The Jack Knife

The Jack Knife gif

About

This advanced Pilates move really challenges your lower abs and spine control.

How to The Jack Knife

Starting Position

1. Lie on your back and raise your legs vertically.

2. Your arms support your body on the sides.

Proper Form

1. Lift your pelvis while swinging your legs behind your head.

2. Extend your legs towards the ceiling using your abdominal strength.

3. Lower your spine in order as you return.

Breathing Technique

Exhale when you go up, and inhale when you go down.

Precautions

1. Do not put weight on your neck.

2. Keep your abdomen engaged to prevent excessive extension of the lower back.

3. Gradually lower your spine.

From the Community

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Curious about a Core workout plan that includes the The Jack Knife

The Jack Knife Alternatives

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Cable Crunch

The Jack Knife vs Standing Bicycle

The Jack Knife

About

How to The Jack Knife

Starting Position

Proper Form

Breathing Technique

Precautions

From the Community

The Jack Knife Related Reading

Creatine works for women — here's what 69 studies and a 2-year RCT of 237 women actually found

Squat vs. leg press: the muscle gains are the same when volume matches, per a 2025 RCT of 70 women

10 sets per muscle group per week is probably enough — here's the number that actually matters.

Mechanical tension is the primary driver of muscle growth — and 5 peer-reviewed reviews in Sports Med explain exactly why

Magnesium won't stop your muscle cramps — unless you're deficient, per a 2020 Cochrane review

Creatine is not bad for your heart — in fact, creatine cut mortality in a 2016 meta-analysis

The Jack Knife Alternatives

The Jack Knife vs

The Jack Knife

About

How to The Jack Knife

Starting Position

Proper Form

Breathing Technique

Precautions

From the Community

The Jack Knife Related Reading

Creatine works for women — here's what 69 studies and a 2-year RCT of 237 women actually found

Squat vs. leg press: the muscle gains are the same when volume matches, per a 2025 RCT of 70 women

10 sets per muscle group per week is probably enough — here's the number that actually matters.

Mechanical tension is the primary driver of muscle growth — and 5 peer-reviewed reviews in Sports Med explain exactly why

Magnesium won't stop your muscle cramps — unless you're deficient, per a 2020 Cochrane review

Creatine is not bad for your heart — in fact, creatine cut mortality in a 2016 meta-analysis

The Jack Knife Alternatives

The Jack Knife vs