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An Old Okinawan Karate Secret?
The Double Bone Block

By Ron van de Sandt

It was in the late 1970’s when I got my first clue that I was on to something.

I was just a green belt competing in kata in a large Midwestern open tournament. In my kata, however, instead of doing a standard down block, I used a modified version using the flat of my arm (double bone block) that my teacher had taught me. I came in second. Then something interesting happened. When the competition in my ring was over, an older Okinawan teacher, a guest of honor at the tournament, came over and took me aside. He was wearing a red and white belt so he must have been a seventh, eighth or ninth degree black belt.

An old 1920’s photo of the famed karate pioneer Choki Motobu executing a double bone forearm block

This teacher said to me in broken English, “No block like this (demonstrating the same down block as I had done), block like this.” He then demonstrated a standard block using the side of his forearm. Then he added the kicker. “Block like this (again using the outside surface of the forearm to block), should not be shown.”

At the time, I didn’t think too much about this statement. After all, the block I did was just what my own teacher had taught. My teacher had said it was a stronger block, one that had once been taught in Okinawa, but was not seen much anymore.

Fast forward a couple of decades. I became a surprise participant in a demonstration that all too graphically demonstrated the weakness of a standard down block as used in karate. In October of 2002 I attended a Midwestern Renaissance Festival and it had been raining all day. Late in the afternoon as I was crossing a muddy path over a small wooden bridge, my feet slipped. Without thinking I reached out with one hand to the bridge’s rail to catch myself.

Later that day, I sat contemplating my aching, broken forearm. I thought to myself, I wish I could say “that this was the result of trying to defend myself against five big thugs.” But in reality I only slipped in the mud. My left little finger side forearm bone broke about two and one half inches above the wrist as it hit across the rail. And the hit had not been very hard. Well, “Better my arm than my head,” I thought to myself.

Then it occurred to me. The movement I had used to catch myself was very similar to the movement used in a normal karate downward block. At this point my mind flashed back to the Okinawan teacher and his words at the tournament many years before.

If this little impact could break my forearm, how much in danger are the forearms of karate-ka when they perform other basic blocks that make contact with just one or the other of the two bones in the forearm? This danger would be maximized at the very time the block was need most, and especially against strong techniques, like a hard shin roundhouse kick as done by Muai Tai (Thai Boxing) practitioners; or against a downward strike of an attacker using a cue stick, baseball bat or police batten.

A rare photo of Gichin Funakoshi, who many consider the father of Japanese karate, demonstrating an open hand two bone forearm block against a downward staff (bo) strike.

I then began thinking about the modified, double bone, block taught by my teacher and several other Okinawan karate styles, as well as the mechanics behind it. This was what the Okinawan teacher had said many years ago: “Block like this should not be shown.” I asked myself, “Are these modified blocks a secret of old Okinawan karate, something that in some styles is only shown to senior students?”

So, what are double bone blocks, what are their advantages, and how are they applied?

A double bone block is any basic block that is modified by the wrist/forearm position so both bones in the forearm make contact in a block rather than just a single bone on the edge of the forearm. As normally preformed, upper, downward and inside blocks twist the wrist and forearm so only the outer, little finger side of the forearm bone makes contact. The inside block does the same with the inside bone of the forearm. This same two bone forearm principle can even be applied to two hand circular blocks as often used in Goju Ryu and Uechi-ryu karate.

Some Basic Anatomy

The two bones of the forearm

The middle and upper forearm are cushioned with a layer of muscles.

This section view of the forearm shows the thickness of muscle padding in the upper forearm.

Double bone forearm blocks have some very distinct advantages over their single bone cousins. To understand these advantages one must first look at the anatomy of the forearm, and then the anatomy of a block.

If you hold your hand in a vertical fist position (with the outer edge of the palm down, thumb up), you can feel for yourself the two bones that run the length of the forearm. The upper, thumb side bone is the radius and the little finger side bone is the ulna. In this position (thumb up, little finger down) the bones are positioned parallel to each other. In other positions, however, such as the typical rotated fist karate punch, as a result of the twisted forearm position the two bones actually cross.

