Whap! The noisy authority of a hand meeting the top of a foot in one instant of explosive power and consummate timing; everyone in Kung Fu is familiar with that sound, the loud clap of the performer slapping her own foot just as it peaks in a high kick.

For instance, the slap is meant to be a high, distracting hand gesture coupled with the lower, truer foot attack. But why the stretched palm and fingers? Because, in at least one interpretation, the hand is meant to cover the opponent’s vision long enough for the kick to do its job.

Also, students should be made aware that the downward motion of the slap counter-acts the upward force of the kick lending stability to the action. Slapping does require some stretching and ‘heightening’, because you have to arc the leg back enough for your short arm to match your long leg. (If you can’t reach this height, you can always slap higher on your leg. Foot contact is not mandatory.) But just like a professional football kicker, we kick hard not to hit high—the ball is on the ground after all—but as a follow-through for all that excess power. The ball-kicker can just let his leg fall back to the ground, but for a martial artist the high kick must be reversed immediately, and that’s just what the slap accomplishes: it reverses the kick just as it begins to fall. Also, as far as equilibrium, I add a second aspect to this stabilizing slap: that reaching forward with the hand keeps the back arched forward, counter-acting the common tendency to arch backward and possibly fall.

The third, and key, explanation for the slap is about using it to limit the kick itself. What do I mean?  The classical idea is that the slapping hand defines a border, a limit to your kicking range. Unlike some arts, Kung Fu does not (generally) subscribe to the idea of kicks that reach outside the range of the hands. A kick you cannot slap is a kick over-extended.

When kicks are not over-extended they are far more useable at a closer range. There are important reasons for this.

The first is that the hip and knee can be adjusted to close distance through proper training and postural control. The internal adjustments required to kick and slap help the students develop correct hip placement. People tend to over-stretch as they move the pelvis toward the opponent. This shows the advantage of using the full range of motion of the pelvis.

The next reason echoes the Wing Chun theory that there are times when you should be in both punching range and kicking range. It certainly changes your delivery to realize that you can mix and match punches and kicks because you have proper control of upper and lower body attacks.

Finally, a true Kung Fu kick always includes hand positions as well as leg execution. The reason for this might be called “order of operations.” Traditional Kung Fu sees the kick not as an entry device but as something delivered after hand contact is made; either because the hands created a situation the legs can capitalize on, or because the opponent got away from your hands and you have a parting gift for him.

Even in one simple motion of Kung Fu, such as the kick-slap, there are many layers of meaning and usage. It’s up to the teacher to introduce these ideas at the proper time and place in the training. But it is also up to the student to both play with and ponder on the motions he or she is practicing so diligently.