Jackknife Sit-Up

How to perform

1. 01Lie 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.
2. 02As 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.
3. 03While inhaling, lower your arms and legs back to the starting position.
4. 04Repeat for the recommended amount of repetitions.

Form cues

• —Brace your core before the first rep and keep it braced.
• —Lead with the elbows and finish by squeezing the target muscle.
• —Control the lowering phase — that is where most of the growth stimulus lives.

Common mistakes

• —Using momentum instead of the target muscle.
• —Cutting the range of motion short to add load.
• —Adding weight before the movement pattern is clean.