A properly stacked body’s inherent elasticity will absorb and rebound the force of striking an opponent most effectively in a certain direction.  This is called the body’s power line.  The goal of learning to be stacked and developing our kinesthetic sense is to maximize our ability to generate power in technique and be able to maintain this power line in relation to our opponent at all times.

In addition, we can use ground reaction force to “bounce” out of our frame.  When we compress our weight into the ground, it exerts an equal and opposite force against us, which stretches the muscle-tendon complexes.  This “loading,” as it is called, causes a storage of potential energy.  That energy enables us to spring forward into the opponent as the muscles shorten, or contract, during the “unloading” phase.  Developing this elastic strength is the goal of modern plyometric training. 

These are all aspects of compression.  But, it’s important to always remember that alignment comes first.  Compressing a body that is not properly aligned can lead to injury.  Often, we need to prepare our bodies for more stressful activities through physical therapy or corrective exercises.  Don’t be in a hurry to do the rough stuff.  Your body will thank you, later.

Rotation, or swinging the body around an axis, generates angular momentum.  Some form of compression always initiates the rotation of the body.  And, we rarely use pure angular momentum.  Practical applications will usually combine rotation with body shifting.

Body shifting is the primary method of generating linear momentum and always involves some sort of footwork, either a specific stepping method or, at least, a change in stance.  We use footwork to generate momentum by putting the entire body mass in motion.  The best example of this is Jack Dempsey’s “falling step.”

In the 1950 classic book, Championship Fighting, Dempsey gives a detailed description of punching mechanics.  He divides a punch into two parts:  (a) setting the weight in motion, and (b) relaying the moving weight to a desired point on an opponent with a stepped-up impact or explosion.

Dempsey uses two examples to illustrate the force of gravity.  First, he asks the reader to imagine what would happen if a baby fell from a fourth-floor window and struck a truck driver in the head, standing on the sidewalk below.  Obviously, we would predict serious injury to the man on the sidewalk.  As Dempsey wrote, “Even an innocent little baby can become a dangerous missile WHEN ITS BODY-WEIGHT IS SET INTO FAST MOTION.”

In the second example, we picture a boy sledding down a snowy hill.  The slope of the hill prevents him from falling straight down, but it is still the force of gravity that propels him.  At the bottom of the hill, the boy will continue sledding at a right angle to the straight-down pull of gravity for a while.  This demonstrates that weight-in-motion can be deflected away from the perpendicular.

Dempsey goes on to describe how these principles apply to the performance of his falling step.  When standing with his weight on the front leg, he causes himself to fall by stepping without shifting the weight to his back leg first.  This allows the force of gravity to set his body weight in motion.  He then redirects that motion forward by pushing off the rear foot.

This motion will be conveyed to the opponent as we literally “catch” ourselves by planting our fist in him.  If the momentum is transferred correctly through our power line, we will be able to explode into the opponent with our stacked frame.  This can be considered the “follow-through” part of the technique and has to do with proper timing and distancing.  These we practice by hitting the makiwara or heavy bag…and karate people love to hit stuff, right?!?

My next article will discuss moving rhythmically as a coherent unit centered in the hips to conclude this series on the basic principles of body use.