The foundation of sōng (鬆) begins with the body. Before the mind (xīn, 心) can be clear or the spirit (shén, 神) can be open, the physical frame (shēn, 身) must be released. This stage, shēn sōng (身鬆), concerns dissolving the habitual muscular contractions (jīròu jǐnzhāng, 肌肉緊張) and structural blockages that distort alignment and obstruct the free flow of jìn (勁, trained force).

To “relax” in Taiji does not mean collapse (tǎn, 坍) or becoming limp, but rather a release that allows the body to settle into its natural architecture: the skeletal frame (gǔjià, 骨架), the fascial network (jīnmó wǎng, 筋膜網), and the connective tissues that distribute load and transmit elastic force. True sōng means that the bones bear the structure, the fascia conducts the energy, and the muscles are freed from unnecessary contraction, maintaining only what is required for stability.

In classical language, this is described as zhōng zhèng ān shū (中正安舒) — upright, balanced, and at ease. The shoulders (jiān, 肩) must sink (chén, 沉) and broaden, the hips (tún, 臀) must loosen, and above all the kuà (胯) — the deep inguinal folds that connect the legs to the torso — must open (kāi, 開). If the kuà is locked, energy stagnates (yù, 鬱); if the kuà is released, movement integrates through the spine (jǐzhù, 脊柱) and expresses naturally through the limbs.

Modern biomechanics supports this principle: when unnecessary muscular tension is released, the skeletal system provides the load-bearing architecture, the fascia transmits elastic recoil, and the nervous system reduces antagonistic firing. This results in a body that is both grounded and agile — solid without stiffness, soft without weakness.

Thus, the first dimension of sōng is not a passive relaxation, but an active refinement of posture, load distribution, and tissue state. It is the physical gateway through which the higher dimensions of mind and spirit must pass. Without shēn sōng, there can be no true xīn sōng (心鬆) or shén sōng (神鬆).