Energy Systems

ATP-

• Made up of an adenosine molecule with three phosphate molecules attached with three phosphate molecules attached

• When energy is required for muscular contraction, one of the phosphate molecules breaks off, releasing energy

• When one phosphate molecules for ATP breaks off and energy is released, adenosine diphosphate (ADP) is all created

There are three different pathways, or energy systems responsible for the resynthesis or rebuilding of ATP.

1. ATP-PC system (without O2)

2. Anaerobic Glycolysis (without O2)

3. Aerobic system (O2)

The proportional contribution of each energy system is dependent upon the following:

• The intensity of the exercise

• The duration of the exercise

• How urgently the energy is required

• How urgently the energy is required

• Whether oxygen is present or not

REVISION AREAS

ENERGY SYSTEMS

Food Fuels

The energy used by muscles comes from a chemical compound called adenosine triphosphate (ATP).

ATP is stored in limited quantities within muscle, so each muscle fibre must be able to create its own from the food fuels. These include carbohydrates, proteins and fats.

·       Carbohydrates – Glucose in blood/Glycogen in muscle/Liver – Glycogen

·       Fat- Adipose Tissue/Blood/Muscle – Fatty Acids/Triglycerides

·       Protein (growth and repair)– Muscles/Adipose Tissue – Amino Acids

Food Fuels at Rest & during Exercise

During exercise there several factors that determine which food fuel is the major contributor of energy for a particular activity. It depends on:

-        the intensity of the activity

-        the duration of the activity

Carbohydrates are the main

-        supplier of energy for most exercises including short duration, high intensity  long duration and light to moderate intensity (submaximal)

-        As glycogen stores gradually deplete (after approximately 90mins of continuous exercise), fats become the main source of energy.

ATP & ADP

We store energy in the form of Adenosine Triphosphate (ATP) within our muscles as this energy enables all muscular contractions to occur. In other words, chemical energy is converted into mechanical energy.

When energy is required for muscular contraction, one of the phosphate molecules breaks off, releasing energy making adenosine diphosphate (ADP) plus Energy for Movement

Energy Systems

Three different pathways, or energy systems responsible for the resynthesis or rebuilding of ATP

·       ATP-PC (no-O2)

·       Anaerobic Glycolysis (no-O2)

·       Aerobic – (O2)

The contribution of each energy system is dependent on:

• the intensity of the exercise

•  the duration of the exercise

•  how urgently the energy is required

•  whether oxygen is present or not

Fuels

ATP-PC

-        High energy

-        Creatine phosphate donates its phosphate to ADP to resynthesis ATP.  

-        Anaerobic

-        Immediate

-        Limited amount

This energy system is for immediate activity for activities of short duration (lasting 0-10 seconds), high intensity and explosive activities, therefore, fast twitch muscle fibres are recruited. 

Anaerobic Glycolysis

-        Short/medium term high intensity

-        Glycogen or glucose is broken down for energy

-        No O2 so lactic acid builds up causing fatigue

-        May last longer if the intensity is lower

This system provides energy for short term high-intensity exercise (15sec – 2 min), therefore fast twitch muscle fibres are recruited. 

Aerobic

-        Uses O2

-        Has largest capacity of producing ATP

-        Slowest to contribute

-        Low to moderate intensity (sub-maximal)

-        Longer duration type activities

This system is the prime energy source for endurance-based activities, therefore slow twitch muscle fibres are recruited.

Energy System Interplay

How all three energy systems work together to provide energy is also known as the energy system

interplay. As the activity time increases, the influence of the Aerobic system for ATP production also increases. However, the relative contribution of each of the three energy systems varies according to the intensity and duration of the activity.

·       Few sports rely on one single energy system

·       Most sports and sporting activities use a combination of energy systems

·       The energy systems overlap rather than switch on and off

·       All 3 energy systems may be used at once but some are stimulated more than others

·       Which one is dominant?

ATP-PC System: