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Lower Back Pain and Spinal Loading

Lower back pain is a very complex problem and may have many causes.  One cause is when spinal tissue failure occurs as a result of high compression forces applied through the spine leading to spinal injuries.  High spinal compression forces may lead to micro fractures in the vertebral endplates, compression fractures of the vertebral bodies and damage to the spinal discs (1-3).

Activities which cause high spinal compression forces include:

  • Lifting heavy weights.
  • Lifting lighter weights in weak postures which increase the functional weight of the object and thus the load on spinal tissues (e.g. lifting from the floor or above shoulder height).
  • Sustained spinal bending postures (with or without a load in the hand).
  • High repetition spinal bending postures (with or without a load in the hand).
  • Exposure to whole body vibration in vehicles that experience vibrational acceleration including shocks between 2-6g (11).

(1-4,11).

Certain body postures also create higher compression forces through the spine than others.  For example, bending the spine while lifting, increases the pressures on the spinal discs by more than 100%.   Spinal bending combined with twisting increases spinal disc pressures by more than 400%.  On the other hand, when people recline backwards in a chair, even while adopting a slouching posture, spinal disc pressures reduce by 50-80% – a posture most of us adopt when we’re getting tired during extended bouts of sitting.  Sitting up straight in a chair actually creates twice the spinal compression compared with reclining backwards in a chair – something to tell your granny or your teacher when they criticize your reclined slouching posture!

(3,4).

In 1979, it was noted that when heavy lifting was performed while holding one’s breath (for a few seconds), the intra-abdominal pressure was raised, the spinal extensor muscles activity reduced and both led to reduced compression loading on the lumbar spine, reducing the risk for spinal injury.  However, if the heavy lifts extended for longer than a few moments, the breathe was released and the intra-abdominal pressure fell to much lower levels, reducing this spinal support mechanism substantially (5).  This reduction in spinal compression due to raised intra-abdominal pressure was supported by research published in 2003, 2006 and 2010 and showed that the greatest benefit occurred when the body was in flexed (bent) postures (6-8).

The question arises as to how raised intra-abdominal pressure reduces spinal compression and helps to protect the spine from spinal compression failure leading to spinal injury and lower back pain.

Both abdominal and spinal extensor muscle contraction cause an increase in the spinal compression forces.  However, the abdominal muscle contractions (0- 40% MVC) also assist in raising the intra-abdominal pressure, and when doing so, the net forces on the spine result in reduced spinal compression.  In these circumstances it was also found that there was a reduction in the activity of the erector spinae muscles, with a greater reduction in these muscles’ activity corresponding to a greater increase in intra-abdominal pressure (8).

Furthermore, a 2013 published study revealed that chronic lower back pain sufferers who were experiencing a remission from their pain still exhibited lower levels of agonistic abdominal muscle activity and higher levels of antagonistic paraspinal muscle activity when compared to healthy individuals when performing spinal flexion (stooping/bending) with or without handling a load.  This alteration in their abdominal and spinal muscle recruitment activity/ patterns could result in increased spinal loads (not measured in their study) and possibly contribute to the recurrence of lower back pain in individuals where these altered recruitment patterns have become the norm (9).  On the other hand, research published in 2011 showed that activation of the core muscles showed no improvement in spinal stability, casting doubt on the mechanism in which core muscle rehabilitation is used to assist in the treatment of chronic lower back pain (10).

 

References:

  1. Chaffin D.B.; Park K.S (1973). A longitudinal study of low-back pain as associated with occupational weight lifting factors. Am Ind Hyg Assoc J. 34(12):513-25.
  2. Freivalds A.; Chaffin D.B.; Garg A.; Lee K.S. (1984). A dynamic biomechanical evaluation of lifting maximum acceptable loads.  J Biomech. 17(4):251-62.
  3. Adams M.A.; McNally S.D.; Chinn H.; Dolan P. (1994). Posture and the compressive strength of the lumbar spine. J Biomech. 27(6):791-791.

