The goal of exercises like the bird dog is to generate stiffness in spinal, abdominal, and upper back muscles for spinal stabilization.

“this is about generating strength of contraction and I know the word sounds bad but rigidity it's about generating stiffness in the spinal muscles and in the abdominal muscles and in the upper back muscles and the other muscles that are requ requ ired for this and when I say stiffness I don't mean a lack of ability for the muscles to move once you're in sport or once you're about your daily activities what I'm talking about is an ability to generate a really firm muscular contraction”