Functional Applications From Naihanchi Nidan

Here is a video exploring a sequence of 5 movements from Naihanchi Nidan. This portion of the kata illustrates how to address resistance encountered while trying to apply tuidi (joint techniques). Instead of trying to muscle the techniques, the kata shows how to reverse direction and co-opt the attacker's force while transitioning into a new technique. In other words it shows how to "go with the flow".

Nagamine shinshii's Naihanchi Nidan is very similar to the version in the video below 

I think the slapping wrist lock may be new to some people. The slap lock is actually fairly easy once you learn it but there are a few key points to keep in mind.

I used some clip art to try illustrate these key points below.

The force of the slap is focused (with a heavy feeling) on the opponent's fore-knuckles on initial impact and your finger are allowed to curl over the hand. The palm heel of your right hand and thumb of your left hand press against the back of the opponents hand. As your left hand rotates to apply this thumb pressure it also causes the pink side of your left hand's grip to press against the inside of the opponent's wrist. The opponent's fingers must not be allowed to uncurl. The combination of these causes the wrist to buckle and fold in on itself. Be very careful, the fact that the fingers are forced to remain in a fist (ie hand isn't allowed to open) causes the strain on the connective tissues in the wrist to be greatly increased (as is the pain and potential for injury).

Oyata Seiyu shinshii (circa 1980)

As I have mentioned here before, I believe Oyata Seiyu shinshii was instrumental in the preservation of many nigh forgotten aspects of the Suidi (Shuri-te) family of Okinawan martial arts. Far more importantly, he triggered an awareness of the deeper combative value of Okinawan martial arts kata (Tichiki / old-style Okinawan bunkai) beginning in the early 1980s.

This awareness rippled throughout the karate community and Oyata shinshii can be credited to a large degree with triggering what has been called the "bunkai revolution" of the 1990s.

I personally believe the awareness of practical bunkai that Oyata shinshii initiated was of similar importance to the work being done in promoting functional Okinawan bunkai by Taira Masaji shinshii over the last several years. [Obviously Taira shinshii has been doing this much longer than a few years, I am speaking more about the way he is currently engaging a much larger segment of the karate world]. (see Taira shinshii's videos)

I also personally believe that the martial arts of these two Okinawan masters (one of Suidi lineage; the other of Nafadi lineage) have far more commonality than is generally realized. I suspect this will gradually become clearer to the karate community as time passes.

The following video is apparently from circa 1980 which would make it quite early in Oyata shinshii's "spreading of the bunkai gospel".

The sound quality is poor, and it is often difficult to see exactly what is going on, but this is made up for by the quality of the content. In my opinion this should be regarded as a valuable historical resource and should be treasured by those intelligent enough to add it to their library.

I sincerely hope you find it useful.

Makiwara Misconceptions

"There are no karate men who do not use the Makiwara."
 - Nagamine Shoshin shinshii

This is the second article in my series on training with the Makiwara (Machiwara in Uchinaaguchi). The previous article provided a look at my indoor makiwara design to give folks some ideas about building their own. In this article I want to address what I see as the four most widespread  misconceptions which exist about Makiwara training. This hopefully will allow us to move forward into the instructional articles with a minimum of inaccurate baggage...

Misconception #1:  Makiwara is mainly about hand conditioning.

Okinawan martial artists have a gazillion conditioning methods (most of which they inherited from the Chinese) so they hardly needed to invent a new one. Moreover, I am not convinced a makiwara is ideal for that function anyway. Conditioning is a side benefit but not the -main- purpose. The two things that set a makiwara aside from all other punching-posts and punching-bags are:

a) Progressive resistance

and

 b) The forceful "spring back" (the makiwara returning to its original position)

Progressive resistances means the harder you hit or push the device, the more resistance the makiwara offers. This makes it ideal power development. Heavy-bags, Chinese style punching posts, and wooden-man dummies (devices which Okinawans also used, which are usually called sunabukuro, ude-makiwara, and kakete-biki) simply do not offer any progressive resistance and are therefore inferior for developing power.

