The Conduit – Building Internal Pressure
Author's Note This article represents my personal understanding and interpretation of traditional karate as taught by Hidetaka Nishiyama Sensei and followed by Avi Rokah Sensei. While I have endeavoured to accurately represent their teachings and methodology, any errors, misinterpretations, or misunderstandings are entirely my own. The insights and principles discussed here reflect my current level of comprehension as a student of this art, not the definitive word of my teachers. Andrzej
Stances as Tools for Ground Pressure
In our practice, stances are never static poses; instead, they are ways to position the legs and hips to manage floor pressure while keeping the spine aligned. The goal is to ensure the floor’s reaction force travels directly from the ground to the target without being absorbed by loose joints [7]. Nishiyama Sensei insisted that the “surface muscles” stay soft for speed while the deep muscles close to the spine—like the pelvic floor and the muscles of the lower back—create the density needed for a strike [6, 16, 21]. This internal density is what allows for kime, the moment when the energy transitions into impact force through total body contraction. But setting up the body correctly is only the first step. The real question is: how do we maintain that pressure without becoming rigid? How do we stay both grounded and mobile at the same time?
This is where Sensei Avi’s metaphor of the “water balloon” becomes essential. By using the breath to create intra-abdominal pressure (IAP), we turn the trunk into a pressurised cylinder that doesn’t buckle upon impact [15, 16, 25].
This internal pressure is the medium that allows us to utilise the fascial spring—the connective tissue that wraps the body and acts like a high-tension rubber band [11]. Fascia is most effective when it is pre-loaded. By maintaining “expansion” against the floor and moving from the centre, we keep this fascial network under tension. This is the difference between a loose string and a tuned guitar string; the pressurised body allows a karateka to go from a relaxed state to maximum force instantly, with no visible muscular “wind-up.” If the internal pressure drops, the “string” goes slack, and the kinetic energy is lost to heat and vibration within your own muscles rather than being delivered to the opponent.
However, this pressurised “balloon” only works if the top and bottom are anchored. This is achieved through a specific engagement of the deep muscles of the lower back that “locks” the ribs to the pelvis, creating a solid, vertical axis. Without this vertical compression, the hips “float” and power leaks through a soft middle. It is this pressurised axis that allows the centre of mass to carry the weight of the arm into the target.
In this way of training, the elbow is essentially a “passenger” on the centre. We often see practitioners trying to “throw” the hand, which disconnects the arm from the core and relies on the relatively small muscles of the shoulder. By contrast, Sensei Avi teaches that the arm must be “plugged” into the pressurised trunk. When the axis rotates, the weapon moves because the unit moves. If the arm moves independently, the connection to the floor is broken and the strike becomes hollow—a mere “push” rather than a decisive impact backed by the mass of the earth.
Watch the "Body as a Unit" in Practice: Avi Rokah - Body-Elbow Connection https://www.youtube.com/watch?v=QZYRHbv2ZDE Observe how Sensei demonstrates that the elbow must be "carried" by the centre. If the arm moves first, the connection to the floor is broken. Note how the structural unity remains constant even as the arm changes position. Notice the "elbow down" cue. This ensures the shoulder stays down and the force vector stays directed through the pressurized centre rather than leaking upward.
In Part 3, we'll explore how these mechanical principles come alive in practice — the role of mind and eyes, the evolution from conscious control to intuitive response, and how all of this manifests in the ultimate test: kumite.