Stability ball leg extension crunch exercise
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Stability ball leg extension crunch

Exercise details

  • Target muscles: Quadriceps, Rectus Abdominis
  • Synergists: Internal and External Obliques, Tensor Fasciae Latae, Iliopsoas, Pectineus, Sartorius, Adductor Longus, Adductor Brevis
  • Mechanics: Compound
  • Force: Push (Leg Extension) and and Pull (Crunch)

Starting position

  1. Lie supine (on your back) on the floor with your knees bent and a stability ball clasped between your feet.
  2. Place your hands behind your head.
  3. Raise the ball off the floor a little by flexing your hips.
  4. Press your lower back against the floor to keep it supported.


  1. Exhale as you simultaneously flex your abdomen to raise your upper back off the floor (crunch) and extend your knees to raise the stability ball into the air (leg extension).
  2. Hold for a count of two.
  3. Inhale as you simultaneously relax your abdomen and flex your knees to lower your upper back and the stability ball to the starting position.
  4. Repeat.

Comments and tips

  • Keep the ball off the floor and your lower back pressed against the floor.
  • The stability ball leg extension crunch combines an isolation push exercise—the leg extension—with an isolation pull exercise—the crunch—to produce an interesting and rarely seen compound movement.
  • To ensure that your quadriceps experience resistance throughout the leg extension, keep your thighs slanted a little forward at the top of the movement. If you keep them vertical, your quadriceps will experience no resistance as your knees near full extension.
  • To make the crunch element more difficult, either hold a weight plate behind your head or extend your arms backward.
  • See also the crunch with stability ball leg raise.

Stability ball leg extension crunch video

Sorry, couldn’t find any! The stability ball leg extension crunch is a rare exercise. Instead, see separate videos for leg extension and crunch below.

Stability ball leg extension


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