Zhan zhuang (Chinese: 站桩, lit. “standing like a post” is a method of training in many Chinese martial arts using static postures most often seen in tai chi chuan.
Unlike many Western exercises these static poses don't require great strength but often expose our incorrect posture or breathing.
Typically beginners of zhan zhuang even when physically fit can experience severe muscle fatigue and subsequent muscle trembling .
Later after focus on the breath, posture and finding onces centre “zhong ding”. Some schools use the practice as a way of removing blockages in Qi flow.