Why do we practice hollow rocks and how are they any different from, say, planking? While planking is a static position, the hollow rock excels at creating dynamic stability. It’s one of the most important skills for developing strength and for exercising safely with intensity.

Dynamic stability is the body’s ability to maintain form while moving. Usually that looks like keeping a rigid core while the body’s extremities are moving. It’s a technique that’s applicable to a wide array of movements—lifts such as deadlifts, cleans and snatches, of course—but also push-ups, running, rowing, and more. In fact, there are few movements that don’t require at least some dynamic stability.

Hollow rocks help us practice moving our bodies while maintaining a rigid shape. Carl Paoli of GymnasticsWOD.com offers a great example of the ideal hollow rock:

But there are other dynamic stability exercises beyond the hollow rock. Try these out to build dynamic stability along your core and your extremities:

Single-Leg Deadlift

Place a light kettlebell on a platform about six to eight inches off the ground (at mid-shin height). Then, hinge forward at the hip and allow one leg to come off the ground. Using the hand from the same side, pick up the kettlebell, keeping your back straight and your grounded leg steady. This movement is closest to a Romanian-style deadlift. It trains dynamic stability both in your back and in the leg that is on the ground.

Here’s a good video example:

Banded Knee and Ankle Stabilization

If you have shaky knees or ankles, this is a great exercise for building strength and balance. Using a thin band looped around a pole, step one leg inside the band so that it is wrapped at the top of the knee. Create slight tension by stepping away from the pole, then lift the non-banded leg off the ground and bend the banded knee slightly. Balance for 20-30 seconds in this position. Repeat two more times, then switch legs.

Here’s a video example, with ways to make it even more challenging:

Shoulder Stability with Offset Weight

If normal shoulder rehab exercises aren’t doing the trick, this is an advanced movement to develop better scapular stability. You’ll need a hammer or some kind of implement where there is a handle and a weight on one end (we have one of these in the gym). Lying on your stomach on a table or a box, hold the implement in your hand and do a reverse fly motion. The offset weight forces you to maintain rigidity in the rotating muscles in your shoulder and back.

Here’s a visual example of this from physical therapist Mike Reinold:

The more you practice dynamic stability exercises, the better you’ll be able to train with intensity because your body will be equipped to keep good form even when you’re exercising at high intervals or heavier weights. Most of all, just keep doing those hollow rocks!