Dragon Flag

The dragon flag is the most demanding bodyweight exercise for the anterior core, and it earns that reputation honestly. Lying on a bench and gripping it behind your head, you raise the whole body until it is vertical, supported only on the upper back, then lower it as one rigid piece without letting the hips fold or the lower back arch. The abdominals are working the entire time to prevent the spine extending under the leverage of your own bodyweight, which is precisely what they are built to do. Very few people can perform a full repetition without preparation. The sensible route is a tuck version with the knees drawn in, then one leg extended, then both, and finally slow negatives from the top position. Grip the bench firmly and never let the descent become a fall.