Burpees make everything burn: Your muscles, your lungs, and most importantly, a ton of calories. The exercise—which entails going from pushup position to a jump and back to a pushup position again—is so tough that performing about 10 fast-paced reps is just as effective at revving your metabolism as a 30-second all-out sprint, according to a recent study published by the American College of Sports Medicine.
In the study, researchers enlisted ROTC cadets for something called the Wingate Anaerobic Power Test: a 30-second sprint with 4 minutes of rest in between for 4 rounds. Some cadets performed 30 seconds of sprinting on a stationary bike while the others did 30 seconds of burpees as quickly as possible. The result: Both high-intensity exercises resulted in serious metabolic and cardiovascular spikes.
But here’s the difference: "Pedaling on a stationary bike is a relatively simple motor pattern, whereas the burpee involves some degree of agility, balance, coordination, and total body strength” thanks to the exercise’s multiple steps, says lead researcher Nicholas H. Gist, Ph.D., deputy director of the Department of Physical Education at the U.S. Military Academy.
And since the burpee is a total-body exercise, you feel the muscle-building benefits from head to toe, instead of just in your legs and lungs.
If you want make them extremely hard you can make push up or even push up clap when you are down and when you going up try jump with high knees. Try few of them :)