On and near the wrist these bones have little muscle padding. But as you proceed up the forearm, the muscles (including the extendor digitorum communis and extendor carpa ulnaris) thicken and serve to protect the underlying bones. In contrast, the sides of the forearm have very little muscle padding, with the ulna (opposite side from the thumb) having the least amount.


In karate, this bone is very susceptible to an impact break. I have seen it often in practice fighting. A student tries to block a front kick, but instead of sweeping the kick to the side with a downward block, the unfortunate student just lowers his or her forearm horizontally to block the vertical kick and “snap.” Shins are a lot bigger and stronger than an ulna bone.

I have also seen students break their forearms when trying to do basic blocks against weapons. Here is an X-ray of a student who tried to use a standard middle outside block against a staff (bo). You will notice that the forearm bone just above the thumb suffered a clean break.

A double bone block is much stronger. Any impact is spread across two bones. Thus, structural strength is doubled. Impact is further dissipated by the muscle padding.


But that’s not all. Looking at the illustration, notice that on both sides, next to the two forearm bones there are nerves -- the lateral and medial antibrachial cutaneous. If struck, these nerves can cause a lot of pain. Of course, in some traditional styles of Okinawan karate, practitioners have spent years doing toughening and deadening exercises. For these students the pain of impact to this area will be less intense.

On either side of the forearm, you will also find two major arteries (radial and ulner) and branches of another (brachial). Of the two branches, the ulnar artery is the largest, itself having four branches in the forearm. Both arteries are close to the surface of the arm, near the wrist, and lying next to the bones. Likewise, major veins run through the forearm and wrist.

If either of the two bones in the forearm is broken there is danger of collateral damage. The sharp or jagged edge of the broken bone can easily tear into, penetrate or sever nearby arteries, veins or nerves.


Demonstrating The Double Bone And Single Bone Blocks

Now look at the differences between the two blocks (standard and double bone), first using a low block as an example. In the single bone block (the version almost universally taught), the blocking surface is either the fatty part of the fist on the pinky side of the hand, or more often the outside of the forearm near the wrist. If it is the outside of the forearm, the impact hits the ulna bone, while also impacting the nerve and artery that lie close to the surface.

By simply turning the hand so the thumb is up (the same structural position as a vertical fist), the block changes. Any impact is absorbed across both bones (double bone block) and is cushioned by the muscle on the outside of the forearm. Nerves and arteries are thus less likely to be damaged.

A word of caution, however. If you are trying to block a front kick this way, be careful. If you make contact with the top of the hand rather than the outward surface the forearm, you could be easily hurt. There are many bones in the back of the hand that can easily break, such as the carpus and metacarpus bones. If the top of your hand connects with the ankle or shin of a kicking (rising) foot, you could be in a world of hurt.

A close up of an inside block (some styles of karate call this an outside block) which has been modified so that the block makes contact with the top of the forearm buttressed internally by its two bones and padded by overlaying muscle. Compare the arm position here with the photo at right.

A standard inside block that makes contact only with the outside bone of the forearm.

The same concept of double bone contact also applies to the middle inside (seen above) and outside blocks as well as the upper block. The way middle blocks are usually taught is that the forearm twists as it moves, ending up with the palm of the hand facing toward you and only one bone (radius or ulna) making contact against a target. These blocks can become double bone blocks with only a simple change in forearm position. In either case if the thumb side of the hand is up at the moment of contact, both bones padded by overlying muscle will make contact rather than only one bone without padding.

In the normal upper block the wrist is turned so the little finger forearm bone makes contact (photo at left above). If instead the wrist is turned so the thumb is up, the forearm is again positioned (both bones parallel) so any impact will be absorbed across both bones, and padded by muscles if the blow is absorbed on the middle or upward forearm (right photo above).

Double Bone Blocks Are Also Stronger

Anatomically, the double bone block also provides more strength and leverage to the block. Try this as an experiment. Slowly using a standard outward block with your right hand (with the palm facing you, thumb to the outside), have someone resist its action (from the right) at the wrist. Now try turning the fist slightly until the palm is facing left (thumb upward). Again, have someone resist its action at the wrist. Which is stronger? Then do a right upper block, turning your palm facing front, have someone pull down on the arm at the wrist. Now turn the palm to face toward the ground, and lower the elbow so the forearm is at about a 45 degree angle. Again, have someone pull down at the wrist. Which is stronger?

