There are two types of Internal Trainings which are training in motion and training in quietness according to Zhong Guo Wu Shu Shi Yong Da Quan (Chinese Martial Arts Practical Encyclopaedia) edited by Kang Gewu (1990, p. 290). Zhan Zhuang (standing pile) is classified as a kind of training in quietness, and Tai Hang Dao Gong and the Yi Quan of Wang Xiang Zhai have lots of such examples. Lu He Ba Fa was taught openly by Wu Yi Hui who was a close associate of Wang Xiang Zhai and they exchange students. Of course there are also the traditional martial arts such as Taijiquan, Xingyiquan, Baguaquan. I am not sure about Chen Style Taijiquan as a traditional art which was taught openly in the late 1920s in the same period as Yi Quan and Luhebafa. I am interested in the biomechanics of motion and quietness in the internal training of martial arts. Maybe members of this forum would like to share some of their experiences in internal training and the meanings of internal training.