The "spring back" forcefully pushes your arm back a spit second after impact. This makes it ideal for solo training of "immovable body" skills. In so-called “internal arts” like Tai-chi and Aikido they spend much time and effort practicing remaining immovable while a partner forcefully pushes on their arm (actually this skill is part of Okinawan shime/kitae training too, but that is another topic). A makiwara allows you to practice this same “immovable body” skill but without the need for a partner. You just do a progressive "body audit" by mindfully paying attention to joint after joint, feeling for any "give" or movement. You do this "body audit" from the hand all the way through the body to the feet. Eventually you can hit the makiwara with a hard shot that bends it well back, but results in zero discernible push-back (the makiwara remains bent and no motion can be seen in the body until the practitioner -chooses- to release it). So while the makiwara does condition the hands, conditioning was never its *main* function.

If the device does not offer progressive resistance and a forceful “spring back” (which can be used for kinesthetic feedback) then that device is NOT a makiwara.  This leads me to the next misconception…

Misconception #2: The devices which cause arthritis or joint damage are types of makiwara.

In truth, the devices which are most commonly associated with joint damage which are *called* makiwara are NOT in fact actually makiwara at all (I think the most common example would be punching a 4x4 post).

An iron-shot filled wall-bag is not a makiwara. A wall mounted pad/target is not a makiwara. A clapper style wall device is not a makiwara. A post in the ground is not a makiwara. A thick inflexible board is not a makiwara. If it doesn’t bend backwards several inches when struck and then immediately spring back to its original position (if not impeded) then it is SOME OTHER type of punching device and is not a makiwara. Because genuine makiwara DO bend when hit, they are very unlikely to ever cause joint damage (when struck by a normal healthy individual).

This is not to say you can’t injure yourself on a makiwara. You most certainly can…  but you won’t wind up with badly damaged hand joints. Wrist injuries are  another issue but they are avoided with good form. I’m not saying all of the other devices will damage the joints (or cause arthritis) if they are -used correctly- .

I am just saying that the makiwara gets blamed for injuries that were actually caused by completely different punching tools which are only erroneously CALLED makiwara.

Misconception #3: Hand conditioning is about calluses.

As already mentioned, conditioning is only a secondary goal to power-development and developing a rooted structure. Although it is secondary, it -is- still a goal. However, conditioning has little to do with calluses.  Body conditioning is about strengthening bones (via bone remodeling) as well as strengthening dense regular connective tissues containing closely packed bundles of collagen fibers.  These connective tissues include fasciae, aponeuroses, ligaments, and tendons. All of these tissues remodel according to imposed demands and bulk mechanical properties like modulus, failure strain, and ultimate tensile strength can be significantly increased over time with consistent training.

Creating callus does little to strengthen anything of any importance. Callus is a bit harder to rip so it can prevent some skin tearing. However, callus is generally less flexible which can actually make tearing more likely in the case of rotational force (violent twisting while in contact) so it is a bit of a mixed bag… Hitting a makiwara without callus feels like the skin is getting pinched between two hard objects (because it is). This pinch is annoying but far from debilitating. In my mind discomfort (to a degree) is good because it develops mental toughness. However I’ll admit I was glad when the pinch stopped being felt. You don’t need to have a lot of callus for the pinch to be dulled or eliminated. 1/5 of an inch is probably plenty. Lemus shinshi has mentioned that many Okinawan teachers do not want to advertise their martial experience, and choose to remove the accumulation of callus as it develops. This is probably a good idea IMHO. If somebody knows you are dangerous they are likely to attack you with a tire-iron to the back of the head rather than punch you in the jaw!  The subject of callus removal segues nicely into the next misconception…

As you can see, the hand is largely normal looking after callus removal

Misconception #4: Makiwara hand care is mostly about hit-medicines.

