Stability Ball Bent Knee Lying Twist — how to, muscles worked, alternatives

How to do the Stability Ball Bent Knee Lying Twist

Lie on your back, arms out wide, ball held behind your knees.
Lower both knees and the ball to one side.
Stop before your opposite shoulder lifts.
Return to the center and switch sides each rep.

Full technique — 7 steps

Lie on your back with your arms out to the sides, palms up, forming a T.
Bend your hips and knees to about 90 degrees and hold the stability ball between your calves and the backs of your thighs.
Tighten your stomach and keep both shoulders and arms flat on the floor.
Lower both knees and the ball to one side under control, keeping the knee bend the same.
Stop before your opposite shoulder lifts off the floor.
Bring your knees back to the center using your obliques.
Lower them to the other side the same way and keep alternating sides.

Common mistakes

Shoulder lifting off the floor
Dropping the legs to the floor
Swinging legs with momentum
Letting the ball slip out
Changing the knee bend mid-rep

Form cues

Shoulders stay down
Arms press into floor
Squeeze the ball
Move through the trunk
Control the way back

Substitutes by equipment

Same muscles, same movement — pick the version you have the gear for.

Where to start and where to go next

Same muscles, same movement. Too hard for now — step down; once it gets easy — step up.

Easier Bent Knee Lying Twist 10% of bodyweight
This exercise Stability Ball Bent Knee Lying Twist 20% of bodyweight
Harder Hyperextension Bench Oblique Crunch 40% of bodyweight
Harder Hanging Oblique Knee Raise 60% of bodyweight

Too hard for now? Start with the Bent Knee Lying Twist.

Quick answers

What muscles does the Stability Ball Bent Knee Lying Twist work?

Primary: Obliques 9/10. Also works: Abs 5/10, Lower back 4/10.

When should I do the Stability Ball Bent Knee Lying Twist in a workout?

Finisher. Goes last, once the heavy work is done. ≈ 5 min with rest.

How many sets and reps of the Stability Ball Bent Knee Lying Twist?

Strength: 2–3 sets of 8–12 reps, rest 1 min, 3–4 reps in reserve. Muscle growth: 3 sets of 10–16 reps, rest 45 s, 3 reps in reserve. Endurance: 2–3 sets of 16–24 reps, rest 30 s, 4 reps in reserve.

What can I do instead of the Stability Ball Bent Knee Lying Twist?

Cable machine: Cable Oblique Twist, Cable Horizontal Woodchop. Barbell: Seated Barbell Twist, Stability Ball Barbell Twist. Dumbbells: Dumbbell Russian Twist, Dumbbell Straight Leg Russian Twist. Resistance bands: Resistance Band Bicycle Crunch.