10 Flexion Leg Sit Up (straight Arm) Alternatives for Core

Ranked Flexion Leg Sit Up (Straight Arm) Alternatives

10 substitutes, ranked by how closely each one matches the Flexion Leg Sit Up (Straight Arm) 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

   Play demonstration

   1. Flexion Leg Sit Up (Bent Knee)

   99% match

   • Abs
   • Bodyweight
   • Beginner
   • Isolation

   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 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
2. Play demonstration

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

   97% 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
   • Balance: harder to stay steady on than the Flexion Leg Sit Up (Straight Arm)
3. Play demonstration

   3. 3/4 Sit-up

   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. 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
4. Play 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
5. Play demonstration

   5. Groin 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 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
6. Play demonstration

   6. 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
7. Play demonstration

   Progression

   7. Incline Twisting Sit-up

   89% match

   • Abs
   • Bodyweight
   • Intermediate
   • Compound

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

   How to perform this exercise

   1. Set up an incline bench at a 45-degree angle.
   2. Lie down on the bench with your feet secured under the foot pads.
   3. Place your hands behind your head or across your chest.
   4. Engage your abs and lift your upper body off the bench, curling forward.
   5. As you curl up, twist your torso to one side, bringing your elbow towards the opposite knee.
   6. Pause for a moment at the top, then slowly lower your upper body back down to the starting position.
   7. Repeat the movement, this time twisting your torso to the other side.
   8. Continue alternating sides 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
8. Play demonstration

   8. Arms Overhead Full Sit-up

   89% match

   • Abs
   • Bodyweight
   • Intermediate
   • 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 overhead, keeping them straight.
   3. Engaging your abs, slowly lift your upper body off the ground, curling forward until your torso is upright.
   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 10 to 15 reps.

   Why this matches

   • Primary muscle: abs, the same as the Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
9. 

   9. Frog Sit-ups

   89% match

   • Abs
   • Bodyweight
   • Beginner
   • Isolation

   How to perform this exercise

   1. Lie with your back flat on the floor (or exercise mat) and your legs extended in front of you.
   2. Now bend at the knees and place your outer thighs by the floor (or mat) as you make the soles of your feet touch each other.
   3. Now try pushing both soles and bringing them up as near you as possible while you keep the outer thighs on the floor (or at least almost touching it). Tip: In this position your legs should create a diamond shape.
   4. Now, cross your arms in front of you by touching the opposite shoulders. This will be your starting position.
   5. As you exhale flatten your lower back to the floor while curling the torso upwards. Tip: This will be like performing the first 1/4 movement of a sit up. Hold at the top position for a second.
   6. As you inhale, slowly lower back to the starting position.
   7. Repeat for the recommended amount 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 Flexion Leg Sit Up (Straight Arm)
   • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
   • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)
10. 

    10. Sit-up

    89% match

    • Abs
    • Bodyweight
    • Beginner
    • Isolation

    How to perform this exercise

    1. Lie down on the floor placing your feet either under something that will not move or by having a partner hold them. Your legs should be bent at the knees.
    2. Place your hands behind your head and lock them together by clasping your fingers. This is the starting position.
    3. Elevate your upper body so that it creates an imaginary V-shape with your thighs. Breathe out when performing this part of the exercise.
    4. Once you feel the contraction for a second, lower your upper body back down to the starting position while inhaling.
    5. Repeat for the recommended amount 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 Flexion Leg Sit Up (Straight Arm)
    • Equipment: bodyweight only, the same as the Flexion Leg Sit Up (Straight Arm)
    • Body position: lying on your back, the same as the Flexion Leg Sit Up (Straight Arm)