Hit-medicine is only one of several things you should have available to care for your hands. An emery board will remove the callus efficiently with no pain and leave your hands mainly normal looking. It also will remove (mostly anyhow) what I call “perma-scab”. If you look at a serious makiwara person’s hands you will often notice a small scab-like sore in the middle of at least one knuckle. These take months or even years to go away. However, an emery board will remove this perma-scab and the surrounding callus pretty effectively. Once removed, you should apply “new-skin” to the area to prevent the perma-scab from re-forming. “New-skin” is my second essential tool in the makiwara hand care kit. When you get the inevitable skin tear, just remove the skin that was detached with a nail-clipper (it NEVER will reattach in my experience so get rid of it right away) and apply pressure with a paper y towel until the bleeding stops. After that dab the area every few minutes (you want to remove the liquid which accumulates and will turn into a scab) until the area remains dry. Then apply the new-skin in a thin layer to the whole area (including a little past the tear itself) and blow on it to speed drying. Add a second (and possibly a third) coat the next morning. At that point you are GOOD TO GO. No need to miss any makiwara training!! It belongs in every makiwara kit.  Next, I recommend using a good hand lotion once in a while to prevent the skin from drying and cracking. This is especially true if you live somewhere with really cold winters.

Regarding hit-medicines, I believe much of the value of applying them comes simply from the act of thoroughly massaging the hands and knuckles before and after training. Just the massage (without any medicine) will speed recovery time a great deal. In terms of the medicinal value of hit-medicines, their main significance seems to be their remarkable anti-inflammatory properties. The reduced swelling, reduced bruising, and faster healing are all (IMHO) directly the result of the anti-inflammatory effect.

I use the "Golden Lotus" 34 herb formula as my hit-medicine of choice. I was quite impressed with the reduction in swelling which took place very quickly and also the increased speed in bruise healing (which was less dramatic but still impressive). The same formula is also available from Shen and several other suppliers but this supplier was recommended to me by Rod Morgan.  

http://www.coilingdragon.com/index.php?main_page=product_info&cPath=52&products_id=388

Another Great Loss: Toma Shian shinshi

I was deeply saddened to learn of the passing of Toma Shian shinshi on May 30 2013.

The last several years have taken a sad toll on the karate community, especially with respect to "old style" karate. Many of the masters who made it their mission to preserve nigh forgotten aspects of the art have passed away. Thankfully they were largely successful and left a legacy of competent practitioners to carry the torch forward.

Toma Shian shinshi was perhaps best known as one of the first Okinawan teachers to teach the Okinawan art of tuidi in real depth to Westerners. Tuidi, also spelled "tuite", but usually spelled "toide" in Seidokan, is the ancient Okinawan joint locking art. It probably traces back to 12th century Okinawa. Here is a playlist I created to highlight Toma Shian shinshi's interesting approach to this art.

Seidokan Toide (Tuidi) Playlist

From The Bubishi Karate Do Organization Newsletter edited by Katherine Loukopoulos

Toma Shian Sensei of Seidokan Karate Do passed away on May 30th, 2013

“Toma Shian sensei, Kancho of Zen Okinawa Seidokan passed away on May 30th, 2013. Born in 1929, Toma Sensei was an expert in Shorin Ryu, Okinawa Kenpo and Motobu Ryu, Toma Sensei was a charismatic teacher and mentor to students throughout the world. He will begreatly missed.”

Photo Courtesy and Text: Cezar Borkoski

“Dear Seidokan Members,
First, I would like to take this time to thank everyone who took the time to pay their respects to Sensei Toma “Head Master of Seidokan Karate.”

As I read through the comments it made me realize that it made no difference if you met Sensei only once or if you met him many times. For most, it was a surreal moment that people would never forget. It makes me so proud that Sensei Toma gave so much to the people he loved the most.

