TETSUJackknife Sit-Up
The Jackknife Sit-Up is a bodyweight exercise for the core that primarily targets the abs, with the hip flexors assisting. Follow the 4 steps below for correct form, with an animated demonstration.
abswaist
hip flexors
body weight
How to do the Jackknife Sit-Up
- Lie flat on your back with your legs extended and your arms overhead.
- Engage your core and lift your legs and upper body simultaneously, reaching your hands towards your toes.
- Pause for a moment at the top, then slowly lower your legs and upper body back down to the starting position.
- Repeat for the desired number of repetitions.
Common questions
What muscles does the Jackknife Sit-Up work?
The Jackknife Sit-Up primarily targets the abs. The hip flexors work as supporting muscles.
What equipment do I need for the Jackknife Sit-Up?
None. The Jackknife Sit-Up uses your body weight only, so you can do it anywhere.
How many sets and reps of the Jackknife Sit-Up should I do?
3 to 4 sets of 10 to 15 controlled reps of the Jackknife Sit-Up suits most programs — smaller muscle groups respond well to moderate loads and strict form. Progress by adding reps first, then small weight increments.
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