In the 2017 HSC PDHPE exam, question 25 was worth 7 marks and asked: “Compare TWO different energy systems by exploring their duration, sources of fuel and causes of fatigue. Use examples to support your answer.” Below is a sample answer for this question provided by Melissa. As always remember to use the NESA marking guidelines to critique sample answers and identify ways to improve upon them.
Two different energy systems include the alactacid and aerobic energy system. In the ATP/PC system, an explosive movement causes the ATP molecule to split providing energy for muscular contraction. Then, creating phosphate splits releasing energy in the process. This allows for an activity to be repeated in intense short bursts without immediate exhaustion. It lasts for 10-15 seconds and occurs first as it is the shortest. It uses creatine phosphate as a source of fuel and its cause of fatigue include depletion of PC and ATP. Examples include 100m sprint or weightlifting.
The aerobic energy system requires the presence of oxygen to ensure the continuation of muscular contraction. The aerobic energy system lasts for more than 30 seconds and its source of fuel are glycogen and fats. It also uses protein if nothing else is available. For the aerobic energy the cause of fatigue is when there is a glycogen to fat shift. This is also known as ‘hitting the wall’. Examples include long distance events such as a marathon, triathlon, walking and team sports such as soccer and basketball as they require large amounts of oxygen and lasts for a few minutes, therefore these are part of the aerobic energy system.
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