His guidance over the decades has helped everyone accomplish his or her dreams at one time or another. Each student requires different needs at different times. Sensei Toma knew that when many of us didn’t. In many cases the answers he provided wasn’t the same for all, which sometimes confused even the best students.

When I look back at the Gate 2 / Awase dojos… it all makes sense in how he taught his children. It was much like the same as we teach our own…. be flexible…. and knowing one size doesn’t fit all.

Again, I’m so glad Sensei Toma gave his children power, speed, skills but more
important “memories” to last a lifetime and beyond. ”

Contribution Story and Photo Courtesy: Ron Nix Sensei

“I first met Toma, Sensei, during the 1960s on Okinawa aboard Kadena Air Force Base where regular karate events were held. I also visited his Gate 2 Street dojo just outside Kadena AFB. He ran a very tough dojo and was a good friend of Shimabukuro, O Sensei. He was always a friendly gentleman and a superb karate master who became the head of Seidokan.”
William R. Hayes, Major, United States Marine Carps (Retired)

Hojo Undo and Martial Makers

Hojo Undo methods are a category of "supplementary exercises" (involving specialized equipment) that are utilized in Okinawan martial arts. Most of these methods fall into one of two categories: 1) weight resistance tools for "functional strength" training and 2) tools which involve various types of impact conditioning. Most of these methods had a long history in China before they were imported to Okinawa.

There is so much discussion of Hojo Undo in various groups that I felt there was enough interest in the topic to warrant creating an independent group dedicated to it. IMHO the popularity of "functional strength training", shows how Hojo Undo is actually "coming into its own". Most of the weight resistance tools used in Hojo Undo have modern/Western equivalents: Chi-ishi = Clubbell, Big Chi-ishi = Macebell, Tetsuarei = Dumbell, Ishi-sashi = Kettlebell, Tan = Barbell, and so on...

Somebody should quickly patent the "Jarbell" (and thus corner the Nigiri-game market) and introduce the newest exercise fad to the world ;-)

Anyway, everyone is invited to join:

The Hojo Undo Facebook Group

There is another webpage that is quite closely related that I wish to bring to people attention. It is called Martial Makers and this is how the site describes itself:

"Martial Makers, a website devoted to do-it-yourself martial arts training equipment.

This site will feature links to great examples of DIY projects from around the internet as well as original how-to guides for making your own high quality martial arts training gear at a fraction of the cost of purchasing similar equipment, and using materials that are easily available.

Curious about how to make your very own traditional training implements? Want to create a custom, home-made version of an expensive modern training apparatus? Love duct tape? Then you’ve come to the right place!"

Here is the link:
The "Martial Makers" Webpage

So now that you've visited these pages and have built some equipment the question is "how do I use it?" Here is a YouTube playlist that will show you the basics (and even a bit that is not so basic):

Quality Hojo Undo Videos

I hope that you find these resources useful in your journey.

Moveable Indoor Makiwara: Dimensions & Design

"There are no karate men who do not use the Makiwara."
 - Nagamine Shoshin shinshii

This is the first of a series of posts on Machiwara training. I thought it best to start out by offering a look at a couple of simple designs for moveable indoor machiwara which can be constructed with a minimal amount of skill required. Building these two machiwara cost less than $100 total and they have held up to many months of daily abuse so far (with only minimal maintenance).

 

Heavy Duty Moveable Indoor Tachi-Machiwara

The vertical "shaft" of the machiwara is constructed of 3 separate pieces or Red Oak (1" thick, 1/2" thick, and 1" thick again). The three boards are all 4" wide and are fastened together with a high strength bonding agent called "Gorilla Glue" as well as a few wood screws for extra strength.

This is designed for a person 75 inches tall. Adjust proportionally to your height.

