Swiss Ball Prone Bridge
The plank is an overused, misunderstood and poorly executed exercise, in my opinion. It creates excessive tension in the six pack muscle (rectus abdominus) and therefore increases the curvature of the upper body. This leads to bad shoulders, back pain and neck problems to name just a few.
The prone bridge can be a nice alternative because it works the same muscles but you can vary the intensity more easily depending on your needs/ability and it also incorporates other planes of motion. Therefore there is more going on.
Watch to learn more: