This is a single move that can be added to any circuit station or bootcamp drill. Go down into a push up position, bring one knee to the chest so you have one leg bent and one leg extended out behind you. Rapidly and repeatedly alternate the legs into opposite positions. Work this with either designated counts (x10, x20 etc.) or timed intervals. Monitor form. Core is to be strong and fixed, no sagging (bouncing) at lower back while performing movement. Otherwise it is to advanced or the participant is over fatigued.
Worked for me and my crew.
Haydn