Click to enlarge

The below picture just shows the same machiwara with the pad at 3 heights. People sometimes ask me why I built such a tall machiwara... These days people are mainly only familiar with the Nafa-Machiwara (Naha-Makiwara, named for the town it was popular in) which is solar-plexus height. However there were also taller machiwara such as the mid-to-high sternum level Sui-Machiwara (Shuri-Makiwara) and a machiwara as high as the bottom of the chin (utagee). Using a tall machiwara allows me to practice at any of the three heights merely by adjusting the pad. The Nafa-Machiwara is the best to begin on as it discourages raising the shoulder (which I believe is why it became the most popular). It is quite easy to punch downward (with the direction of gravity as in the Nafa-Machiwara) without raising the shoulder. This builds sound neuron-muscular habits. It is more difficult to punch straight out (roughly mid-shoulder height) without raising the shoulder (as in the Sui-Machiwara). It is fairly difficult (without sufficient training) to punch upwards without raising the shoulder (as in the Utagee-Machiwara). I think this progression in difficulty explains why the various versions are more or less common... The most basic being the most common. I would suggest that the reason for the varying popularity of the different heights/designs of machiwara is the same reason that solar plexus (up to mid-sternum) level punches became the norm in karate... The more difficult methods being practiced (and thus passed-on) by fewer people than the less difficult / less advanced methods. While I believe a certain amount of weight must be given to the hypothesis that head level punches are quite rare in kata because head punches are more likely to result in injuring the hand... I would also stipulate that a martial artist that engages in frequent machiwara training and also engages in Okinawan hand conditioning (tetsusa-te / tetsu-te) would be unlikely to injure himself/herself when punching to the head...

Light & Flexible Moveable Indoor Tachi-Machiwara 

The light tachi-machiwara below is made of a single piece of 1" X 4" Red Oak. Being more flexible than a machiwara which is thicker at the base it is used for training with Keikoken, Nakadakaken, Boshiken, and similar strikes which utilize small surface areas. Like the heavy duty machiwara it still provides progressive resistance (meaning the more force that is applied the greater the resistance).

Click to enlarge

Ryukyu Martial Arts: Compilation Videos

Here are a few compilation videos highlighting the Ryukyu martial arts. Many of the masters in these videos were in their 70s or 80s when this footage was recorded. I hope you find them inspirational and that they help you to see the practice of Ryukyu martial arts as an endeavor that lasts a lifetime (hopefully a very long lifetime).
 


 

 
 


Here is one more video. It is an advertisement for a 2 part set of DVDs available at Amazon.com. These DVDs are well worth owning IMHO. The are many useful and interesting tidbits on these including Senaha shinshi's discussion of Okinawan kiko / kokyu-ho.

"3 Major Schools of Okinawa Karate" Part 1 and Part2

Small Surface Strikes & Structural Support

General Information On Small Surface Strikes
knowledge often lacking in modern karate-do but commonplace in "old style" karate

Small surface area strikes were very common in “old style” karate. In modern karate-do, the existence of these strikes is generally remembered, but they are rarely practiced. Even when they are practiced, the structural strength of the hand formation is almost never tested through hard impact against suitable surfaces. This has resulted in a degradation of information about these techniques. With generation after generation rarely practicing these techniques and never testing their strength, some of the important keys to hitting with these strikes were largely forgotten or at least not emphasized.

Pick up any “comprehensive” text on modern karate-do and you will see most of these techniques in pictures. If you look closely at the pictures you can tell that the person in the photographs has never hit anything with them with any real force, and that if he attempts to do so, the structure would most likely collapse due to joint buckling. However, with a little guidance it is easy to learn how to form these weapons in a way that will not collapse (at least not until *much* higher levels of force are applied). 

So, here are few tips from “old style” karate on how to brace the joints which are likely to buckle and how to create structural support which is aligned with thedirection the force travels. These tips are all pretty simple affairs but in most cases will at least double or triple the amount of force which can be successfully applied. In some case it is even higher.

I apologize for the fact that the wrist angle is wrong is many of these photographs. I was taking pictures of my own hand which was usually placed against a wall right in front of me. This resulted in awkward wrist angles but since this article is about hand formations this defect doesn't impact the value of the photographs.

