Jackknife Sit-Up

How to do the Jackknife Sit-Up

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.

Muscles worked

Role	Muscles
Primary	abs
Equipment	no equipment
Difficulty	beginner
Type	compound

Train the same muscles a different way

6 alternatives for the same abs, with and without kit.

Spell Caster Dumbbell Bent Press Kettlebell Exercise Ball Pull-In Exercise Ball Kettlebell Pass Between The Legs Kettlebell Kettlebell Windmill Kettlebell Dumbbell Side Bend Dumbbell

Harder than the Jackknife Sit-Up

Hanging Leg Raise expert · Bodyweight Hanging Pike expert · Bodyweight Bent Press expert · Kettlebell

Superset the Jackknife Sit-Up with

Opposing lower back work — alternate sets without extra rest.

Hyperextensions With No Hyperextension Bench lower back Stiff Leg Barbell Good Morning lower back Hyperextensions (Back Extensions) lower back Barbell Deadlift lower back

Common questions

What muscles does the Jackknife Sit-Up work?

The Jackknife Sit-Up primarily works the abs. 3/4 Sit-Up, Ab Roller, and Air Bike train the same muscle, across 9 equipment types.

What equipment do you need for the Jackknife Sit-Up?

None — the Jackknife Sit-Up is bodyweight, so it works at home, in a hotel room or outdoors. 3/4 Sit-Up and Ab Roller also need nothing.

Is the Jackknife Sit-Up suitable for beginners?

Yes, the Jackknife Sit-Up is rated beginner. Hanging Leg Raise, Hanging Pike, and Bent Press are the progressions from here.

Where should the Jackknife Sit-Up go in a workout?

Early — the Jackknife Sit-Up is compound, working 1 muscle group, so run it first or second while you are fresh, then superset Hyperextensions With No Hyperextension Bench and Stiff Leg Barbell Good Morning later.

Similar exercises

3/4 Sit-Up Bodyweight Ab Roller Other Equipment Air Bike Bodyweight Barbell Ab Rollout Barbell Barbell Ab Rollout - On Knees Barbell Barbell Rollout from Bench Barbell