Jackknife Sit Up

Like a bear folding up for a quick roll, the jackknife sit-up brings your legs and torso together in one smooth crunch. It lights up your abs, challenges control, and rewards steady rhythm over wild flopping.

Instructions

1. Lie flat on your back with legs straight.
2. Raise your arms overhead and brace your core.
3. Lift your legs and upper body at the same time.
4. Reach your hands toward your feet at the top.
5. Lower back down with control and repeat.

Benefits

• Builds stronger abs for daily movement
• Improves control during floor exercises
• Challenges full-body coordination
• Needs no gym equipment
• Adds variety to core training

Key Points

• Keep your lower back controlled
• Lift legs and torso together
• Move with steady tempo
• Reach through the middle
• Breathe out on the lift

Common Mistakes

• Swinging arms for momentum
• Bending knees too much
• Dropping down too fast
• Pulling on the neck
• Arching the lower back hard