Why Reclined Sitting Is Better for Your Clients: What 50+ Years of Research Actually Shows

The 90-degree sitting posture has been the default recommendation in ergonomics for decades. But does the science actually support it? In this evidence-packed episode, we examine over 50 years of peer-reviewed research—including intradiscal pressure studies, EMG analysis, and MRI imaging—to answer a question that affects every office assessment you conduct.

You’ll discover why reclined sitting (95–115 degrees) actually reduces intradiscal pressure by up to 50–60% compared to standing, decreases paraspinal muscle activity by 13–24%, and maintains lumbar lordosis closer to what we see in optimal standing posture.

In this episode, you’ll learn:

• The biomechanical case for reclined sitting (backed by intradiscal pressure data)

• Why reclined sitting approximates standing posture better than upright sitting

• What EMG research reveals about muscle fatigue and backrest angle

• The optimal backrest angle range supported by ergonomic standards

• How to address common client objections to reclined sitting

• Practical clinical recommendations you can implement immediately

Whether you’re conducting office assessments, recommending chairs, or educating clients about posture, this episode gives you the evidence-based foundation to update your practice.

Resources mentioned:

• Roman-Liu et al. (2023) – Comprehensive literature review on intradiscal pressure

• Wilke et al. (1999) – Landmark in vivo disc pressure study

• Zanola et al. (2024) – Systematic review on sitting and disc degeneration

Are you a healthcare professional curious about how office ergonomics assessments could fit into your services? I’ve got you covered with some valuable (and free!) resources at www.ergonomicshelp.com/free-training.

