Suspension Jack Knife

Also known as: Jack Knife (Suspension)

From a suspended plank, pull your knees toward your chest by curling the hips and spine, working the abdominals. Return under control to the straight-plank position between repetitions.

How to do the Suspension Jack Knife#

  1. Place your feet in the suspension cradles and set up a high plank with hands under your shoulders and your body in a straight line.
  2. Tighten your core and initiate the movement by tucking your hips and drawing both knees toward your torso.
  3. Allow your hips to lift as your knees approach your chest while keeping your shoulders stable over your hands.
  4. Pause briefly at the top, maintaining abdominal tension.
  5. Slowly extend your legs back out to the starting plank position with a controlled motion.

Muscles worked#

Common mistakes#

Track the Suspension Jack Knife in Gript: your previous sets in view while you train, records detected automatically, and an estimated 1RM chart from every hard set.

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Frequently asked questions#

What muscles does the Suspension Jack Knife work?

The Suspension Jack Knife primarily works the abs, hip flexors. The obliques, front delts, chest, triceps assist as secondary muscles — they stabilise the movement and take over when the main target fatigues. If you feel it mostly in the obliques, front delts, chest, triceps, lighten the load and slow the lowering phase.

What equipment do I need for the Suspension Jack Knife?

The Suspension Jack Knife needs the following: Suspension trainer. Nothing beyond that is required to run the movement as described above.

Is the Suspension Jack Knife suitable for beginners?

Not as one of your first exercises. The Suspension Jack Knife is rated intermediate, so it suits lifters who already have a few months of consistent training behind them. Build the pattern on an easier variation first, then come back to it.

What are good alternatives to the Suspension Jack Knife?

Ab Coaster, Ab Wheel, Air Bike all train the same primary muscles as the Suspension Jack Knife. Pick whichever one matches the equipment in front of you.