Side Jackknife — start position
Start
Side Jackknife — end position
End

Core / Beginner / Compound (multi-joint)

Side Jackknife

A bodyweight exercise for the obliques and abs, with the hip flexors assisting.

At a glance

Primary
Obliques, Abs
Secondary
Hip flexors
Equipment
Bodyweight
Movement pattern
Side bend, Hip flexion, Trunk flexion
Level
Beginner
Type
Core, Compound (multi-joint)

How to do it

  1. See the images for the movement.

Common mistakes

  • ✗ Using a big jerk to get up.

    Why it hurts: The lower back and hip flexors are yanked fast.

    ✓ Instead: Lift the arms and legs together with control; bend the knees to make it easier.

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Muscles worked

Neck (Front)Upper traps (Front)Front delts (Front)Side delts (Front)Chest (Front)Serratus anterior (Front)Biceps (Front)Forearms & grip (Front)Abs — primary (Front)Obliques — primary (Front)Hip flexors — secondary (Front)Quads (Front)Adductors (Front)Shins (tibialis) (Front)Calves (Front)Outer shins (peroneals) (Front)Feet (arch & toes) (Front)Neck (Back)Upper traps (Back)Upper back (rhomboids, mid/lower traps) (Back)Rear delts (Back)Side delts (Back)Rotator cuff (Back)Lats (Back)Lower back (erectors) (Back)Triceps (Back)Forearms & grip (Back)Hip abductors (glute med) (Back)Glutes (Back)Hamstrings (Back)Adductors (Back)Calves (Back)
FrontBack
  • Primary: Obliques, Abs
  • Secondary: Hip flexors

Best for

How specific this exercise is to each movement.

Similar exercises

Photos and instructions: free-exercise-db (github.com/yuhonas/free-exercise-db), public domain.