An Jin

An Jin (Chinese: 暗勁; pinyin: àn jìn) is a concept in Neijia (internal martial arts) such as Taijiquan, Baguazhang, and Xingyiquan. It refers to a refined, hidden, or internal force or power, generated through proper body alignment, relaxation, and coordinated movement, rather than brute muscular strength.

An Jin is typically described as a higher level of skill and development compared to Ming Jin ("obvious force"). While Ming Jin relies on visible, external exertion, An Jin emphasizes subtle, internal mechanics to generate power that is often not readily apparent to an observer. The manifestation of An Jin is said to be fast, penetrating, and capable of affecting an opponent's structure internally.

Developing An Jin requires extensive practice and understanding of internal body mechanics, including the proper use of the Dantian (a center of energy in the lower abdomen), fascial connections, and spinal alignment. It involves training the body to move as a unified whole, allowing force to be generated and transmitted efficiently through the body to the point of contact. Teachers often emphasize concepts like relaxation (Song), rooting (stabilizing the body's connection to the ground), and spiraling (chan si jin) as fundamental components in the development of An Jin.

The attainment of An Jin is not solely about physical strength but also involves mental focus (Yi) and the circulation of Qi (vital energy). It represents a deeper understanding of the principles underlying Neijia martial arts and the ability to generate significant power with minimal outward exertion. Mastery of An Jin is often associated with advanced practitioners who have dedicated years to rigorous training and refinement of their technique.