Day 36 upgrades the anchor. For eight abs sessions the supine days have been built on crunches; from today they are built on sit-ups, and that change holds for the rest of the program. Four 15-second intervals - sit-ups, reverse crunches, sit-ups, sitting twists - three, four or five sets with a minute of rest.
A sit-up is a crunch that keeps going: instead of curling the shoulder blades off the floor and stopping, you come all the way up until your torso is upright. It brings the hip flexors into the movement and roughly doubles the range, which is why it arrives now rather than on Day 4. The reverse crunch works from the other end - knees drawn in and hips curling up off the floor - so the session covers the abdominal wall from the top down and the bottom up before the sitting twists finish with rotation.
Come all the way up on the sit-up and lower under control rather than dropping back; the way down is where most of the work goes unclaimed. On reverse crunches, lift the hips with your abs rather than swinging the legs for momentum. Keep the feet hovering through the sitting twists.
Same position on the floor, twice the range - the abs days just grew up.
Make it Harder: Cross your arms over your chest for the sit-ups and take three full seconds to lower back down on every rep.
Make it Easier: Keep the crunches you know for the first and third intervals and leave the rest of the session as written.
