Abdominal hollowing (or the draw-in maneuver) and abdominal bracing are both incorporated by therapists, trainers, and other exercise specialists to benefit persons with lumbar instability (Vaičienė, Berškienė, Slapsinskaite, Mauricienė, & Razon, 2018). There is a tendency for professionals to pick one of these interventions while downplaying the validity and value of the other. Integrated training is based on the implementing all evidence that works during the appropriate time with an understanding of how we can optimize outcomes for our clients. We will review the research surrounding abdominal hollowing and abdominal bracing to provide a better understanding of the evidence of their practical applications.
Evidence shows that deep abdominal muscles are more activated with abdominal hollowing and surface muscles more activated with abdominal bracing (Vaičienė, Berškienė, Slapsinskaite, Mauricienė, & Razon, 2018). Hollowing has shown to increase local spinal stabilizers (Lee et al., 2013; Suehiro et al., 2014; Kim & Oh, 2015; Lee et al., 2016) and LPHC stability while minimizing the facilitation of global muscle activity during exercise (Suehiro et al., 2014; Kahlaee, Ghamkhar, & Arab, 2017). Abdominal hollowing was found superior to abdominal bracing for increasing LPHC stability and leg stiffness in hopping tasks (Dupeyron, Hertzog, Micallef, & Perrey, 2013). Though it does seem that maintaining a neutral spine (Reeve & Dilley, 2009) and costodiaphragmatic (chest / belly) breathing is important to the optimization of muscle activation while performing abdominal hollowing (Ha, Kwon, Kim, & Choung, 2014).
Multiple data questions the efficacy of treating LBP solely using abdominal hollowing (Unsgaard-Tondel et al., 2012; Vasseljen et al., 2012; Wong et al., 2013). McGill, arguably one of this generation’s top researchers on exercise and the spine, is not a fan of abdominal hollowing, and argues that the transverse abdominus should activate when abdominal bracing is done appropriately without the need to draw-in the navel (2016). He provides evidence that core stiffness is of far more value when it comes to protecting the back (Lee & McGill, 2015).
Evidence supporting both abdominal bracing and abdominal hollowing work to increase LPHC stabilization. We are not left with a debate on efficacy of these two techniques, but application. Which application should we employee and when?
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You're listening to the NASM-CPT Podcast with Rick Richey, the official podcast of The National Academy of Sports Medicine.
Welcome to The NASM-CPT Podcast, my name is Rick Richey, and today we're going to have a debate. The debate is on whether there is a controversy here between drawing in the navel to stabilize the spine, or abdominal hollowing, versus to brace, this abdominal bracing.
So, abdominal hollowing, or drawing in the navel, sucking in the belly button towards the spine, and that's where the Transverse Abdominis is primarily, which wraps around the entire abdominal region. When you contract that, it sucks the belly button in towards the spine.
Abdominal bracing, on the other hand, is almost like, you're going to get punched in the abdomen and you tighten your core really tight in order to make your abs tight. So, which is of value in order to stabilize the spine?
And the debate is really coming because there are people that have a tendency, and these are professionals in the field that do this as well, they have a tendency to pick one and then they downplay the validity and the value of the other, even though they both have plenty of research behind them to show value. It's just why are they valuable and what did they do, and is there a potential where one would work in lieu of another or work better than another?
So, we're going to look at the evidence today. This is going to be a research-heavy day and I don't actually, I've got all the research here, and I've got it written out, but I read out their names, so, I can't pronounce a lot of these peoples names, and there's a lot of et als in here. So, what I'm going to do is I'm just going to say research shows and that's going to help to cover my base for the purposes of this podcast and then we'll be able to provide, maybe, some written content so you can look at some of the research itself if you wanted to look it up and find out where it comes from.
But, let's talk about research surrounding abdominal hollowing and abdominal bracing, where provided better understanding of the literature and the research and the evidence that is out there.
Now, one thing very important to note, a research study doesn't prove anything. Research studies don't prove anything. Research studies show a correlation between variables and it is important to use all of the research that's out there. So this is things like systematic reviews, these are meta-analysis, this is taking all or many of the research that is out there on a particular topic, put it together in a large study to find out what content is there and see if it creates a better whole picture understanding of what certain things do.
