“Is there a visible difference between the right and left sides?” I asked. My friend Julia, a massage therapist, was working on the always-tight muscles alongside my spine in my lower back.
“Not really,” she said.
I lifted my head up from the face cradle to express my astonishment. Sometimes the two halves of my body felt so different it seemed as though I was living in two entirely disconnected bodies.
“Oh, wait—“ she said. “When you’re just lying there you look pretty symmetrical. But when you move, the muscles of your back engage, and there’s a difference, all right!”
“The muscles on one side stand up when you lift your head,” she continued. “The other side doesn’t do that.”
That was more in keeping with my own experience of my chronically achy, scoliotic back. The erector muscles, running alongside my spine, always feel tighter and achier on one side.
The body has several methods of keeping the spine upright and stable. It uses passive, non-contractile structures like bones, ligaments, and fascial sheaths, and the actively contractile tissue called muscle, which research has shown to play a pivotal role in spinal stability.
Beneath the long muscles running parallel to the spine is a muscle called multifidus. Well, multifidus is often spoken about as though it were only one muscle, but it’s actually many, many individual muscles (collectively called multifidi) running the length of the spine from the low back to the neck. Each individual multifidus attaches at a bony process of the spine, spanning the length of two to four vertebrae.
While all the muscles of the low back have a part to play in supporting the spine, multifidus’s role is pivotal. It appears to provide a lion’s share of support between the spine’s multiple individual joints. In fact, according to Jim Johnson, P.T., author of The Multifidus Back Pain Solution, multifidus contributes a full two-thirds of muscular support to the spine.
While all the muscles of the low back have a part to play in supporting the spine, multifidus’s role is pivotal.
Although it spans the entire spine, multifidus is thicker, and can be most easily palpated (touched) in the low back. To feel your own multifidi, place your fingers on either side of your lumbar spine, below your rib cage and above your pelvis, on your low back. Now walk around a little. The movement you feel beneath your fingers is multifidi stabilizing your spine as you move.
Multifidus is one of those bad-boy muscles that have garnered a lot of attention lately. It has been the recipient of a good deal of research over the past decade. That’s because in recent years, ultrasounds have shown that, among people with back pain, multifidus is often smaller and weaker on just one side of the back—the side that is experiencing pain.
An earlier study concluded that one year after being treated for back pain, only 30 percent of a group of volunteers who performed exercises for multifidus had a recurrence of pain; 84 percent of the non-exercising control group still experienced flare-ups of pain at the one-year mark.
For all its current notoriety, it’s important to remember that no living muscle exists in isolation. Multifidus is just one of four muscles that form the body’s inner core. The other three components of the inner core are the transversus abdominis, the diaphragm, and the muscles of the pelvic floor.
However, multifidus is distinctive for the unusually high number of muscle spindles it contains. Muscle spindles are sensory receptors in muscles that detect changes in the length of the muscle and report this information back to the central nervous system. The central nervous system uses the information to calculate the body’s current position.
This ability of the body to perceive where all of its parts are in space, at any given moment, is called proprioception. Proprioception is the reason you know where your mouth is when you lift a fork to it and the reason you can touch your nose with your eyes closed. (Unless you’ve had too much to drink.)
Postural Muscles Hold You Up and Phasic Muscles Move You Around
Postural muscles are anti-gravity muscles, responsible for keeping the body upright. They’re generally located deep within the body. Sometimes they’re called slow twitch muscles. Rectus femoris, for example, on the front of your thigh, is a postural muscle that helps you remain standing. As a postural muscle, multifidus should work bilaterally—meaning on both sides of the spine—to resist the action of forward bending so you don’t fall forward when you bend over to pick something up.
Phasic muscles are the complementary partners to postural muscles. Phasic muscles are responsible for moving the body around. They’re generally more superficial, and are sometimes called fast twitch muscles. Gluteus maximus, for example, is a powerhouse phasic muscle that propels you forward when walking and elevates you when you stand up from a seated position. While gluteus maximus moves you around, multifidus remains busy stabilizing your spine in an upright position.
Both postural and phasic muscles are skeletal muscle, which is categorized as voluntary muscle: voluntary, as opposed to the smooth muscle your organs are made of, which is involuntary—meaning your organs continue to do their job without your conscious control or consent (even, for example, when you’re not thinking about what your small intestine is doing).
Both postural and phasic muscles are skeletal muscle, which is categorized as voluntary muscle.
Rethinking “Good Posture”
Often we think “good posture” is simply about attentiveness, overcoming laziness, and “standing up straight.” This is generally not the case.
Your posture is predominantly governed by the part of the iceberg of consciousness that lies below the surface of awareness. Most postural muscles—although designated voluntary in anatomy books—are actually governed by the autonomic nervous system. This means that for the most part they are regulated unconsciously.
Postural muscles have a tendency to work too hard and become irritable, while phasic muscles—particularly in sedentary societies like our own—have a tendency to loaf. Multifidus can overwork or underwork, but, in regard to its association with back pain, most of the research I’ve seen has focused on its tendency to underwork, or, in other words, to be inhibited.
