To get the most benefit from the heavy bag you must be alive yourself, use your imagination, circle it, move in, move out, move from side to side (moving should not be a pre-conceived plan), practice bobbing, weaving, feinting, slip punches. You have to spar with the bag as if you are fighting an imaginary opponent. Always remember to keep your guard up and do not forget about footwork.
Most beginners just stand there and punch it out trying to destroy it rather than learn from it. In doing so they disregard their own protection, they do not protect areas of their own body and develop bad habits by being careless (as the bag is not alive, so it does not hit
The main purpose of the heavy bag is to develop power in your punches and kicks. It strengthens your hands, wrists, arms, legs and feet. Power in punching comes from the realization that your arms are merely an extension of your body you are really trying to hit with the body. Use your whole body.
While working for power one must not forget about form. This means using the correct body mechanics or body leverage for a particular blow or kick. Your strikes should be sharp, smart, explosive and snappy. In other words, do not push the punch or kick. Mix your hard strikes with soft strikes and retain your balance at all things.
The heavy bag offers a means to know yourself, a means to get a body feel into your punches and kicks.
Wear bag gloves or tape your hands and wrists to prevent injuries while working on the heavy bag.
Practice sessions should contain three rounds at two to three minutes per round.
Any less than three rounds will not do much good.