​​If the body moves as one, what organizes that movement?

In the traditions of Aiki, the answer is often given as the tanden. For many people, the word immediately creates confusion. Some imagine it as a mystical energy center. Others think it refers to a specific point in the lower abdomen. Still others treat it as a concept belonging entirely to Eastern philosophy, with little relationship to anatomy or biomechanics. The reality is more useful.

The tanden is best understood as a functional center rather than a single anatomical structure.  It is not one muscle, one organ, or one precise point hidden inside the body despite often being referenced as the Ren-6 acupoint. Instead, it describes a region in which multiple anatomical systems converge to create stability, regulate pressure, transmit force, and coordinate movement. Like the hub of a wheel, the tanden serves as a meeting place through which forces from the upper and lower body can be organized. When this region is poorly integrated, movement tends to become fragmented. The shoulders move independently of the hips. The arms attempt to generate power by themselves. The legs push without effectively transferring that force through the torso. When the tanden is developed and integrated, however, these separate movements can become expressions of a single connected body. Understanding the tanden therefore begins with understanding the structures that comprise it.

​One of the most common instructions given in martial arts is, "just relax." While well-intentioned, it is also one of the least helpful pieces of advice an instructor can give. Strictly speaking, relaxation is the wrong word.

​If you were to truly relax every skeletal muscle in your body, you would simply collapse into a limp heap on the floor. Healthy movement always requires a certain level of muscle activation to maintain posture, support the joints, and interact with the environment. The real objective is not relaxation, but the elimination of unnecessary tension. Unfortunately, that distinction is often lost. Muscle tension is not something you can consciously switch on or off through willpower. Rather, it is the consequence of how the nervous system recruits muscle to solve a movement problem. The goal is therefore not to "relax," but to teach the nervous system that it can accomplish the task with less muscular effort while preserving structure, stability, and efficiency.

In the Chinese internal arts, the process of releasing unnecessary tension is called Song 松. In Aiki Jujutsu, the functional equivalent is Batsu Ryoku 抜力, literally "releasing power" or "power from release."

Neither term means becoming limp or weak. Rather, Batsu Ryoku is the result of continuously minimizing unnecessary muscle recruitment while preserving the body's structural integrity. It is not relaxation itself, but the product of increasingly efficient motor control.