This classic burpee improves lower back and hip flexor dynamic power through range of motion as well as cardiovascular fitness and chest strength. Squat until you can reach the ground with your hands, then jump your feet back into a plank. Descend to the ground until your chest touches, then do a pushup to return to plank. Jump your feet back in underneath you, stand to full height, and execute a straight vertical jump with your arms in the air. That is one rep.