The Stress Series: Part 3 – Stress and Posture

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Chiropractors and posture – they are a seamless fit. From the very first visit in clinic, posture is assessed. As subluxations are checked and corrected, posture can improve over time. But is posture just a symptom, or is it stressor that can kick off a physiological stress response impacting both brain and body? We’ve taken a quick look at the research to see what the deal is.

In 2015, the Journal of Health Psychology published a randomized trial regarding posture and stress [1]. The hypothesis of whether or not muscular states were related to stress had been supported by research on facial expressions (as cited in the Health Psychology report), but Nair et al wanted to examine stress and posture through a slightly different lens. 74 participants were randomly assigned to either a slumped-seated posture, or an upright-seated posture and held in place by physiotherapy tape. They completed a range of tasks measuring reading, speech, mood, self-esteem and perceived threat.

Interestingly, the upright-seated participants reported, “higher self-esteem, more arousal, better mood and lower fear, compared to slumped participants.” Whereas slumped participants used “more negative emotion words, first-person singular pronouns, affective process words, sadness words, and fewer positive emotion words and total words during the speech.”

The inference was clear – sit up straight at your desk. It’s not just about your posture. While the researchers suggested that “sitting up straight may be a simple behavioural strategy to help build resilience to stress,” and noted the consistencies with “embodied cognition theories that muscular and autonomic states influence emotional responding – there could be much more to the stress-posture conversation.

Sress Affects Posture And Posture Affects Stress – The Basic Science Version

It starts with a simple observation. What is slumped posture? A head that has dropped forward and shoulders that are rounded. This is classic, flexion of “fight or flight” posturing can have very real neurological and psychological impacts. But in a world where we slump at our desks, and slump over our phones and devices, here’s the big question: which came first, the posture or the stressor? We can have a neurological and physiological “chicken and egg” situation going on unless we consciously intervene to change it.

In the above study, stress and posture were linked. If you sat up straighter, these negative responses were lessened. Put simply, posture affected stress. But stress also affects posture. It’s a primitive, reflexive thing – an innate response for the survival of the organism. The contiguous nature of the body, giving feedback and responding to feedback, can be our enemy here.

What does this mean? If you perceive a threat, your body readies the response. You need to be able to run or fight, so your shoulders become rounded and your head drops forward.  This is an action triggered in the brain but also in the upper thoracic cord, which is important in rib excursion. This in turn can impact tidal volume and pulmonary function [2, 3, 4]. As we know, the stress response involves an adrenal hormonal response as well. In cases of long-term stress, the impacts can potentially be significant [4].

Postural Stress On The Spine And Spinal Cord

Studies have shown how forward head posture can increase weight on the cervical spine, a significant stressor in itself. Hansraj et al assessed stresses on the cervical spine and found that [5]:

  • At 15 degrees, the head weighs 27 pounds (12.3 kilograms)
  • At 30 degrees, it increases to 40 pounds (18.2 kilograms)
  • At 45 degrees, it weighs 49 pounds (22.3 kilograms)
  • At 60 degrees, it exerts a force of 60 pounds on the cervical spine. (27.3 kilograms)
  • At 90 degrees the force could not be measured.

The impacts this could have on subluxation and nociception have not yet been studied, yet are potentially significant. Add to that the already proven health problems that could result from poor posture. They include, but are not limited to [6]:

  • Headaches
  • Shoulder and back pain
  • Reduced lung function (rib excursion and tidal volume, and lung capacity reduced by up to 30%). “When your lungs do not perform as well, your tissues, including your heart and brain, do not receive as much oxygenated blood. This can lead to shortness of breath, clouded thinking, and heart and vascular disease.”
  • Peristaltic function (which affects gastrointestinal function)

In a three part series on the biomechanics of the central nervous system, Harrison et al examined spinal cord stressors from postural loads and their neurologic effects. They broke spinal postures into four types of loading (axial, pure bending, torsion and transverse, which “cause normal and shear stresses and strains in the neural tissues and blood vessels [7]”)

They concluded that [7]:

“Four types of postural loads create a variety of stresses and strains in the neural tissue, depending on the exact magnitude and direction of the forces. Transverse loading is the most complex load. The stresses and strains in the neural elements and vascular supply are directly related to the function of the sensory, motor, and autonomic nervous systems. The literature indicates that prolonged loading of the neural tissue may lead to a wide variety of degenerative disorders or symptoms.”

