ENERGY SYSTEMS

The energy systems

Energy pathways - Anaerobic and Aerobic

Energy systems - ATP-PC, Anaerobic glycolysis and Aerobic

ATP is able to be produced by more than one system/pathway. All three systems are working from the start of exercise and contribute to energy production. But there will always be one main providing system - depending on the duration and intensity of activity,

Aerobic energy system

ATP is produced by breaking down two fuels (CHO and fast) aerobically:

Aerobic glycolysis (CHO):

• less powerful system (moderate rate of ATP)

• limited capacity (moderate amount of ATP)

Aerobic lipolysis (Fats):

• least powerful system (slowest rate of ATP)

• unlimited capacity (largest amount of ATP)

Anaerobic energy systems

ATP is produced by these energy systems:

ATP-PC (F1 engine):

• exclusively uses PC

• most powerful systems (fastest rate of ATP)

• Limited capacity (smallest amount of ATP)

Anaerobic glycolysis (V8 engine):

• Exclusively uses CHOs

• powerful system (Fast rate of ATP)

• limited capacity (small amount of ATP)

Replenishing ATP

ATP needs to be continually resynthesised for exercise.

This occurs via the energy systems that use fuel or substrates such as PC, CHO fats and sometimes proteins to enable ATP to be replenished,

The purpose of energy systems iss to break down chemical fuels to release energy for ATP resynthesis.

ATP can be replenished with/out oxygen:

• Aerobic metabolism

• Anaerobic metabolism

Comparing the energy systems

fastest to slowest (rate): ATP-PC - Anaerobic glycolysis - Aerobic

Amount of ATP produced (yield): Aerobic - Anaerobic Glycolysis - ATP-PC

Exercise intensity determines rate of ATP resynthesis needed - exercise duration determines yield of ATP resynthesis.

ATP-PC~0.7-1.0

Anaerobic glycolysis~2-3

Aerobic glycolysis ~36-38

Aerobic Lipolysis ~147

Anaerobic Glycolysis

Rate: moderate/fast

Yield: moderate 

Fuel used: glucose 

Duration: maximal events lasting 10-60 seconds

Sports: 400m, 100m swim, repeated high intensity efforts

Intensity: 85-95% max HR or near maximal

By-products: lactic acid - accumulation of hydrogen ions (fatiguing by-products)

Other notes: Does not use oxygen. Cannot be used forever due to build up of fatiguing by-products.

ATP-PC system

Rate: Fastest

Yield: lowest

Fuel used:PC

Duration: Maximal continuous events (lasting up to 10 seconds)

Sports: shot put, 100m, explosive movements in team sports (i.e. jump)

Intensity: 95%+ max HR, maximal (above VO2 max)

By-products: No fatiguing by-products

Other notes: Does not need oxygen, most rapid, but also lasts the shortest (depleted PC stores)

Aerobic system

Rate: Moderat/low/slowest

Yield: high/highest

Fuel: Glycogen (CHO) during exercise, fats (lipids)

Duration: until ~90-120 mins of stored glycogen begins to deplete, after 990-120 minutes (lipids)

Sports: most intermittent or team sports, 3000m, marathon, ultra endurance (lipids)

Intensity: 70-85% max HR or submaximal, below 60% max HR (lipids)

By-products: CO2, heat, sweat: no fatiguing by products

Other notes: can continue indefinitely if there is enough glycogen stores and intensity is not too high. (lipids) can continue indefinitely if there is enough triglyceride stores and intensity is not too high,