So, with that being said, there is a lot of research on each one of these topics. So, what I want to do is discuss it and get into the idea of where these things started and really a part of it started with Bergmark, who in 1989, identified the lumbo-pelvic-hip Complex and divided it into two systems, like a local system where those are the intrinsic stabilizers of the spine, and a global system, which are the larger movement muscles of the spine that also cross the lumbo-pelvic-hip complex.
And these muscles influence everything that we do because the LPHC, the lumbo-pelvic-hip complex, the core, is the center of the body so anytime we push with the arm, then it has to anchor itself onto our axial skeleton with muscles and the axial skeleton has to stay strong in order for us to push, pull, rotate, and stabilize things we are grasping. So, same thing goes with our legs.
The core is very important in exercise and we're going to look at… let's talk about abdominal hollowing first. Alright, so let's just have the conversation. Abdominal hollowing is drawing in the navel towards your spine, and there's a landmark study that created this real big buzz around the transverse abdominis and its importance in training. So, a very long time, you started getting people across the boards in fitness and in Pilates and modalities that were really important in helping with spinal stabilization. Cueing over and over again, draw the navel in, belly button in, belly button towards the spine. So, whatever their language was, in order to use it, people are trying to get people to suck their belly buttons in towards their spine, activating their transverse abdominis, and creating this intra-abdominal pressure through the drawing in maneuver. Well, that's good. It was good because there's content to support that, we're going to talk about it, but let's talk about where it got its start.
Richardson and Hodges had a landmark study back in the day and I don't actually have this study written down in my notes right now but it is a landmark study. And it showed that there was a delay in transverse abdominis activation for people that experienced chronic low back pain. So, people with chronic low back pain, when they would have them do a movement, muscles would activate and then it would be a delayed activation of the transverse abdominis. This was a very important thing to notice. So, they started pushing this concept and the industry started picking up on the concept that spinal stabilization and lower back pain, was linked with the transverse abdominis.
Now, we don't know if it's a chicken or an egg situatio. Is the lower back pain in existence because there was a delayed reaction in the transverse abdominis, or is there a delay in the transverse abdominis because their back hurts? We don't know but I think one of the concepts here is that people would start creating this pre-activation of the transverse abdominis to support the spine. So, they would say draw in your navel, and that would then create this spinal support before people would start to do movement and exercise.
But, a study in 2009 came out and said that these patterns are exhibited in multiple different muscle types, not just the transverse abdominis. So, that might happen with the internal obliques, it might happen with rectus abdominis or the Q-L, that these delayed activation patterns are not solely seen in the transverse abdominis with people with low back pain and they're not solely seen in people with low back pain, that there is always some type of delay in something when people are doing exercises when it comes to muscle recruitment and activation. So, we're almost at a stalemate right now with these concepts because, yes, is a transverse abdominis important to spinal stabilization? I believe so. Lower back pain? Yes, we believe so. But, what does the literature then continue to say about the drawing in maneuver? And then we'll spend a little bit more time talking about abdominal bracing.
So, the stabilization of the spine is incredibly important. I don't think you're going to find any therapist or researcher that's going to argue that point, that it's not, it definitely is. And we're going to go through some of the literature talking about a gentlemen named Stu McGill, Stuart McGill, he's kind of like the father of spinal exercises and spinal research when it comes to exercise. But, Stu McGill downplays the value of drawing in the belly button, or abdominal hollowing solely. So, just solely abdominal hollowing.
So, let's talk about some of the research that's out there. Let's talk about Stu McGill's stance, let's talk about abdominal bracing, and evidence does show that the deep abdominal muscles are going to be more activated with abdominal hollowing than surface muscles that actually are activated more when you do abdominal bracing. And abdominal hollowing has shown to increase local spinal stabilizer strength. It's been shown to… say that we're going to minimize the facilitation of the global muscles during activity when you're drawing in. So, the other muscles don't have to support in the stabilization as much when the drawing in maneuver takes place.
Abdominal hollowing was found superior to abdominal bracing for increasing lumbo-pelvic-hip stability and leg stiffness in hopping tasks, so single leg dynamic activity. Well, again, that's one study, but this was the outcome that was seen. Though it does seem that maintaining a neutral spine and costo-diaphragmatic breathing, that is chest and belly breathing, is important for the optimization of abdominal hollowing when it comes to stabilization of the spine. So that means when you go into like an anterior pelvic tilt and do abdominal bracing, or posterior pelvic tilt, then it doesn't stabilize the spine as much as when you maintain more of a neutral spine position.
