YOU PROBABLY THINK you know how to do a plank. The ab training staple is relatively simple, after all—boiled down to the basics, all you need to do is get down on the ground and hold in place.

A plank is more difficult than it looks. You have to use all of your muscle groups, including your core, abs, arms, back, shoulders, glutes and legs. It’s normal to struggle to do a plank. Many of my ...

Pilates pro Simone de la Rue demonstrates how to do a plank jack—aka the ultimate cardio and core-strengthening move—with proper form. A little known fact about planks: In addition to working nearly ...

The plank is a simple yet highly effective bodyweight exercise that builds core strength and stability using the benefits of isometric contractions. This foundational move is crucial for anyone ...

The plank is one of the greatest exercises for working a whole bunch of different muscles at once (including those hard-to-reach lower abdominals) with no equipment other than a flat surface. And ...

Unless you’ve been living under a rock for the last five years, you’ve probably heard about the plank — one of the all-time best exercises for strengthening and toning the core. But let’s get real — ...