12. 1 = Highest 5 = Lowest Duration Intensity Primary System Used Work to Rest Ratio (Training) Rate of ATP Production Capacity of ATP Production 0 – 6 seconds Extremely High Phosphagen 1:12 – 1:20 1 5 6 – 30 seconds Very High Phosphagen and Fast Glycolysis 2 4 30 seconds – 2 minutes High Fast Glycolysis 1:3 – 1:5 3 3 2 – 3 minutes Moderate Fast Glycolysis and Oxidative 4 2 3 minutes + Low Oxidative 1:1 – 1: 3 5 1