Transcript

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Well, hey there. Welcome back to the Business of Ergonomics podcast. Today we are tackling a topic that continues to generate significant debate in our field, reclined sitting. Specifically, we're diving deep into peer reviewed literature to conduct a critical question that affects virtually every office assessment you conduct. Welcome to the Business of Ergonomics podcast. I'm your host, Darcy Jeremy. I'm a board certified professional agonist with over 15 years of experience delivering ergonomics programs to employers of all different types. In this podcast, I share what other healthcare professionals are already doing and being with ergonomics assessments and how to land those clients that you dream of. Without further ado, let's jump into this episode right now. Now, if you've been in this field for any length of time, you've probably encountered the persistent myth. That's right. I'm going that far to say that. That sitting built upright at 90 degrees, and we already know at this point That perching forward is probably one of the worst, if not the worst postures for the lower back. Right? We already know that we're already seasoned professionals. We're talking about. The 90 degree stereotype that some may consider to be the gold standard. we're talking about that today. It's absolutely everywhere. If you've been in this field for any period of time, You've probably seen this in corporate training materials. In popular wellness content, even in some of the professional certification courses that I see there spotted around the internet. But here's the thing, the scientific evidence doesn't support this whatsoever. And us as people who love the truth, who love evidence, and as evidence-based practitioners, we need to address this heads on to tackle it. Right, so the National Institute of Neurological Disorders and Stroke reports that approximately 80% of the US population will experience lower back pain at some point in their lives. And for our clients, particularly those in sedentary occupations, chair design and how that person sits in that chair, obviously is gonna play a really big role in either contributing or mitigating this epidemic. And of course, this just is just scratching, the tip of the iceberg, right? So of course we can recommend certain things to reduce the amount of sedentary activities within our control as an organist. However, sometimes we just can't avoid the fact that someone is gonna be sitting to complete the main essential tasks, their jobs. So they're in a sedentary occupation. So today we're going to examine what the latest peer reviewed research tells us about reclined sitting. Why it may actually be superior to upright position for many of your clients and how you can apply this evidence in your practice. Let's get into this right now. the best way to start this episode is to look at the foundational biomechanics. When we shift from standing to conventional upright setting, significant anatomical changes occur. And this is where many practitioners miss a critical distinction. In standing, the lumbar spine naturally maintains an inward curve. That's what we call lumbar lower doses. This curve is biomechanically optimal. it distributes load across the posterior elements of the spine, maintains appropriate disc pressures and positions. The vertebra bodies in their most structurally sound alignment. However, when someone sits with their thighs at 90 degrees to their trunk, the pelvis rotates posteriorly, the lumbar lordosis flattens. in many cases it can even reverse into an outward curve. This is where the trouble usually begins. A comprehensive 2023 literature review published by Roman Le and et al. Examined Intradiscal pressure data across multiple studies. Their analysis demonstrated that unsupported sitting increases intradiscal pressure by approximately 30% compared to standing. However, and this is the key finding, slouching in a chair with the trunk reclined or reclining against a table actually reduces intradiscal pressure by 50 to 60% compared to standing upright. this challenge is the fundamental assumption that standing is always superior to sitting for spinal health. A 2023 finite element study published in bioengineering, examined pressure distribution across different sitting postures. The researchers found no significant difference in intradiscal pressure between standing and erect sitting with proper lumbar support. However, slump sitting that forward flexed posture we see so often in our assessments Significantly increased pressure on the nucleus, pulposus, annulus, fibrosis, and cortical bone during all movement patterns. The clinical implication here is profound. It's not sitting per se that damages the spine. It's how your clients are sitting Reclined sitting with appropriate lumbar support creates a biomechanical environment closer to standing than conventional, upright sitting does. This brings us to a crucial concept that I think we don't discuss enough in our field. The sitting angle continuum. Think of posture on a spectrum. At one end, you have lying down minimal spinal loading, okay? Maximum lordosis. On the other end, you have forward flex sitting with high spinal loading, minimal. Or reversed lordosis standing occupies a middle ground here and recline sitting when done correctly. That's key. Moves the trunk angle closer to that standing position as landmark MRI study examined spinal curvature across three sitting positions forward inclined. Upright and reclined. The researchers measured lumbar lordosis angles in each position. The mean Lord at angles were, 16 degrees in the forward inclined position, 24.7 degrees in the upright position, and 28.7 degrees in the reclined position. That nearly 29 degree lordotic angle in reclined sitting approaches the lumbar curvature we see in relaxed standing. In contrast, the forward inclined position which many workers naturally adopt when focusing on monitors and paperwork reduces lordosis by nearly half. Why does this matter clinically? Because Latic lumbar spine functions as a load absorbing. Spring research has demonstrated that lumbar lordosis reduces intradiscal pressures and transfers load to the posterior annulus and sial joints. This protective mechanism is compromised when we lose the natural curve. The 2024 systematic review published in the Journal of Body Work and Movement Therapies confirmed this concern. The researchers found that prolonged sitting contributes to increased pressure on lumbar intervertebral discs, which can lead to dehydration and decreased disc height. Three of the four studies in their analysis, documented measurable reductions in disc height associated