Before you launch into the advanced ab workout, you will want to ease into it with some basic core exercises to warm up the abdominal muscles. The Plank is a great way to begin. The plank provides a simple and effective core warm-up because engages all the muscles of the core from your toes up to your head. Holding the plank requires the activation of all the major ab muscles as well as many stabilizer muscles that are often ignored.
Why it made the list: There are many reasons to like leg raise variations, but one is their scalability. You can start doing bent knee raises in the Roman chair or ab straps to focus on the lower core, work up to straight leg raises, and then move to a hanging bar. By the time you can do full straight-leg toes-to-bar raises, your entire core will have strength for days.
Lie faceup with feet flexed in the air so body creates a 90-degree angle and arms are rested palms down at sides. Use core to pulse legs straight up towards ceiling, lifting butt off floor and pushing weight into hands. Think about stamping the bottom of your shoes on the ceiling and avoid using momentum to swing legs forward and up. Lower back to floor and repeat.
To do it: Stand with your feet planted 3-4 feet apart, toes slightly turned out, hands on your hips. Lower into a plie by bending your knees out over your toes and lowering your hips directly underneath your shoulders. Then, as your straighten back up, slowly lift the right knee up towards the right shoulder. As you go back into the plie, slowly return the foot to the floor. Be sure to move at a very controlled pace to really engage the obliques the entire time—on the way up and on the way down. Do 10 repetitions on the right side, then another 10 repetitions on the left side for a total of 20.