order to generate energy for exercises, the body must breakdown food to energy by using these three pathways. (1, 2 ,3) These three pathways breakdown the nutrient such as protein, fat, and carbohydrate in three different ways. These three pathways convert the nutrients into a form of energy the body can use called adenosine triphosphate (ATP). (1) The energy from ATP is necessary to support most kinds of "bodily processes". This energy requiring processes are muscle contraction and exercises.

The first pathway is the ATP-CP Anaerobic Energy Pathway and is called " the phosphate system", which does not require any oxygen to generate ATP energy. First, the ATP-CP pathway used up all its ATP stored in muscle, and this usually last about 2-3 seconds. Second, it used creatine phosphate (CP) to re-generate more ATP until the creatine phosphate (CP) runs out; this usually last about 6-8 seconds. When all the ATP and CP are used up , the muscle and cells of the body will eventually move to either aerobic or anaerobic metabolism to continue on making ATP for energy required for exercise. Since the ATP-CP Anaerobic Pathway does not require oxygen and occur in short amount of time to produce ATP, the exercises that used the ATP-CP Anaerobic Pathway is usually a short burst of exercise " like a 100 meter sprint or playing ping pong." (1, 2) Such exercise require short, explosive burst of movement, which only fit with the ATP-CP Anaerobic pathway. The amount of energy released for the ATP-CP pathway only last for about 10 seconds; so it only used for short burst exercises. (1, 2)

The second pathway is the anaerobic pathway called the glycolysis pathway that produce ATP only from carbohydrates, using lactic acid as the byproduct. (1) In the anaerobic glycolysis, glucose is being broken down to energy without the need for oxygen. (1, 2) This glycolytic pathway provide short, high intensity burst of energy for short activity, which last about several minutes. (1,2) After several minutes of intense muscle activity, the lactic acid start to build up and the lactate threshold is reached. As a result, there will be muscle pain, burning,and fatique. (1, 2) The exercise that used the anaerobic glycolysis pathway is weight lifting, sit up, crunches, and arm lifting.

The third pathway for energy metabolic is the aerobic metabolism pathway that supply most of the energy required for long duration activity. (1) The aerobic pathway work by using oxygen to convert carbohydrates, fat, and protein into ATP. The system required the circulatory system to transport the oxygen to the muscles and creating ATP, which make it a longer process compared to the other two pathways.. (3) It consists of four metabolic processes to produce ATP. The aerobic glycolysis metabolize glucose to form two ATPs. (3) The Kreb cycles oxidizes glucose to more ATPs. (3) The electron transport chain require oxygen and produce 34 ATP from glucose. (3)The oxidation system, which can produce ATP from fatty acids or carbohydrate oxidation reactions. ( 3) The aerobic metabolism pathway is slower than the anaerobic pathway and the body can make ATP for a long period of time because of the required circulatory system to move oxygen to all cells and the four other pathways that come into play. (3)

To sum it up, these are the sports that used these three pathways: The examples are specifically design to fit the pathway and it is also the nature of the exercise that meet the requirement for these pathways, such as if the exercise require long duration or short durations. The duration of the exercise dictate what pathways if will fall into.

SPORTS ATP-PCR Glycolysis Oxidative
Basketball 60% 20% 20%
Running long distance 10% 20% 70%
Tennis 70% 20% 10%
Swimming (50m freestyle) 40% 55% 5%
Swimming long distance 10% 20% 70%

Foss M L and Keteyian S. (1998) The Physiological Basis of Exercises and Sport: 6th Edition.
Stager JM and Tanner DA. (2005) Swimming: 2nd Edition.