Cocoons are a great exercise for strengthening the entire core section.
Unlike regular crunches that isolate the ab muscles, this exercise includes the arms and legs and engages the whole body.
It primarily works on the rectus abdominis (the six pack muscles) and transverse abdominis (the inner ab muscle). And it also works on secondary muscles in the hip flexors, lats, and quadriceps.
How to do
Lie on the floor on your back, fully extending your legs and arms straight.
Bring your knees toward the chest, and lift your hips off the floor.
Simultaneously flex your spine, bring your arms over your head to raise your shoulders off the floor and perform a crunch motion.
Hold this position for a moment.
Slowly return to the starting position, and repeat.
Risky for the lower back because of too much flexion
This movement is very similar to the crunch. This involve flexing your spine repeatedly, Too much flexion is the exact mechanism that causes injuries like a herniated disc.
To stay on the safer side, try to hold your lower back flat on the floor as you bend.