The document summarizes three energy systems: 1) ATP-PC system uses phosphocreatine to produce energy instantly for intense bursts up to 10 seconds. 2) Lactic acid system uses glycogen to produce fast energy for activities lasting 10-75 seconds through anaerobic glycolysis. 3) Aerobic system uses oxygen and fuels like carbohydrates and fats to produce sustained energy over 75 seconds through aerobic glycolysis.

1. Energy Systems
ATP-PC energy Lactic acid Aerobic energy
system energy system system
Alternative Alactic system, Anaerobic glycolysis, Oxygen system, aerobic
name phosphocreatine or lactacid system glycolysis
creatine phosphate
system, phosphagen
system
Fuel source Phosphocreatine (PC or Glycogen At rest: FFAs
PCr) or creatine During exercise:
phosphate (CP). CHO
Interchangeable names Fats (when glycogen
for the same chemical sparing and when
glycogen stores
diminished)
Protein (last resort)
Intensity of Very High (>95% max HR) High (>85% max HR) Resting
activity Used for increase in Sub max intensity (<80%
intensity in long duration max HR)
events
Duration 1-5 seconds 5-60 seconds >75 seconds
system is
dominant
during activity
Peak Power 2-4 seconds 5-15 seconds 60-90 seconds
Amount of 0.7 ATP for each PC 2-3 ATP for each glucose CHO (38 ATP per glucose
ATP produced molecule molecule molecule)
Fats (441 ATP per
triglyceride molecule)
Speed of Instantaneous Fast Medium
production Simple chemical Longer chemical Complex chemical
reactions reactions reactions
Availability of oxygen
delays max power
By products Inorganic phosphate (Pi) Lactic acid C02
ADP Hydrogen (H+) ions H20
ADP Heat
Total duration 0-10 seconds 10-75 seconds >75 seconds
during activity