EP9 - Energy Systems

Where does energy come from?

• from the Sun in the form of heat and light

• converted into chemical energy in the form of food

• the energy from food is used to produce ATP

• ATP = the basic fuel that powers our bodily functions (e.g. contraction of muscles)

Three Main Systems

• work together continuously to generate energy (ATP) for muscular work

• ATP-CP / Lactic Acid systems can generate energy without oxygen

(for high-intensity output, for short periods of time)

1. ATP-CP

• anaerobic

• sudden, powerful, explosive movements

• causes fatigue quickly

• Duration: 0 - 10 seconds

2. Lactic Acid

• anaerobic

• intensive work

• Fuel: Carbs in the form of glucose / glycogen

• Duration: 10 seconds - 2 minutes

3. Aerobic

• steady supply of energy over a sustained period of time

• Fuel: Carbs, fats, sometimes proteins

• Duration: 2 minutes - several hours

e.g. long-distance events, prolonged sports 

Relation of Energy Systems

e.g.

• two people run together starting at a brisk jog (aerobic system)

• as soon as they run up a hill, demand for energy increases

• so the lactic acid system tops up any extra energy

(after aerobic system reaches its max output)

• as they head down the hill, the aerobic system supplies most of the energy

• the ATP-CP / Lactic Acid systems store fuel in case for future use

• they finish the race quickly to the tree nearby, so the ATP-CP system is used