The dynamic range will be crucial when establishing anatomical restrictions.
When we talk about dynamic range, we’re referring to how far a joint can actively move, from its neutral position to its maximum limit.
For a more in-depth look at this concept, check out the "Mobility" section (link at the bottom of the page).
In this guide, we’ll go through a practical exercise to illustrate the difference between creating an anatomical restriction in the active range versus the passive range.
Understanding this concept and learning how to adjust to each person’s range is essential for applying the "Tetori Sankaku" (手取三角) technique later on. This technique is used to position the arms behind the back in forms like gote, for example.
Important: Each person’s dynamic range is unique—not just from one individual to another, but also from day to day. It can even change within a single session as the body warms up and the relevant muscles engage.
The menstrual cycle also plays a role: during certain phases (such as the follicular phase), mobility increases, but joint stabilization becomes more challenging.
As with all exercises, we encourage you to practice from both perspectives.
Practical Exercise
This exercise consists of three parts.
Part 1: Identifying the Active Range
Start by moving one arm (just one) backward as far as you can while maintaining full muscular control—meaning you should rely only on the muscles of that arm (you can check this by feeling them activate).
Be careful not to compensate with other parts of your body. THIS ISN’T ABOUT HOW FAR YOU CAN REACH. It’s about recognizing your active dynamic range.
The goal is to identify your limits so you can work within them, ensuring safe and controlled movement, rather than forcing past them.
Part 2: External Support
Once you’ve identified your active range, move on to the second part of the exercise.
Your partner should provide light support at the top of your forearm, along the pinky side.
This is just support—no gripping or pushing.
The person in the active range should be able to press against this support, as if preparing for a forearm plank.
When done correctly, they should feel engagement in the muscles along the front and side of their body.
The person providing support should sense this activation and a slight pressure. This isn’t a test of strength—apply only minimal resistance.
The key here is to feel the activation—the sensation of providing support on one side and leaning into it on the other.
Recognizing when the tied person’s body is actively engaged and within their dynamic range is a skill the person tying must develop. At the same time, the person being tied must cultivate this awareness, as it directly impacts their physical safety.
Take some time to explore this support and how it feels. Rest for a few minutes before moving on to the third part.
Part 3: Applying Force
In the final step, repeat the process, but this time, the person tying should apply a small upward force and observe the response throughout the entire body of the other person.
We recommend starting with an upward movement because it’s the easiest to see and feel. Once you're comfortable, you can explore other directions.
If the activation is correct and the arm remains within the shoulder’s active range, the body will lift as a single unit.
If the activation is incorrect, only the shoulder will rise, and the body may twist.
⚠ Caution: If you apply force and there’s no muscular activation, the joint is unprotected, increasing the risk of injury. Stop immediately.
Key Anatomical Points to Observe
- Maintain a neutral posture.
- Keep the pelvis aligned—neither tilted forward nor backward.
- Position your feet hip-width apart, pointing forward.
- Avoid locking or stiffening your knees; if needed, maintain a slight bend.
- Ensure your ribs don’t protrude past your hips.
- The scapula on the side of the working arm should remain flat against the back, not flared out.
- Bending the elbow often causes muscle disengagement and shifts the joint into a passive range.