Coaches often refer (just about every class) to a neutral or flat back when engaged in a loaded position. This is where midline stabilization comes into play. Before an athlete moves into a loaded position, whether under their own body weight or with a loaded bar, they want to engage their “core” in order to maintain correct posture from head to hips. The disengagement of this stability can potentially lead to movement dysfunction, less force production, or worse; spinal injury.
The understanding and practice of midline stabilization isn’t just important to the newer, less experienced athlete but to the most seasoned veteran as well. How many times have you witnessed someone (or experienced yourself) hyper-extend their lower back when weight is put overhead? How about their mid AND low back when performing a clean? This happens because of a break in midline stabilization and therefore loss of control.
You should be going through this process before every lift (press, deads, squats, cleans etc.) as well as things like double unders. It is your strongest and safest position and it makes it easier to transfer power from your legs and posterior chain to a bar or other external object.