Starte with simple Drawing in of the TVA in a supine position, then progress to holding the drawn in TVA in a supine position while marching in place (do not let the hips move and keep back pressed into the floor)
Glute bridge while maintaining a drawn in TVA.(don’t allow the movement to happen throught the lumbar)
Single leg Glute bridge while maintaining level hips(don’t let one side drop) while maintaining an active TVA.
Opposite arm and leg raise while maintaining a rigid LPHC (no movement in the core). These can be done on the floor prone, on a bosu supported with a little instability, in a quadraped position, and on a ball. The starting body position is determined by the ability to control the core.
Plank raises, get in a ready position (prone on elbows) draw in TVA then lift hips into a plank position hold for 3-5 seconds then lower, reset, and repeat for programed reps.
Side plank, get in ready position placing elbow directly below the shoulder while lying on side. Draw in TVA, then raise hip off of the floor hold the same as the plank raise.
Start with stability, then mobility of limiting muscles that are creating autogenic inhibition, then start with movement while controlling the core. The multifidus are segmental local stabilizers of the spine, don’t start moving till you can stabilize the segments.
As stated in the other post, knowing the functional anatomy of the multifidus is half of the battle. Once you know what they do and how they are activated just plug in some exercises that activate that function.
Something that is worth mentioning is that most back pain is a combination of limited hip mobility causing instability of the Lumbo Pelvic Hip Complex. If we look at the moving and stabilizing segments of the body we see a stabilize, mobility, stabilize, mobility, combination of segements. The ankels need mobility, the knees need stability, the hips need mobility, the lumbar/pelvis need stability, the thoracic spine needs mobilty, and so on. So in most cases the inability to stabilize the LPHC is due to limited hip mobilty.