Jackknife Sit-Up

Jackknife Sit-Up is a compound strength exercise using body only that trains the abdominals.

Open in MyoAmigo →

Primary muscles: Abdominals

How to do it

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

Track it with MyoAmigo

MyoAmigo pre-fills every set of the Jackknife Sit-Up from last time, charts your estimated 1RM trend so you can see strength move without testing a true max, and flags a stall with a concrete fix. It also credits this work toward your weekly Abdominals volume on the MyoMap heatmap. New to the movement? Start with picking a working weight and progressive overload.

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