This subject can be quite complicated, and also controversial, so I have tried to explain it in simple terms. Whilst it is important that we understand the principles, never lose sight of the most important thing - that your techniques work effectively!
It cannot be stressed enough to allow the beginning student to move naturally first and get a feel for the movements rather than bombard them with scientific and mathematical concepts of 'Sine Wave'.
Knee-Spring (or 'Sine-Wave', or "Down-Up-Down")
History: The basis of this motion is a concept often referred to as 'Sine Wave', because General Choi likened the motion to a mathematical sine wave in the 1970's, which is an oscillating up-and-down motion.
'Knee-Spring' is a better description, and the one we will use, because it describes what is happening - i.e. using the knees to 'spring' from one position to another (this does NOT mean bounce!). It is actually the natural way a human body moves from one point to another. Perhaps we could say we are 'springing into action'.
Important: Though the 'down-up-down' motion of Knee-Spring is often exaggerated to make it clearer, in practice the motion should be slight, not exaggerated.
Knee-Spring is characterised by a down-up-down movement (as seen in the diagram above, and why General Choi likened it to a Sine Wave).
- Down - Relax: we relax so we can start to move more quickly (accelerating), and in so doing we drop slightly because we flex our knees as we relax. This is a subtle movement. At this point we are compressing the knees like a spring. We move our arms to the 'neutral' position in front of the chest, still relaxed.
- Up - flowing into the movement: We are now accelerating into the technique and have released the compression of our knees, which is why we rise up, creating potential energy. We continue accelerating towards the target in a flowing motion, chambering our next technique - i.e. move hands/feet to the point where we are ready to unleash the block/attack.
- Down - Power: this is the point where everything comes together and we deliver an effective technique! We have reached full acceleration (speed) at the moment of impact with the target. We use our reaction force to achieve more speed. We exhale (breath-control) to maximise our body-weight (mass) and bring everything together, using kinetic energy and (to a small extent) gravity. We are balanced. We use the correct blocking/attacking tool, concentrating on the correct target.
When trying to describe this process, I often think of a wave breaking onto a shore when the power is unleashed... a smooth motion, not a jagged saw-tooth motion.
In order to understand the purpose and correct application of Knee-Spring, I suggest you review the Training Secrets of TaekwonDo, and take a good look at the Theory of Power.
Unfortunately, some TaekwonDo schools over-exaggerate the 'Sine-Wave' motion, forgetting the most important part of any technique, which is that it should work in a real situation! Over exaggerated Sine-Wave motion slows us down, which is the exact opposite of the most important part of delivering a technique that works - speed.
To emphasise the point:
- Knee-Spring (Sine Wave) should be a natural movement, not a forced or conscious action.
- The focus should be on the technique you are about to execute and focussing all your power into the blocking or attacking tool.
- During a ‘normal’ or regular stepping motion, Knee-Spring is generally created by the relaxation of the leg muscles at the initial stage of the technique’s execution, whether it be whilst stepping or whilst stationary.
So, hopefully we now understand how to move from one technique to the next properly, and the basic principles of why we use a Knee-Spring to do so.
But there's more!
There are various 'types of motion' used in Patterns to describe different ways to deliver techniques; it is useful to learn these and to understand why we use them.
Please refer to the table at the bottom which summarises the use of Knee-Spring in each type of motion.
1. Normal Motion - This is the most common execution of a technique utilising the principles (or training secrets) of TaekwonDo. Techniques are executed one at a time, using a full Knee-Spring, culminating with a single breath-control at the end of each movement when the power is applied.
Example: All movements in Sajo-Jirugi, Sajo-Makgi and Chon-Ji use this motion.
Summary: 1 technique, 1 Knee-Spring, 1 breath
2. Continuous Motion - We see this first in Dan-Gun tul. In movement numbers 13-14, we execute a left outer-forearm low block followed by a left outer-forearm rising block in a continuous motion -meaning the two techniques are executed with a single count, with one continuous breath-control (which lasts from the beginning of the first movement until the end of the second movement). There is a full knee-spring for each movement.
