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Jackknife Sit-Up
PullCompoundBodyweightBeginner
Muscles worked
Front
Abdominals
Instructions
- 1Lie flat on the floor (or exercise mat) on your back with your arms extended straight back behind your head and your legs extended also. This will be your starting position.
- 2As you exhale, bend at the waist while simultaneously raising your legs and arms to meet in a jackknife position. Tip: The legs should be extended and lifted at approximately a 35-45 degree angle from the floor and the arms should be extended and parallel to your legs. The upper torso should be off the floor.
- 3While inhaling, lower your arms and legs back to the starting position.
- 4Repeat for the recommended amount of repetitions.
table_chartRecommended sets and reps
These ranges vary depending on your training goal — adjust the load accordingly.
| Goal | Sets | Reps | Rest |
|---|---|---|---|
| boltStrength | 4–5 | 3–6 | 3–5 min |
| fitness_centerHypertrophy | 3–4 | 8–12 | 90 s |
| timerEndurance | 2–3 | 15–20 | 30–45 s |
About Jackknife Sit-Up
The jackknife sit-up, or V-up, simultaneously combines a leg raise and a crunch into one fluid movement, with the arms and legs meeting at the top forming a V shape. This advanced exercise intensely works the entire abdominal region and requires good coordination between the upper and lower body, reserved for those who already have solid ab strength.
check_circleBenefits
- check_circleIntensely works the entire ab region
- check_circleCombines two movements into one efficient exercise
- check_circleBuilds upper-lower body coordination
lightbulbExecution tips
- lightbulbKeep the legs and arms extended throughout
- lightbulbSynchronize raising the arms and legs
- lightbulbControl the descent well to maintain tension
warningCommon mistakes
- warningLegs bending during the ascent
- warningLack of synchronization between arms and legs
- warningUsing momentum rather than abdominal contraction
helpFrequently asked questions
Is this exercise suitable for beginners?expand_more
No, it's better to first master the crunch and the leg raise separately before combining them.
Do my hands need to touch my feet?expand_more
Ideally yes, but the ab contraction remains more important than maximum range at any cost.
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