The beginning form "chi xi" immediately uses all of the foundational elements of Chen Taiji. As the body sinks the knees fold slightly and are slightly turned in. This forms peng within the legs, creates an arch at the "qua", and an arch over all in the lower body. The hips bow out slightly and release at the buttocks. This bowing out at the hips causes the knees to slightly turn in to create the arch found in peng.