A few weeks ago, I finished another gross anatomy dissection lab. Every lab I do, I realize what I know or think I know is not a lot. The opposite can be said in the world of training and social media. A space where humans tend to make bold claims of certainty. But when are we ever 100% certain regarding the adaptable human body and movement? Humans and our movements are both dynamic and complex. Just think about some of the different factors influencing how we move, such as age, genetics, and morphology. What about each person's experience, load, and intensity of the task being performed? And lastly, the environment you are doing the task in, outside vs. inside, temperatures, practice vs. real-time competition, flat/smooth terrain vs. uneven terrain. We can include even more inquiries, such as: How well rested and recovered are we? What has our nutrition been like? Are there other life stressors we deal with: hormones, work, school, mental health, cultural or society-type pressures, etc.?
The lens you view human movement through. We either take a dynamic + complex viewpoint or a reductionist one. If you are the latter, I challenge you for the rest of this blog post to take on the dynamic + complex view because we are talking all things lumbar spinal flexion.
Lumbar spinal flexion while under load has been an ongoing debate for a long time. The driving force behind ‘to flex or not to flex’ is centered around pain and injury. The thinking is that we are at greater risk if we flex our lumbar spine during activities such as deadlifting vs. if we minimize a flexed position. Thankfully(!) life isn’t black and white. This ongoing debate depends, starting with some of the variables listed above. You might wonder what the risks are and whether or not they are substantiated. The emphasis on bony positioning and posture seems to outweigh the more critical and necessary fact that we need some error to learn. What is an excellent way to “protect” your system while building a resilient body? Load. Yes, our tissues crave stimulus. These tissues also desire to learn new tasks, and sometimes that stimulus, which comes in the form of coordination, shows up as messy noise as we embark on the process of learning.
It is my opinion that the ongoing debate on whether or not it is injurious to flex your lumbar spine is a boring conversation. Instead, I believe things become interesting by listening to how coaches and trainers approach cueing spinal movements. Considering how spines often go through various positions and ranges throughout our daily lives, I often wonder: when someone does not move as a trainer or coach thinks the person should be moving, say the person does flex their lumbar during a deadlift or squat - is this when the trainer starts to cue neutral spine? Or do they set their clients up from the beginning, teaching that a flexed spine is inherently dangerous, not providing them the tools (or empowerment) to gradually build up resiliency throughout different ranges?
What is neutral? The research defines a neutral spine as a “zone” where we start to feel a sense of resistance to the task we are performing (Howe and Lehman, 2021). This zone is generally less than the total available range of motion. If you know me, you know I am big on definitions. It might be helpful to define what range of motion is. In physics, “motion” means to change position with “range” as amplitude or amount. Under the context of human movement, the term “range of motion” is the amount that an object, bony segments attached to the joint, has changed (past tense) position. Another way to think of this is the axis where motion occurs. The bones protruding from the joint are what is being measured. Pausing for a moment, think about all the zones your spine personally moved through today as you read this. These zones are less than your total available range of motion, where the sense of resistance changes depending on the task being performed.
How do researchers measure ranges in the lab on cadavers? Interestingly, they do not take the cadavers to the end range. They usually measure by placing a sensor on T12 and one on S1. This provides them a difference between those markers defined as full lumbar flexion. Using heavy loading cycles of 250 on up to 1,000 above 80% within a short window of 2-4 hours, they flex and extend the spine, only measuring where they placed the sensors. What about the variables? An important one is whether the sensors are placed in the same spot each time—placement matters. To reduce the margin of error, sensors would need to be placed in the same spot on T12 and S1. This is not always the case. When these sensors are not placed in the exact location, every reading will provide different results. Furthermore, if they measured between L2 and S1, the total flexion would be less since the thoracic is not being measured.
Do you kettlebell swing? If so, research shows that the lumbar spine flexed 26 degrees at the bottom of a 16kg swing and extended 6 degrees at the top = a total angular displacement of 32 degrees. (McGill and Marshall, 2012). Oddly enough, in this study, every participant was cued “neutral spine,” and it did not matter one bit because some lumbar spinal flexion during lifting is inevitable. On average, an intact lumbar spine’s neutral AVAILABLE range is between 60-80% degrees of spinal flexion. In another study, at the beginning setup of the deadlift, “participants were asked to maximally extend their lumbar spine in the functional lifting position.” The outcome? Their lumbar spine was flexed 22 degrees (Holder, 2013 - read her entire thesis ). Her thesis states that when you flex your hips, your pelvis automatically rotates posteriorly, which creates lumbar flexion. You can challenge this by laying on your back, feet flat, knees bent, in a hook-lying position. What is happening in your low back? Then bring your legs to 90 degrees - floating in space or by placing your feet on the wall. Yup! Lumbar flexion is unavoidable.
