Usually a karateka begins tamashiwari with woods planks (12''X12'' - 3/4'' thick pine planks). During various belt test he may be required to brake a number of those planks with a specific technique.On higher levels, usually shodan and above, a karateka begins breaking ciment, bircks, roof tiles or even baseball bats.
Warning: it is Extremely Dangerous for an untrained person to attempt Tameshiwari. Improperly executed and without adequate hand conditioning, it can lead to serious injury.
Wooden boards are the most common breaking item in most martial arts, Individual boards used may range from nominal sizes as small as 6"x12"x1" to as large as 12"x12"x1" (a board with a nominal width of 1" has an actual width of 3/4"). The typical adult testing board is approximately 10"x12"x1".
The grain of the board must be cut so as to be parallel with the striking hand.
Children may use narrower and thinner boards with 4 and 5 year olds sometimes breaking boards as small as 4"x12"x1/2".
In general, breaking is used both as a method of measuring force of strikes for martial artists, as there was no other way to do this and only recently have devices such as accelerometers been used in martial arts, and as a measurement of mental fortitude, the ability of the mind and body to overcome.
Generally, a martial artist engaged in breaking practices hitting something hard. Masutatsu Oyama, a famous breaker who was known for breaking the horns off bulls, would use trees. In karate, a device called a makiwara is used; this device has found more popular use by practitioners of other martial arts today. In the past, Shaolin and other earlier martial artists would use many different types of devices in order to condition themselves, not always for simply breaking, but using the same concepts used today. For instance, there is Iron Palm, Iron Shin, Iron Shirt, Iron Head, and other types of training which center around conditioning various parts of the body so they could withstand or give blows such as what is seen today in martial arts breaking. Many Chinese systems also are of the school of thought that "internal energy" or Chi is used when breaking, which is not dependent upon muscle strength and body weight.
The general principles used in martial arts breaking training is similar to the same principles used for most athletics. The body adapts to stress. There are generally three areas a martial arts breaker wishes to force their body to adapt to: the bones, the skin (calluses), and muscles (for both mass and speed). The general principle here — for instance, for the bones — is found in Wolff's law, which states that the skeletal system will, after healing, be stronger if injury is put to it. Craig Edmunds demonstrates this theory after breaking hand in seminar measuring bone density then measuring bone density after healing. In this manner the breaking practitioner operates not unlike a bodybuilder who works out with weights, then takes a period of rest to heal and allow the muscles to come back stronger.
This kind of training is called "progressive resistance training"; see Weight training for more information. Often differences in body structure can be seen in the form of calcium deposits between a breaking practitioner and a non-practitioner.Mike Reeves, a champion breaker, advocates in his book the usage of a makiwara and knuckle push-ups. With knuckle push-ups, he recommends starting on softer floor material and working your way up to concrete.
USBA/WBA Founder Drew Serrano, producer of the documentary "Breaking All Records", encourages practitioners to gradually increase the difficulty and amount of a material to avoid injury. He suggests that beginners should start with wood boards and increase the amount as technical prowess increases. Once a level of comfort, both physically and mentally, is reached, harder materials such as concrete can be attempted.
There are safety concerns with martial arts breaking, so one should seek out an instructor. The knees and elbows, for instance, have weak and small, but essential bones on them. There are many small bones of the foot and hand which need to be very carefully and slowly conditioned for safety. The tendons run over the knuckles on the fist and many damages can result from being overeager and impatient.
Speed vs. Power vs. Impulse
There are generally two common classifications of breaks: speed breaks and power breaks. There is a third lesser-known classification known as the impulse break.
Speed breaks are breaks where the striking object is not held in place. The only way to break the object is to strike the surface with sufficient speed at a focused point of impact. Sometimes a board to be broken is held lightly between two fingers by a person; an advanced dan test may involve an attempt to break a board as it falls through the air. Regardless of the strength of the striker, the board will only break if it is struck with sufficient velocity.
Another type of "Speed Break" is that which involves breaking a number of objects over a given amount of time. A common time span is 1 minute, but this can vary depending on the material and venue. In competition it is very common for a speed breaking category to limit the time to 8–10 seconds, enabling more competitors to participate. Records and specifics are kept track of by leading martial arts breaking organizations such as the USBA/WBA (United States and World Breaking Associations) and the ISKA (International Sports Karate Association).
