Sitting Ergonomics And The Impact on Low Back Pain

Introduction

We all, at some point in our lives, will sit for a long period of time. Whether that is at a desk at work, eating dinner at the table, or sitting to watch a film. Many theories have been produced about how our posture should be during this time. From sitting up straight with no support to using specialised equipment to keep our backs in a correct and safe position. Below will discuss what the evidence says to keep our backs healthy and (Add aims in).

Ergonomics

Explain here what ergonomics is.... specifically sitting - I think this bit could be quite simple? just like a little introduction to it because if we start talking about the spine we haven't given relevant anatomy yet and yeah?

The Lower Back

A little introduction to the back - what we use/ how we use our backs every day - important to keep healthy... again quite simple

Clinically relevant anatomy

The lumbar spine, where most back pains occur (REFERENCE), has 5 vertebrae (numbered L1-L5). In between each vertebra, there is an intervertebral disc. This is known as the intervertebral disc joint. There are also two (left and right) facet joints between each vertebra (REFERENCE).

The vertebra

There are several distinct features of the typical lumbar vertebra. These include:

• Large vertebral body
• Short and thick spinous process
• Relatively vertical facet joint
• A mammillary process on the posterior aspect of the superior articular process
• L5 has the largest body and transverse process of all vertebra.

Structural function

The main function of the lumbar spine if to bear the weight of the body. It absorbs the stress of lifting and carrying objects as well as general movement.

https://mayfieldclinic.com/pe-anatspine.htm

• The spine holds an increasing amount of weight as you move down into the lumbar region, for this reason, the lumbar vertebra has the larger bodies in the spine.
• Due to the relative size of the spinous process and body, the lumbar spine has the largest degree of extension.
• The lumbar spine allows flexion, extension, and lateral flexion but not rotation and this is due to the orientation of the facet joints
• The mammillary processes provide an attachment point for many lower back muscles.

The intervertebral Disc

Between each vertebra, there is an intervertebral disc. The intervertebral disc is made out of the nucleus pulposus, annulus fibrosis, and the cartilage endplates.

Nucleus pulposus - This is a highly hydrophilic substance that is located in the centre of the intervertebral disc. It acts as a shock absorber as it allows for the distribution of pressure in all directions.

Annulus fibrosis - This contains multiple fibrocartilaginous bands. It surrounds the nucleus pulposus and its main function is to protect the nucleus pulposus.

Cartilage endplates - This is found on the superior and inferior ends of the disc and represents the anatomic limit of the disc. Its main functions include protecting the contents of the disc and providing a source of nutrition to the disc. - https://www.sciencedirect.com/science/article/pii/S0004951414606206

Ligaments

The main ligaments of the lumbar spine include:

Anterior longitudinal ligament - This is a thick band of tissue that runs along the anterior surfaces of the vertebral bodies. It protects against hyperextension of the spine.

Posterior longitudinal ligament - This is thinner than its anterior counterpart and runs along the anterior wall of the vertebral canal. It is involved in preventing disc prolapse.

Ligamentum flavum - This runs between each consecutive laminae and is extremely elastic. Its function is to help maintain an upright posture and to resume this position after flexion. It also prevents buckling of the ligament during extension.

Interspinous ligaments - This connects consecutive spinous processes together within the spine. It mainly limits the flexion of the spine.

Supraspinous ligament - Connects the ends of each spinous process together. Helps to prevent hyperflexion

Iliolumbar ligaments - This consists of two parts, an anterior and posterior part. It plays a huge role in the stability and restricts both side flexion and rotational movement at the lumbosacral junction

Muscles of the trunk - is this right?

Flexors - external oblique, internal oblique, psoas major, psoas minor and rectus abdominis

Extensors - erector spinae, Latissimus dorsi

Lateral rotators - internal obliques, external obliques, and quadratus lumborum

Rotators - external obliques and internal obliques

Low Back Pain

What is it? definition? epidemiology and prevalence of low back pain for those who sit a lot compared to those who don't - driving? desk-based work...those who sit for ... hours a day are more likely to experience lower back pain, just kind of outlying how sitting a lot can impact the spine? how sitting can affect the disc? physiology impact... pig studies... basically explain how sitting is bad for us...

What is a good sitting posture?

government guidelines?

pictures of different sitting postures...

studies to back up what is a good posture or is it changing your posture so you're not sitting for long period of time - like what should we be doing originally to keep good posture - does this reduce low back pain?

now more than ever this is important?

Prevention of low back pain due to sitting posture

Use of equipment for prevention and management

With back pain being such a common issue the market has been flooded with equipment to try and alleviate back pain or relieve the symptoms. The equipment ranges from exercise balls and back braces to standing desks which are appearing in offices more and more. Research has been carried out on all the equipment to varing degrees, for example there is minimal research on exercise balls, however, they are used frequently due to them being cheep and easily accessible.

Exercise Ball

There has been a considerable increase in the use of exercise balls as a rehabilitation and exercise tool. Because of the increase in popularity the public eye more people have tried the alternative not only to combat back pain but also to aid concentration while working. However research on how effective exercise balls on back pain is limited and draws mixed conclusions.

Early research by Kingma and Dieën, (2008) investigated static and dynamic posture in females while working at an office computer on a office chair compared to an exercise ball. They measured the effect of sitting on a ball by measuring muscle activity in the spinal muscles. They found that when sitting on the ball compared to the office chair with armrests that there was 33% more trunk motion and in 66% more variation in lumbar muscle activation. However, when sitting on the ball more spinal shrinkage occurred. The research concluded that the advantages may out way the disadvantages and there for there is no real benefit to sitting on a ball as opposed to a supportive office chair

Elliot et al., 2016 conducted a randomized experimental cross over trial to investigate whether sitting on a ball for 90 minutes/day instead of a chair has an effect on low back pain and core muscle endurance. They found no statistically significant results. They concluded  Ball-sitting had no significant effects on Low bacl pain, but did improve core endurance in the sagittal plane.

based on both research papers there is little benefit for sitting on an exercise ball for lower back pain. more research needs to be conducted to see if there are any benefits of long term effects of ball-sitting instead of sitting on a chair.

Standing Desks

Equipment...keeping a certain posture? exercises at desks? use EBP

Rehabilitation of low back pain caused by sitting

Exercises for low back pain caused by sitting and the rehabilitation of this