This is a great video sharing anatomy information about the multifidus and how to activate it correctly. Why is this important, you ask? The “CORE” consists of: pelvic floor muscles, transversus abdominis, and multifidus. These muscles need to activate properly for all activities- even nose blowing, coughing, sneezing, walking, jumping and lifting.
Another fantastic reference for this is Diane Lee’s work: http://dianelee.ca/articles/PELVICFLOOR.pdf