Fold at the hips by lifting your torso and drawing your knees toward your chest in a coordinated movement that primarily works the abdominals.
How to do the Jackknife Sit Up#
- Lie on your back with your arms at your sides and your legs extended, feet resting on the floor.
- If using resistance, hold a dumbbell or medicine ball overhead with your arms extended.
- Brace your core and simultaneously curl your upper body up while bringing your knees toward your chest; allow a small bend in the knees if needed.
- Lower both torso and legs with control until you return to the starting position and repeat for the desired reps.
Muscles worked#
- Primary: Abs, Hip flexors
- Secondary: Obliques
Common mistakes#
- Swinging the torso and legs instead of moving deliberately.
- Pulling on the neck or tensing the head with the hands.
- Dropping quickly on the descent instead of controlling the return.
