The double crunch is a trunk flexion exercise that increases core strength while targeting lower abdominal and hip flexor regions.
Lie flat on your back and place your hands behind your head. Bring your feet close to your glutes so your knees are bent and place your feet flat on the ground. This is your starting position.
With elbows flared to the side and behind your head, brace your core and lift your shoulders and upper back off the ground. Simultaneously, bring your knees to your chest. Contract the core at top of movement, pause, then return to starting position.
Make sure to raise your shoulders and upper back completely off of the ground.
Avoid pulling on the back of your head and straining the neck.