Muscles worked
The hollow rock builds on the hollow hold but adds movement. Your abs hold the rounded shape, and as your centre of gravity shifts with every rock, the load keeps changing, so they must adjust their tension without the shape giving way. Keeping your legs raised and arms overhead also works your hip flexors, quads and shoulders. It is common in gymnastics and CrossFit for building the tight body needed for hanging exercises and handstands.
Common mistakes
- Your arms and legs create the rock. Kicking your legs or throwing your arms changes your body's shape. Let the rock come from tipping your whole body as one unit, rather like the runners on a rocking chair.
- You hold your breath. Breath-holders tend to lose their shape late in the set. Take short breaths in time with the rock without letting your abs go.
- You roll crooked. If one leg or arm sits higher than the other, your body tips to the side. Keep your legs together and your arms equally far out, so the rock runs straight.
Variations and alternatives
- The hollow hold is the step before: hold the position still until you can manage about half a minute before you start rocking.
- The V-up uses the same long body but folds it into a V on every rep.
- The V-sit hold is another balance position on your bum and works well for variety.
Sets and reps
The hollow rock is counted in rocks or time. Three to four sets of 10 to 20 rocks, or 15 to 30 seconds, suit most people. End the set when your body starts to flatten at one end. How sets and rest work together is explained in the guide to sets and reps.
Make it harder by stretching your arms and legs further from your body, or by adding rocks to each set. That gives you progressive overload when your body is the only resistance. A few short sets also fit at the end of a session or in your warm-up before hanging exercises. If your lower back hurts, rather than your abs simply working hard, stop and have a doctor or physiotherapist look at it.