the multifidus

Today, Dr. Tom Padilla, owner of The Doctors of Physical Therapy in Scottsdale, talks with Dr. Jo Armour Smith about the brain’s involvement in body mechanics and the root cause of chronic back pain. 

Dr. Tom Padilla

I have a very special guest today, someone who I know from when I was going to physical therapy school. She was doing her PhD research at the time, and I have followed her research since then. Much of what makes our clinic’s results so different from other physical therapy comes from applying her research to our practice and our patients see amazing results. 

This is Dr. Joe Armour Smith, she trained as a physiotherapist, emigrated to New York, and worked in an outpatient ortho clinic there. She did a lot in dance medicine before going on to USC, where we met, to do her PhD research with Dr. Kornelia Kulig. Together, they investigated how the body adapts to maintain posture in the trunk while walking, specifically in young adults who had recurrent low back pain. 

I really became interested in the research of this time, because these younger individuals were already showing signs of recurrent symptoms of low back pain, something that we tend to see in individuals as they age, and Dr. Jo Armour Smith really started investigating and trying to figure out why. I love that you did that research for us. Thanks for speaking with me today. 

Now you’re at Chapman University, and your main research is on neuromechanics. It’s my understanding that that is combining biomechanics, which is the science of movement, with neuroscience.

The Biomechanics-Neuroscience Connection

Dr. Jo Armour Smith

Exactly. That’s right. Biomechanics gives us an opportunity to measure multiple aspects of movements or motor behavior, whether that’s how much joints are moving, how much muscles are being activated, and how we accomplish movements. Then the neuroscience piece is looking at how the brain, as the central nervous system, is controlling that movement. And since these two systems are completely interlinked, they’re interacting all the time to produce the movement that we can see. 

I like to look at both aspects of that. So both the movement that happens, and also how the central nervous system, particularly the brain, is accomplishing that movement.

The Root Cause of Chronic Back Pain

Dr. Tom Padilla

Absolutely. To me, that’s always made absolutely the most sense because movement doesn’t start at the body. Right? It starts at the brain. So that’s why I’ve always been fascinated with this. Let’s do a little bit of background. Why did you become a researcher? What drew you to this particular area of research specifically?

Dr. Jo Armour Smith

I trained as a physiotherapist, the UK name for a physical therapist, and when I entered the profession I had no interest in research whatsoever. It didn’t even sit across my radar that that would be something I would end up doing. However, I had a series of experiences along the way during my clinical career that gradually nudged me towards doing what I do now. 

When I first started working as a physiotherapist in a hospital in London, I was fortunate because they had a really good program there where clinicians working in the hospital could get some mentorship to come up with research ideas, and carry out research in the hospital setting and get a lot of support on figuring that out. So I had a nice opportunity to sort of try that out in a hospital setting. 

Then, once I emigrated to the United States, I started working in an outpatient clinic and I became particularly interested in back pain just because it’s so challenging. It’s so variable. Every time somebody comes into the clinic with back pain, it’s a different presentation. Everybody brings these really different, very specific experiences of how and why they’re having pain, and I just found that challenging to treat. 

Being a practicing PT and taking on continuing education courses and learning about back pain and about movement, there were things I was being taught along the way that didn’t seem very well-supported by evidence. Maybe those of us who are physical therapists and other healthcare providers, you know, we sometimes hear things and we’re like, is that really true? 

So I became really fascinated in the idea that I could actually test some of these things and see if these received wisdoms or things that we think we know are really true. So that then prompted me to pursue a PhD. I ended up at the University of Southern California, where I was fortunate to work with Kornelia Kulig, who had a long history at that point of back pain research and looking at the biomechanics of back pain, or movement in people with back pain. 

Dr. Tom Padilla

So you were drawn to the challenge. What did you find in your investigation of the truth? Were there things that you were able to prove and disprove or confirm or deny the things that you were taught or thought? 

Dr. Jo Armour Smith

Yes. Along the way I’d heard that some very specific patterns of motion were believed to occur during walking. This was specifically what got me into being really interested in walking and back pain. 

So I had been taught that there were very specific characteristics of the way that the spine moves during walking in people with back pain. And that was kind of what I set out to test and learn. One of the big things we learned was that the mechanics were not the same in everybody who has back pain, so step number one is to say, in people with back pain, we expect to see this movement behavior or this characteristic is problematic. But in reality, it’s difficult because it’s very individual. And also that there are many things that are very difficult to measure at the level of precision that would really allow us to be able to get the evidence for some of these things. So all of that to say, yes, the thing that got me into this, in part, is in fact not true.

When The Science Doesn’t Check Out

The level that I had been taught, which was very general in terms of people with back pain, but then very specific in terms of movement and parts of the spine moving differently, was not true. I did find some other things were a little bit more constructive, other than just, oh, it’s not true. During my PhD and working with Dr. Kulig, we built upon some work that other people had previously done. We were able to show that, specifically in young adults, which has continued to be the group of people with back pain that I’m most interested in, there were some specific differences in how they were using some of the muscles, particularly the multifidus. 

In young people with back pain, the multifidus, this really important spinal muscle, is used differently than in those without pain. And that interested me because I come at this with the idea that if we can understand better what’s happening really early on, when people get back pain, which tends to be when they’re young adults, or even when they’re teenagers, then we can maybe start to address it more effectively early on.

Dr. Tom Padilla

I feel exactly the same way. There are no gospel commonalities when it comes to back pain. However, in early-onset, acute, recurrent low back pain with young adults, there are certain commonalities. And then sometimes what happens as we go on, as everybody adapts to those commonalities differently, our bodies develop altered movements and characteristics that we might read in those individuals that have had it going on for a longer period of time, which is what can point us to the root cause of chronic back pain.

The Root Cause of Chronic Back Pain

Dr. Jo Armour Smith

That’s a really nice way of describing it. Yes, I think when somebody first has an episode of pain, or starts to have that sort of recurrent pattern of pain that you’ve described, we see some changes in the way they move, some changes in the way the muscles are used, and also some structural changes in the muscles, which we can talk about more in a bit, and also some changes in the brain. 

Importantly, that happened pretty early on. And then, exactly as you said, over time, when people start to have had back pain for years, decades, by the time people are middle aged, the way that that back pain has altered the way they move and the way that their brain is processing movement is going to be very different across individuals, because it’s going to be influenced by a whole lot of other individual factors. 

And what do I mean by somebody’s movement, what did they do in terms of using their movement? Influences like their job, their hobbies, the way they perceive pain, their experience of pain other than back pain, their family experience of pain, their genetics, you know, we could go on for a long time about all the things that will ultimately influence the way their body moves over time. Over time, we almost see this divergence of how people move, given that they’ve got back pain.

Dr. Tom Padilla

Absolutely. I think that sometimes what I have seen is because a lot of the reasons center around why people have repeat occurrences. And there’s a lot of research that you’ve done that shows that there are brain changes and structural changes that could be the root cause of chronic back pain, which suggests that figuring out how to treat it during a first instance, and do so correctly, might be able to prevent those changes from occurring down the road.

To listen to the rest of the conversation, check out our podcast, UnCut: Back Pain and Neuroscience with PhD Jo Armour Smith.