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.