Particular to the martial art of ITF taekwondo is a unique aesthetic called "sinewave". If you have ever seen ITF taekwondo's basic techniques or forms you may have noticed this peculiar way of movement. The practitioner seems to be bobbing up and down during the execution of basic techniques.

The sinewave theory is based on two main principles, namely relaxation and the acceleration of mass behind or into ones technique(dropping your body weight). Basically the ITF practitioners starts their technique in a consciously relaxed state, then lifts their body weight (acquiring potential energy), where after they drop their (accelerated) body weight (employing gravitational and kinetic energy) into the technique.

A typical sinewave motion (called a full sinewave) consists of three phases: Firstly, conscious relaxation (the first downward phase); secondly, lifting the body mass (an upward phase); and thirdly, dropping the body mass into the technique (the second downward and last phase).

In an attempt to get beginners to get accustomed to this way of movement one may often hear an instructor coaching his or her students with "down-up-down; down-up-down". Such a strict bracketing may cause practitioners to move in a zig-zag fashion. This is wrong as it prevents a natural and continuous acceleration throughout the motion. The movement should in fact be a (sine)wave with no stopping anywhere from start to completion. One of the highest goals in perfecting the sinewave motion is to make it as relaxed, fluid and natural as possible.

The wavelength differs depending on the stance or purpose of the technique. The amplitude is sometimes accentuated in forms. The sinewave motion is sometimes inverted, broken into sections (eg. only up-down), and connected so that the last downward phase of the first technique becomes the initial downward phase of the following technique, depending on the purpose of the technique(s). One might even see the implementation of multiple techniques within a sinewave, for example blocking during the upward phase and counter-attacking during the final downward phase.

The sinewave expresses itself also in other parts of ITF taekwondo, not just in stepping motions. For instance when the wrist is grabbed the defender does not meet force with force by resisting. Instead she momentarily moves with the force (the relaxed phase), then change the direction (second phase) before changing direction again (final phase) to perform some kind of release or counter-attack. The aim is to momentarily confuse the neurology of the attacker. Another example is in typical throwing techniques, such as the hip throw. The ITF practitioner first lowers underneath the opponent's body mass, lift up to uproot the opponent, and finally throws the opponent as part of the final downward phase. These examples have much in common with other arts such as Jiu Jitsu, Aikido or Judo.

The basic sinewave is sometimes also expressed as a circle. Imagine drawing a circle by starting on the left side of the page. There are three basic phases. Firstly an arc moving down and towards the right, reaching the bottom the arc continues upwards towards the right side of the page and then it starts to travel left again yet continuing upward. Eventually it will reach the top whereupon it goes down again towards the starting point. Note that there are a downward, upward and again downward phase (down-up-down).

This circular motif is often seen in the motion of different techniques and manifest as ellipses, loops and minute turns. For instance when doing a traditional low block with the forearm, the arm is brought up, but instead of stopping and changing the direction and accelerating toward the target (think of how it would look if performed by a karateka), the arm never stops. Rather, towards the apex of the movement the arm will perform a small circular motion as it changes direction, theoretically keeping some of the already accumulated momentum and then further accelerating towards the target.

In sparring the sinewave is manifested in bobbing. The bobbing in sparring is similar to that seen in western Boxing. The fighter will slightly bend and “bounce” in the knees. This is to ensure that the thigh muscles are relaxed and ready for quick plyometric movements. The perpetual motion, especially when combined with weaving (moving from side to side) and other footwork can add to out-manoeuvre and confuse an opponent.

The typical sinewave motion is uniquely ITF and not trained by other taekwondo styles (except where such styles are offshoots from ITF). It is often appreciated for both its technicality and innate aesthetical contribution.