In this episode of the Evidence Based Chiropractor, host Dr. Jeff Langman (also referred to as Dr. Jeff Lengmaid) reviews a 2025 systematic review and meta‑analysis published in Frontiers in Cardiovascular Medicine that examined the impact of cervical spine mobilization and manipulation on arterial health using controlled animal experiments. Six eligible studies were identified, comprising both healthy animals and animals with pre‑existing atherosclerotic disease. The review found that in healthy arteries, adjustments produced no measurable changes in tensile stress, strain, vessel structure, blood flow, inflammatory markers, or mortality. In diseased arteries, adjustments did not cause stenosis, rupture, dissection, or death, but did elicit a moderate increase in macrophage infiltration, indicating mild inflammation. The animal protocols employed extreme rotation angles (often >100°) and daily manipulations over weeks—conditions far more aggressive than typical clinical practice. The host interprets these findings to mean that cervical adjustments are mechanically safe for healthy vasculature, and that the primary safety concern should be proper screening for patients with significant vascular risk rather than the adjustment itself. Practical take‑aways include incorporating cardiovascular risk questions into intake histories, using clinical judgment to tailor technique when needed, and communicating evidence‑based reassurance to patients. The episode also contains sponsor messages for chiropractic tables, shockwave units, a diabetes reversal program, and an osteoarthritis recovery program.
Welcome to the Evidence Based Chiropractor where each week we deliver the latest chiropractic research and marketing strategies all in the time it takes to get to your office. Now here's your host, Dr. Jeff Langman.
Hello and welcome to the Evidence Based Chiropractor. I'm your host, Dr. Jeff Lengmaid. On today's episode we have another fantastic piece of research recently released and this one is all about cervical adjustments and how they interplay with the arteries. This is a fantastic study that ties directly into the safety of what you and I do. A lot of clinical pearls take home messages. I think you're gonna love what the research says. But more importantly, we'll discuss the how this can be applied in the conversations that you're having in your practice. We're gonna do that and much more on today's episode. Before we get started, big shout out to two partners of the Evidence Based Chiropractor that are hooking you up with big deals on what they have for being a listener. Number one is Leander Tables. You can save $1,000 off their Series 950 table. Absolutely awesome. By connecting with their team and learning more down in the show notes. Additionally, Shockwave Centers of America, $500 off their shockwave unit plus a free cart. So for being a listener already, you're a minute and a half in $1,500 in savings right there. Fantastic. Partners and sponsors of this podcast highly recommend connecting with them and having a conversation. But as I said on the top of today's episode, all about the research. This is really the question does cervical adjustments damaged arteries. Now this study is going to showcase, I'm going to say the truth behind that, which is not really spoiler alert. And the title of the study we're going to talk about, link it down below in the show notes. It is the effects of mobilization and manipulation on mortality and structure, function and inflammatory markers in cervical blood vessels. A systematic review and meta analysis of studies in healthy animals and animals with pre existing vascular pathology. That is quite a long title. This was in Frontiers in Cardiovascular Medicine came out in 2025, so brand new one. This is an animal model just to be super clear at the top. So we'll talk about why that matters as we dive in. So the question around safety of what we do has been a question I think since just after the first adjustment. There are many people out there, consumers, patients, people in your community, other doctors that have a concern. Now I'm not saying a criticism but a concern invalidly. So you see you know, you see somebody receiving a neck adjustment and you know, not every profession does it. It's not something you see every single day. It's really the hallmark of what we do as chiropractors. And by definition we see a minority percentage, 15% of the population. So not everybody is getting a neck adjustment every single day. Right. It's a minority of people that have this done. So the questions around safety are good ones and it's something we should continue to explore with studies just like this, which is a systematic review and meta analysis. So often the question of safety can come up and I find a lot of, there's a lot of docs out there that aren't sure how to answer it. I'm going to say super effectively. It's either, you know, brushed under the rug sometimes. Other times there could almost be a little bit of defensiveness if we're honest with each other about how we might answer questions around safety. And neither needs to be the truth. I think there can be a really rational, direct and clear answer and we're going to talk about some of that on today's episode. So chances are in your daily life, conversations around safety pop up every now and again and you probably are really aware that the risk is incredibly small based upon your own experience adjusting thousands of people, probably over the course of your career. But also that's what the research