Lower yourself onto your forearms with your elbows directly under your shoulders, fists lightly closed, and step both feet back until your body forms a straight line from your head to your heels. Hold that line. With your forearms as the base, the angle shifts the work squarely onto your abs - there's no hiding behind straight arms here, just you, the floor, and a slowly growing awareness of every muscle between your shoulders and your hips.

Works: abs and obliques, shoulders, lower back, glutes

Breathing: Breathe slowly and steadily throughout the hold - don't trade breath for tension.

Common Mistakes: Letting the hips sag toward the floor, lifting the hips into a pike as the hold wears on, and sliding the elbows forward of the shoulders.

Make Easier: Rest your knees on the floor while keeping a straight line from head to knees, or break the hold into shorter intervals.

Make Harder: Extend the hold time, lift one foot off the floor and alternate, or rotate onto one forearm into a Side Elbow Plank Hold.