Also, when it comes to breathing, doing just belly breathing, or just chest breathing, is not as advantageous when it comes to stabilizing the spine, as it is if you use both. You breathe as a unit, not just pick your chest or pick your belly, in order to breathe from, which, I believe is probably a better outcome when it comes to breathing anyway, using the entire abdominal thorax region to support breathing. Then we find research that supports that doing that while abdominal hollowing helps to support the spine.
There's also some very interesting information about breathing when it comes to stabilization of the spine, and there was a study done and McGill was part of this study that talked about expiration. And the full expiration, if you just breathe everything out, showed significant increase in external obliques, internal obliques, transverse abdominis activation, when compared to both abdominal hollowing and abdominal bracing. So, I like adding this into it because we're looking at now using our breathing to help create support for the spine while doing exercise and what that might look like.
So again, this is the research. We're not looking at any practical applications right now. We're just finding research that's supporting the validity of doing the drawing in maneuver, abdominal hollowing. But, the debate is not over because there are researchers that note that abdominal bracing is a more effective technique to activate the deep core musculature. And, I think that's interesting because usually when you get people who are advocating for one or the other, then you'll have the abdominal hollowing crew that says it's better for the smaller muscles around your spine. And the bracing is better, can be better, for certain things, because the global muscles are starting to work and to help stabilize the spine. But, I don't think that that is completely and always the case. So, we want to be conscience of what the information says and in how we start to apply it.
So, we've got here, a vertical jump landing test, and they had abdominal bracing and it says that it's shown to enhance pelvic stability, increase sensory motor control, and positioning of the lower extremity, and helps with reducing bio-mechanical factors associated with ACL injury, while protecting the lumbar spine. That sounds valuable. Let's look at check-mark for abdominal bracing. We've got multiple data out there that questions the efficacy of treating lower back pain solely by using abdominal hollowing. So, for those that say somebody's got lower back pain, just do abdominal hollowing and that can help mitigate the effects of lower back pain. And, that's not necessarily true either. Research out there supports it. But, if you're looking at it and said all you're doing is abdominal hollowing, then you might not be doing enough.
So, let's continue down this line of questioning here. Let's go back to McGill now, who's arguably one of the generation's top researchers in exercising the spine, and admittedly, he is not a fan of abdominal hollowing because he argues that the transverse abdominis should activate when you do abdominal bracing. And he's a big proponent of abdominal bracing in order to stabilize the spine. But, why only draw in when you could support the spine from multiple different ways, create intra-abdominal pressure, and have the transverse abdominis be a supporting role in that as well?
As a matter of fact, he said in his textbook, let's see, his textbook which I had purchased recently, I am a big fan of, it's called 'Low Back Disorders, Evidence-based Prevention and Rehabilitation.' It's in its third edition, which is the one I have. And, I like this, and in there he talks about the transverse abdominis and says that yes, you need to have the transverse abdominis be a part of this and it's a vital importance for the transverse abdominis to participate in stabilization of the spine. But, he just doesn't believe that abdominal hollowing is the best way to do that. He believes abdominal bracing and engaging the transverse abdominis is highly indicated for that. And, I like that. I like the idea of saying, well, let's do bracing. And, he's not saying do abdominal hollowing. As a matter of fact, he says that the isometric activity should take place, that when you do your abdominal bracing, you're not drawing in, and your abdomen's not protruding at all. As a matter of fact, there is no change in the size of the abdominal muscles. You're just creating stiffness. And his ultimate goal, when it comes to protecting the spine, is creating stiffness around the spine. Well, I agree. I think this is really wonderful information.
So, so far, I've agreed and pointed out literature, and empirical evidence that shows abdominal hollowing helps to increase stability at the spine and helps with low back pain. I've also found research and pointed out that doing abdominal hollowing solely for mitigation of low back pain is not ideal, and that abdominal bracing can be more effective, in certain circumstances, than hollowing.
So, what do we do? What do we do? We've got evidence to support both. But, here's the thing, in application, which we employ, I think early on in stages of training, you've got to cue abdominal hollowing. And, it's probably a good starting point, when it comes to trying to get somebody, neuro-muscularly, to understand what's going on, and how to create this transverse abdominis drawing in maneuver. So, practicing drawing in is valuable, and practicing abdominal bracing is valuable. Because once you go into abdominal bracing, you're going to get more out of your stabilization.
