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Abs

Hollow Rock

The Hollow Rock is a strength exercise with no equipment for your abs. Share of the load in the Zulta muscle model: lower abs 29%, upper abs 29% and obliques 19%.

Level: IntermediateEquipment: BodyweightMulti-joint (compound)

How to do it

  1. Lie on your back and lift into a hollow hold: arms overhead, shoulders and legs off the floor.
  2. Lock the shape so the body is one rigid curve.
  3. Rock back toward the shoulders, keeping the shape.
  4. Rock forward toward the hips without letting the curve open.
  5. Keep rocking in a smooth rhythm for the set, then lower to the mat.

Tips

  • Drive the rock from the whole body, not by kicking the legs or throwing the arms.
  • Keep the lower back rounded into the floor at every point.

Common mistakes

  • Bending at the hips so the body folds.
  • Letting the feet or head touch the floor.
  • Opening the shape as the rock slows down.

Muscles worked by the Hollow Rock

  • Lower abs Primary29%
  • Upper abs Primary29%
  • Obliques Secondary19%
  • Hip flexors Secondary9%
  • Gluteus maximus Stabilizer6%
  • Spinal erectors (lower back) Stabilizer4%
  • Quads (rectus femoris) Stabilizer4%

Share per muscle in the Zulta muscle model. The model spreads the load of one rep over 40 muscles, based on EMG and biomechanics research.

Lying on the back with arms and legs lifted. Holding the body straight against gravity is anti-extension: rectus abdominis and the obliques brace, with the shoulders, glutes and hip flexors holding the position.

Hollow Rock alternatives

Same equipment

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Similar exercises

Frequently asked questions

What muscles does the Hollow Rock work?

Mainly the lower abs and upper abs. The obliques and hip flexors assist.

Is the Hollow Rock good for beginners?

The Hollow Rock is rated intermediate. If you are new, learn the Dead Bug first and build up from there.

What is a good alternative to the Hollow Rock?

For example the Weighted Hollow Body Hold, Dead Bug (Band) and Weighted Plank. They train mostly the same muscles, some with different equipment.

How do you make the Hollow Rock harder?

Add weight or reps, or move on to the Weighted Hollow Body Hold and Weighted Plank.

Sources

  • McGill 2010, Strength Cond J 32(3):33-46 (core training)

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