Jack Knife Sit-up

Jack Knife Sit Up


This exercise involves lying on your back with your legs straight and arms extended above your head. You then lift your legs and upper body simultaneously, bringing your hands and feet to meet in the middle in a jackknife position. This movement engages the core muscles and can help improve abdominal strength and stability.

Muscle Group

Equipment Required

Jack Knife Sit-up Instructions

  1. Start by lying flat on your back with your arms extended above your head and your legs straight out in front of you.
  2. Engage your core muscles and lift your legs and arms simultaneously, bringing them towards each other in a jackknife motion.
  3. As you lift your upper body off the ground, bring your knees towards your chest and reach your hands towards your feet.
  4. Exhale as you reach the top of the movement and hold for a second or two.
  5. Slowly lower your arms and legs back down to the starting position, inhaling as you do so.
  6. Repeat for the desired number of repetitions.

Jack Knife Sit-up Form & Visual

Jack Knife Sit Up

Jack Knife Sit-up Benefits

  • Strengthens core muscles
  • Improves balance and stability
  • Targets lower abs and obliques
  • Can be modified for different fitness levels
  • Can be done with or without equipment

Jack Knife Sit-up Muscles Worked

  • Rectus abdominis
  • Obliques
  • Hip flexors

Jack Knife Sit-up Variations & Alternatives

  • Jackknife crunch
  • Reverse jackknife crunch
  • Weighted jackknife crunch
  • Decline jackknife crunch
  • Side jackknife crunch