How Much Bounce Is Sine Wave? ITF's Most Argued-About Motion

He shakes his head. "No sine wave." Next month your own instructor watches the correction and stops you again, because now you are bouncing like you are on a boat, up and down on every step, the technique arriving a half-second after your knees do. Both men used the same words. Somewhere between their two demos is one of the longest arguments in ITF Taekwon-Do, and this article maps it honestly: what sine wave is, where it came from, what the other two waves are, and how to judge your own movement without taking a side in somebody else's forty-year dispute.

Section 01The Definition Everyone Agrees On

Strip the argument away and a core definition survives in every ITF school. Sine wave is a way of moving the body's mass so that it rises and falls in a smooth curve as techniques are delivered, instead of travelling flat. The body relaxes upward at the start of a movement, then drops, and the technique lands at the bottom of the drop, with the body's weight falling into it. The picture the name carries is the curve itself: up, over, and down, like the mathematical wave, one continuous motion rather than a hop.

The purpose is mechanical, not decorative. A technique thrown from a level walk carries the force of the arm or leg alone. A technique that lands as the body's mass drops behind it carries the mass too. ITF teaching connects sine wave to the theory of power in General Choi Hong Hi's writings: reaction force, concentration, and the use of the body's weight are all named sources of power, and the wave is the delivery system that lets a falling body weight arrive at the same moment as the fist or foot. Whether a given school emphasises the wave heavily or lightly, that claimed purpose is the same, which is why the argument is about amount and shape, not about existence.

Section 02The Three Waves

The first thing the argument usually gets wrong is the idea that sine wave is the only wave ITF has. The ITF's own teaching material describes three distinct motions of the body's mass, each fitted to different techniques. This is the structure the argument forgets.

Read the table as a toolkit, not a ranking. A sitting-stance punch forced into a sine wave would look wrong in any school, because the stance has no step to ride the curve on. A sequence of fast punches performed as one long sine curve would smear together. The three waves exist because techniques differ, and an instructor arguing that "everything is sine wave" or "the wave is a modern invention" is usually arguing about one row of this table while the other two sit unmentioned.

Section 03A Short, Honest History

The wave has a birthday, and knowing it explains most of the argument.

The Chang Hon patterns themselves are older than the wave's promotion. Through the 1970s, ITF technique was performed with far less vertical travel, closer to the flatter delivery the patterns were first taught with. In the early 1980s, around 1983 by the most commonly repeated account in instructor writings, General Choi began pushing sine wave hard: demonstrating it as the correct reading of his own theory of power, and teaching it on seminar tours as the standard motion for ITF technique. The general himself, in other words, changed the art's mind about how its own patterns should move, decades into the art's life.

Two consequences followed, and both are still with us. First, a generation of students learned the patterns flat, were retrained wavy, and in some cases retrained again as the demonstration standard settled. Second, performance drifted. A motion taught as a relaxed rise and drop, demonstrated by senior men to halls of students copying by eye, grew in the copying. By the time it reached colour belts three schools removed, the gentle curve in some places had become a deep bounce, knees bending twice per step, head travelling up and down like a buoy. Instructor writing from inside the ITF has been pushing back on the exaggerated version for years, describing the modern heavily-performed wave as something quite different from what was originally taught. That is the argument in one sentence: the founder's late correction, amplified by imitation, now has its own correction movement, and students in the middle hear both and cannot tell which man is describing their class.

Section 04So How Much Is Right?

This article will not hand you a number of centimetres, because the honest sources do not agree on one and a source of truth does not invent agreement. What the evidence does support is a set of tests you can apply to your own movement, whichever school you stand in.

The technique lands at the bottom. Whatever your rise looks like, the block or strike should arrive as your weight settles down into the stance, not before it and not after a bounce of recovery. If your fist lands and then your body drops, the wave is decoration. If your body drops and the fist rides the drop in, the wave is doing its one job.

The rise is relaxation, not a jump. The upward half of the curve is the body unweighting, knees softening, the mass floating up as the foot moves. The moment the rise becomes an effort, a visible lift or hop, the motion has left every version of the teaching, the exaggerated ones included. Nobody's sine wave has air under both feet in a walking stance.

The head path tells the truth. Film yourself from the side. Your head should trace a smooth, shallow curve. A flat line means no wave at all. A deep repeated valley means the bounce has eaten the technique. Instructors who judge the wave well judge this trace, because it cannot be faked by bending the knees theatrically while the mass goes nowhere.

The wave serves the stance's timing. In the patterns, most techniques and their stance land together. If your wave has you arriving in the stance early and waiting for the technique, or landing the technique and then settling, the wave and the form are fighting. In a correct reading, whichever size your school performs, they arrive as one event.

Consistency inside your own school wins gradings. A grading panel examines against the standard it teaches. The student who performs a textbook version of a different lineage's wave gets corrected all day, not because the wave is wrong, but because patterns are examined as a school standard. Learn your school's size of the curve and perform that, while understanding the landscape well enough not to call the school down the road wrong for its own.

Section 05Where It Goes Wrong

Bouncing instead of dropping. The most common fault: up-down-up-down on the spot, knees pumping, mass travelling vertically without going anywhere. The wave is a travelling curve tied to the step and the technique. Fix: think of the drop, not the rise. Practise arriving heavy, and let the rise be whatever relaxation the next step needs.

Waving the arms instead of the body. Students told to add wave often add a dipping motion in the shoulders and hands while the hips travel flat. The wave lives in the legs and the mass. If your hips do not rise and settle, no amount of shoulder choreography is sine wave.

One wave for everything. Forcing the curve onto sitting-stance techniques and fast connected sequences erases the horizontal and saw-tooth waves the system itself teaches. Check the table before you correct a flat technique: flat may be exactly its assigned wave.

Treating the other lineage as ignorant. WT converts training in ITF rooms often read the wave as sloppiness, and ITF students read WT's flatter delivery as dead technique. Both are systems performing their own standards. The argument survives because each side grades the other by its own rulebook.

Chasing a number. Students ask how many centimetres the head should travel, hoping for a measurement to hide behind. There is no federation-wide figure, and a head path that is right for a tall student's walking stance is wrong-sized for a child's. Judge the curve by the tests above: landing, relaxation, trace, timing.

Section 06The Companion Guide

This article gives you the knowledge and the honest map of the disagreement. The companion guide turns it into training. The Sine Wave Workbook prints the three-wave comparison chart for the wall, gives a self-video check sheet for reading your own head path frame by frame, and lays out pattern-by-pattern application notes for the colour-belt tul, flagging which movements in Chon-Ji, Dan-Gun, and Do-San ride the sine wave and which are taught flat or saw-tooth. It includes a fault-fix table for the bounce, the arm-wave, and the late landing, and a page for recording your own instructor's standard so the book argues with nobody. It is for ITF students caught between two corrections, and for converts arriving from flatter arts who want to learn the motion as a skill rather than an argument.