10 Best 3/4 Sit-up Alternatives for Safer Core Training

The 3/4 Sit-up is done lying on your back. Ranked closest by our scoring: the Groin Crunch, the Flexion Leg Sit Up (Bent Knee) and the Frog Crunch. Two harder versions, the Flexion Leg Sit Up (Straight Arm) and the Oblique Crunch, are listed below as progressions rather than swaps.

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

Original Exercise: 3/4 Sit-up

3/4 Sit-upPlay demonstration
Primary muscle
Abs
Equipment
Bodyweight
Difficulty
Beginner
Type
Isolation

Secondary muscles: Hip Flexors, Lower Back

How to perform 3/4 Sit-up
  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.
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Ranked 3/4 Sit-up Alternatives

10 substitutes, ranked by how closely each one matches the 3/4 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
    Groin CrunchPlay demonstration

    1. Groin Crunch

    99% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation

    It uses the same equipment and 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, lift your legs off the ground, bringing your knees towards your chest.
    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 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  2. Flexion Leg Sit Up (Bent Knee)Play demonstration

    2. Flexion Leg Sit Up (Bent Knee)

    96% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    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. At the same time, lift your legs off the ground, bending your knees and bringing them towards your chest.
    5. Pause for a moment at the top, then slowly lower your upper body and legs back down to the starting position.
    6. 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 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  3. Flexion Leg Sit Up (Straight Arm)Play demonstration

    Progression

    3. Flexion Leg Sit Up (Straight Arm)

    96% match
    • Abs
    • Bodyweight
    • Intermediate
    • Isolation

    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 legs extended and arms straight above your head.
    2. Engaging your abs, lift your upper body off the ground while simultaneously lifting your legs towards your chest.
    3. Reach your hands towards your toes as you lift your upper body and legs.
    4. Pause for a moment at the top, then slowly lower your upper body and 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 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  4. Frog CrunchPlay demonstration

    4. Frog Crunch

    95% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    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, 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 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  5. Knee Touch CrunchPlay demonstration

    5. Knee Touch Crunch

    95% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    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, lift your shoulder blades off the ground and reach your right hand towards your left knee.
    4. Return to the starting position and repeat, this time reaching your left hand towards your right knee.
    5. Continue alternating sides 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 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  6. Stability Ball Crunch (Full Range Hands Behind Head)Play demonstration

    6. Stability Ball Crunch (Full Range Hands Behind Head)

    93% match
    • Abs
    • Stability-ball
    • Beginner
    • Isolation

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

    How to perform this exercise
    1. Sit on the stability ball with your feet flat on the ground and your knees bent at a 90-degree angle.
    2. Place your hands behind your head with your elbows pointing outwards.
    3. Engaging your abs, slowly curl your upper body forward, bringing your chest towards your knees.
    4. Pause for a moment at the top, then slowly lower your upper body back 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 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
    • Balance: harder to stay steady on than the 3/4 Sit-up
  7. Half Sit-upPlay demonstration

    7. Half Sit-up

    89% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    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 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  8. Quarter Sit-upPlay demonstration

    8. Quarter Sit-up

    89% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    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 sets of 8 to 12 reps, and add reps before you add load.

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  9. Alternate Heel TouchersPlay demonstration

    9. Alternate Heel Touchers

    88% match
    • Abs
    • Bodyweight
    • Beginner
    • Isolation
    How to perform this exercise
    1. Lie flat on your back with your knees bent and feet flat on the ground.
    2. Extend your arms straight out to the sides, parallel to the ground.
    3. Engaging your abs, lift your shoulders off the ground and reach your right hand towards your right heel.
    4. Return to the starting position and repeat on the left side, reaching your left hand towards your left heel.
    5. Continue alternating sides for the desired number of repetitions.

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

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up
  10. Oblique CrunchPlay demonstration

    Progression

    10. Oblique Crunch

    88% match
    • Abs
    • Bodyweight
    • Intermediate
    • Isolation
    How to perform this exercise
    1. Lie on your back with your knees bent and feet flat on the ground.
    2. Place your hands behind your head or cross them over your chest.
    3. Engage your abs and lift your shoulder blades off the ground, rotating your torso to one side.
    4. Pause for a moment, then lower your shoulder blades back down to the starting position.
    5. Repeat on the other side.
    6. Continue alternating sides for the desired number of repetitions.

    Sets and reps: 3 sets of 10 to 15 reps on each side.

    Why this matches
    • Primary muscle: abs, the same as the 3/4 Sit-up
    • Equipment: bodyweight only, the same as the 3/4 Sit-up
    • Body position: lying on your back, the same as the 3/4 Sit-up

3/4 Sit-up FAQ

What muscles does 3/4 sit-up work?

The 3/4 sit-up primarily targets the rectus abdominis through spinal flexion, with secondary activation of the external obliques. The hip flexors (iliopsoas and rectus femoris) assist, especially as the torso lifts higher, increasing their contribution.

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Similarity scores compare exercise metadata such as movement pattern, muscles, equipment and body position. They are not a safety rating or a check that you own the equipment. Learn about our methodology