Lifting is a common risk factor for the development and exacerbation of low back pain. In our clinic, lifting back pain is one of the most common things we treat. This is frequent discussion about the proper back position while lifting, often being instructed to keep a “neutral spine”. However, does research or simply folklore recommend these lifting biomechanics?

Anatomy of Spine

This is a very brief breakdown of the anatomy of the spine. You can view more details here.

  • Vertebrae – Spinal segments which are comprised of bone
  • Intravertebral Disc – Gelatenous substance with hard outer covering.
  • Ligaments – Tissues which connect bone to bone.
  • Muscles – Contractile tissue that links tendons to the bone and moves the body. These can often create back spasms, read about back spasms here
  • Tendons – Links muscles to the bone to facilitate movement.
  • Spinal Cord – The information “Super Highway” connectin the brain to the body.
  • Peripheral Nerves – Nerves that connect the spinal cord to the body which transfer information for sensation and movement.

History of Lifting Biomechanics Research

In the past, lifting advice has been extrapolated from cadaveric (yes, cadavers) studies. These studies suggested the lumbar spine is susceptible to failure when repeatedly flexed, and is weaker when flexion and compression are combined. However, there is uncertainty about how transferable cadaveric findings are to real-life lifting situations. Another influence on lifting advice has been early in-vivo (in live humans, not just cadavers) work that demonstrated higher lumbar disc pressure during forward bending of the trunk or when a load was lifted.

A limitation of the in-vivo studies was that they did not consider lumbar spine curvature during lifting and were conducted without comparing between groups with and without LBP. Spinal loads are similar when lifting with a flexed spine to lifting with a ‘straight’ lumbar spine. While there is some evidence from epidemiology studies that high mechanical loads are a risk factor for LBP, those studies did not examine whether lumbar flexion during lifting was a risk factor.

Literature Review of Lifting Back Pain

Overall, only four studies have measured lumbar flexion with intra-lumbar angles (between all the low back segments). There were no differences in peak lumbar spine flexion when lifting.

Seven cross-sectional studies measured lumbar flexion with thoraco-pelvic angles. People with LBP lifted with 6.0 degrees less lumbar flexion than people without low back pain.

Conclusions on lifting low back pain

This review found low quality evidence of the relationship between greater lumbar spine flexion during lifting and lifting back pain onset or persistence. There was also low quality evidence of no cross-sectional relationship between greater lumbar spine flexion during lifting and lifting low back pain.

There is no credible in-vivo evidence to support the dogma that lumbar spine flexion should be minimized when lifting to prevent low back pain onset, persistence or recurrence. More comparisons found those with low back pain used less lumbar flexion when lifting, although this may have been in response to advice following their low back pain onset or a response to pain itself

While the verdict is still out on low back flexion and back pain, we have ample evidence of the following factors increasing risk of lifting low back pain.

  1. Increased exposure to forward trunk inclination (bending) and lifting have separately been associated with LBP in other reviews.
  2. Greater exposure to forward trunk inclination in the workplace, and lifting frequencies of greater than 25 lifts/day or regularly lifting over 25kgs, were associated with increased risk of LBP.

Clearly, more research is necessary to truly understand if this lack of research supports the notion that a flexed spine does not increase lifting back pain. This is one reason there are so many back pain confusions in the World

Practical Implication

Like most things, an individualized program is key for improving low back pain, but also preventing low back pain.

This makes it challenging to research and create universal criteria. Therefore, if you are trying to prevent or improve lifting low back pain, an individual approach is mandatory for prevention and relief. Click here to get more information to help your back pain today!

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Reference

  1. Saraceni N, Kent P, Ng L, Campbell A, Straker L, O’Sullivan P. To flex or not to flex? is there a relationship between lumbar spine flexion during lifting and low back pain? a systematic review with meta-analysis. The journal of orthopaedic and sports physical therapy. 2019;1-50:1-50. doi:10.2519/jospt.2020.9218