Jackknife Sit-Up
Jackknife Sit-Up is a strength - simultaneous long-lever jackknife exercise involving Rectus abdominis. Use these steps to learn the movement and work with your coach to choose a suitable level.
Last updated: · DynPerformance
- Primary muscles
- Rectus abdominis
- Secondary muscles
- Iliopsoas, Rectus femoris
- Exercise type
- Strength - simultaneous long-lever jackknife
Exercise technique
- Lie down
Lie face up with arms overhead and legs extended forward.
- Prepare
Brace your abdomen and control the lower-back gap.
- Rise
Curl your torso while raising both legs simultaneously.
- Jackknife
As your legs reach about 35-45 degrees, reach your hands parallel to them.
- Balance
Form a brief, controlled fold balanced on your hips.
- Open
Slowly lower your arms and legs together.
- Limit
Stop the return before losing lower-back control.
Key technique points
- Move the limbs together.
- Reach forward with your arms.
- Do not forcefully lock the knees.
- Exhale into the fold.
- Protect lower-back alignment at the bottom.
- Partially bend the knees if needed.
Common mistakes
Throwing the arms
Do not initiate torso rise with swinging.
Lifting the legs separately
Do not guide the two long levers unevenly and rotate the pelvis.
Arching the lower back
Do not release abdominal support during the long opening.
Folding into the neck
Do not force your chin to your chest or pull the head forward.
Dropping onto the hips
Do not turn top balance into an uncontrolled seated landing.
Opening rapidly
Do not free-fall into the bottom position.
Frequently asked questions
Jackknife Sit-Up: why is “Throwing the arms” a mistake?
Do not initiate torso rise with swinging.
Jackknife Sit-Up: why is “Lifting the legs separately” a mistake?
Do not guide the two long levers unevenly and rotate the pelvis.
Jackknife Sit-Up: why is “Arching the lower back” a mistake?
Do not release abdominal support during the long opening.
Jackknife Sit-Up: why is “Folding into the neck” a mistake?
Do not force your chin to your chest or pull the head forward.
Jackknife Sit-Up: why is “Dropping onto the hips” a mistake?
Do not turn top balance into an uncontrolled seated landing.
Jackknife Sit-Up: why is “Opening rapidly” a mistake?
Do not free-fall into the bottom position.
What should I focus on when doing Jackknife Sit-Up?
Move the limbs together. Reach forward with your arms. Do not forcefully lock the knees. Exhale into the fold. Protect lower-back alignment at the bottom. Partially bend the knees if needed.
Related exercises
- Kneeling Ab Wheel Rollout
- Bear Plank
- Bicycle Crunch
- Cable Crunch
- Captain's Chair Knee Raise
- Exercise Guide
Add this exercise to your program with your coach
If you have a health condition, consult a qualified professional.