I should clarify that my use of the word "useless" doesn't mean there will be zero effect. Generally you can get some effect from those hand-forms. However, the hand form itself offers little support to the structure of the striking weapon and it is likely to buckle in some way when significant force is applied. At minimum it will not be nearly as effective and useful as the methods I call "effective" and "optimal".

Ipponken (Keikoken, Shoken etc)

 

Notice how the above fist form has nothing *behind* the  index finger. It is impossible to do foreknuckle push-ups on this structure. It makes a very poor striking weapon because it obviously has very poor structural support and joint bracing.

The above hand-form has good structural support and joint bracing and it would be possible to do push-ups on this fist. However, it can only penetrate as deep as the tip of the thumb making it just slightly less than optimal.

The above hand-form has good structural support and joint bracing and it would be possible to do push-ups on this fist. It can penetrate as deep as the knuckle of the thumb (slightly deeper than the one above it)  making it the optimal Ipponken.

Nakadakaken (Nakadaka-Ipponken)

Notice how the above fist form has nothing *behind* the middle finger. It is impossible to do push-ups on this structure. It makes a very poor striking weapon because it obviously has extremely poor structural support and joint bracing.

Because of the straightened index finger, the above hand-form has good structural support and joint bracing and it would be possible to do push-ups on this fist. It is the optimal way to strike with Nakadakaken

Remember that these foreknuckle fist formations are not only useful for striking they also can be used to exert rubbing and grinding pressure to sensitive areas. These include the intercostal spaces, behind the jaw under the lower earlobe, the phitrum, and in the hollow directly under the zygomatic bone.

Nihonzuki (Nihon-Nukite, Secret Sword, Two Finger Strike)

Neither the thumb nor the two bent fingers offer any stabilization or structural support. This hand form somehow crept into Chinese martial arts from Chinese folk magic and folk medicine where it is very common. Those two endeavors require no strength in the structure so joint bracing is a moot point. Martial applications on the other hand do require structural strength.

The thumb and bent ring finger offer some stability and structural support and it is easy to put rigid strength into the hand and fingers in this position (unlike the ritual mudra above it). This makes it effective for striking soft areas of the body.

The thumb and bent fingers offer a stability and structural support and it is easy to put rigid strength into the hand and fingers in this position. Notice how the middle finger is pressing again the back of the index finger (and reciprocally the opposite) creating decent joint bracing in a way the hand-form above it does not. This makes it the optimal position for the two finger thrust.

A side view allows a better look at how the thumb provides structural support. You also get a different view of how pressing the index finger into the middle finger (and reciprocally the opposite) creates some additional joint bracing.

Ipponzuki (Ippon-Nukite, Single Blade of Grass)

There is no structural support for the index finger whatsoever in the above hand form

The thumb and bent fingers press very firm against the index finger creating good joint bracing from two directions up to the second knuckle of the index finger. There is also a general firming of the fingers and hand proving a little additional stability and support. Although this is the optimal hand form, it is still a weak structure and is only useful against very soft targets. However, if it is used against the right areas it can still produce devastating effect.

Nukite (spear hand)

Because the middle and ring fingers are bent and merely stacked on each other, this structure will easily collapse if significant force is exerted as a finger tip strike. It also makes a very poor thumb strike (and will likely result in self-injury if used in that way).

Nukite side view (thumb and finger impact look identical from the side)

Notice how the back of the index finger presses against the front of the middle finger (and reciprocally the opposite) and how the back of the pinky presses against the front of the ring finger (and reciprocally the opposite) creating as much support and joint bracing as is possible for a "spear hand" finger tip strike. Notice how the thumb is in good alignment to strike as well.

Nukite - fingertip impact (viewed from above)

Seen from above, this is the optimal position for a finger tip strike.

