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Home > PDHPE > Core 2 - Factors Affecting Performance > How does training affect performance? > How does training affect performance?

The human body requires energy to enable it to carry out the functions necessary for survival. One of these functions is movement. The energy for movement comes from the molecule adenosine triphosphate or ATP. ATP releases energy when it splits to form adenosine diphosphate or ADP plus a phosphate ion.

ATP is stored in small amounts in the muscle, therefore once it is utilised the body needs to resynthesise ATP if movement is to continue. The intensity (the effort needed) and duration (period of time) of the activity determines the way in which ATP is resynthesised.

Student activity
Complete the following table which summarises facts about the three energy systems. To read more about the energy systems go to the Nicholas Institute of Sports Medicine and Athletic Trauma site .

A further source of fuel is fat, which can be used over longer periods of exercise.

	Alactacid system or ATP/CP	Anaerobic glycolysis or lactic acid system	Aerobic glycolysis system
How it works		During high intensity activity the body breaks down muscle glycogen without oxygen to form ATP. This process is called anaerobic glycolysis.
Fuel	Creatine phosphate- it is produced naturally in the body and acts like a bandaid to resynthesise the floating phosphate molecule to an ADP molecule, which reforms ATP.		Carbohydrate-through food or glucose stored as glycogen in the muscles and/or the liver.
Efficiency of ATP production	Creatine phosphate (CP) combines immediately with ADP to resynthesise ATP. It is a very efficient process and for each molecule of CP, one molecule of ATP is produced. (1:1)	The lactic acid system produces ATP very rapidly. However due to the lack of oxygen it is very inefficient. For each molecule of muscle glucose and glycogen, two molecules of ATP are produced (1:2). Note: two molecules of lactic acid are also produced.
Duration	Has the shortest duration of the 3 systems. Will only last at < 95% intensity for 10 -12 seconds.
Cause of fatigue			Aerobic glycolysis will continue as long as the body has sufficient levels of blood glucose, muscle glycogen or stores of energy (e.g. fat stores) which can be mobilised and used in energy production.
By products
Recovery	The body will naturally replace stores of creatine phosphate. After 30 seconds there is 50% recovery, after 2 minutes there is 100% recovery.	As exercise slows or stops oxygen begins to break down lactic acid and remove it from the bloodstream. Recovery may take between 20 mins to 2 hours depending on duration and intensity of exercise. A thorough warm-down after exercise will assist in lactate removal.
Exercise type most suited for this energy system	e.g. throwing events.

Check the answers

The following graphs show the percentage of energy supplied by the three energy systems while exercising for a given period of time.

Graph 1: Energy systems for an activity of 0 - 20 seconds duration.

Graph 2: Energy systems for an activity 20-80 seconds duration

Graph 3: Energy systems for an activity 80-200 seconds

 

Student activity

Examine the graphs and answer the following questions. Describe the role of oxygen in each of the energy systems. In graph 1, describe what is happening in each energy system. Why does the ATP/CP graph drop so quickly in graph 1? In graph 2, which energy system is providing the most energy? Why? In graph 3, which energy system becomes the predominant system? Why? In graph 3, the contribution from the lactic acid system continues to fall. What would result if its contribution to energy needs remained high?

If you would like a more detailed understanding of the way in which energy is used to produce muscular movement go to the Nicholas Institute of Sports Medicine and Athletic Trauma site

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