with conventional sitting postures. When we recommend recline sitting, we're essentially telling our clients, maintain your lordosis while seated. approximate the spinal alignment you'll have if you are standing comfortably. The recline backrest becomes the mechanism that makes this possible. Now let's examine the EMG evidence. What's happening with the paraspinal? Muscles in different sitting postures. This is where the case for recline sitting becomes even more compelling. Early EMG research by Anderson and colleagues examined muscle activities across different backrest configurations. they found a consistent pattern as back rest inclination increases erector spinal. Muscles activity decreases. The inflection point appears to be around 110 degrees of recline. The classic sitting biomechanics literature review published in the Journal of Manipulative and Physiological Therapeutics sympathized decades of EMG research. They found that subjects seated with back rest inclination of. One 10 to 130 degrees combined with adequate lumbar support, demonstrated the lowest levels of back muscle activity. The EMG readings. Specifically favor 110 degree seat back incline with one to two centimeters of lumbar support prominence. But here's an important nuance for severely degenerated patients. They actually showed a preference for a hundred degree incline rather than 110 degrees. This underscores what we know as agonist. There is no single optimal posture for everyone. Individual variation, particularly in the presence of pathology, must inform our recommendations. A study published in BMC musculoskeletal disorders examined EMG activity in both low back pain patients and as symptomatic subjects when participants shifted from an upright position to an offloading posture. With enhanced lumbar support, EMG activity at the lumbar levels decreased significantly. the asymptomatic group showed 13 to 24% reduction in lumbar paraspinal muscle activity. While the low back pain group showed six to 10% reductions, this differential is clinically important. While both populations benefit from reclined sitting, healthy individuals may experience even greater muscle offloading. This suggests that reclined sitting could play a preventative role, not just a therapeutic one. The mechanism is straightforward. When the back rest is reclined, it supports more of the upper body's weight, the erector spine. muscles no longer need to work as hard to maintain trunk position against gravity. Less sustained muscle activity means less fatigue, less metabolite, accumulation, and reduce risk of muscle spasms and discomfort that plague sedentary workers. Let's talk about the gold standard measurement in spinal loading research. Intradiscal pressure. In the 1960s, the 1970s in vivo measurements demonstrated that unsupport sitting in a forward slump posture increases intradiscal pressure by approximately 90% compared to standing. This finding has been repeatedly confirmed in subsequent studies. The landmark 1999 WIL study expanded on this work using modern telemetric pressure transducers. A pressure sensor was implanted in the L four L five disc of a volunteer, and measurements were taken across dozens of activities and postures. Over a 24 hour period, the results were illuminating, relaxed, sitting in an armchair with reclined back rest, produced lower intradiscal pressures than standing, sitting upright in a chair, or even walking. The 2023 comprehensive literature review I mentioned earlier, synthesized this intradiscal pressure data. They identified a critical relationship as the trunk flexes forward and sitting intradiscal pressure increases according to a polynomial function. Conversely, as the trunk reclines against a supportive backrest, pressure decreases Studies have shown that armrest can decrease the load on the spine by approximately 10% of body weight. However, this is important when the back rest is already reclined. The armrest have to be absolutely positioned optimally if there's any. Adjustments that is not there, then this 10% body weight benefit literally does not exist. So keep that in mind too. And when the backrest is also already reclined, the additional effect of armrest becomes non-existent. The recline back wrist is already doing the heavy lifting. If you pardon the expression, you know what I'm saying? The evidence supports this biomechanical, finding a classic case control study by Kelsey found that sedentary occupations increase the risk for herniated lumbar discs. Particularly among those 35 years and older age in our sitting, were identified as significant risk factors for disc herniation at the L four L five level, precisely where intradiscal pressures are highest during conventional sitting. More recent research published in PMR used MRI to evaluate lumbar disc changes. After four hours of continuous sitting, they documented measurable, decreases in disc height, particularly in the L four L five level when subjects incorporated movement breaks. Every 15 minutes, these changes were attenuated, the underlying message is clear static sitting, especially in non reclined postures. Exacts, long lasting toll on disc health. So what does this evidence mean for you as a professional organist? Let me give you some concrete recommendations based on the literature. First, the optimal backrest angle. Based on the convergence of EMG and INTRADISCAL pressure research, I recommend that the backrest recline b BT 95 and 115 degrees for most office applications. This range balances several competing demands, maintaining adequate lumbar lordosis, reducing paraspinal muscle activity, decreasing intradiscal pressure, And keeping the visual angle appropriate for screen work. This recommendation aligns with the ergonomic standards. You're not operating outside the professional guidelines. When you recommend this, you're actually implementing evidence-based practice, Any sort of change that you make to lower the hand working height, such as increasing the recline in the back rest has to be mirrored by the workstation setup. So generally speaking, the keyboard height and the monitor height also needs to change in order for that person to be sitting with an optimal setup. If you want more information on how to set up a workstation, I have lots of information on my website, ergonomics help.com. And if you want even more information to do really thorough office ergonomics assessments, I wanna invite you to enroll into my program called The Ergonomics Blueprint. where I show you exactly how to set up an optimal position that includes all this stuff, and I want you to head to the show notes. I'm gonna tell you how you can sign up today. The second thing I wanna talk about is that lumbar