Exercise technique

jackknife sit-up

The jackknife sit-up is a bodyweight exercise targeting the abdominal muscles. It involves simultaneously lifting the legs and upper body to meet in the middle, engaging the core and hip flexors.

How do you perform this exercise?

  1. Lie flat on your back with your legs extended and your arms overhead.
  2. Engage your core and lift your legs and upper body simultaneously, reaching your hands towards your toes.
  3. Pause for a moment at the top, then slowly lower your legs and upper body back down to the starting position.
  4. Repeat for the desired number of repetitions.

Which other muscles are involved?

Hip flexors.

How do you log your sets?

How do you track progressive overload?

Source: ExerciseDB catalogue and demonstration. Related movements are options to compare, not equivalent loads or a prescribed progression.

Alternatives to explore

STARK is a strength training tracker for iPhone and Apple Watch. Log sets, repetitions and weights, then follow your progress. Core features are free. Explore STARK’s features