If you’re not familiar with double bone blocks, experiment using the double bone block versions for upper blocks, lower, middle and outward blocks, and see what happens. But be careful, and do so under the watchful eyes of a qualified instructor.

Does this mean that we should always do nothing but double bone blocks? The answer is, of course, no. Each block can be valuable, and have its own purpose, advantages, and disadvantages. For example, as noted above, if you attempt a lower double bone block against a front snap kick, you stand a chance of catching the opponent’s ankle bone with the top of your hand. Equally, you would not want to attempt a double bone inside block against a trusting knife attack because this would expose the arteries and ligaments of the inside of the wrist and lower arm to injury. In other situations a blocking hand, wrist or forearm only lightly guides or slides past an attack to move it or hold it away from its target. Here speed and agility rather than structural strength is needed. In other situations the single edge of a forearm can be used to strike into a soft nerve area of pressure point area.

On the other hand, double bone blocks offer extra structural strength. This is often needed to protect your forearm and yourself when blocking, or absorbing powerful kicks, strikes or other blows, such as in a weapon attack – especially against anything with a hard surface.

With practice you should be able to tell which block is most appropriate for you against any given technique and in what circumstance.

Here you may be asking yourself: “If I have not been shown this type of block by my teacher or if I haven’t practiced it in my style of karate, has my training been incomplete?” The answer is that you have all the training and tools, but may just not be aware of how to use what you have been taught. You may have been doing these blocks all the time but didn’t realize what you were doing was a hidden variation of the two bone forearm block whose secret was timing.

Take the standard upper or rising block. The blocking arm usually moves as follows: the blocking arm starts with the palm side of the forearm facing the body, and then as the block rises, the forearm rotates with the wrist upward and the radius (little finger side) bone makes contact.

Just a little change in timing can turn this same block into a double bone block. Simply by not fully rotating your forearm before contact the upper side of the forearm and thus both bones and muscle padding will absorb the initial impact. Without stopping, however, you continue to rotate the wrist outward to a position where the little finger side of the wrist is upward. This movement in effect redirects an attack upward and past the forearm.

This means that using the same movement you already know, you can perform either a single bone or double bone block. The only difference is the timing you use in the execution of the technique.

In similar fashion other basic karate blocks (inside, outside and downward) can be modified in execution so they make contact as double bone blocks, but then continue to rotate to redirect the attack.

To the casual observer a two bone blocks performed this way would look virtually the same as a standard single bone block. Seen this way, an old Okinawan secret is contained within each block most karate-ka perform.

And, from experience I can tell you, the next time you find yourself slipping in mud and having to block a fence rail, I would recommend that you remember to use the mighty double bone block as your block of choice. Otherwise you might find yourself writing an article such as this.


I would like to thank Christopher Caile, of, for his editing, many suggestions and his contribution of historic karate photos used in this article.

I would also like to thank my students, Penny Burnett (in Gi) and Mark Wiley, who helped illustrate the blocking techniques.The anatomical illustrations used in this article were reproduced from Henry Grays Anatomy of the human body:

Thanks also to P.B., the student who contributed the X-ray of his forearm break.

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About the Author:

Ron van de Sandt has been in the martial arts since 1972 and has studied American Kempo, Shorin Kempo and Sholin Karate - a blend of Shorinji Ryu and Shorin Ryu Karate. Mr. van de Sandt currently holds a Dan rank in Sholin Karate, and runs the Sholin Karate Club, at the Fairborn YMCA, Fairborn, Ohio. He is a frequent contributor to

To find more articles of interest, search on one of these keywords:

Karate, karate-do, chudan uchi-uke, chudan soto uke, uchi uke, soto uke, jodan uke, inside block, outside block, upper block, karate blocks, blocking in karate, ulna bone, radius bone, bone breaks, karate injuries

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