has shown over time. But these questions still come up. So we're gonna look at the systematic review that asked the following question. If cervical adjustments were actually harming arteries, would we see measurable damage in the controlled experiments? Really great question. And, and since it's really difficult to test the answer to that question on humans, researchers used animal models to measure. And what did they measure? They measured some things that are really critically important. One, artery structure two, blood flow, three, inflammation, four, even mortality. And the results, they are not what the fear based headlines would have you believe. This paper. Again, systematic review, meta analysis, which basically means instead of one small study that they gathered every controlled animal experiment they could find where researchers had tested cervical spine adjustments or mobilization and then measured what happens to the arteries. So they searched things like PubMed, Embase, all, you know, thousands of papers screened, six met the criteria. So we're not talking about this massive amount of like hundreds of studies, but it's still the best controlled evidence that we have on the mechanical effects of adjustments on blood vessels. And they were trying to answer three primary questions. One, what happens in healthy arteries? Two, what happens in arteries with pre existing disease? Like atherosclerosis 3, does underlying vascular disease make arteries more vulnerable during an adjustment? And the third one is huge because it lines up exactly with, I'm gonna say, a framework or the idea that complications likely require pre existing pathology. I'll say that one more time, that complications likely require pre existing pathology. So let's hit some of the numbers on the top. So in the healthy animals, adjustments, manipulation, no, no significant effect on tensile stress, tensile strain, blood flow volume, excuse me, vessel structure, or inflammatory markers. So healthy arteries basically didn't care. They did not have any measurable damage, no structural change, no inflammatory spike, nothing meaningful happened. And this is important as well. When I think about an adjustment delivered by definition, an adjustment gets into that paraphysiological space, and I'll say one step farther, by definition, the paraphysiological space is prior to any injury, it's beyond normal range of motion, yet before there should be any injury. So just logic alone, which research is important to prove the logic, of course, but just logic alone dictates the fact that if you are staying within the paraphysiological space and if the artery is healthy, there should be no challenge to that artery. Now, I am specifically speaking about the arteries. I'm not talking about the mechanisms of action within a chiropractic adjustment, biochemical change, markers, biomechanical changes, segmental changes. I'm not talking about the effects. I'm talking strictly about the effect on the artery itself. So our arteries do have enough, quote, unquote slack in order to get into a paraphysiological space and have no challenge. And I think that's where, why I repeated the line a moment or two ago, but which was when there are no pre existing conditions. Preexisting conditions can change things. We'll talk about that in just one moment. But again, remember, by definition, or the paraphysiological space beyond range of motion, this is kind of where some of the magic happens. Not all of it, but where some of the magic happens. You're getting beyond normal range of motion. But prior to any sort of injury, now, in animals with vascular disease, atherosclerosis, they found no increase in stenosis, no structural damage, no blood flow compromise, and no mortality. But they did find a increase in macrophage infiltration, and the effect size was kind of moderate. So there was some more inflammation inside of already diseased arteries. There was not rupture, there was no dissection, there was no blockage, but there was some inflammatory activity. And that is a very, very different story than a manipulation Quote, unquote, causing a stroke. There was zero mortality, zero deaths related to the adjustments or manipulations across all of the studies. And we'll take that one step farther in a moment. So if, if cervical adjustments were mechanically tearing arteries, we would expect to see things like thinner vessel walls, reduced blood flow, higher incidences of stenosis, structural breakdown, or at least some tissue damage. And in this study, they found none of that whatsoever. And that was even in arteries that were already suboptimal. The only constant finding or consistent finding across these studies was that inflammation markers did increase in previously or existing diseased vessels. Which totally makes sense from a biological perspective. If you have like a rusty pipe and you tap it, you might stir up some debris, right? You're not breaking the pipe. And that's that. Probably the easiest explanation here. Now, before, before we get too far on it, there is. The authors did make a big point that really matters. So, and, and this is, these are really important points. So in these animal studies, they actually used extreme rotation angles, sometimes 100 degrees or more. Probably not what you're doing in your practice. Two, they delivered these manipulations basically daily rotation for weeks on end. So probably not what you're doing. Most of your patients, they used severely atherosclerotic models and often all of this is just way more