Stretch DOWN the “Cuckoo”, UP the Cranium

 Tuck Pelvis? NOT

The word coccyx comes from the Greek kokkyx, meaning "cuckoo," due to the bird’s beak-like shape of the bone. In the first photo you see me "sitting back" as I pull Master Hwa's arm.  Notice the yellow line in the 2nd photo as an imaginary wall.  The "sit-back" would not touch the wall with the shoulders but always with the rear. When teaching at Universities or High School gyms, I would train students to "sit-back" using gym or hallway walls this way. Notice how well Master Hwa does his "sit-back"! This is the stretch/droop down of the tailbone/coccyx/buttocks NOT a tuck under of the pelvis.  A good sit-back will enlist gravity to pull down and the equal / opposite reaction will be a natural stretching motion of the cranium upward.  Newton's third law.

Pushing hands in the "perpendicular"

A VIDEO LINK

The Sit Back Move: When performing the "sit back" movement, you must sit straight back without wiggling your hips while moving backward or forward. The turning happens only when you are fully back or forward. Many people IN THE VIDEO tend to stay too upright during this movement, not allowing gravity to stretch the tailbone downward. In the video, you can observe individuals pushing hands and sitting back onto the rear foot, but their hips rotate excessively. This move is practiced intensely from the first lesson, "Tai Chi Walk", and continues throughout form practice. Many beginners find this move awkward and often don’t sit back completely, meaning not all their body weight rests on the back foot. To execute this move correctly, you must fully stretch downward in the sitting position, allowing the backward momentum to be absorbed by the stretch and transmitted to the legs. Some of the momentum can also be absorbed by the forward foot, with the heel firmly planted on the ground and the toe lifted slightly due to the leg muscle stretch.

In Classical Tai Chi, the 'Sit back' movement involves specific alignment and movement principles, focusing on the buttocks' role or the “coccyx/tailbone”. The action of 'drooping' the buttocks, or allowing them to 'drop', is not just a movement, but a crucial element that significantly influences the entire process. 

As the buttocks droop, the influence of gravity pulling downward on the sacrum is felt, creating a natural opposing force from the upper body that stretches the spine and surrounding musculature in an upward direction. Thank you, Sir Isaac Newton!

The action of 'stretch buttocks down, stretch neck/head up' in Classical Tai Chi is not a 'tucking motion', but a crucial element for achieving internal movement. This action simultaneously contributes to loosening the waist, a key aspect in Classical Tai Chi. The waist, located beneath the belly button, should turn from the lower abdomen independently and not be initiated by the shoulders.

The process also involves pulling the body backward by engaging the rectus abdominus and oblique muscles. This engagement helps sharpen the differentiation between active and relaxed body parts, aligning with the Tai Chi principle of selectively utilizing muscles to maintain relaxation elsewhere. Stretch down the tailbone and spine, allowing gravity to help. One can achieve this by pulling the body back and maintaining proper alignment using "internal discipline". 

In Classical Tai Chi, the concept of "stretching down the buttocks" is closely related to the proper alignment and structure of the body, particularly the lumbar vertebrae and the sacrum. Great grandmaster Wu Chien Chuan highlighted the importance of "drooping the buttocks" as a key element in achieving the "loosening" of the waist, which is essential for effective Tai Chi movement.

The idea is that when the buttocks are appropriately engaged and "stretched down," they help align the spine and facilitate internal energy flow. This is part of the broader principle of using the body's internal core (the abdomen and back) to initiate movements rather than relying on the external limbs.

In Classical Tai Chi, the principle of 'stretching down the buttocks' is not to be confused with tucking the pelvis. This principle of 'internal discipline' generates 'internal energy' and empowers the core, abdomen, and back rather than from the extremities. Tucking the pelvis, often misunderstood as being 'internal', is, in fact, a purely mechanical action.

Classical Tai Chi emphasizes the balance between yin and yang, where every internal movement has a corresponding stationary part that provides support and power for the move. The junction between yin and yang is always located in the torso, and this principle applies to movements such as pushing the hand forward, turning, and stepping forward.

While tucking the pelvis is common in some Tai Chi styles, it is not the focus in Classical Tai Chi. Stretching down the buttocks is more about internal energy flow and correct body alignment, rather than a specific pelvic movement.

Some sources discuss the importance of pelvic tilt and rotation in Tai Chi and Qigong, emphasizing the need to force the pelvis into a tucked position and not allowing it to move naturally by stretching down or up, releasing the back and neck. The goal is to achieve a balanced and relaxed posture, which is crucial for effective Tai Chi practice.

In summary, while tucking the pelvis ois used in many contexts, Classical Tai Chi focuses distinctly on 'internal movement and energy flow'. This approach differs significantly from the mechanical action of tucking the pelvis.