They went on to advise the questioning of any postural loading of the central nervous system that involved any “procedure or position requiring spinal flexion.”

It’s generally accepted that pain is the product of noxious nociception, and all nociception is negative feedback from the body to the brain, hence it is a stressor. The amygdala recognises nociception as stress and responds to it [8]. Forward head posture and rounded shoulders can be the result of ‘fight or flight’ readiness, but they can also be the result of postural stressors in daily life, like looking down at phones or laptops.

Hence, the postural deviation involved in the stress response can itself be a stressor. This can be a repetitive loop in the body, continuing to fire unless intelligent, targeted measures are put into place. Our own chiropractic researchers have offered up research indicating that, if the spine is functioning better mechanically, signals from the body are better interpreted by the brain, which in turn helps us respond better to our environment [9].

Additionally, when we look to principals of neural plasticity, we see that the more we repeat the firing of a neural pathway, the easier it becomes. Habits become entrenched and tasks become simpler as the neurons involved in performing such tasks fire repeatedly [10]. Hence, breaking the habit of poor posture takes effort, intention and time.

It is well-accepted knowledge that chiropractic is good for back pain. Even in this model, postural stressors are checked and adjusted. But it is becoming clear that posture isn’t just aesthetic. It is functional. It can have neurological and even emotional impacts. When you think back to Chiropractic College when you were taught the causes of subluxation (depending on the language, either “Trauma, toxins and stress” or “physical, chemical or emotional stress”) you can see that posture is and continues to be a big issue – one we are very well equipped to help correct..

References

[1] Nair S, Sagar M, Sollers J, Consedine N, and Broadbent E (2015), “Do slumped and upright postures affect stress responses? A randomized trial.” Health Psychol. 2015 Jun;34(6):632-41. doi: 10.1037/hea0000146. Epub 2014 Sep 15.

[2] Beck, R (2008), “Functional Neurology for Practitioners of Manual Therapy,” Churchill Livingstone Elsevier, Philadelphia USA

[3] Landers, M, Barker, G, Wallentine, S, Wesley-McWhorter, J and Peel, C (2003),“A Comparison of Tidal Volume, Breathing Frequency, and Minute Ventilation Between Two Sitting Postures in Healthy Adults,”Physiotherapy Theory and Practice, DOI: 10.1080/09593980390194119

[4]  Todd, W (2015), “SD Protocol,” Todd Wellness Group, www.sdprotocol.com.au

 [5] Hansraj, K, “Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head,” Neuro and Spine Surgery, Surgical Technology International XXV

[6] Nall, R (2017),”Health problems from bad posture,” Livestrong, https://www.livestrong.com/article/31223-negative-effects-poor-posture/  retrieved 7 Sep 2018

[7] Deed H, Cailliet R, Harrison D, Troyanovich and Harrison S (1999), “A review of biomechanics of the central nervous system—part III: Spinal cord stresses from postural loads and their neurologic effects,” JMPT, Vol. 22, Iss. 6, pp 399-410

[8] Staff Writer (2018), “The Stress Series Part 1: Stress physiology a central theme in chiropractic,”  https://spinalresearch.com.au/the-stress-series-part-1-stress-physiology-a-central-theme-in-chiropractic/

[9] Murphy B, Haavik H,“The Role of Spinal Manipulation in Modulating Neuroplasticity and Sensorimotor Integration,”Replace, Repair, Restore, Relive – Bridging Clinical and Engineering Solutions in Neuro-Rehabilitation, Springer international publishing 2014, pp 113-115

[10] Michelon P (2008), “Brain plasticity – how learning changes your brain,” Sharp Brains, https://sharpbrains.com/blog/2008/02/26/brain-plasticity-how-learning-changes-your-brain/ retrieved 21 Sep

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