What is the predominant energy system used by an athlete in a 400-metre running event? A - HSC - SSCE Personal Development and Physical Education - Question 4 - 2021 - Paper 1

In a 400-metre running event, the predominant energy system used is the lactic acid system. This energy system is primarily anaerobic and is utilized due to the high intensity and relatively short duration of the event, typically lasting about 45 seconds to 1 minute.

Explanation of Energy Systems

1. Aerobic Energy System: This system is predominantly used during longer events where oxygen supply is sufficient. It is not the primary energy system for a 400-metre event due to its intensity.
2. ATP-PC System (Phosphagen System): This system provides energy for short bursts of high intensity, typically lasting up to 10 seconds. It is significant in the early stages of the race but does not sustain effort throughout.
3. Lactic Acid System: Active during events lasting longer than approximately 10 seconds and up to around 2 minutes, this system involves the breakdown of glucose without oxygen, producing lactic acid as a by-product. This is why option D, the lactic acid system, is correct for a 400-metre sprint.