Fa jin

Fa jin, fajin or fa chin (fājìn, 發勁), is a term used in some Chinese martial arts, particularly the neijia (internal) martial arts, such as tai chi, xingyiquan, baguazhang, liuhebafa, ziranmen, bak mei, and bajiquan.

It means to issue or discharge power explosively or refining the explosive power, and is not specific to any particular striking method. With this definition in mind, a boxer is also capable of fa jin.^[1] However, in the context of internal martial arts, the term usually refers to a set of methods to generate and focus force, resulting in physical feats with far less visual physical expression such as the one-inch punch.

Jin (勁; jìn; 'power') is often confused by Westerners with the related concept of jing (精; jīng; 'essence'), possibly because when jin is an adjective it is also spelled jing (jìng, 'strong') but with a different pinyin tone mark. Jin describes the ability to generate force. Jin and qi are intrinsically linked concepts in internal martial arts. To generate the fa jin, according to the traditional explanation, it is necessary to transfer qi from dantian towards the limb or body part (e.g. shoulder, head, hip) that will perform the technique with explosive force (bàofālì, 爆發力). If a person is off balance and stiff, they have no jin, as qi cannot penetrate the muscle to produce force.

In terms of biomechanics, fa jin is a matter of utilizing body alignment and coordination to form an extremely efficient kinematic chain. The body begins in a relaxed physical state, which is then quickly accelerated in a coordinated whole-body movement.^[2][3]