A summary of the energy systems and how they relate to sport
and training – Year 10 HPE
© Cengage Learning Australia 2011
Predominant Energy Pathways
•ATP-CP Energy System (0-10 seconds)
•Anaerobic Energy System (up to 2-3
minutes)
•Aerobic Energy System (2 minutes +)
Food Fuels
•Carbohydrates, fats and proteins are the only food fuels that produce energy
•Phosphocreatine (PC) is a chemical fuel source
• Carbohydrates are our preferred exercise fuel either as blood glucose or
muscle glycogen (2/3) and liver glycogen (1/3). They are:
•easy to access
•quick to breakdown (either with or without oxygen)
•plentiful (stored in large amounts)
© Cengage Learning Australia 2011
© Cengage Learning Australia 2011
ATP = energy, and we only have a small amount
stored at muscles (only enough for a few movements)
•The three energy systems all work together
(known as INTERPLAY) to rebuild ATP and keep us going.
A-P-P-P
↔ A-P-P
&
P
•We have two anaerobic energy systems:
ATP-PC – also known as the phosphogen or phosphocreatine or creatine phosphate
system
anaerobic glycolysis – also known as the lactic acid or lactacid system
•as well as one aerobic energy system:
Aerobic – also known as aerobic glycolysis or oxygen system
© Cengage Learning Australia 2011
Systems and fitness components
© Cengage Learning Australia 2011
Summary of the ATP–PC energy system
• Does not require oxygen to liberate energy (anaerobic)
• The ATP–PC system provides the most rapidly available source of ATP for energy
because it depends on simple and short chemical reactions and the ready availability of
PC at muscles (PC being broken down to P + C).
• A limited amount of PC is stored at the muscles (about 10 seconds worth at maximal
intensity), with larger muscles capable of storing slightly more PC than this (12 to 14
seconds at maximal intensity).
• There is approximately four times as much PC stored at muscles as there is ATP.
• Once phosphocreatine has been depleted at the muscle, ATP must be resynthesised
from another substance, typically glycogen, which is stored at the muscles and the liver,
via anaerobic glycolysis using the lactic acid system.
© Cengage Learning Australia 2011
Summary of the anaerobic glycolysis
energy system
• The lactic acid system is also anaerobic (doesn’t require oxygen to liberate energy) but
involves more complicated and longer chemical reactions than the ATP-PC system to
release energy.
• It supplies energy from the start of intense exercise and peak power from this system is
usually reached between five and fifteen seconds, it will continue to contribute to ATP
production until it fatigues (two to three minutes).
• It produces lactic acid, which can be broken down to glycogen to provide further energy.
• It supplies ATP at a slower rate than the phosphagen system.
• It provides energy for longer during submaximal activities when PC is depleted and lactic
acid accumulation is slower. This provides a stopgap until sufficient oxygen is transported to
working muscles for the aerobic system to become the major energy contributor.
• It provides twice as much energy for ATP resynthesis as the ATP-PC system.
© Cengage Learning Australia 2011
Summary of the aerobic energy system
• The aerobic system is the slowest system to contribute towards ATP resynthesis due to the
complex nature of its chemical reactions.
• It is capable of producing the most energy in comparison to the other two energy systems
– between 30 to 40 times.
• It preferentially breaks down carbohydrates rather than fats to release energy.
• It provides 50 times as much ATP as the ATP-PC and lactic acid systems combined.
• It contributes significant amounts of energy during high-intensity/maximal activities lasting
one to two minutes.
• The aerobic system is activated at the start of intense exercise, peak power from this
system is usually reached between one and two minutes and will continue to be the major
ATP contributor as the lactic acid system decreases its contribution.
© Cengage Learning Australia 2011