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Exercise guide

Plank Jack

  • Intermediate
  • Compound
  • Timed hold
  • Back
  • Chest
  • Lower arms
  • Lower legs
  • Shoulders
  • Upper arms
  • Upper legs
  • Waist

The Plank Jack is a dynamic core exercise that combines a high plank with a jumping jack motion to challenge stability, cardiovascular endurance, and full-body coordination. It effectively targets the rectus abdominis and obliques while requiring significant isometric strength from the deltoids and glutes.

Reviewed by the Crucible team · Updated June 2026

Watch the Plank Jack demonstrationGuided video and your full workout live in the Crucible app.

Muscles worked

Primary

  • Abs
  • Deltoids
  • Obliques

Secondary

  • Erector spinae
  • Serratus anterior

Equipment

  • Body weight

Setup

  1. Start in a high plank position with your hands placed directly under your shoulders.
  2. Position your feet together and engage your glutes to create a straight line from head to heels.
  3. Maintain a neutral spine and fix your gaze slightly ahead of your hands on the floor.

How to do it

  1. Jump both feet out wide to the sides, slightly beyond shoulder-width, while keeping your hips level.
  2. Exhale as you jump out, ensuring your core remains braced to prevent your lower back from sagging.
  3. Jump your feet back together to the starting position while inhaling.
  4. Maintain a fast, rhythmic tempo while keeping your upper body as still as possible.

Form checklist

  • Keep your hips level with your shoulders; do not let them bounce up or sag down.
  • Maintain a strong push through your palms to keep your shoulder blades from winging.
  • Land softly on the balls of your feet to reduce impact.
  • Ensure your hands remain directly under your shoulders throughout the movement.

Pro tips

  • Focus on 'pushing the floor away' to maximize serratus anterior and deltoid engagement.
  • Imagine a glass of water on your lower back; try to move your legs without spilling it to maximize core stabilization.

Make it harder

  • Perform the exercise in a low plank (on forearms) to increase the demand on the core and shoulders.
  • Place a small resistance band around your ankles to increase glute and hip abductor activation.

Frequently asked

What muscles does the plank jack work?
The plank jack primarily targets the abs, deltoids, and obliques, and also works the erector spinae and serratus anterior as secondary muscles.
What equipment do you need for the plank jack?
The plank jack requires no equipment — just your body weight.
Is the plank jack good for beginners?
The plank jack is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.

Related exercises

  • Knee Tap Sky ReachIntermediate · abs, calves, deltoids, obliques, and pectorals
  • Alternate Front Kick In Place With Arm CirclesBeginner · abs, calves, deltoids, and pectorals
  • Body Saw PlankIntermediate · abs, lats, and obliques
  • Elevated Lunge T Spine RotationIntermediate · abs, glutes, hamstrings, obliques, and quadriceps

Train this with a plan, not guesswork

Crucible builds the plank jack into a precise program around your body, equipment, location, and time.

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