The plank is a rather new staple for core training. It’s quickly replaced the crunch in many routines and for good reason. That said, there are still plenty of ways the plank is abused and misused. Trying to hold the position for too long and trying to keep the body strait are a couple that come to mind.
In this quick video I show off my own plank variation which is much more effective at targeting the abs while keeping pressure off the lower back.