This reason is related to the structure of the spine, and the space is limited, so I won't go into details.

Friends who know anatomy or spinal structure should not be difficult to understand.

Note 2: During the twisting process, always keep the pelvis straight, the ischium stable, the shoulders flat and the spine extended.

Note 3: Don't twist immediately before or after the spinal column recline. This combined with the structure of the spine, I believe everyone is not difficult to understand!