Archive re-post - Core Stability: Science or Hocus Pocus?

21 Jun 2013

Core Stability: Science or Hocus Pocus?

1. Aim

To investigate whether core stability should be used in exercise and rehabilitation programs; and if so, how and when should it be used.


2. Intended audience

The general public, however, there are some interesting pieces of research here for any trainer or health professional.


3. Introduction

These days the public are bombarded with the term core stability. Many different trainers and therapists proclaim that core stability training should be at the heart of any exercise program to help prevent or treat injury. I myself have used various core stability exercises in the rehabilitation of clients with back injuries, as I was taught during my studies. I have also used core strength exercises to self treat my own injuries. However, since then much information has come to light indicating flaws in the core stability concept and whether we should be using it at all.


4. The Concept

The basic idea is that within your abdominal cavity there is an imaginary box and that by contracting the muscles that form this box it will increase the pressure within it (intra-abdominal pressure), thus you will support the lumbar spine. See muscles and pictures below.

1. Top of the box - diaphragm
2. Sides of the box - obliques
3. Front of the box - transversus abdominis (TVA)
4. Back of the box - lumbar multifidus
5. Bottom of the box - pelvic floor muscles

There are, however, other models of core stability that include all combinations of muscles between the sternum and the knee1. This of course poses the first problem which is how do we objectively measure “core” when there is still no consensus on exactly which muscles are involved.






www.cityedgephysio.com.au




cerin.wordpress.com

The principle is to illicit 30% of maximal voluntary contraction (MVC) of the core muscles. The focus is generally on holding the contraction for a period of time to increase endurance in the core muscles and so create a solid foundation for the limbs to then work from. Below is one example of a schematic explaining the overall ideology.




http://www.truebalance.com.au

5. What the evidence says

In short the journals don’t seem to support the principles mentioned above.
One article by Professor Eyal Lederman2 highlights these negative factors in some detail supported by a hefty reference list. In particular he believes the focus on TVA is misplaced. His view is that there is an over emphasis on TVA contraction (often performed by the drawing in of the naval towards the spine). He agrees that TVA plays a role in supporting the lumbar spine but so do many other muscles in the body; so why focus on TVA?
He also tackles the issue of timing. It is believed that whenever you perform any action (like reaching into a cupboard or kicking a ball) your core (TVA) should fire before your limbs move. This is supposed to protect your back. However, the research doesn’t support this either. The difference in onset of contraction for those with chronic lower back pain (CLBP) and those without is about 1/50 of a second. Too small to consciously effect and too small for any therapist to analyse without some pretty sophisticated kit!2
Sharrock et al, 20111, conducted a pilot study to investigate the link between core stability and athletic performance. Although they found some positive results giving direction for further research, they concluded by stating:
“Until the relationship between core stability and athletic performance can be scientifically demonstrated in the evidence, it will remain hypothetical and theoretical in nature”
Wang et al, 20123, found some data indicating that in the short term core based exercise programs had some advantages over a traditional physiotherapy approach in the management and function of low back pain (LBP). However, they caveat this by highlighting the fact that the data used for the meta-analysis was of low quality and that further definitive studies would need to be conducted.

Muthukrishnan et al, 20104, found no difference in pain or function outcomes for those presenting with chronic low back pain (CLBP) concluding that core stability exercises were not as good as traditional physiotherapy approaches.
Gordon et al, 20135, conducted a study to review if there was any relationship between core stability, hip external rotator strength and balance. They found there was no link between the test parameters and therefore a strong core had no effect on prevention of lower limb injuries.
Gorbet et al, 20106, investigated if there was any difference between TVA activation in healthy individuals and those with LBP. They found no difference. Yet proponents of core stability exercises state that a lack of TVA activity is one of the main causes of LBP. They did however find that the Abdominal Draw In Method (ADMIN) was better than four point kneeling for activating TVA.


ADIM start position from Gorbet et al6

Quadruped start position from Gorbet et al6


Martuscello et al, 20137, concluded that strength and conditioning programs should focus on multi joint free weight exercises and not core specific exercises when looking to improve the core muscles.


6. Summary of the evidence

It is very difficult to find even one study that out right proves, unequivocally that specific core stability exercise directly improves LBP or sporting performance more effectively than traditional physiotherapy and training programs. One study showed that a nine-week core program improved volleyball jumping performance10, however, it didn’t compare this with the effects of standard exercises. We have seen that other studies indicate standard physiotherapy and training interventions give the same if not better results so maybe these too would help improve jumping performance in volleyball?

Some of the studies have found there to be some benefits from a core program for those with LBP8, 9 however, the dominant finding is that LBP (especially CLBP) is too multifaceted to be treated by core stability exercises alone and should be incorporated into a wider rehabilitation program. On a separate note instability devices have been shown to help in rehabilitation as it increases co-contractions which aid stabilisation of recovering joints and soft tissues.


