The monks of the Shaolin Temple developed several kung fu styles over the centuries, some of which were based in northern China and some in southern China. Northern Shaolin kung fu systems did not normally emphasize forearm hardening exercises, but some southern Shaolin arts did. This skill was known as "iron arm."
Steel Jacket Skills
Southern Shaolin kung fu systems often used special exercises to make certain parts of the body impervious to strikes. It was commonly believed that this "steel jacket" or "iron shirt" kung fu skill could give the practitioner almost superhuman skills, including the ability to resist spears, swords and even bullets. In reality, no training can give you the skill to resist a serious cut from a sword or a bullet from a gun, but superstitious beliefs about steel jacket training still linger. When steel jacket training is focused on the arms, it is known as "iron arm" kung fu.
Iron Arm Training
Shaolin iron arm kung fu training can be conducted in various ways such as by striking poles or sand bags. Another method is to strike the arms repeatedly on a daily basis, beginning with chopsticks and moving up to bars of metal over time. At first the arms are struck lightly, but more force is used until the arms become so hard that they can endure heavy strikes from the bars. These exercises are always conduced in conjunction with special meditation practices. The idea of iron arm training is to make your forearms so hard and powerful that if you block the opponent's attack the block alone will be enough to injure him.
Arm Ring Enhancement
The southern Shaolin art of hung gar kung fu makes use of brass or steel arm rings for forearm training. These can weigh anywhere from 1 pound to 1-1/2 pounds, and the practitioner can wear any number of rings depending on strength and experience level. The arm rings are worn while performing the training sets of Shaolin hung gar, and they condition the forearms to receive impacts as well as improving the strength and endurance of the person using them.
Evaluating Myth and Fact
If you are considering the practice of iron arm, remember that just because a certain exercise is ancient or associated with a credible source such as the Shaolin monks, it does not mean that it is healthful or even effective. Some of the traditional Shaolin skill-training has been associated with dangerous superstitions, such as the idea that the "steel jacket" skill can make you invulnerable to weapons. Always use common sense when evaluating whether a practice is right for you. If you decide to give iron arm a try, seek out competent instruction from an experienced practitioner who can help you do it safely.