Sanchin (三戦) is a kata of apparent Southern Chinese (Fujianese) origin that is considered to be the core of several styles, the most well-known being the Okinawan Karate styles of Uechi Ryu and Goju 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.
The name Sanchin, meaning "three battles/conflicts/wars" is usually interpreted as the battle to unify the mind, body, and spirit; however, there are other interpretations.
Uechi-ryu practices a form of Sanchin with nukite zuki (貫手突) "open spear hand" strikes, while the version used by many other styles such as Goju-ryu use a closed fist.https://en.wikipedia.org/wiki/Sanchin
What are the 3 battles referred to in the name Sanchin?
There are many theories about this, but here is mine.
First Battle: Breath. Your life began with your first breath, and it will end with a final breath. Learning Sanchin kata will teach you to control your breathing and time it with your movements.
Second Battle: Structure. Learning Sanchin Kata will teach you to have a strong base and protect your joints.
Third Battle: Muscle control. Practicing Sanchin properly teach you to control contrasting muscle groups, and uses slow, methodical isometric movements to build strength.
Jesse Enkamp has created a fantastic 3 part video series on Sanchin Kata. It is highly recommended to review all 3 videos a few times while learning Sanchin Kata.
Depending on the style, Sanchin kata may be performed with open hands, using nukite, spear hand, techniques. Or it may be done with closed fist, straight punches. Below are video examples of both. In the Mountain River Dojo, we practice a hybrid version of that taught my Uechi Ryu and Goju Ryu.
Uechi-ryu variant with open hands.
More common use with closed fists.
Personal Note: In many examples of Sanchin Kata, you will hear the demonstrator tense their throat, and make a horrendous sound like they are trying to hock a loogie. This really is totally unnecessary to accomplish the kata provided you are still creating tension and power in your breathing.