The movements used when kicking and striking a heavy bag help develop "gross motor skills," which are simple, large muscle actions that form the base for any technique. Impact training helps develop a "hit attitude" where a person is willing to hit and be hit. The impacts help you gauge the power of specific techniques. The impact reaction forces help increase bone density, toughen the joints, and strengthen the muscular structure of the body.
"Blitz" training on a bag is an intense, rapid-fire barrage of strikes and kicks. It helps develop physical and mental stamina and the tenacity needed to fight for your life. This type of training cannot be accomplished by any other means. Blitz training also helps simulate the burst of energy required with sparring or fighting. Sparring is not a continuous output of energy; it is a series of bursts of energy.
Our brains and bodies have evolved to ensure our survival. At the first detection of danger, the "fight or flight" response prepares our bodies to either stay and fight or run away. There are no more man-eating saber tooth tigers to worry about, but the stresses of modern life tend to trigger the same responses. When this extra energy is not released, it may lead to medical problems. Furious bag work helps release the energy and satisfies our inherent need to fight. Bag training is not all work. With some pounding music and a macho attitude, you will have fun and feel refreshed after a strenuous workout. Instead of feeling exhausted, such as after a hard run, you feel uplifted and ready to take on the world.