Melt Off uses large muscle groups under a heavy load to test your VO2 Max. Form and rep count are important here. Bring your knees to waist height during High Knees and work fast and hard with your Burpees to get in as many as you can in each 20 second time slot. Your active recovery is the Elbow Plank so breathe slow and deep during those times to oxygenate your muscles. Add EC and the load becomes interesting.