Ab exercises typically fall into one of two categories. The first involves some kind of trunk flexion. Sit-ups and knee tucks are two of the most common examples.

The second category finds the abs utilized in a stability/anti-extension role. The plank is probably the best-known example.

Ab wheel rollouts, however, work both functions: They involve flexing and extending the trunk, but the abs must also work in an anti-extension capacity as you roll the wheel away from your body. As your body gets closer to the ground, the leverage becomes less favorable, and it becomes more challenging. Ease in gradually.

You need to build a proper foundation of core strength before practicing rollouts, and it helps to have a decent amount of upper-body strength.

If you think about it, the upper-body movement of the ab wheel rollout is a lot like a pullover. And, because the lats, pecs, triceps, and the entire upper body all play a part, it's difficult and downright incorrect to think of it solely as an abs exercise (although it'll torch your abs).

Given all that, ab wheel rollouts aren't the best choice for a beginner. They require a baseline of strength and an understanding of how to properly brace your body – things most beginners lack.

Before you try the rollout, build up to it by mastering a gymnastic hollow-body hold. Work at it until you get comfortable holding that position for a minimum of 30 seconds.

To do the hollow body, lie flat on your back with your arms in the air overhead and your legs and feet about an inch or two from the floor.

Tuck your chin towards your chest, crunch your upper body slightly upward, and don't let your lower back come off the ground. Your lower back, mid-back, and glutes should be the only parts of your body touching the floor.

If this isn't possible for you yet, practice the same movement but with your knees bent while maintaining that strict contact between your low back and the floor. Over time, you'll be able to work towards straightening your legs.

Once you can hold a strict hollow body for 30 seconds, the next step is to practice kneeling rollouts.

1. Begin in an all-fours position while holding the ab wheel beneath your chest.
2. Roll the wheel away from your body as you pivot from your knees, bringing your hips and torso down toward the ground as you extend your arms overhead.
3. Try to reach your arms completely overhead with your elbows locked and your torso hovering an inch or two above the floor.
4. Pause briefly in the bottom position, then roll the wheel back to the start position.

Focus on maintaining that same flat back position you mastered in your hollow-body hold. Don't leave your hips too high in the air, and don't let them sag, either.

The lower you bring your torso to the ground, the harder it becomes to maintain proper alignment, so feel free to start doing the movement with a partial range of motion.

A small amount of spinal extension may be unavoidable when your body is fully extended, but anything more than a few degrees is too much. Remember, people sometimes hurt their lower back by going too far, so be careful.

Work up to 20 consecutive kneeling ab-wheel rollouts with a full range of motion before you begin working toward the full-standing rollout.

The standing rollout may very well be the most intense ab exercise available, and it takes a lot of strength and control to perform even a single rep. Give it the respect it deserves.

Start by just working the negative. You can even drop to your knees partway through if you can't do a full negative. Remember to maintain that same full-body tension you learned by doing the hollow-body hold.

Eventually – if you're patient and put in the work – you'll even be able to reverse the movement pattern and come back up to a full standing position.

Since rollouts involve a lot of upper-body muscles, do them on the same day as your other upper-body exercises. If, however, you're doing a split with more than one upper-body day, do them on whichever day you see fit.

Begin by doing them once per week. They may leave you sore for a while. As you get better conditioned, start to practice them more frequently.

Once you're ready to approach the standing rollout, treat it almost like a one-rep max. Give yourself plenty of rest between efforts, and don't practice them too frequently.

As you gain strength and control, you can eventually do them more often and work toward performing multiple reps at a time.