Crunch - Legs On Exercise Ball

Crunch - Legs On Exercise Ball is a strength – spinal flexion with supported legs exercise involving Rectus abdominis. Use these steps to learn the movement and work with your coach to choose a suitable level.

Last updated: 2026-10-31 · DynPerformance

Primary muscles: Rectus abdominis
Secondary muscles: Internal and external obliques, Transversus abdominis
Exercise type: Strength – spinal flexion with supported legs

Exercise technique

Mat
Lie on your back and place the stability ball under your feet.
Knees
Bend your knees to approximately a right angle.
Feet
Place your feet comfortably and symmetrically on the ball.
Hands
Hold your hands lightly beside your head.
Crunch
Maintain lower-back control and curl your shoulder blades off the mat.
Top
Pause briefly without pulling the ball with your legs.
Lower
Inhale and slowly lower your upper back.

Key technique points

Keep the ball still with your legs.
Do not change your knee angle.
Do not pull your neck with your hands.
Use a small torso range.
Keep your pelvis on the floor.
Exhale as you curl.

Common mistakes

Pulling the ball

Do not turn the crunch into a hamstring-assisted knee pull.

Crowding the feet

Do not force your knees into uncomfortable inward rotation while keeping your feet on the ball.

Lifting only the head

Do not replace rib movement with neck flexion.

Raising the pelvis

Do not press into the ball and lift your hips into a bridge.

Dropping the upper back

Maintain controlled spinal extension on the descent.

Swinging the arms

Do not use arm momentum to complete the shoulder lift.

Frequently asked questions