Yaoxi (腰隙), meaning “waist gap,” is the body-structure concept at the lumbar-hip junction — the space between the lumbar spine and the hip joint where the lower body meets the torso. It is not a standard acupoint but a structural landmark central to Tai Chi theory.

Role in Tai Chi

The Tai Chi Classic by Wang Zongyue states: “命意源头在腰隙” — “the origin of intent is in the waist gap.” This locates the source of movement intention at the lumbar-hip junction, not the shoulders or arms.

In practice, Yaoxi refers to the subtle opening and closing (开合) of the lumbar-hip crease:

• When the weight shifts back, the waist gap opens, allowing the hip to fold and the spine to lengthen
• When the weight shifts forward, the waist gap closes, transmitting power from the legs through the waist
• The command center of movement (主宰于腰) is expressed through this junction

Yaoxi works together with:

• Mingmen (命门) — the lumbar hinge on the back side
• Opening the Kua (开胯) — the hip crease release
• Dan Tian (丹田) — the lower abdominal center of intent

Understanding Yaoxi is the difference between moving the arms and moving from the waist — the core of “movement is commanded by the waist” (腰为车轴).