This is the 2nd of 3 phases in the step. It is the mid-part of the step for Lead or Follow. Regardless of whether this is a Forward, Side, and Backstep, all steps have versions of this idea. In the Perihelion phase the Leg fully extends, and the knee ‘pops’, meaning that it elongates and fully straightens out. This phase only happens for a moment or two in the entire step, even in the Long Step idea. 🙂