7. Conclusion

By no means is this article designed to rubbish what trainers and therapists are currently using to treat their clients, it is simply meant to highlight the research and to get health and fitness professionals thinking. Does this mean as a client you should quit your Pilates subscription today? No! Many people profess to greatly enjoying Pilates and gaining great benefit from it. As yet there is no sound evidence to suggest that core stability exercises are hurting people (although this point is raised by Professor Lederman2). However, do I think that core stability is the foundation of any training and rehab program as many proclaim ........ I think not. Could you achieve your goals more quickly and efficiently by spending less time focusing on a few muscle groups in isolation......I think you can!

N.B. I strongly recommend reading the article by Professor Lederman as a basis for further reading on the ideas put forward above.


References

1. Sharrock C., et al. A pilot study of core stability and athletic performance: Is there a relationship? International Journal of Sports Physical Therapy. 2011 June; 6(2): 63–74. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109894/

2. Lederman E. The myth of core stability. Journal of Body Work and Therapies. 2010; 14: 84-98. http://www.craigliebenson.com/wp-content/uploads/2010/08/sdarticle.pdf

3. Wang X., et al. A Meta-Analysis of Core Stability Exercise versus General Exercise for Chronic Low Back Pain Public Library of Science One. 2012; 7(12): e52082. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3524111/

4. Muthukrishnan R., et al. The differential effects of core stabilization exercise regime and conventional physiotherapy regime on postural control parameters during perturbation in patients with movement and control impairment chronic low back pain. Sports Medincine Arthroscopy Rehabilitation Therapy Technology. 2010; 2: 13. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2903540/

5. Gordon A.T., et al. Relationship between core strength, hip external rotator muscle strength, and star excursion balance test performance in female lacrosse players. International Journal of Sports Physical Therapy. 2013 April; 8(2): 97–104. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625788/

6. Gorbet N., et al. No Difference in Transverse Abdominis Activation Ratio between Healthy and Asymptomatic Low Back Pain Patients during Therapeutic Exercise. Rehabilitation Research and Practice. 2010; 2010: 459738. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3200274/

7. Martuscello J.M., et al. Systematic review of core muscle activity during physical fitness exercises. Journal of Strength & Conditioning Research. 2013 Jun;27(6):1684-98. http://www.ncbi.nlm.nih.gov/pubmed/23542879

8. Behm D., Colado J.C. The effectiveness of resistance training using unstable surfaces and devices for rehabilitation. International Journal of Sports Physical Therapy. 2012 April; 7(2): 226–241. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3325639/

9. Di Lorenzo C.E. Pilates: What Is It? Should It Be Used in Rehabilitation? Sports Health. 2011 July; 3(4): 352–361. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445206/
10. Sharma A., et al. Effects of a nine-week core strengthening exercise program on vertical jump performances and static balance in volleyball players with trunk instability. Journal of Sports Medicine and Physical Fitness. 2012 Dec;52(6):606-15. http://www.ncbi.nlm.nih.gov/pubmed/23187323


Bibliography

Allison G. T., Morris S. L. Transversus abdominis and core stability: has the pendulum swung? British Journal of Sports Medicine. 2008;42:930-931. http://bjsm.bmj.com/content/42/11/930.full

Brumitt J., Dale B.R. Integrating Shoulder and Core Exercises When Rehabilitating Athletes Performing Overhead Activities. North American Journal of Sports Physical Therapy. 2009 August; 4(3): 132–138. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953337/

Childs J. D., et al. Effects of Traditional Sit-up Training Versus Core Stabilization Exercises on Short-Term Musculoskeletal Injuries in US Army Soldiers: A Cluster Randomized Trial. Physical Therapy. October 2010 October; 90 (10): 1404-1412. http://ptjournal.apta.org/content/90/10/1404.long

Erbulut D.U., et al. Biomechanics of Posterior Dynamic Stabilization System. Adv Orthop. 2013; 2013: 451956.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3626386/

Freeman J., et al. Pilates based core stability training in ambulant individuals with multiple sclerosis: protocol for a multi-centre randomised controlled trial. BMC Neurology. 2012; 12: 19. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3364845/

George S.Z., et al. Brief psychosocial education, not core stabilization, reduced incidence of low back pain: results from the Prevention of Low Back Pain in the Military (POLM) cluster randomized trial. BMC Medicine. 2011; 9: 128. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3286400/

Granacher U., et al. Effects of core instability strength training on trunk muscle strength, spinal mobility, dynamic balance and functional mobility in older adults. Gerontology. 2013;59(2):105-13. http://www.ncbi.nlm.nih.gov/pubmed/23108436

Lee T., et al. A comparison of pain level and entropy changes following core stability exercise intervention. Medical Science Monitor. 2011; 17(7): CR362–CR368. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539569/

Reed C.A., et al. The effects of isolated and integrated 'core stability' training on athletic performance measures: a systematic review. Sports Medicine. 2012 Aug 1;42(8):697-706. http://www.ncbi.nlm.nih.gov/pubmed/22784233

Sukalinggam C.L., et al. Stability Ball Training on Lower Back Strength has Greater Effect in Untrained Female Compared to Male. Journal of Human Kinetics. 2012 June; 33: 133–141. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3588679/

Van Dieën J.H., et al. Effects of fatigue on trunk stability in elite gymnasts.Eur J Appl Physiol. 2012 April; 112(4): 1307–1313. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3299971/