Nukite - thumb-tip impact (viewed from above)

Notice how the thumb separates from the index finger up to (but not beyond) the first knuckle of the thumb. This is the optimal position for the "tip of the thumb strike" application of nukite

Boshiken (Thumb Strike)

                      

Notice how the thumb knuckle is bent making joint collapse much more likely. It is impossible to do push-ups on this fist form (thumb push-ups)

Notice how the thumb knuckle is straight making joint collapse much less likely. It is definitely possible to do thumb push-ups on this structure.

The superiority of this structure is easily felt/tested on a Machiwara

Rarer Information About Small Surface Strikes

I actually feel a reluctance to share this information despite my general dislike of secrecy.

Anyone who has been around the Okinawan martial traditions for a while will notice that some Okinawan teachers can use a few techniques with dramatically more effect than any of their Western students (and often their Okinawan students as well). We'll call these the "specialty techniques". In most cases students just say "wow, sensei can really put the hurt on with that" (or something similar) and never stop to ask WHY they are not able to do the technique to the same effect. Even those who do ask this question often only get part of the answer right. For instance, they will conclude their teacher has a lot of power and has developed very strong fingers through years of Hojo-undo. Generally this will be true, but as with most things in life, there is usually a bit more to the story. Not only can these teachers hit with more force, but they are usually doing their "specialty techniques" in a way that is ever-so-slightly different from their students. There are only two ways to learn these differences. The first is to become somebody the teacher is very fond of. The other way is to first become aware that a difference even exists, then to repeatedly *feel* and keenly observe the teacher doing his "specialty techniques" (if possible in close up frame-by-frame slow motion).

I don't know the secret to many such "specialty techniques"...  but I do know the keys to a few. This was hard won knowledge, and I have to admit I have loved having these as my own "specialty techniques." It is quite cool to be able to do a few techniques in a way which produces dramatically better results than 99% of karateka. If looking cool and cultivating an impression of a very high level of skill were my main goals, then I would not share these. I would greedily hoard them for myself. However, as a friend recently said: the real secret of karate is that everything you share you will still have, and you will be given even more in return.

My goal is to learn and preserve "old style" karate as best as I possibly can (not look cool). Preservation means sharing. So, despite feeling a bit of loss at no longer having these "specialty techniques" for myself, I want to share what I can of the few I know (these are just the "specialty techniques" which relate to the structure of small surface strikes).

Shi-zuki (Washide-uchi, Beak Strike, Gojushiho strike)

Poorly supported in that the force isn't focused on a single well supported structure. It is too blunt to make a good strike behind the collar bone or to the Brachial plexus, Scalene muscles, or Omohyoid muscles.

The above uses a single well supported structure (the index finger) and the force is concentrated into a very small area and this is easy to slide behind the collar bone. It is also great to attack the Brachial plexus, Scalene muscles, or Omohyoid muscles. I'm told this technique is still remembered in several kung fu systems (which is second hand info since I've studied no Chinese martial arts) 

The above hand form (like the one above it) uses a single well supported structure (the thumb) and the force is concentrated into a very small area. It is easy to access the area behind the collar bone with this hand form.  Like the previous technique it is also great to attack the Brachial plexus, Scalene muscles, or Omohyoid muscles. The reason it is considered optimal is that the thumb is an inherently stronger structure and can deliver considerably more force than the index finger. Otherwise the "effective" and "optimal" are very similar.

To form the optimal structure, press the index and middle finger against the pad of the thumb with the tip of the thumb protruding. Then brace the side of the thumb with the remaining two fingers (ring finger and pinky).

How to test the difference for yourself

                   

Compare the "useless" and "optimal" versions of Shi-zuki by lightly striking the area shown above at an inward and downward angle. The "useless" version will likely only cause a wince reaction from pain. The optimal version will likely drop your partner to the floor with even relatively light force. Despite looking essentially identical, the two methods produce dramatically different results. So there you are, now you have Shi-zuki as your own "specialty technique". 

