Boxing coach Bill Packer notes that just about anybody can punch a boxing bag around. However, knowing how to hit the bag right is a rare skill. Proper use of a punching bag can build strength, endurance, power and technique. Punching it wrong is, at best, a waste of time. At worst, it can skin your knuckles, sprain your wrist or even break your hand.
Put on your gloves. Use regular boxing gloves, thin bag gloves or even heavy work gloves.
Stand close enough to the bag so you can hit it if you rotate your hips behind the punch, but far enough away that you can't reach without rotating your hips.
Dig into the ground with the big toe of the foot on the same side of the body as your punching arm to start your punch. Let the force from your toe rise up through your leg, then turn your hips and shoulders.
Drive the punch with your torso, rather than reaching out with your fist.
Strike the bag with the large knuckles of your index and middle fingers. Hitting with the smaller knuckles can cause a painful break.
Drive your other hand forward as you withdraw your first punch.
Perform a cycle of four to eight solid strikes. Rest and evaluate how the punches felt. If the bag popped when you hit instead of just swinging, you did it right. If your elbow, wrist or shoulder hurts, you did it wrong. Adjust the angle of your punches until they feel right.