Day 5 opens the second cycle and puts your waist in charge. The circuit is knee crunches, heel taps, knee-in and twist, and sitting twists - four exercises, 30 seconds each, two minutes on the clock. Two are done lying down and two are done sitting up, and rotation runs through nearly all of them.
The design here is oblique work approached from four different postures. Knee crunches bring the knees and the chest toward each other from a face-up start, closing the body from both ends at once. Heel taps keep the shoulders lifted and the feet planted while you reach side to side toward each heel, which is a small movement that the side abs feel immediately. The last two shift you upright: knee-in and twist has you leaning back on your hands and drawing the knees in with a rotation as they arrive, while sitting twists balance you on your seat with the feet off the floor, rotating the hands from one hip to the other. Sitting up removes the floor's support, so your core has to hold the position and produce the movement at the same time.
In knee crunches, meet in the middle - the knees travel toward the chest as the chest travels toward the knees. During heel taps, keep the shoulder blades off the floor the whole time; if they touch down, the obliques get a rest they have not earned. In knee-in and twist, keep the chest tall rather than collapsing backward. In sitting twists, lean back just far enough to lift the feet and turn from the ribcage, not the arms.
Every exercise today happens through rotation - your waist is doing the steering.
Make it Harder: Extend your arms straight out in front of you through the sitting twists instead of keeping the hands close to your body.
Make it Easier: Rest your fingertips on the floor behind you during the sitting twists and let your heels stay down.
