If you want rock solid abdominals then you should be all about the Plank.
As far as exercises go, you get the best bang for your ab-rocking buck with planks because it is considered an exercise that engages multiple muscles.
7 reasons to get excited about doing planks
For being a basic isometric exercise, planks strengthen your entire body—they make your core pop, strengthen your lower back, and build your shoulders.
The longer you can hold the plank, the more resilient your lower back will be to injury.
Planking exercises have a great impact and improvement on your posture.
You’ll decrease your risk of injury in the back and spinal column.
You’ll improve your overall balance.
Planks require a small time investment on your part, and offer the chance to achieve substantial results in a relatively short span of time.
Best perk of all...you don’t need any equipment.
Ask your P/oP instructor for their recommendations and tips for conquering the plank.
You’ll be better for it, guaranteed.