Techniques>Blocks>Single versus double bone blocks

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Single versus double bone blocks


Traditionally, taekwondo and some other hard martial art styles usually use single bone forearm blocks where the inside or outside edges of the forearm make initial contact, such the inner forearm block and the outer forearm block. Single bone blocks are also viewed as being strikes that can do damage to the attacker as well as block. If you block correctly, the pain it causes the attacker may cause him or her to reconsider any making any more attacks. Some martial arts, such as isshin-ryu karate, usually use double bone blocks where the top or bottom sides of the forearm make initial contact. Martial arts that use double bone blocks use arm conditioning training to make their forearms muscles seem as hard as bones.

Single bone block

With the inner forearm block, the inner forearm (the bottom) faces upward so, if the block moves outward, the striking surface is the radius bone that extends down the thumb side of the forearm. If the block moves inward, the striking surface is the ulna bone that extends down the little finger side of the forearm. With the outer forearm block, the outer forearm (the top) faces upward. If the block moves outward, the striking surface is the ulna; if moving inward the striking surface is the radius.

At and near the wrist, these bones have very little muscle or fat padding them. However, as you move upward along the top or bottom of the forearm, the muscles (including the extendor digitorum communis and the extendor carpa ulnaris) and fat layers thicken and serve to protect the underlying bones. However, the sides of the forearm have very little muscle or fat padding covering the bones, with the ulna having the least.

When single bone blocks, only one of the forearm bones contacts the attacking weapon, and the bone will have little padding. The reasoning is that the bone acts as an edge that will cut into the attacking limb, causing the attacker pain and/or injury. However, sometimes the pain and injury can to the blocker’s arm. On both sides of the forearm, next to the two forearm bones, are nerves: the lateral and medial antebrachial cutaneous. If struck during a block, these nerves can cause extreme pain. Through training, the forearms can be gradually toughened so the pain of impact is lessened.

On either side of the forearm are two major arteries (the radial and ulnar) and branches of another (brachial). The largest artery is the ulnar and it has four branches. These arteries are relatively close to the surface of the arm near the wrist, and they lay next to the bones. Likewise, major veins run through the forearm and wrist. If either of the two bones in the forearm is broken, a sharp or jagged edge of a broken bone may easily tear, penetrate, or sever a nearby artery, vein, or nerve.

Double bone block

In a double bone block. the forearm is turned so the striking surface is either the inner (bottom) or outer (top) forearm. With this type of block, both forearm bones make initial contact. A double bone block is less likely to cause the blocker any injury since the impact is spread across two bones. With two bones blocking, the structural strength is essentially doubled. The impact is further dissipated by the extra muscle and fat that pad the bones.

Anatomically, the double bone block provides more strength and leverage to the block. To demonstrate this on yourself, hold your forearm in a middle inner forearm block (palm upward) and have a friend try to pull or push your arm horizontally. Then try the same thing with the palm facing inward. Which is stronger?

Which should you use?

So, should we change our taekwondo single bone blocks to double bone blocks? The answer is no. Both the single and double bone blocks have their own purposes, advantages, and disadvantages, and each has its place in taekwondo. For example, with single bone blocks, if the hand strikes the attacking object accidently, the contact area will be the padded sides of the fist, so the chance of injury will be slight. With a double bone block, the contact area will be either the fragile bones on the knuckle side of the fist or all the fingers on the other side of the fist and injuries to the hand can incapacitate it. Also, double bone blocks expose the arteries, nerves, and ligaments of the inside of the wrist and lower arm to injury, which can incapacitate the arm. On the other hand, double bone blocks offer extra structural strength and padding when blocking powerful kicks or hard surface weapons. The single edge of a forearm is useful in striking soft nerve areas or pressure points.


Do you have the time or desire to harden your muscles to the degree necessary to use double bone blocks effectively and consistently? I think not; I use my arms for delicate work, not to mention using them when typing all day on the computer. Also, why punish yourself to train for a self-defense situation that for most people will never occur during their lifetimes. It is much wiser to use the single bone to block and use the time saved from not doing all the extra training to work on perfecting other techniques. Single bone blocks should continue to be the primary blocks used in taekwondo. However, when blocking powerful kicks or hard surface objects, remember the advantages of a double bone block.

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