Jackknife Crunch exercise is an effective exercise for targeting the rectus abdominis and transverse abdominis.

It also engages the serratus, oblique muscles, hips and lower back.

Jackknife Crunch travels a short pathway but creates an intense contraction at the top position.

Jackknife Crunches can be used as a warm up to prime the hip flexors and lower back before training your back and legs.

It can also be used as a finisher in an abdominal workout routine.

Jackknife Crunch How To

  • Lie on your back with your knees bent at a 90 degree angle. Your arms should be in a fully extended position behind your head.
  • Contract your hip flexors then bring your knees toward your abdominal area. Extend your knees to straighten your legs up toward the ceiling while simultaneously bringing your arms up toward your feet, keeping your shoulders off the floor. Hold the position for a count of “one”.
  • Flex the knees and return to the bent position then slowly bring your feet back to the floor. Simultaneously lower your torso back to the floor and bring your arms back to their fully extended position behind your head.
  • Repeat the exercise until you have completed the targeted number of reps.

Form and Technique

Jacknife Crunch is a two-part exercise and requires coordination and focus.

The first part is to bring your knees toward your abdominal area which works the transverse abdominis.

The second part is to simultaneously extend your legs straight up while bringing your upper body off the floor with your hands reaching toward your toes.

This engages the rectus abdominis and serratus muscles.

Focus on contracting the abs and hip flexors at the top part of Jackknife Crunch.

Variations: Jackknife, V Up

Routine for Strength: 5 sets x AMRAP (30 secs rest between sets)

Routine for Muscle Gains: n/a

Jackknife Crunch

How To Do Jackknife Crunch