|三戦 (三戰, 三進, 参戦)|
|Min Nan POJ:||saⁿ-chiàn|
Sanchin (サンチン Sanchin?) is a kata of Southern Chinese (Fujianese) origin that is considered to be the core of several styles, the most well-known being the Okinawan Karate styles of Goju Ryu and Uechi Ryu, as well as the Chinese martial arts of Fujian White Crane, Five Ancestors, Pangai-noon and the Tiger-Crane Combination style associated with Ang Lian-Huat. Tam Hon taught a style that was called simply "Saam Jin" (Cantonese for "Sanchin"). The name Sanchin, meaning three battles, is sometimes interpreted as the battle to unify the mind, body, and spirit; however, there are other interpretations of it.
The version of Sanchin used by most styles of Karate was developed by Goju Ryu founder Chōjun Miyagi and uses a very strong, tense closed fist "push". In Uechi Ryu and in Ryusei, the practice of Sanchin is closer to the Chinese version with faster spear hand strikes that are more snake like.
Only one stance is used—the sanchin (meaning "three battles") stance, from which a name of the kata is derivative now (initially it was named as Peppuren. Sanchin-dachi is a practical stance, and yet is the most difficult stance to master. The legs protect the body from sweep kicks; the thighs are to trap low kicks. According to a tai chi manual (Zhengzi 13 postures), the punch draws its power from the earth through the legs—the flip of the hips enables the strength of the whole body to be channeled and focused into one punch.
When properly executing Sanchin kata, all the muscles are to be flexed and tensed throughout the kata. Most styles of martial arts employ a version of Sanchin kata that follows the "hard" style of karate. This hardness contributes to the belief that Sanchin is one of the most strenuous katas in martial arts.
In Goju-Ryu, the idea is to remain soft until a hard motion is executed, and then tense briefly at the right moment. This allows for better overall movement since continuous tensing is not conducive to easy or speedy movement. Sanchin is often practiced as a means of developing hardness of the external muscle sheathe of the body, making it easy for the practitioner to withstand solid, powerful blows from an opponent. But the steady tensing used by some styles, e.g., Goju Ryu, in its practice tends to slow one's movements if the practitioner doesn't learn to turn the hardness on and off easily. There have also been claims that the isometric method of practice can have long term deleterious effects on practitioners' blood pressure and circulatory systems. Styles like Kyokushin often incorporate sanchin method of practice, as seen in the Goju version of the style, in everything they do. Many who have seen the Okinawans performing Sanchin have accepted a notion that the form requires hardness and tensing in its very nature but practicing in this manner can make it difficult to learn from the kata, to achieve a better understanding of the techniques it contains, when it's performed in a state of constant strain and tension.
Some exceptions to this occur in the Okinawan style Uechi-ryū where a balance of tension and softness is employed. In the Uechi-Ryu form of Sanchin all muscles are tensed like Sanchin in other martial arts most of the time; however a brief softness and looseness is employed for the muscles being moved to make explosive strikes and movements, while the rest of body remains tense to protect vital organs, and weak spots in the body. Therefore sanchin in Uechi-Ryu is considered more of a combination of "hard" and "soft".
As the foundation of Uechi-Ryu unlike most other styles, sanchin kata is the first kata that new Uechi-Ryu students learn, practice, refine, and develop as they gain experience and rank.
In Chinese training, sanchin kata (known as sanzhan)also introduces the student to the use of "qi" (Japanese "ki") for training and fighting applications. It can be understood to be a form of "qigong" as employed in Chinese Wushu. In qigong, the hands are not closed into a fist as it would be deemed as restricting the flow of chi. The focus in qigong is on the controlled breathing to generate chi in the body. Many western interpretations of qi/ki explain it as an enhanced understanding of internal body dynamics and muscle control through repeated and strenuous training. The Chinese form San Zhan, which is apparently the ancestor version of modern Okinawan and Japanese Sanchin, can look quite different from the later versions seen in classical karate. 
In Gōjū, there are two sanchin kata: the first one, Miyagi's sanchin (or "sanchin dai ichi"), the most widely taught as initial and Kihongata, was created for such purpose by Chojun Miyagi, and has no turns so the karateka goes forward and then backwards. The second sanchin, Higashionna's sanchin (or "sanchin dai ni") is a full-version Sanchingata and is older and was taught by Higashionna Kanryo. In this kata the karateka always goes forward, but turns 180 degrees twice. Initially it was taught with open hands, as sanchin-kata still is in Uechi-ryu, but later it was also revised to closed fists by Miyagi's co-student Juhatsu Kyoda, founder of To'on-ryu, and adopted by Chojun Miyagi as well.
This kata was adopted by other styles such as the later Okinawan style Isshin-ryū and Kyokushin, a later Japanese style created by Mas Oyama, a Korean-born immigrant to Japan. Oyama's style, emphasizes the hardness and body toughening of classic Goju with the forward moving, aggressiveness of Shotokan, generally thought to be the earliest Japanese style and tracing its roots to the Shuri te school of combat in Okinawa rather than to the Naha te school which formed the basis of Okinawan Goju Ryu and Uechi Ryu.
Some say the meaning of sanchin ("three battles") relates to the three journeys of life: Developing body, mind and spirit. Through proper martial arts training, one properly learns to develop her or his body through exercise and practise of kata/forms. Later, one begins to understand the true meaning of one's training and develops an understanding of bunkai and history, developing the mind. Spirit is developed much later in life and is only understood by those who have achieved this.
The Sanchin routine uses only its namesake stance and is carried out with controlled breathing (ibuki breathing). Inhalation and exhalation are performed in unison with the various blocking and striking movements. In the most commonly taught versions, emphasis is placed on the tension of the practitioners' muscles, and movement of the body as a solid, stable unit. The Chinese and Uechi-Ryu version uses open hands while other Okinawan and Japanese versions tend to use closed fists. Certain schools of Five Ancestors kung fu, most noticeably those hailing from the Chee Kim Thong lineage, employ minimal tension during execution. This is intended to facilitate the correct training of qi (or ki).
The following description does not apply to the Chinese Sānzhàn stance.
The narrow (shoulder width) upright "pigeon-toed" foot position of the Sanchin stance (Japanese: sanchin dachi) balances stability in two directions (front and side) with the flexible waist rotation needed for strong punches and kicks. The toes attempt to "grip" the floor, attempting to turn the feet outward while actually turned inward, creating a rooted stance, whilst the pelvis remains tilted upward along with the turned-in position of the front knee and the bent back knee help protect the groin from kicks.
Some styles use Sanchin as a method of checking strength and posture, as well as concentration. All hits directed towards the karateka are done at the end of the punch, when they are in their most tense position. Most Goju-ryu schools use the following checking procedures:
In Uechi-Ryu, the practitioner stops the kata for each sequence of shime checks, then the kata starts up again - stopping and starting for each series of checks; as opposed to the kata being done continuously without regard to the person giving shime. Also in Uechi-ryu, the practitioner is open handed and the shime involves roundhouse kicks directed to the legs and occasionally the arms. Shin conditioning is checked by toe-kicks directly to the shins.
Traditional Okinawan schools will vary on their application of shime.