The figure eight is a great way to mix up a stale abs routine. This weighted move puts your entire core musculature — rectus abdominis, obliques and your deep transverse abdominis — to the test, helping you to burn more calories while strengthening your midsection.
TARGET: Entire core musculature
START: Sit on the floor with your knees bent, holding a medicine ball in front of you. Lean back slightly and lift your feet off the floor.
MOVEMENT: Bring your left knee toward your chest while straightening your right leg. Pass the medicine ball under your left leg, then bend your right knee toward your chest while straightening your left leg. Pass the medicine ball under your right leg. Repeat for 30 seconds.