Day 20 splits its time between big jumps and the floor. The circuit is 20 split jacks, 20 butt kicks, 20 split jacks and 20 plank leg raises - straight through for a set, 2 minutes rest, 3, 5 or 7 sets by level. It is the first day where the split jack, rather than a running exercise, frames the circuit.
Split jacks open and return: from a staggered stance, jump and switch the legs so the other foot lands forward, the opposite arm reaching up each time - 10 landings per side in each block, 40 in a set. Butt kicks between them keep the legs running while the intensity drops slightly from a scissoring jump to a run in place. Plank leg raises are the new finisher: in a high plank with hands under the shoulders and body straight, lift one straight leg a few inches off the floor, lower it, then the other, 10 per leg. There is no jump and no run in it - it is a plank held while the legs move one at a time - and after 40 split jacks that stillness is its own kind of hard, because the glutes and lower back have to keep the hips level while the shoulders hold everything up.
Land every split jack with soft knees and the front knee over the ankle, and get a full reach overhead. Butt kicks light and quick. In plank leg raises, lift the leg with the glute rather than by arching the lower back - the hips should stay square to the floor and the leg only needs to come to hip height, not above it. Keep the head in line with the spine.
Forty scissoring jumps and twenty quiet leg lifts in plank - the legs jumped for most of it and held still for the rest, and both were work.
Make it Harder: Hold each plank leg raise at the top for a full count with the glute squeezed before lowering.
Make it Easier: Do the plank leg raises with the hands on a raised surface such as a step, so the plank is less steep.
