Energy Systems

Phosphocreatine (PC) System

Phosphocreatine broken down into creatine through the enzyme creatine kinase

--> inorganic phosphate and energy is released which can be used to resynthesise ADP into ATP

  • Fuel source: phosphocreatine (located in the skeletal muscles)

  • Duration: up to 10 seconds

  • Intensity: max (100m)

  • Found in the sarcoplasm

  • Also known as Alactic System

  • Activated by an increase in ADP

  • Anaerobic

  • Produces 1 ATP molecule

  • Limited energy stores

  • No by products

 

Lactic Acid System

Glycogen is broken down into glucose through phosphofructokinase

If oxygen is present pyruvate is produced

If oxygen isn't present lactic acid is produced

Energy is given off to produce ATO

  • Fuel: glucose

  • Duration: up to 75 seconds

  • Intensity: medium (400m)

  • Found in sarcoplasm

  • Also knowns as Anaerobic glycolysis

Activated by a decrease in PC levels

  • Anaerobic/aerobic

  • Produces 2 ATP molecules

  • Adequate energy stores

  • Lactic acid is a by-product

 

Aerobic System

  1. Aerobic Glycolysis: glucose is broken down into pyruvic acid (oxygen is available so lactic acid isn’t produced)

--> occurs in the sarcoplasm producing 2 ATP molecules

  1. Kreb Cycle: pyruvic acid moves to the mitochondria and mixes with the coenzyme A to create acetyl coenzyme

-->  the acetyl coenzyme is broken down to produce 2 ATP molecules, carbon dioxide and electron carriers for further energy production

--> hydrogen atoms are removed and the hydrogen carriers then transport electrons to the electron transport chain

  1. Electron Transport Chain: the hydrogen atoms combine with oxygen in the mitochondria to make water and carbon dioxide

--> produces 34 ATP molecules

  • Fuel: glucose, lipids, protein

  • Duration: 75 seconds plus

  • Intensity: high (marathon)

  • Takes 30 seconds to kick in

  • Hours of energy

  • Supplies oxygen to the muscles

  • Produces 34 ATP molecules

  • Carbon dioxide and water are by-products