When it comes to foundational strength exercises such as the deadlift, back squat, overhead press, front squat, and barbell row, the ability to maintain a stiff core is necessary to tolerate heavy loads as well as limit the risk of injury. Scientists at the University of Waterloo in Ontario, Canada, created an experiment to see what kind of training improved core stiffness the most. One group of subjects performed a dynamic movement program for six weeks, which included Russian twists, back extensions, Supermans, and lateral medicine ball throws. Another group performed isometric exercises (in which the torso does not flex or extend) such as planks, suitcase carries, bird dogs, and inverted rows. At the end of six weeks, the isometric group enhanced their core stiffness to a greater degree. Everyone loves crunches and leg raises, but don’t forget the power of planks and holds.