With this information, it can be argued that most of the time, when we think we are in neutral, minimizing lumbar spinal flexion, we are not. Even if you are yelling at your screen now: “Damn it, Gina! When my trainer cues neutral, not only do I feel like my spine is straight, but my trainer tells me it is once I have reached that point.” I get it. Your trainer has impressive and extremely powerful near x-ray vision EMG eyeballing skills, but it is more likely that your “neutral” is coming from the thoracic spine, decreasing flexion. Again, refer to the studies noted above.
Does a neutral spine protect against injury? Unfortunately, there is not a lot of evidence to support this. One study with 861 participants (manual labor workers and office workers) over three years showed that flexing the spine >60 degrees was a risk factor for low back pain. However, this study did not differentiate the contribution of lumbar spinal flexion from the hip joint or thoracic spine to the total trunk flexion (Hoogendoorn, 2000). Side note: always read the methods in the study. Then ask more questions.
Something else to keep in mind is the flexion-relaxation phenomenon. In “healthy” backs (you might be asking: how do we define a healthy back?), when the lumbar spine is flexed, the lumbodorsal fascia assists the spinal extensors (Adams, 2007). The lumbodorsal fascia has a high resiliency to load (Howe and Lehman, 2021). EMG studies have shown that it takes on most of the load when it is stretched tight. Considering these load-sharing abilities between passive structures of our spine, this could be regarded as an optimal strategy for some.
Is there anything wrong with cueing a neutral spine? Not necessarily. It depends. As mentioned earlier, the ‘to flex or not to flex’ under load debate seems to be a protective measure hoping to minimize pain and injury. However, that is a reductionist way of thinking. It ignores the many variables at the beginning of this post and then some. Along with the complexities regarding pain and injury, and the principles surrounding adaptability and gradually exposing tissues = progressive overload. I would ask: if you use the cue, are you clear on your intent behind it? Depending on what you are trying to accomplish, are you providing appropriate additional instructions and reasoning for the task?
Why are some so hell-bent on training in neutral? I have no clue. It has always bugged me. We do not live our daily lives there. I am flexing as I sit here typing this. This is why my purpose for this post was to offer up a new narrative supplied by current research and some good ole’ critical thinking. I believe that we can do better. If you have finished reading this and disagree with everything presented, I challenge your rationale with a few more questions: Throughout regular everyday movements, how much do you flex? What if you train 1RMs? Do you think you stay neutral during the entire lift? Let’s say you train twice weekly for heavy 80+% deadlifts: How many reps and sets did you do? Have you measured and identified your (or your client's) neutral zone and range of motion to determine if you’re close to your end range? What was your in-between max 80+% day recovery like? How long were your rest periods in between each set? Next, we have to factor in the experience of the lifter. Experienced lifters (defined as 8+ years) movement strategies often incorporate higher degrees of flexion while performing traditional strength training lifting exercises. When you flex both your thoracic and lumbar spine, you decrease the moment arm, bringing the line of pull closer to the body. From a mechanical viewpoint, this strategy has a lot of potentials to maximize how much weight you want to lift. Circling back around to adaptations of the spine, when appropriately programmed (progressively loading), the lumbar spine will adapt to whatever positions and loading demands.
Rather than being overly concerned and insanely focused on “neutral,” can we focus on all the ways available to increase our client's tissue capacity? Of course, this is NOT saying they should go to full end range, exhausting their flexion capacity. But remember! If you work with the general population as a trainer, coach, yoga/pilates teacher, group exercise instructor, etc., you have a fantastic opportunity to build your clients up and teach them super RAD things about the human body. Otherwise, you might be missing the big picture.
References:
Howe, L, Lehman, G. Getting out of neutral: the risks and rewards of lumbar spinal flexion during lifting exercises. Strength and Conditioning, March 2021
McGill SM, Marshall LW. Kettlebell swing, snatch, and bottoms-up carry: back and hip muscle activation, motion, and low back loads. J Strength Cond Res 26: 16-27, 2012.
Holder L. The effect of lumbar posture and pelvis fixation on back extensor torque and paravertebral muscle activation (Doctoral dissertation), Auckland University of Technology; 2013
Adams MA, and Dolan P. How to use the spine, pelvis, and legs effectively in lifting. In: Movement, Stability, and Lumbopelvic Pain. Churchill Livingstone, Edinburgh, pp. 167-183, 2007.
Hoogendoorn WE, Bongers PM, De Vet HC, Douwes M, Koes BW, Miedema MC, Ariëns GA, Bouter LM. Flexion and rotation of the trunk and lifting at work are risk factors for low back pain: results of a prospective cohort study. Spine 25: 3087-3092, 2000.