Unit 3 AOS 2: Energy Systems Interplay

Energy System Interplay

Introduction

• The body produces energy through the interplay of three energy systems. The predominant energy system depends on the intensity and duration of physical activity.

Key Concepts

• Energy System Interplay: The interaction of the ATP-CP (phosphagen), anaerobic glycolysis (lactic acid), and aerobic systems to meet the body's energy demands during exercise.
• Fuel Source: The duration and intensity of exercise determine which fuel source is primarily used for ATP production.
• For most sports and activities, there is an interplay between energy systems.
• All energy systems contribute, but a predominant system is determined by the specific activity/effort requirements.

Energy System Interplay at Rest

• At rest, the aerobic system predominantly resynthesizes ATP.
• Fats contribute approximately 2/3 of the energy.
• Carbohydrates (CHO) contribute approximately 1/3 of the energy.

Energy System Interplay During Exercise

• At the start of exercise, all three energy systems begin contributing to ATP production simultaneously.
• ATP-CP System:
  • In the initial 0-5 seconds of exercise, the ATP-CP system is the primary ATP provider due to its rapid ATP production rate.
  • However, it depletes quickly.
• Anaerobic Glycolysis System:
  • As the ATP-CP system depletes (around 5-6 seconds), anaerobic glycolysis becomes the dominant ATP provider.
  • It can produce ATP quickly but generates fatiguing by-products.
  • Remains dominant until about 30 seconds.
• Aerobic System:
  • From 30 seconds onward, the aerobic system produces ATP at a rate that meets the body's demands.
  • It becomes the dominant provider.
  • The aerobic system remains dominant unless exercise intensity increases, at which point anaerobic glycolysis increases its contribution.

Energy System Contribution Over Time

• ATP-CP System:
  • Main energy source in the first 10 seconds.
  • Output peaks at approximately 5 seconds.
  • Fatigues quickly due to ATP/PC depletion.
• Anaerobic Glycolysis System:
  • Main energy source from 10-30 seconds.
  • Output peaks at approximately 20 seconds.
  • Fatigues due to lactic acid build-up.
  • Provides energy for up to 2 minutes.
• Aerobic System:
  • Main energy source from 30 seconds onward (when oxygen supply sufficiently increases ATP contribution).
  • Unlimited capacity to work unless fuel supply (food) is insufficient.

Anaerobic and Aerobic Contribution to Exercise

• The graph illustrates the interplay between anaerobic and aerobic systems during exhaustive exercise of varying durations.
• As the duration of exercise increases, the contribution of the aerobic system increases while the contribution of the anaerobic system decreases.

Practical Examples of Energy System Predominance

• 400m Run: Predominantly Anaerobic Glycolysis because the duration is approximately 45-60 seconds at high intensity.
• Pole Vault: Predominantly ATP-CP System because it is performed at very high intensity over a short duration (approx. 5-10 seconds) and requires explosive power.
• 100m Hurdles: Predominantly ATP-CP System because it is performed at a very high intensity over a short duration (approx. 10-12 seconds).
• 1500m Swim: Predominantly Aerobic System because it is performed at a sub-maximal intensity over a duration of approximately 15+ minutes.
• Dive off the blocks: Predominantly ATP-CP System because it is performed at a very high intensity over a very short duration (approx. 1-2 seconds) and requires explosive power.
• Game of Hockey: Aerobic System is predominant overall because the match duration is approximately 60 minutes, with much of the time spent at low intensity (e.g., walking, jogging, or standing). However, there will be times when the predominant energy system changes, with increased contribution from Anaerobic Glycolysis during repeat sprint efforts.

Energy System Continuum

• The slide shows where the energy system lies on a continuum between anaerobic and aerobic energy production for various sporting activities.