Kicking High or Low: The Forces and Risks Involved
Kicks – High or Low: The Forces, and Risks, Involved
As a self-defense orientated art, techniques should be judged on their effectiveness for survival in combat. Ideally, techniques should allow for delivery in unfavorable conditions such as difficult terrain, inclement weather, icy ground or fighting while wearing restrictive attire that limits movement. Originally kicks were therefore taught to break or dislocate joints, disable knees, sweep away legs or ‘go for gold’. (The Japanese term for a kick to the groin is ‘kin geri’. Kin here means gold—as in gold jewels.)
In the past two decades many martial artists have been drawn towards performances where high kicks are considered impressive. Indeed in some particular styles or competitions techniques demonstrating highly developed gymnastic abilities appear to be judged favorably and may score the same as, or higher than, those that are probably more effective. There are definite benefits in developing agility and having a wide range of techniques. Training in kicking high is useful, being able to kick the head of an opponent opens up potentially vulnerable areas, but what are the differences that need to be acknowledged between high and low kicks? What are the risks and disadvantages of high kicks that the martial artist should understand when fighting for real? What lessons can be learnt by kicking a real target, such as a punch bag or makiwara, rather than just fresh air?
(a) Stability during the kick
It is fairly clear that when a kick is delivered directly into the target with only a horizontal component then the reactive force, the force pushing back, is also only in the horizontal plane. This is shown schematically in the book “Parting the Clouds”.
A high kick, however, is directed upward rather than only in the horizontal direction. This gives the force line two components, one horizontal (going forward) and one vertical (going upward). The angular sum of these two components provides the resultant force moving along the line of the kick. This is outlined and sketched in the book “Parting the Clouds”.
This upward vertical component has consequences; the strike can ‘ride-up’ the target, rather than penetrate, and the upward motion can try to take weight off the supporting leg, making it more difficult to remain ‘grounded’ and stable. You can experiment and feel these effects. Stand opposite a wall and with a slow front kick push against the wall; firstly with a mid height kick where the leg pushes horizontally. In pushing against the wall, and feeling the wall pushing back, you will notice the forces on the heel of the supporting foot, trying to push you backwards. If you try this wearing socks and no shoes, on a polished wooden floor, you can easily make the supporting foot slide backwards. With the supporting leg sliding back, the tendency is for the upper body to lean forward, towards the target.
Now, if you are flexible enough, take the kicking foot high onto the target wall and feel the difference in effects. Become aware of how ‘pushing in’ with the body tends to cause the kicking foot to move higher, and as the foot moves higher the static stability is reduced, with the upper body now starting to want to rotate away from the target. You can begin to feel the supporting foot being un-weighted. The higher the kick, the closer the center of gravity of the body is to being under the supporting foot, rather than being further forward of this point, towards the target. This is an example of a ‘turning moment’, where the forces act about an axis of rotation, in this case the axis being at the contact point between the floor and the supporting foot. (Note that to see forces in action just kick or punch a helium balloon around and watch the directions of movement when it’s struck.)
The ‘turning moment’ experienced by such a structure has a force trying to ‘knock back’ or more accurately rotate the kicker. This turning moment is proportional to the force applied and the height of the kick; as explained and drawn in the book “Parting the Clouds”.
The height here is the distance of the kicking foot from the ground level: The higher the kick the greater the turning moment trying to ‘flip’ the kicker. This can also be felt in training. Attempt to do high kicks on a polished, wet or slippery floor and you become very aware of the risk of slipping and falling on your back: During sparring it becomes easier to over extend and ‘lose’ the standing leg. This is another applicable point of caution for self-defense on the streets.
In summary, that impressive head high kick displayed in the training hall may not be so easy or effective in real life circumstances. Faced with a nasty surprise on the street, with no warm-up prelude or stretching, wearing restrictive clothing, perhaps with a full stomach and maybe even the effects of wine or beer on the system, it is best to keep it simple, keep any kicks low. There are always exceptions but in my view head high kicks are generally not recommended in the real life (or death) circumstances of the street. Section 6 of the book “Parting the Clouds” deals with front thrusting kicks and makes the comment that from a force delivered perspective these kicks are most effective at about mid section height or below.
(b) Penetration of the kick:
It has already been noted that with a horizontal kick there is no vertical force component hence there is nothing that prompts the kick to slide up the target rather than penetrate. The high level kick, on the other hand, has a significant vertical upward component, which makes it more likely that the kick will glance off the face of the target. For kicks below the horizontal line the non-horizontal force components are downward, into the target, with obvious advantageous consequences. The kicker is more likely to penetrate into the target and there is less of a ‘turning moment’ that can cause the kicker to be uprooted or un-weighted.
A classic front kick has been used in this section to illustrate the effect of kicking height levels. Very similar comment and analysis applies to other straight-line kicks, such as a thrust kick or straight-line back kick. A slightly different analysis applies to round or turning kicks such as the roundhouse kick or spinning back kick. The points about penetration, however, basically remain applicable to a roundhouse or round kick. At the point of impact you want the kick to be at least horizontal and preferably pointing down and into the target. This is a learning point; all too often the desire for a higher kicking range causes the technique to be sacrificed and thereby result in the kicking foot pointing upward. A lower roundhouse kick to the opponents’ ribs or knee can be more penetrating and thereby more effective. In a case of self-defense, a roundhouse kick to the head is tempting because of the vulnerability of the opponent, but it is more risky and for those of us that are mere mortals it is probably better to kick low.