Low Back Pain and the Role of the Multifidus Muscle in Rehab

Low back pain (LBP) is often a recurrent condition.  Most people understand on some level the importance of strengthening the low back to help alleviate chronic low back pain. Traditional strengthening exercises will focus on the larger back muscles but more recent studies have shown it is actually the small deep muscles that run closest to the spine, specifically the multifidi that are the most important posterior stabilizers of the lower back. Dysfunction in these muscles is strongly associated with LBP.

The individual multifidus muscles attach from vertebra to vertebra. All together they run the entire length of our spine. The multifidi control segmental movement of one vertebra on another. They also have an attachments on the joint capsules of the spine so that when the muscle contracts, it helps to pull the capsule out of the way so that it won’t get pinched. This could explain why a simple movement will sometimes cause sudden back pain. The muscle is innervated by only one nerve whereas the other back muscles have two or three that supply them. So if there is compression of that nerve from say a disc herniation, or spinal stenosis the multifidus muscle at that level will lose its ability to contract.

Research shows that the multifidi activate before any action is carried out. When we do activities such as lifting grocery bags, or even bending over to pick up a sock, our back needs to stiffen to protect the joints, discs and ligaments from being overloaded. A back that has good stability has the ability to keep its vertebrae, joints, and discs aligned and be able to control its motion well. A back that has poor stability is unable to control motion well and therefore is set up for possible injury. In a healthy back the first action that should occur, in our lifting bags example, is that the multifidus should contract first to stiffen the spine, and then our arm moves to grab the bag. In people that have poor motor control of their spine the contraction of these muscles is delayed, or does not happen at all, which leaves our back unprotected and vulnerable to injury.

When we injure our back, the multifidus muscle is shut off through a reflex reaction that is initiated by the joint that that multifidus is in control of. This shutdown occurs to protect the joint, because any further contraction would compress the joint and cause more injury to the joint. A key finding of research is that once the back has recovered from the injury episode, the multifidus muscle is not automatically turned back on. Over a short period of time it will begin to atrophy and in chronic low back pain it can become quite atrophic and the muscle is replaced by fat. So as we continue to live our lives and move, bend, or twist, our back is not protected because this muscle is turned off. This is the reason why the recurrence rate is so high for back pain sufferers. It can be taught to be reactivated or turned back on and with consistent training it can be brought back to its original level of strength and endurance. Muscle training directed at teaching patients to activate their mulifidus should be an important part of any rehab protocol for the patient with an acute or chronic history of low back pain. The exercises to retrain the multifidus are very simple and can be easily taught.

As with any exercise program that has the intention of building strength and/or endurance, the key is consistency. These exercises require that they are done daily. After 3 months’ time of consistently working out the multifidus muscle, it will have reached a level of strength and endurance that should keep you pain free. One thing to remember is that since these exercises are for motor retraining it is more effective to perform several sessions of short duration throughout the day rather than one long session.

Here is one simple multifidus retraining exercise:

Step 1: Locate the multifidus muscle: Lie on your side with your knees bent. Roll slightly forward.  Use your thumb or fingers to apply gentle pressure over the muscle bulk on the side of your back pain. You will find that the area of the multifidus atrophy will feel spongy or flat compared to the other side

Step 2: Activate the multifidus: the easiest way is to use your breath and imagery. Imagine a wire that runs from the back of the pubic bone to your spine. On your exhale find that connection and feel a slow swelling or bulging of the multifidus under your thumb/fingers. Another helpful cue for some people is to lift the muscles of the pelvic floor up and in on your exhale and again feel for multifidus swelling. Remember the multifidus is a small, deep muscle do not force a strong contraction.

Once you are able to isolate and contract your multifidus, you can practice it in many different positions, such as in sitting, standing or bending. You can also progress with arm movements like raising one arm forward and upward while maintaining the multifidus activation.