The Sin wave is a technique used in ITF. Older oractitioners may know it as the hip flick or drawing the circle on the wall. The basic concept behind the Sin wave is that there are 3 levels - Low, Neutral and High The Sin wave starts when you get ready for the attack, say a middle section front punch, as you rise you bring the reaction hand back and start to prepare to execute the punch when you are at 'high' You then drop all your weight back into the neutral position whilst giving the punch. This is said to add power to the punch and should be mastered.