Power breaks are breaks where the striking object is supported. Either the break will employ human holders for horizontal, angular, or upward vertical strikes, or the break will require that the objects be stacked for downward vertical strikes. For a stacked break the object is placed on sturdy supporting objects, such as concrete blocks, that are placed on the ground. Many color belt (belts before black belt) promotion testing breaks are power breaks—it is substantially easier for an inexperienced person to muster sufficient energy to break a wooden board with a power break (Note, this is not true for all breaks). The vast majority of these employ human board holders. Often a stronger or more powerful striker may substitute some strength for technique and successfully accomplish the break. Most records that are catalogued are for power breaks. It is very common for black belt tests to use bricks, concrete patio blocks, or several boards stacked on top of supporting objects for challenging downward strikes.
Taped boards are sometimes used to lessen the amount of human influence from the holders for a break. It is very difficult to hold a stack of boards more than 4 inches steadily enough for challenging break. Therefore, some strikers will tape a stack of boards together to make a "brick" for their holders to hold. Usually however, test breaks at promotions and events are done without taped boards.
Both the speed and power breaks deliver the energy required to overcome the tensor and flexion forces of the board through mass displacement, where the kinetic energy is given by 1/2 m*v2. That is, either the speed of the striking implement (hand/foot/etc) has to be high enough, or the striker must be strong enough to increase effective mass brought into the break (i.e. his or her body weight) to exceed the brick/board's threshold. For single boards, it is generally easy (as in the casual person has a sufficient reserve of mass) to reach this threshold through a power break.
Though fundamentally different, the third kind of break—the impulse break—is often confused with a speed break, because the striking implement can (but need not) reach a high speed. But that is where the similarity ends. The energy transmission from an impulse break derives not from mass displacement, but from wave transmission. (As an ocean wave hits a beach) The mass of the hand/foot/etc does not travel much further than necessary to deliver the wave—this results in an extremely brief contact with the brick or board face (as opposed to going "through it"), and the wave itself causes the striking surface to flex and buckle. The less flexible the striking surface, the more likely to break.
Spaced vs. unspaced
There are two types of multiple stacked board settings: pegged (spaced) and unpegged (unspaced). Unpegged stacks are stacks where multiple items are stacked directly on top of each other. Typically, whether stacked or human held and whether taped or untaped, approximately 6-7 boards is equivalent to a brick in terms of degree of difficulty (the required force and form to successfully execute the break). However, a single brick is more dangerous in terms of the potential for injury. Therefore, many schools for liability reasons substitute a stack of boards for a single brick. (Please keep in mind that because of the wide variety in the consistency and material of bricks and concrete patio blocks that comparisons between materials is hard to gauge. Experience is an important factor in cross-material comparison.)
Pegged stacks are stacks where multiple items are stacked with spacing items (often referred to as spacers) between them. Common spacing items are pegs, nuts, coins, and pencils. Most records involved stacked boards because people think that these are more forgiving and cause fewer injuries to strikers who are pushing themselves to their physical limits, when in reality they hit harder because they were more confident. A given number of pegged boards is NOT equated in difficulty with a larger number of unpegged boards.
This is due to the way in which the two materials break. Wood, which is a natural fibrous matrix, flexes to a certain degree before it snaps at the target point. When unpegged, this allows for an entire stack of wood to flex upon impact, resulting in the break occurring in the order of furthest board from impact to the closest board (albeit a fraction of a second difference separates each board, making it appear instantaneous). This can be witnessed in many novice demonstrations where the rear board will break, but the remaining top boards are intact. When pegged, the gap between the boards necessitates each individual board to flex and snap before the next board is reached in succession; the person performing the break must physically touch every board in a pegged stack of wood.
Bricks, on the other hand, are ceramic, and snap (or shatter) upon impact, with no flex action. When a stack of bricks is unpegged, the amount of force required to break all of the bricks increases with each additional brick (which is why security barricades are made of solid, not gapped, concrete). When bricks are pegged, the gap created actually doesn't affect how much force is needed, but with the belief that it does the higher confidence allows people to hit harder.
Concrete patio blocks, used in most major breaking competitions, require the competitor to "shock" the material and drive through from top to bottom.(this can be witnessed at any credible competition).
Spacing of materials in competition is also important to enable a clear winner to be established as the number of stacked items increases. Where as a limit of 5 unspaced patio blocks may be a common sticking point from one competitor to another, a stack of spaced patio blocks can provide more variables because of the increased confidence, which will narrow the field of competitors. This use of spacers makes competition more dynamic and exciting for competitors and spectators alike.