Big or small movement?

Bruce's fist may have started just one inch from the target, but look at the hip extension!

Bruce Lee was famous for a technique called “The inch punch”. By holding his hand just one inch from the target, he could hit with enough force to knock a grown man across the room. The same concept was used by The Bride in her escape from the grave in Kill Bill part 2.

There are some people who say that such feats are about channelling chi (body energy) through a single point, but I prefer a more rational scientific argument, which is that the Inch punch was about focusing all of his muscles and power through his punch by the use of subtle body movement, and muscle contraction, and of course, by using his hips...

In class, when punching on the spot in forwards stance, we usually practice hip movement by turning fully off to 45 degrees, then squaring up for a strike (or by starting square and turning off to 45 degrees for a block). However, you have to ask, is this amount of turning realistic, or is it simply an exercise done to make students aware of their hips?

Returning to our formula for force, (force = mass times acceleration) the greater the distance travelled in the same amount of time, the greater the acceleration. By the same token, the greater the distance you travel whilst continuing to accelerate, the more force you can exert at the moment of impact.

Your hip rotation is generated by three major actions: twisting the torso using the stomach muscles, pushing with the foot, and straightening the leg.

In a shorter, more upright stance, the leg contributes almost nothing to the hip rotation because the straightening action delivers motion upwards, not forwards. Most of the movement in this stance is generated by abdominal rotation. Because you reach maximum hip acceleration very soon after you start turning, the majority of the journey is performed at a uniform speed. The longer the distance at uniform speed, the lower the overall acceleration. Thus, the shorter the journey, the quicker the hip will arrive, and the greater the acceleration, and the force. Therefore, it makes sense to reduce the distance the hips have to move if you stand in a short stance. This is the underlying principle employed by styles that fight from a relatively upright stance, such as Wing Chun.

To achieve smaller hip movements, you work on a process called minimisation – eliminating unnecessary movements from your strikes. Bruce Lee equated martial arts to the process of making a sculpture out of marble. You start with a big lump of rough marble then chip away all that is unnecessary. Likewise in karate, we often start with big movements and reduce them until all we are left with is the bare minimum required to do the job. This assists recovery time and speeds up our techniques.

In your karate, your goal is to chip away at the unneccesary, to leave just the functional

Knowing this, you can understand that there must be an optimum amount of hip movement that delivers maximum acceleration. This will be different for each person, according to the size of his or her body, and the strength of his stomach and abdomen muscles, as well as the effectiveness of his technique and his timing. However, I believe (based on nothing more than intuition and observation), that this distance in an arc, is no more than 3-6 inches, which probably represents no more than about 15 degrees of hip rotation.

However, when you lower and lengthen your stance during delivery, the straightening of your back leg contributes additional motion to the equation. The amount of travel required to move from a bent leg, to a straight one, now dictates the optimal amount of hip rotation, assuming the body achieves maximum acceleration at the moment that the leg locks out.

The hip movement can now be divided into two phases. The initiation comes from the floor, and is comprised by a simultaneous plantarflexion (pushing) of the foot, and extension of the knee. This creates a large movement that accounts for the majority of a 45 degree hip rotation. The second phase, which overlaps the completion of the first phase, is rotation of the torso. This creates cumulative acceleration, that ensures maximum power at the moment of impact.

Interestingly, you can still apply the principle of minimisation to the second phase of the movement, to maximise the acceleration still further.

It’s worth remembering that a low, long stance is simply where you end up as you deliver the punch. Boxers and mixed martial artists are masters of powerful punching (they hit much harder than karate ka in general), yet they only really adopt a long stance whilst lunging, quickly returning to about 1 – 1.5 shoulder widths for moving around.

We adopt long stances during training for their muscle-building benefits, which develop the very muscles needed to move quickly forwards in shorter stances.