All muscle relies on the nervous system to tell it what to do, so good communication is essential. Inhibition is not a simple question of a muscle’s strength or weakness. It’s a communication issue.
The central nervous system is efficient, and a creature of habit. When it has a job to delegate, it calls upon its most reliable “first responders.” This leaves some muscles chronically facilitated (neurologically overstimulated) while inhibited muscles are habitually bypassed by the nervous system.
Strengthening a weak muscle can be a good idea. But my question is, what happens when someone does strengthening exercises for a muscle that’s inhibited because it has poor communication with the central nervous system? Are they creating better muscular balance in the body, or deepening patterns of compensation? My personal opinion is that either outcome is possible.
What happens when someone does strengthening exercises for a muscle that’s inhibited because it has poor communication with the central nervous system?
Let’s look at the classic multifidus strengthener, done from tabletop position. Try coming into it in this more deliberate way to stave off compensatory patterns:
Come into tabletop with your hands set outer-shoulder-width apart (this measure begins at the central notch just below your throat, between your collarbones, and spans out horizontally in both directions to the widest point on the outseam of each shoulder) and your knees below your hips.
Soften your jaw and upper body.
Tone your lower abdomen, and lift the front of your rib cage up away from the floor so that it doesn’t hang down like a hammock and compress your back.
Keeping that abdominal engagement, untuck your tailbone. Release it up like a “happy cat” instead of down toward the floor like a “scary Halloween cat.” If this is done without the support of your abdominals, there’s a good chance you’ll compress your low back, especially if you’re very mobile.
Take your right foot back behind you. Keep the ball of your foot down on the floor for now, and breathe deliberately. Don’t rush through the motion. Notice if your hips have leaned to your left, and try to stay centered. Notice whether it’s challenging to keep the front of your rib cage lifted away from the floor. This may be more difficult than anticipated.
Remember when you felt your multifidus while walking around? Bring your attention to that area now. Imagine the multifidus on either side of your spine closing together like a pair of sliding elevator doors. If multifidus is inhibited, this visualization can help your nervous system start to create a clearer map.
If you can stay centered and keep your rib cage lifted, then slowly lift your back leg to hip height. Take a few breaths here.
If, and only if, you have maintained the good form described above, try reaching your left arm straight out in front of you, parallel with the floor. Keep your shoulder open by rotating your left thumb up toward the ceiling as though you were a hitchhiker.
Maintain smooth control as you release back to tabletop.
Rest for a few breaths in a comfortable, neutral position. Do not skip this step. Rest offers your nervous system a chance to process the movement and learn.
As you grow stronger, you can repeat this exercise several times on each side.
Somewhat surprisingly, even an excited, overused multifidus can benefit from this exercise. Using the muscles breaks the neurological status quo that keeps the muscle fibers short. After engaging the muscle, the nervous system can now reset it to a longer resting length.
If multifidus is simply weak, the exercise will strengthen with use. If it’s inhibited, using the elevator door visualization may help.
Because multifidus is a bilateral stabilizer, it works on both sides of the spine. That’s not a problem if the muscle on either side of the spine is fairly symmetrical. However, in a scenario like scoliosis, one side may be inhibited while the other is facilitated. In that scenario, working multifidus bilaterally can still be helpful, but so can recognizing its other actions.
In addition to stabilization, multifidus also assists with extension of the spine—otherwise known as backbending—especially against the resistance of gravity, as in belly backbends like bhujangasana (cobra pose) and shalabhasana (locust pose). It does some side bending and rotation toward the opposite side, too.
In response to a nerdy question that I asked on my Facebook page, Margaret Pitkin, a physical therapy student and yoga instructor, expressed doubt about the possibility, and even the desirability, of attempting to work muscles too specifically. The trend in physical therapy is toward functional movement and away from myopically specific movement.
Functional movement is effortless, pain-free movement in everyday situations, with good biomechanical muscle and joint function. It represents an entirely different approach than sequestering muscles as though they were disparate mechanical parts. Functional movement seems right in tune with yoga’s holistic approach, and resonates with my own approach to teaching yoga.
Functional movement seems right in tune with yoga’s holistic approach, and resonates with my own approach to teaching yoga.
However, in instances of scoliosis, some specificity may be helpful. Side plank may be the best yoga posture for strengthening multifidus on just one side of the spine. Pitkin explained to me:
“To strengthen unilaterally I would think you would need to focus more on the action of multifidus as a spinal rotator (as it only extends the spine when acting bilaterally). It is a contralateral rotator, so rotating to the right engages the left multifidus.
"I like doing side plank and repeatedly dipping my top hand under my bottom armpit, then reaching it back up again…and doing more repetitions on my weaker side.”
If you’re interested in overcoming multifidus pain, modalities like Feldenkrais and The Alexander Technique may also be helpful for facilitating better communication between the nervous system and largely subconscious postural muscles; and, of course, a slow, deliberate, and conservative asana practice—infused with steady, purposeful breath, and an integration of yoga’s philosophy of connection and interconnection—can be an ideal addition to any back care program.