Footwork is arguably the most important aspect of our Xing Yi training method, it is what saves you from being hit full on, draws the opponent into your range and allows you to enter to punish the opponent with your own strikes. I emphasise footwork and positioning over almost all other training exercises as it the most applicable to immediate gains in fighting ability.

I just came across a quote from Jack Dempsey’s Chamionship Fighting that seems very close to some of the stepping methods we use and it is always interesting to compare methods expecially across arts and styles

The Falling Step

(From a left lead stance with weight on the left foot) “You unquestionably will be tempted to shift some of the weight from the left foot to the right foot just before you step. But don’t do it. Do nothing with the right foot, which is resting lightly on its ball, NO PRELIMINARY MOVEMENT! Just lift the left foot and LET THE BODY FALL FORWARD IN A LONG, QUICK STEP.

The left foot should land flat and solid on the floor at the end of the step. It is a quick, convulsive and extremely awkward step. Yet, it’s one of the most important steps of your fistic life; for that falling-forward lurch is the rough diamond out of which will be ground the beautiful, straight knockout jolt. It’s the gem movement of straight punching.”

Very similar to our method of stepping which uses the shift of the body weight and fall with gravity rather than pressing hard into the ground to create a pushing force. Dempsey explains the right foot acts as a spring or trigger, but rather than pressing and pushing the body forward he is suggesting the roll of the ball of the foot aids in propelling the body mass forward due to the action of gravity, not the action of the leg into the ground.

Continuing to read the section and we see this quote

“The solidity with which your left foot landed upon the floor was caused by your momentum. The late Joe Gans rarely missed with a long, straight punch; but, when he did you could hear for half a block the smack of his left sole on the canvas”

This describes the effect we call “Thunder Sound” which implies whole body unified movement and is expressed when that movement is stopped by the foot landing on the ground, making a loud audible thud which echoes into the ground (not a sudden sharp noise from stamping down with the foot). For us the thunder sound is a result of the coordination of the body movement and connection of the mindset (use of the 3 external and 3 internal harmonies).

See Dempsey’s full book here, the falling step and theory of punching with it start from Section 7 through 8 (page 10)
http://www.e-reading.club/bookreader.php/107333/Vzryvnoii_udar_i_aktivnaya_oborona.pdf