In reality, the long breath is accentuated on the power application for each technique; it may be helpful to say "one and.... two" when practicing this type of motion, accentuating the 'one' and 'two'. So in Dan-Gun 'one' would be the low block, 'and' would be the relaxation/re-chambering between techniques, and 'two' would be the rising block.
Purpose: Continuous motion always starts with a block. The main reason for using this kind of motion is to allow an instant response to an attack, by either blocking the next technique or delivering your own counter attack.
Summary: 2 techniques, 2 complete knee-springs, 1 continuous breath (accentuated on the power)
3. Fast Motion - This consists of two movements executed by a single count, performed 'with urgency' (but not rushed). This differs from continuous motion because there are two breath-controls and a 2/3rd knee-spring between movements: i.e. there is no 'relax' downward movement between the techniques. This motion is used in movement numbers 15-16 and 19-20 of Do-San tul and 2-3/5-6 of Yul-Gok tul (middle punches).
Purpose: to deliver two techniques effectively, as fast as possible. For example, if you have a clear target such as the floating ribs, and are in position to deliver a punch, then two punches delivered in fast motion will be more devastating. So you don't want a pause (relax) between the two punches!
Summary: 2 techniques, 2 knee-springs - but 2nd is only 2/3rds, 2 breaths
4. Slow Motion - Slow motion techniques require an incredible amount of balance, breath control and timing - which is why they are used as a training exercise! We are introduced to this motion in Joong-Gun tul. The pressing blocks and turning punch in Joong-Gun are both executed in slow motion. Everything has to come together simultaneously when performing this motion correctly, which is why it is so challenging. In more advanced patterns, kicking techniques are required in slow motion thus adding to the difficulty of the movement and pattern.
For most slow motion techniques, use a count of 4 seconds ("one and two and three and four")
Purpose: Developing balance, breath control and timing.
Summary: 1 technique, 1 knee-spring, 1 breath-control (all performed in slow motion)
5. Connecting Motion - This motion differs from the others because it involves two movements with only one breath-control and one knee-spring. The movements are linked (connected) to each other. Hence, only one breath-control, which is emphasised at the end of the second movement, and one knee-spring is used for each count.
We first see this in Yul-Gok tul, moves 16/17 - palm hooking block followed by reverse punch. The first movement - the palm hooking block - is delivered on the 'up' part of the knee-spring used to move us from the previous technique; the reverse punch is then delivered during the 'power' downward movement. Therefore this is only considered a 1/3rd knee-spring.
There is no pause between techniques. It is usually impossible to determine where one technique ends and the next begins.
Purpose: Connecting motion is always with two movements using opposite arms. One reason for using this kind of motion is where one technique ‘sets up’ the opponent for an immediate attack.
Summary: 2 techniques, 1 knee-spring, 1 breath-control (at end of 2nd the technique)
6. Natural Movement - Although not technically considered a “motion”, this type of movement describes techniques that are 'neither fast or slow'. They do not require a 'snap' or powerful finish. The execution of the movement can be compared to the motion of picking up a pen or raising your arm. For example, moves 1 and 4 in Yul-Gok, and the hooking blocks in Kwang-Gae are examples of this type of motion. Also, the first movements in Connecting Motion are performed as a Natural movement (e.g palm hooking block/reverse punch in Yul-Gok).
Conclusion
Remember, Sine-Wave/Knee-Spring/Down-Up-Down is not power in itself, it merely contributes along with hip torque, breath control, reaction force, timing, acceleration, concentration, co-ordination and force summation.
Force Summation:
In humans, the production and combination of forces from different parts of the body to work together at the same time. From: simultaneous force summation in The Oxford Dictionary of Sports Science & Medicine
This table summarises the use of Knee-Spring in each type of movement:
| Type | Knee-Spring | Motion | Breath-Control | Movements |
|---|---|---|---|---|
| Normal | Full | down-up-down | 1 breath-control | 1 |
| Continuous | Full | down-up-down | 1 breath-control | 2 |
| Fast | 2/3rds | up-down | 2 breath-controls | 2 |
| Slow | Full | down-up-down | 1 breath-control | 1 |
| Connecting | 1/3rd | down (power) | 1 breath-control | 2 |