Stacy Clifford
'The critical problem with performing martial arts techniques slowly is that without the right frame of reference, the mechanics of the motion are not an accurate predictor of how your body will move at higher velocity. The mass of your body, limbs and weapon move in very specific ways at different speeds. When moving with low speed and low force, small steps are the default, one foot can always remain in contact with the ground, and weapons or body-parts that clash are more likely to "stick together" in a position of mutual equilibrium. At a more athletic pace like three quarter speed, limbs stretch out more, the center of gravity shifts farther, both feet may conceivably leave the ground at some point, and the opposing forces of weapons are much more likely to be unequal, and the rebound forces much higher, requiring greater effort to maintain control or change direction. Each person's body will move differently in response to these forces according to his proportions—a stout, massive body can achieve the same force with less stretching and speed than a light, lean body, but sacrifices distance and time by doing so. Athleticism is an inseparable component of martial arts, and only by moving athletically can you get a true sense of the relative physics involved. The same is true for the perceptual component, where detecting and responding effectively to threats must occur in an instant.'