band jack knife sit-up
band jack knife sit-up is a common strength training exercise. Below are form tips, steps, and demos.
Steps
Step 1
Lie flat on your back with your legs straight and your arms extended overhead, holding the band.
Step 2
Engage your abs and lift your legs and upper body simultaneously, bringing your hands towards your feet.
Step 3
Pause for a moment at the top, then slowly lower your legs and upper body back down to the starting position.
Muscles & body parts
Primary muscles
Secondary muscles
Primary body parts
Common mistakes & warnings
Form & control
Avoid momentum and excessive swing; keep core stable; match breath to movement; control the eccentric phase.
Control breathing and core; keep a steady tempo.
Log workouts & get AI plans in the app
Record sets, weight, and reps precisely; get AI-generated weekly or single-session plans for muscle, fat loss, or strength—quick templates or custom. Download Delibra to get started.