10 Best Jackknife Sit-up Alternatives for Core and Hip Strength

The Jackknife Sit-up is done lying on your back. Ranked closest by our scoring: the Hip Raise (Bent Knee) and the Smith Machine Hip Raise. Two harder versions, the Janda Sit-up and the Incline Leg Hip Raise (Leg Straight), are listed below as progressions rather than swaps.

The Jackknife Sit-up lifts your legs and upper body together, reaching for your toes, and that combined lift is the first thing to go when the move gets too hard. Hip Raise (Bent Knee) is the easier entry point: it is really a bridge, knees bent and feet flat, dropping the leg-and-torso lift, with your glutes and hamstrings doing the lifting while your abs brace. If you want a torso curl instead, the Janda Sit-up lifts your upper body to a 45-degree angle, hands behind your head, feet flat.

Updated Ranked by our 12-factor similarity model How it works

Original Exercise: Jackknife Sit-up

Jackknife Sit-upPlay demonstration
Primary muscle
Abs
Equipment
Bodyweight
Difficulty
Intermediate
Type
Compound

Secondary muscles: Hip Flexors

How to perform Jackknife Sit-up
  1. Lie flat on your back with your legs extended and your arms overhead.
  2. Engage your core and lift your legs and upper body simultaneously, reaching your hands towards your toes.
  3. Pause for a moment at the top, then slowly lower your legs and upper body back down to the starting position.
  4. Repeat for the desired number of repetitions.
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Ranked Jackknife Sit-up Alternatives

10 substitutes, ranked by how closely each one matches the Jackknife Sit-up on movement pattern, muscles worked, equipment and body position. The higher the score, the less you change. Open "How to perform this exercise" on a card for the steps; every card title links to that exercise's own alternatives page. Harder versions are tagged as progressions and kept out of the top spot even when they score higher.

  1. Best match
    Hip Raise (Bent Knee)Play demonstration

    1. Hip Raise (Bent Knee)

    84% match
    • Abs
    • Bodyweight
    • Beginner
    • Compound

    Pick this when you want an easier version that still works the abs.

    How to perform this exercise
    1. Lie flat on your back with your knees bent and feet flat on the ground.
    2. Place your hands by your sides, palms facing down.
    3. Engage your core and glutes, then lift your hips off the ground until your body forms a straight line from your knees to your shoulders.
    4. Pause for a moment at the top, then slowly lower your hips back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: abs, the same as the Jackknife Sit-up
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  2. Janda Sit-upPlay demonstration

    Progression

    2. Janda Sit-up

    99% match
    • Abs
    • Bodyweight
    • Advanced
    • Compound

    Pick this when you want a harder version that still works the abs.

    How to perform this exercise
    1. Lie flat on your back with your knees bent and feet flat on the ground.
    2. Place your hands behind your head with your elbows pointing outwards.
    3. Engaging your abs, slowly lift your upper body off the ground, curling forward until your torso is at a 45-degree angle.
    4. Pause for a moment at the top, then slowly lower your upper body back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 or 4 sets of 6 to 10 reps.

    Why this matches
    • Primary muscle: abs, the same as the Jackknife Sit-up
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  3. Incline Leg Hip Raise (Leg Straight)Play demonstration

    Progression

    3. Incline Leg Hip Raise (Leg Straight)

    84% match
    • Abs
    • Bodyweight
    • Intermediate
    • Isolation
    How to perform this exercise
    1. Lie on an incline bench with your back flat against the bench and your legs extended straight out in front of you.
    2. Place your hands on the sides of the bench for support.
    3. Engaging your abs, lift your legs off the bench, raising them as high as you can while keeping them straight.
    4. Pause for a moment at the top, then slowly lower your legs back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 sets of 10 to 15 reps.

    Why this matches
    • Primary muscle: abs, the same as the Jackknife Sit-up
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  4. Smith Machine Hip Raise

    4. Smith Machine Hip Raise

    79% match
    • Abs
    • Smith-machine
    • Beginner
    • Compound

    A good swap when you have a Smith machine to work with, and it still works the abs.

    How to perform this exercise
    1. Position a bench in the rack and load the bar to an appropriate weight. Lie down on the bench, placing the bottom of your feet against the bar. Unlock the bar and extend your legs. You may need to use your hands to assist you. For added stability grasp the sides of the Smith Machine. This will be your starting position.
    2. Initiate the movement by rotating your pelvis, flexing your spine to raise your hips off of the bench. Maintain a slight bend in the knees throughout the motion.
    3. After a brief pause, return the hips to the bench.
    4. Repeat for the desired number of repetitions.

    Sets and reps: 3 or 4 sets of 6 to 10 reps.

    Why this matches
    • Primary muscle: abs, the same as the Jackknife Sit-up
    • Equipment: a machine, not bodyweight only
    • Body position: lying on your back, the same as the Jackknife Sit-up
  5. Bench Hip ExtensionPlay demonstration

    5. Bench Hip Extension

    74% match
    • Glutes
    • Bodyweight
    • Beginner
    • Compound

    A looser match: it uses the same equipment, but it works the glutes rather than the abs.

    How to perform this exercise
    1. Sit on a bench with your back against the bench and your feet flat on the ground.
    2. Place your hands on the bench for support.
    3. Engage your glutes and hamstrings, then lift your hips off the bench until your body forms a straight line from your knees to your shoulders.
    4. Pause for a moment at the top, then slowly lower your hips back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  6. Butt Lift (Bridge)

    6. Butt Lift (Bridge)

    74% match
    • Glutes
    • Bodyweight
    • Beginner
    • Compound
    How to perform this exercise
    1. Lie flat on the floor on your back with the hands by your side and your knees bent. Your feet should be placed around shoulder width. This will be your starting position.
    2. Pushing mainly with your heels, lift your hips off the floor while keeping your back straight. Breathe out as you perform this part of the motion and hold at the top for a second.
    3. Slowly go back to the starting position as you breathe in.

