Day 21 is abs and core with a lot of plank traffic: 5 plank walk-outs, 10 plank rotations, 10 flutter kicks, 10 high crunches and 10 sitting twists. All five in order is one set, up to 2 minutes rest, 3, 5 or 7 sets by level. Two of the five start from standing, which is unusual for a floor card.
A plank walk-out begins on your feet: fold forward, put the hands on the floor, walk them out until you are in a full plank, then walk them back and stand up; that is one rep, and 5 of them is a surprising amount of shoulder. Plank rotations start in a full plank and rotate the whole body to one side, the top arm reaching to the ceiling, then return and rotate to the other; 10 total, 5 per side. After that you lie down: flutter kicks, then high crunches with the legs raised and bent while the hands reach up toward the feet, then sitting twists to finish.
Walk the hands out slowly and keep the hips from sagging when you reach the full plank. In the rotation, stack the feet or stagger them, keep the supporting arm straight and turn the hips with the shoulders, not after them. High crunches lift the shoulders, not the chin, and the reach is toward the feet, not past them. Sitting twists stay tall and turn from the waist.
From standing to plank and back, five times, before the floor even gets a turn.
Make it Harder: Hold the full plank for a 3-count at the end of every walk-out before walking the hands back.
Make it Easier: Bend the knees on the walk-outs and do the plank rotations from a knee-down plank.