support is a non-negotiable. the research consistently shows that the benefits of backrest recline are maximized when combined with adequate lumbar support. A prominence of one to two centimeters at the appropriate lumbar level helps maintain lordosis even as the trunk angle increases. Without the support recline sitting, can allow the pelvis to slide forward, negating many of the benefits. Third, consider the dynamic sitting paradigm. The human body isn't designed to maintain any static posture indefinitely. The discs between vertebrae, depend on pressure changes to receive nutrients, and remove waste products through osmotic exchange Even. Optimal recline sitting should incorporate periodic position changes. I recommend advising clients to use the free float function in their chairs whenever is appropriate. This synchro tilt mechanism allows the backrest to move with the user, providing continuous support While enabling micro movements throughout the workday, and the thing is, it needs to be supportive of what that person is also doing in the workstation. So if they are on phone calls or are they talking to colleagues, this might work really, really well, but if they are doing word processing or other intense type of analytical work, it's probably not the best to be in a free float function. Fourth address the visual angle concern. The most common objection I hear from clients and also ergonomists about where client's sitting is that they can't see their monitors properly. It's a valid concern. I totally get it. And this requires addressing the monitor position. When the trunk reclines the monitor should. Move slightly upward and potentially tilt downward to maintain the appropriate viewing angles. I actually addressed this in the past podcast episodes, so I want you to look at the podcast episode called when Positive Keyboard Tilt actually makes sense, the biomechanics that most ergonomists miss. Let me address some objections you'll likely encounter when implementing these recommendations. Number one, but will my employees just slouch if I tell them to recline? This conflates? Two different postures, reclined sitting with proper lumbar support, maintains LORD doses and reduces loading, slouching, or forward trunk function with posterior pelvic tilt. It actually increases loading. The key distinction here is that lumbar support and the maintenance of spinal curves. So you need need to look at this as education is essential here and making this really clear for that end user. The second thing that I wanna get into is that the concern that isn't 90 degrees, what the books teach. Okay, let's dive into this one. This is a historical artifact. More than evidence, the 90 degree recommendation emerged from early ergonomics when the priority was typewriters and paper documents on desks. Okay. Let's look at another concern that can pop up. What about workers who need to reach forward frequently? Task analysis is really critical, guys. For workers with significant forward reaching demands, a more upright postures actually gonna be necessary during those tasks. The reclined position is optimal for sustained computer work, reading, and tasks that don't require forward reach. Consider task specific posture coaching rather than a one size fits all recommendation. Here's another concern that can pop up. My client says, reclined sitting feels weird. Absolutely everything can feel weird at first. Neuromuscular adoption takes time. Clients who have spent literally years in forward flexed postures have adapted to that position. The muscles, the ligaments, and even their proprioceptive sense of normal have adjusted. However, a way to deal with this and to recommend is a gradual transition over several weeks with progressive increases in recline angle. This helps people to adapt without discomfort and without the fear of change that can plague all of us. Let me bring this all together with the key takeaways for your day-to-day as an agonist. First of all, the evidence is clear. Reclined sitting with adequate lumbar support reduces intradiscal pressure, decreases paraspinal muscle activity, maintains lumbar lordosis closer to standing posture, and may reduce the risk of disc degeneration associated with prolonged sedentary work. As ergonomics professionals, we have an obligation to follow the evidence even when it contradicts popular assumptions, the 90 degree sitting dogma doesn't hold up to scientific scrutiny at all. We opted our recommendations accordingly and bust this myth, if you know what I'm saying. When conducting assessments, evaluate whether your client's chairs allow adequate recline. Look at the lumbar support. Is it present and is it positioned correctly? Consider the monitor position Relative to the trunk angle, and most importantly, educate your clients about why you're making these recommendations. Evidence-based practice requires evidence-based communication too, right? Remember, different people will find different chairs suitable for them. There is no single best chair for everyone, and that's why I strongly recommend as agonist for people to actually try out that chair whenever possible, whenever feasible too, before making their decision. But the general principles do apply. The any chair that a client wants to look at should promote lumbar lordosis, minimize disc pressure, reduce static loading, and should guide every recommendation that you make. Thanks for joining me today on the Business of Ergonomics podcast. If you found that this episode was valuable, I wanna encourage you to share it with colleagues who might benefit from the evidence-based perspective on reclined sitting. And as always, if you wanna dive deeper into clinical applications of ergonomics, I want you to check out the ergonomics Blueprint to show how you can move your office ergonomics assessments forward with my help and my ongoing support. And if you already know how to do ergonomics assessments, whether it's in the office or in industry, or other types of ergonomics, I wanna encourage you. To look at accelerate. if you wanna scale your practice, do more ergonomics assessments and consultations and trainings, and become that go-to ergonomics expert in your city. Both of these programs and how you can join them are in my show notes. Can't wait to talk to you in the next episode. You can get started with office ergonomics assessments. Today, healthcare professionals are seeing the potential and opportunity to add office ergonomics assessments to their practice and services. Go to ergonomics help.com. Slash begin to get the exact seven step process that works so that you can get started today without the confusion or overwhelm. Just head to ergonomics help.com/begin now.