Exercise as it relates to Disease/Does training lumbar extension improve outcomes in participants with chronic low back pain?

This wikibooks page is a review of the journal article “Isolated Lumbar Extension Resistance Training Improves Strength, Pain, and Disability, but Not Spinal Height or Shrinkage (“Creep”) in Participants with Chronic Low Back Pain” by Steele et al (2020)

What is the background to this research?
Chronic Low Back Pain (CLBP) is a multifactorial condition experienced by millions of people worldwide, representing great economic cost, and pain and suffering for those afflicted. There is growing evidence that a significant percentage of CLBP cases may be caused by intervertebral disc degeneration (IDD), the prevalence of which increases with age. IDD is characterised by a loss of disc height, and a recent study of 85 participants confirmed a significant negative dose-response relationship between the degree of L1 > S1 disc degeneration, and the height of lumbosacral disc(s) in those experiencing LBP.

The use of physical activity and exercise interventions in the treatment of CLBP is common , but it is not known if resistance training for the lumbar spine can promote disc healing and regeneration, or confer any protection against any of the detrimental physiological processes or pathologies involved in IDD.

This study investigated the use of isolated lumbar extension (ILEX) resistance training specifically, to assess whether or not this type of intervention could:


 * increase disc height in the lumbosacral region and thereby increase spinal height, and
 * improve other important outcome measures for ILEX strength, pain, and disability.

Where is the research from?
This study was conducted within the Sport and Exercise Science laboratories at Solent University in Southampton (SSU), United Kingdom. The five authors named have an impressive publication record, collaborating on the topic of lumbar spine strength, pain and disability in more than 10 articles dating back to 2012.

Notably, this study claims to be the first to examine changes to the discs in vivo; in a living human rather than an animal model.

What kind of research was this?
The study used a quasi-experimental wait-list controlled design and received SSU ethics committee approval. Quasi-experimental designs are used to estimate the effect of an intervention in the absence of randomisation. Because the inclusion criteria required participants to have experienced LBP for more than 12 weeks, and be cleared to exercise by their general practitioner, randomisation was not practical.

What did the research involve?
Nine participants undertook pre-testing (T1), a 12 week control period and re-testing (T2), then a 12 week intervention period and post-testing (T3). At each test point (T1, T2, and T3) four outcomes were investigated:


 * 1) Spinal height was measured using seated stadiometry,
 * 2) ILEX strength was tested using the MedX Lumbar Extension machine (MedX),
 * 3) Pain was assessed using a visual analogue scale (VAS), and
 * 4) Disability was measured using the revised Oswestry disability index (ODI).

The ILEX resistance training intervention comprised of one training session per week for 12 weeks. The participants were supervised as they performed one set of ILEX exercise through their full range of movement (ROM) using the MedX.

The variable resistance was set at 80% of the participants maximum (increasing by 5% if the participant achieved strength adaptations over the intervention period), and repetitions were performed until momentary failure.

The repetition protocol used was: Concentric phase = 2 seconds > Full extension = 1 second hold > Eccentric phase = 4 seconds.

What were the basic results?
This study used effect size (ES) as a measure of the magnitude of difference, or change, between each test point. ES was described using common indices of small (ES between 0.20 - 0.49), moderate (ES between 0.50 - 0.79), and large (ES greater than 0.80).

The measure of spinal height using seated stadiometry found small ESs between T1 and T2 (the control period), and small or less than small ESs betweenT2 and T3 (the intervention period). These results showed that there was no change in spinal height or shrinkage using seated stadiometry measurements post ILEX resistance training intervention for this group.

ILEX strength increased significantly between T1 and T3. While the ES over the control period was small, the ES over the intervention period was considered large. These results confirm that ILEX resistance training increases ILEX strength in those with CLBP.

Changes in pain and disability were compared with consensus standards. The intervention saw positive changes in pain using the VAS, finding an ES of moderate post intervention period. Positive changes in disability using the ODI were also found, with an ES considered large post intervention period.

What conclusions can we take from this research?
The use of ILEX and other forms of resistance training and conditioning is recommended for those who suffer from CLBP. This study shows improvement in important outcome measures of ILEX strength, experience of pain, and degree of disability. However, at this time there is little evidence to support the notion that ILEX training can reliably promote healing or regeneration of the intervertebral discs, and in turn, increase spinal height or reduce shrinkage.

This study is encouraging and lays the groundwork for future research. As we progress our understanding of IDD and the physiological processes that influence IDD, research will be more targeted. Similarly, measuring tools and imagery will likely become more sophisticated and provide greater accuracy in the future. Larger sample sizes for research are always desirable, and the prevalence of LBP worldwide indicates no shortage of participants for the research efforts to come.

Practical advice
CLBP is usually complex, and achieving an accurate diagnosis may take time. Numerous red flags to undertaking resistance training for the lumbar spine exist. Most are associated with pain and neural symptoms including (but not limited to): sciatica, tingling, numbness, loss of reflexes, and motor deficits or disability in the legs or hips. Clearance from a medical professional is advised.

Exercise is recommended as a conservative first step, and supervision while learning resistance training exercise is encouraged so that form and control are given the highest priority. Careful planning around training frequency, load, and intensity is essential. Importantly, training frequency of one session per week for 12 weeks has been shown to significantly improve ILEX strength.

Further information/resources
For more information on CLBP, spine health more broadly, IDD, or lumbar extension training, click on the links below:

Spine-Health.com https://www.spine-health.com/ This site has a variety of high-quality resource pages concerning a range of spinal health matters. There are numerous helpful animations showing a variety of spine surgical interventions and other treatments.

MedicalNewsToday.com https://www.medicalnewstoday.com/articles/266630 This page has an excellent explanation of what happens in disc degeneration, symptoms, and treatment.

The PhysicalTherapyAdvisor.com https://www.thephysicaltherapyadvisor.com/wp-content/uploads/2014/10/Lumbar-Extensor-Exercises.pdf This PDF shows a series of key bodyweight spinal extension exercises that can be performed with minimal equipment.