Move your bodyweight fast and you are in the cardio zone. Your muscles begin to go aerobic, your lungs labor for breath and your body temperature skyrockets. Using just two exercises that move the body in two plains Killer Cardio lives up to its promise. Bring your knees to waist height during High Knees and take your body's weight on your arms and shoulders during Climbers so you can move your legs back and forth like pistons.