  4. Nachemson A.L. (1981). Disc pressure measurements. Spine. 6(1):93-7.

  5. Hutton, W. C.; Cyron, B. M.; Stott, J. R.R. (1979). The compressive strength of lumbar vertebrae. J Anatomy. 129(4): 753-758.
  6. Daggfeldt, K.; Thorstensson, A. (2003).  The mechanics of back-extensor torque production about the lumbar spine. J Biomech. 36(6): 815-823.
  7. Arjmand, N.; Shirazi-Adl, A. (2006). Role of intra-abdominal pressure in the unloading and stabilization of the human spine during static lifting tasks. European Spine Journal. 15:1265–1275.
  8. Stokes I.A.; Gardner-Morse M.G.; Henry S.M. (2010). Intra-abdominal pressure and abdominal wall muscular function: Spinal unloading mechanism. Clinical BiomechanicsNov;25(9):859-66.
  9. D’hooge, R.; Hodges, P.; Tsao H.; Hall L.; MacDonald D.; Danneels L. (2013). Altered trunk muscle coordination during rapid trunk flexion in people in remission of recurrent low back pain. J of Electromyograhy and Kinesiology. Feb;23(1):173-81.
  10. Stokes I.A.; Gardner-Morse M.G.; Henry S.M. (2011). Abdominal muscle activation increases lumbar spinal stability: analysis of contributions of different muscle groups. Clinical BiomechanicsOct;26(8):797-803.
  11. Bazrgari, B.; Shirazi-Adl, A.; Kasra, M. (2008). Seated whole body vibrations with high-magnitude accelerations—relative roles of inertia and muscle forces. Journal of Biomechanics. 41:2639-2646.
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How Picking Up Your Kids Can Cause Lower Back Pain

Children.  They’re little bundles of joy and we love to pick them up and cuddle or play with them, but who of you parents find that since you have kids, you’ve been experiencing an ache in your lower back?

Why is this?  They’re small, we’re big and surely we’re strong enough to move them around anyway we like?  Why then do some of us get this nagging pain in our lower backs?

Well, part of the problem lies in the fact that they’re small and we’re big, or, rather tall.  When we go to pick these little people up, it means that we have to bend down quite low, close to the ground to reach them.  What this means is that we inevitably need to do one of two things:

  1. Bend our backs
  2. or Bend our knees
poor child lifting technique, lower back pain, lack of lumbar lordosis
“Bending the back when lifting a child from the floor” by CS Body Health cc. All Rights Reserved. 2016

Ah, the old adage I hear you comment.  We know this already! Really?  If so, why are you still getting lower back pain?  Do you really understand what you need to do? (Sign up for my back class for parents)

Most of us don’t like bending our knees when we go down quickly to pick something up off from the ground.  Why is this?  Well, it takes more energy to bend your knees than to bend your back, and all of nature generally likes to take the easy route.

We know, however, that bending our backs to pick up things (such as our children), is not good for us and leads us to develop lower back pain.  Part of the reason that bending your back is bad for you, is because when you bend your back, you lose the curve in your lower back.  You’ll notice that this is a recurring theme in all my posts if you’ve been following them.

The reason why I keep harping on about your spinal curve is that it is very important.  Your spinal curve helps reduce the loading on your spine and thus the compressive and shearing forces on your spinal discs and joints.  When all these forces become too high, you get mechanical failure that leads to lower back pain.  80% of the world’s population will suffer from lower back pain at some point, so this tells you how important it is to sit up and take note, and the note you need to make is: keep your spinal curve intact when you move and sit, and lift things, and especially when you pick up your children from the floor.

Vertebral Column by Unknown and is licenced in the Public Domain
Vertebral Column by Unknown and is licenced in the Public Domain

Ok, ok, so we finally agree that it’s not worth your while to take the easy way and quickly bend your back to to lift your children up from the floor.  Nobody enjoys lower back pain.  But, if you are observant, you’ll find that bending your knees alone won’t help you maintain your spinal curve either.

Let’s try a little experiment: Place your hand in the small of your back and keeping your legs together, bend your knees.

