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.
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.
5. What the evidence
says
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
Lederman2 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.
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.
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.
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/
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.
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.
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.
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
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.
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.