Hidden Foreknuckle Punch

                    

Maximum Force Foreknuckle Strike (Seiken type hand formation)

This is the most powerful but least well known of the foreknuckle strikes. The hand is in the normal fist formation but the hand/wrist is angled so that the foreknuckle of the index finger makes initial contact. This is the only foreknuckle strike which can be executed with the same force as a person's normal punch. It is not suitable for striking most parts of the head but is a devastating way to punch the torso. It is called a "hidden" strike because when executed at normal speed it is indistinguishable from seiken-zuki. Even at very slow speed it usually will be mistaken for seiken-zuki (and thus makes you look really good if you don't tell people what you are doing) ;-)

Iron Bone Hand (thumb knuckle striking)

        

The following set of pictures illustrate a series of thumb strikes that are all done with the same hand formation. This hand formation is only briefly mentioned in the bubishi and is rarely seen in modern karate-do. Karate-do generally mistakes the first technique with a spear hand (or, depending on the wrist angle, sometimes even a palm strike). The subsequent three techniques are usually mistakenly regarded as "ridge hand strikes". If you were taught how to practice these techniques you most likely study a lineage with a fairly intact connection to the "old ways" IMHO.

Iron Bone Hand (thumb striking): Neutral Position

Strike is applied with the force moving forward and slightly down and is done in the "Neutral Position". It relies on directing the force in alignment with the proximal phalanx. To strike with force it is very important to firmly press the thumb into the hand in order to create structural stability. This is often used to attack the carotid artery (especially at the bifurcation).

Immediately after the strike the fingers grip the sternocleidomastoid muscle from the outside and the thumb (now inserted deep into the neck just inside the sternocleidomastoid) grips the muscle from the inside. After the grip is secure a very powerful jerking pull is applied as if trying to tear the muscle free from the neck. This is not something to do to friends.

Notice how the Nigiri-game grip uses the same thumb knuckle in the same way as the muscle ripping grip discussed above. Likewise the finger tips grip into the lip of the jar in the same way they are used to dig into the neck. These same features are found in many of the nasty gripping techniques in karate. This is why Nigiri-game training was always regarded as essential in "old style" karate.

Starting from the "Neutral Position" this strike rotates as it moves and slight unlar deviation is applied as contact is made (see picture above). The force is concentrated on the knuckle of the thumb closest to the nail. Because the thumb is braced against the hand a very large amount of force can be delivered with this innocuous looking strike.

Starting from the "Neutral Position" this strike rotates as it moves and strong unlar deviation is applied as contact is made (see picture above). The force is concentrated on the second knuckle of the thumb (the distal end of the 1st metacarpal). Because the thumb is braced against the hand a very large amount of force can be delivered with this innocuous looking strike.

Same basic method with force distributed along the length of the proximal phalanx of the thumb.

Design of the lightweight Machiwara can be found here:
Moveable Indoor Makiwara: Dimensions & Design

Below is an amazing video from Paul Enfield shinshii 

(of the Goju Karate Center) 

It shows  a "variety of push-ups for karate hand positions with a view to developing wrist, forearm and finger strength." This is a fanatic video as it shows to systematically and progressively build strength in these hand forms. It includes a section on one-fore-knuckle push-up. I often wonder if Enfield shinshii's students know how fortunate they really are. A summary of the fore-knuckle training shown:

1) Put some padding down for your hands and start by attempting "girl push-ups" (knees down push-ups). Provided the padding is OK, this should prove reasonably unproblematic.

2) Work on "knees down" push ups with no padding.

3) Once you are good at those, start trying to lift the knees and do push ups with one hand in the fore-knuckle-fist, and the other in "finger-tip push-up" position.

4)Finally work on doing push ups with the knees up and both hands in ipponken position.

Personally I recommend adding the additional step between 3 and 4 where one works on doing push ups with the knees up and both hands in ipponken position but with some padding under the knuckles.

Here are some videos of small surface area strike training.