- 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)
- Lie supine (on your back) on the floor with your knees bent and a stability ball clasped between your feet.
- Place your hands behind your head.
- Raise the ball off the floor a little by flexing your hips.
- Press your lower back against the floor to keep it supported.
- 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).
- Hold for a count of two.
- Inhale as you simultaneously relax your abdomen and flex your knees to lower your upper back and the stability ball to the starting position.
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.