Headknocker is a workout that uses a variety of exercises and some combat moves to turn the body into an instrument that recruits different muscle groups to perform each exercise. The result is a total body workout that works quite large muscle groups pushing both aerobic endurance and cardiovascular fitness. Add EC and you also have a powerful core challenger that completes the benefits you get from this workout.
Extra Credit: Keep the plank throughout moves #4, #5 & #6.