• A punching bag is a bag designed to be repeatedly punched. Punching bags are commonly used by boxers, but they can also be used as a tool to build strength and get a cardiovascular workout. Punching bags can come in different shapes and sizes, although heavy bags--large, cylindrical bags that can weigh 70 pounds or more--are one of the most common types.
  
  

Safety

• Safety is one of the most important aspects of training with a punching bag. Although bags are constructed of flexible materials that cushion impacts, striking a bag with high force can result in injuries. For instance, an unsupported wrist might buckle under the force of a punch, or knuckles may develop abrasions by striking a rough bag. The knuckles should always be covered when punching a bag. Wrist and hand wraps or athletic tape should be applied to the hands to reduce the chances of injury. After applying wraps or tape, you should wear gloves appropriate for the type of bag you are using. For heavy bags, 10-ounce gloves may be adequate if you do not have high punching power, but stronger athletes may wish to wear standard 16-ounce gloves for extra padding.
  
  

Warm Up

• You should warm up your body before using a punching bag at full force. Going straight into power punches may increase the chance of injury. To warm up, run, bike, jump rope or shadowbox for a few minutes. Also, consider stretching out your arms, shoulders and wrists. When you use the bag, start off with several minutes of light punching before hitting the bag with full power.
  
  

Take Breaks

• Punching bags aren't meant to be used for hours on end as a pure cardio workout. The more tired you get when using a bag, the more your form will break down. Bad punching form, such as throwing a punch with a bent wrist, can result in injury, especially if you are punching as hard as you can. Always focus on maintaining proper form and do not sacrifice form for power. Boxers and other combat athletes typically fight in rounds that last two to 10 minutes. Punching bag training should mirror the round system to give the body and muscles a chance to recuperate. For instance, if you wanted to work out for half an hour, you could do eight three-minute rounds with a one minute rest period between each round.