Let's say you're doing a standing, single-arm chest press, and you're not bracing your abdomen, you're just drawing in. Well, you're missing out on some of the stiffness that your, all of your muscles can help to create stabilization through your LPHC. So, adding stabilization, and adding in the drawing in maneuver, or the abdominal hollowing to support your spine, is vitally important to know how to do both of them. But what I don't want to do is downplay the importance of increasing neural facilitation towards a particular muscle that may not be doing its job, and we know that the transverse abdominis and internal obliques are very closely linked. It's almost impossible to separate those two muscles when it comes to spinal stabilization.
So, when you draw in the navel, then you are also getting a very strong activation of your internal obliques, that is going to work concurrently with each other through the thoracolumbar fascia aponeurosis to stabilize the spine and the SI joint, which we also have support from drawing in maneuver, and bracing, to support the SI joint. So, doing these particular exercises, drawing in and abdominal bracing, are both valuable. Don't pick one at the loss of the other. I think you should practice both. Same way that you would say, alright, well, I'm going to work, I don't know, let's say calves, alright, but, you don't want to work your posterior tibialis. Well, that's going to be difficult because they're all plantar flexors. So, posterior tibialis is going to be an important component that's going to help support plantar flexion. But, might there be a time where, through trying to get the best out of learning how to control the foot, that we preferentially activate the posterior tibialis, in order to create more support at the foot and the ankle? In that, the answer is going to be yes, of course.
We can put our foot into plantar flexion and then we can create inversion and do plantar flexed inversion exercises in order to strengthen the posterior tibialis. And that can then help to support my foot and ankle complex, as I go through ambulation and movement while going through plantar flexion. And the same thing, or similar thing, would happen at the core. I can work everything together but sometimes you need to pick out some muscles and whether that's the transverse abdominis or wherever is the primary focus on the lumbar multifidi, or whatever, it doesn't matter. Sometimes you have to focus on pieces and not the whole. So, incorporating abdominal hollowing into your training, drawing in the belly button to help support the spine, those local muscles vitally important, they should be practiced. Doing abdominal bracing to support the spine, especially as you start to do heavier lifting. You can't just draw in and do a heavy lift. It is a natural component, where you start to lift heavier, you start to increase the bracing and the intra-abdominal pressure.
So, I would say if you're going to start out with somebody, and we're going to pick a pattern to follow, maybe start out with some abdominal bracing, sorry, abdominal hollowing, getting people to practice sucking in the belly button and support the smaller muscles of the spine. And then start including bracing into it, where you're creating transverse abdominis activation and co-contraction of a lot of muscles.
So, we're talking about the internal obliques, and external obliques, and if you look at the pattern of those things, when you brace and draw in, the internal and external obliques create a crisscross pattern. Think of a crisscross pattern like if you're walking through construction in New York City, and you see scaffolding up, you walk through, all of that scaffolding has X-shaped metal, creating a crisscross in there, and that X-shape, that crisscross pattern, creates stability. We want that stability. Fortunately we have internal and external obliques on both the sides, the flanks of our body, that creates spinal stabilization. Because they run obliquely, they have support, in sagittal plane, transverse plane, and then they're on the side of our body, so also in the frontal plane. Why just pick drawing in when I know that we can do other things that support our spine? We are also looking at rectus abdominis, can be a component that helps to support our spine the way that our thorax and our pelvis stabilize. But it is that drawing in maneuver that does work all the smaller muscles in the lumbar spine.
Let's get both of them practiced in our systems and as we start to get heavier and heavier with the weight, we start adding in more and more bracing because we already know that the drawing in maneuver is there to support the smaller stabilizers in our spine.
Alright, I hope this helped and basically what I said is, both abdominal hollowing and abdominal bracing work and do them both. Why is there a debate? Because, you may do one and not the other, and you may downplay the value of the one that you're not doing. Don't do that. This is an integrated training model and you find information that works and is of value, just start integrating it into your system. Find the truth in as much truth you can fit into your workouts and how you work with coach and trained clients and athletes, let's do it all. Alright, thank you so much for listening. This is The NASM-CPT Podcast with Rick Richey.