    Sets and reps: 3 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  7. Single Leg Bridge With Outstretched LegPlay demonstration

    7. Single Leg Bridge With Outstretched Leg

    74% match
    • Glutes
    • Bodyweight
    • Intermediate
    • Compound
    How to perform this exercise
    1. Lie on your back with your knees bent and feet flat on the ground.
    2. Extend one leg straight out in front of you.
    3. Engage your glutes and lift your hips off the ground, forming a straight line from your knees to your shoulders.
    4. Hold for a moment at the top, then slowly lower your hips back down to the starting position.
    5. Repeat for the desired number of repetitions, then switch legs.

    Sets and reps: 3 or 4 sets of 6 to 10 reps on each side.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  8. Rear Decline BridgePlay demonstration

    8. Rear Decline Bridge

    74% match
    • Glutes
    • Bodyweight
    • Intermediate
    • Compound
    How to perform this exercise
    1. Lie on your back with your feet flat on the ground and your knees bent.
    2. Place your arms by your sides with your palms facing down.
    3. Engage your glutes and hamstrings, and lift your hips off the ground until your body forms a straight line from your knees to your shoulders.
    4. Hold this position for a few seconds, then slowly lower your hips back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 or 4 sets of 6 to 10 reps.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
  9. Glute Bridge Two Legs On BenchPlay demonstration

    9. Glute Bridge Two Legs On Bench

    73% match
    • Glutes
    • Bodyweight
    • Intermediate
    • Compound
    How to perform this exercise
    1. Sit on the edge of a bench with your back against it and your feet flat on the ground.
    2. Place your hands on the bench beside your hips for support.
    3. Engage your glutes and hamstrings, then lift your hips off the bench until your body forms a straight line from your knees to your shoulders.
    4. Pause for a moment at the top, then slowly lower your hips back down to the starting position.
    5. Repeat for the desired number of repetitions.

    Sets and reps: 3 or 4 sets of 6 to 10 reps.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
    • Balance: harder to stay steady on than the Jackknife Sit-up
  10. Physioball Hip Bridge

    10. Physioball Hip Bridge

    71% match
    • Glutes
    • Stability-ball
    • Intermediate
    • Compound
    How to perform this exercise
    1. Lay on a ball so that your upper back is on the ball with your hips unsupported. Both feet should be flat on the floor, hip width apart or wider. This will be your starting position.
    2. Begin by extending the hips using your glutes and hamstrings, raising your hips upward as you bridge.
    3. Pause at the top of the motion and return to the starting position.

    Sets and reps: 3 or 4 sets of 6 to 10 reps.

    Why this matches
    • Primary muscle: glutes, not abs
    • Equipment: bodyweight only, the same as the Jackknife Sit-up
    • Body position: lying on your back, the same as the Jackknife Sit-up
    • Balance: harder to stay steady on than the Jackknife Sit-up

Why You Might Need a Jackknife Sit-up Alternative

You rarely swap the Jackknife Sit-up for equipment, since it needs only floor space. It is the coordination that trips people up: lifting your legs and your upper body at the same moment while reaching for your toes. Hip Raise (Bent Knee) drops that combined lift and works through your hips instead, knees bent and feet flat on the floor, but it is really a bridge: your glutes and hamstrings do the lifting while your abs brace. The Janda Sit-up keeps a torso curl in the mix, raising your upper body to a 45-degree angle with your hands behind your head while your feet stay planted. Smith Machine Hip Raise curls your pelvis up off the bench with your feet pushed against the Smith bar.

How to Choose the Right Jackknife Sit-up Substitute

If lifting your legs and torso together feels like too much right now, take Hip Raise (Bent Knee): it drops that combined lift and works through your hips instead, so it is the easier entry point, though it is really a bridge, with your glutes and hamstrings doing the lifting while your abs brace. If you want the torso half of the Jackknife kept intact, the Janda Sit-up raises your upper body to 45 degrees, hands behind your head, without lifting the legs. Incline Leg Hip Raise (Leg Straight) raises your legs while your torso stays flat on an incline bench. If you have a Smith machine, Smith Machine Hip Raise puts your feet against the loaded bar and has you curl your pelvis up off the bench, pushing your legs into resistance the Jackknife Sit-up never gives them.

Jackknife Sit-up FAQ

Which Jackknife Sit-up alternative works well for a beginner?

Hip Raise (Bent Knee). Lie on your back with your knees bent and feet flat, brace your core and glutes, and lift your hips until your body runs straight from knees to shoulders. It needs nothing but floor space and drops the combined leg-and-torso lift of the Jackknife Sit-up, though your glutes do most of the lifting. Build your reps here before you go back to the original move.

Which swap raises your legs like the Jackknife does?

Incline Leg Hip Raise (Leg Straight) is the one built for that: your torso stays flat on an incline bench while you raise straight legs as high as you can. That is the half of the Jackknife Sit-up most people find hardest, so practicing it on its own carries over well once you go back to the full move.

Is there a machine-based Jackknife Sit-up alternative?

Yes. Smith Machine Hip Raise has you lie on a bench under the bar with the soles of your feet pressed against it, unlock it, then curl your pelvis up to lift your hips off the bench with a slight bend in your knees. The loaded bar gives your legs something to push against, which the Jackknife Sit-up never offers, and you can add plates as you get stronger.

Which alternatives need no equipment at all?

Hip Raise (Bent Knee) and Janda Sit-up both use just your bodyweight, so a patch of floor is all you need. Hip Raise (Bent Knee) lifts your hips with your knees bent, and Janda Sit-up curls your torso up with your hands behind your head.

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