Many people think of dancing to music only as stepping on the beat, but there are much more to it. Dancing with cadencia, for example, is also a part of the equation. Cadencia refers to the swing of the body in correspondence with the rhythm and speed of the music. In other words, dancing to music involves not only timing the steps, but timing the swings of the body also. Cadencia is one of the key techniques in tango that is essential to the dance but often being overlooked.
Imagine, now, that your leg does not start from the hip but from the chest, that is, imagine everything below your chest is your leg. The chest is where you and your partner connect in the embrace. It can serve as a fixed point to swing everything below it as a whole. That way, not only the line of your leg looks long, but your whole body looks tall and elegant as well.
To swing the three sections of the body as a whole elegantly, you need to keep your body tall and in tone. A soft ribbon cannot swing well. If your body is like a piece of spaghetti, it won't work either. You need to keep your body taut as you swing it, imagine it is a pendulum with weight at the bottom, and you imitate the pendular motion to swing the body to and fro in the dance.
The following example illustrates this technique: