Day 5 gets you off the floor entirely. Three standing exercises run back to back before you rest: 8 march steps, 8 knee-to-elbows and 8 side leg raises. March steps drive alternate knees up to hip height with the arms working alongside; knee-to-elbows put the hands behind the head and bring one knee up to meet the opposite elbow across the body; side leg raises lift a straight leg out to the side while the other leg holds you up.
Standing changes what your abs are for. On the floor they curl you up against gravity; upright they have to keep your trunk stacked over one leg while the other one moves. March steps set the rhythm and start the hip flexors working. Knee-to-elbows add rotation to that, so the obliques have to fold the body diagonally rather than straight forward. Side leg raises take the movement out sideways, where the trunk has to resist leaning away from the lifting leg. Three planes of movement, one balance problem running underneath all of it.
Stay tall the whole way through. On march steps, drive the knee up rather than dipping the chest down to meet it. In knee-to-elbows, the rotation comes from the ribs turning, not from the elbow chasing - keep the elbows wide so the twist has to be real. On side leg raises, resist the lean: the standing leg holds the line while the lifting leg goes out on its own, and lifting a little lower with a straight body beats lifting high and folding sideways.
Same abs as yesterday, entirely new problem - and the floor is not there to help you.
Make it Harder: Rise onto the ball of the standing foot for every side leg raise and hold it there until the leg comes down.
Make it Easier: Meet the knee halfway on knee-to-elbows - bring the elbow down toward it rather than driving the knee all the way up.