aggressive than what we see in a clinical practice. So this was like the worst case scenario in this study. Not realistic to the chiropractic care that you're delivering. But this is great because it sets the anchor or the foundation for us to say, man, they were going extreme rotation every single day for weeks on end with massively atherosclerotic tissue. And still the only thing that they found, and this is a systematic review and meta analysis of multiple studies, the only thing that was consistent was, hey, inflammatory markers went up a little bit. Well, no kidding. Now that you know the whole story, right? So the practical takeaway is that this research supports something that most of us already intuitively know, that healthy people tolerate cervical adjustments extremely well. So really the question should never be, although people are going to ask it, that's okay. But you know, the question is not are adjustments dangerous? It's are we properly screening people with extreme vascular risk? Because if anything, this paper reinforces the concept that pre existing pathology is really the variable that matters, not the adjustment itself. So what are some things that you can take away from this? One, in your intake history, in your report of findings, are you asking about these types of things? Is there any red flag screening that you can do maybe blood pressure awareness, cardiovascular risk discussion again, you don't need to go, I'm gonna say overboard on this type of thing, but. And nor does this absolutely mean you need to change technique. Again, these were extreme cases as we talked about. Massive rotation, everyday adjustments, and still only inflammation. But as just being part of a fantastic clinician that you are just understanding what's going on with this patient as they come in and do they have anything in their health history that you should be aware of? Maybe it changes your technique, maybe it doesn't change your technique, but it gives you the opportunity to be aware and make the best clinical decision that you can. So I loved this study because it really, I'm gonna say, reframed yet again, the conversation around safety. There's absolutely zero indication that when a cervical adjustment is delivered that there's any increased red flag. I think we've seen previous studies. I'm kind of trying to think about them alive on the spot right now. But it was like, okay, somebody goes to see a chiropractor or a medical doctor. The risk of arterial dissection was the same. Well, clearly we're doing very different things. So the adjustment is not causing it. Right. If it's the same to both. The other was, you know, I think it was the old hairdresser. This might sound really dated. I don't even know if people have the sinks and like that to wash your hair when you go to the hairdresser anymore. But it was like that. That's an instance that can actually increase risk, extreme, you know, extreme range of motion, et cetera, for an extreme amount of time. So, long story short, this study re emphasizes the fact that what we do is exquisitely safe and extremely safe across every, nearly every single population, but certainly amongst those that have healthy vascular tissue. So might you ask some questions on new patients? Probably, and you probably already are. And you take that into consideration on the technique, how you rotate and how you choose to take care of that individual. But there are absolutely no, I'm going to say yellow or red flags based upon the studies that we see it. And I love studies like this because they move us away from sort of the fear based stories and towards the actual data. And the data says healthy tissue is resilient, that catastrophic complications are extremely rare. And your clinical judgment is what matters most. And that's exactly what you bring to the table each and every day when you see your patient. So cervical adjustments do not appear in any way, shape or form to, to mechanically damage arteries. But smart screening is still a really, really good idea. So keep doing exactly what you're doing. Thoughtful examinations, great reasoning, good patient education. It doesn't need to be about fear and headlines and kind of TikTok experts. This is really just about being a great chiropractor, showing up and delivering the care that you know patients need each and every day. So I love this study. I'll drop a link down to it in the show notes. Additionally, two quick shout outs as we wrap up today. Diabetes Reversal Group, you can click on down below, watch a video and learn from their team about how you can bring diabetes reversal into your practice without any additional overhead, no additional stress. You can take care of the people coming in in a very, very elegant manner that makes it really, really easy for you and delivers awesome results for them. Diabetes Reversal Group I'll drop that down below as well as Novopulse and their OA recovery program. I I love it. Osteoarthritis. Something walks through our door each and every day. Novopulse has a complete OA recovery program and I'm gonna drop a link down below for you to check that out and connect with their team as well. If you have not left a rating or review for this podcast, I would love it if you would take a moment and do so. It helps more and more docs find out about what we're doing. Additionally, I will say thank you so much for tuning in. Thank you for being a chiropractor. Have a fantastic week in practice and I will talk to you soon.
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