  1. How comfortable is that in your legs?  If you answered not very, you get the gold star.
  2. How far can you go bending your knees, with your legs together, before you find you still have to bend your back to reach the floor?
Spinal curve, bending knees, lower back pain, lifting technique
“Bending your knees while keeping the legs together strains the quadriceps muscles” by CS Body Health cc. All Rights Reserved. 2016

So, if you actually took the time to try this, you’ll find that bending your knees with your legs together really is not very helpful and creates a lot of work while still putting your back at risk of developing lower back pain.

The solution? Open your legs.  Wide.  Much wider than you generally think you need to or even want to.  And then jagger your legs so that one leg is more forwards than the other.  Then, bend your knees.  Can you feel how much easier it is on your legs and your lower back?  And did you notice how much easier it was to reach the floor, while maintaining your lumbar curve?  And did you also notice how much stronger you are in this position compared to all the others we’ve discussed above?

"Bending the knees with the legs wide apart" by CS Body Health cc. All Rights Reserved. 2016
“Bending the knees with the legs wide apart” by CS Body Health cc. All Rights Reserved. 2016
"Good child lifting technique" by CS Body Health cc. All Rights Reserved. 2016
“Good child lifting technique” by CS Body Health cc. All Rights Reserved. 2016

 

The interesting thing is, if you have lower back pain, you know that your back will only let you lift your child as in the photo above and not with you bending your back.  Maybe we should all take a bit more time to think about our bodies and move to keep ourselves safe, healthy and pain free.

 

Do you feel you and your friends/family/carers need more help in correcting your postures when moving your children?  Why not create a group booking for my back pain prevention class for parents and carers?

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Why the Spinal S-Curve is Important in Back Pain

Lower back pain is extremely common.  It is so common that 8 out of 10 people will experience it at some point in their lives.

Lower back pain can be caused by many factors.  These include factors such as genetics or birth defects (spondylolysis), trauma (falls or car accidents), infections (bacterial infections or even TB of the spine), and poor posture and movement patterns.  Sometimes a combination of causes is to blame for our lower back pain.  Out of all the factors I’ve listed, the one that we have the most control over on a day to day basis, is our posture and our movement patterns.

Back Pain
Personal Injury Back Pain by SanDiego’s PersonalInjury Attorney’s Photostream is licenced under CC by 2.0

The most at risk postures for developing lower back pain are sitting and bending postures.   These two postures when performed badly put our spines at a high risk of developing lower back pain, and people who do a lot of sitting and people who perform a lot bending are often the people who complain of lower back pain.  Think of office workers, drivers, nurses, machine operators, fatory workers, manual workers and more.  These people and others who engage in a lot of sitting and/or bending on a day to day basis are the people who are at risk and who do develop lower back pain.  Does that sound like most of us?  Exactly, hence the high incidence of lower back pain!

Read my post on driving postures and lower back pain.

One of the most important elements of our posture in helping to prevent lower back pain, is the s-curve of our spine and maintaining the s-curve of our spine in different postures and movement patterns.

Read my post on correct lifting posture for picking up children.

The spinal s-curve consists of 3 different curves.  There’s a curve that goes in at the neck (the cervical lordosis), followed by the curve that goes out in the upper back (the thoracic kyphosis) and the curve that goes in again at the lower spine (the lumbar lordosis).  The depths of these curves may vary in different people, but we all have the 3 curves illustrated below and they are very important for our biomechanics and general spinal health.

spinal s-curve
Vertebral Column by Unknown and is licenced in the Public Domain

The importance of these curves in helping to prevent lower back pain, is that these spinal curves throw our centre of gravity between our feet.  With our centre of gravity lying between our feet, the compressive and shearing forces on our spine which may lead to lower back pain are reduced.  Keeping these shearing and compressive forces as low as possible acting on our spine helps to keep the forces acting on our backs within limits that our body tissues can naturally withstand, which then helps to reduce or prevent lower back pain.

centre of gravity
Center of pressure in relation to centers of gravity while walking by Jasper.o.chang under licence CC BY-SA 3.0

When we change these curves through engaging in poor posture while sitting, standing, lifting, driving, picking up children etc., we increase the forces on our spine unnecessarily causing many problems with the complex spinal biomechanics and anatomy that result in injury and lower back pain.

 

How often do you lose your spinal curve in your activities during your day?  Do you suffer from back pain?  Is your poor posture partly to blame?