Core stability relates to the bodily region bounded by the abdominal wall, the pelvis, the lower back and the diaphragm and its ability to stabilise the body during movement. The main muscles involved include the transversus abdominis, the internal and external obliques, the quadratus lumborum and the diaphragm. The diaphragm is the main muscle of breathing in the human and so breathing is important in providing the necessary core stability for moving and lifting. It is the action of these muscles contracting together upon the incompressible contents of the abdominal cavity (i.e. the internal organs or viscera) that provides support to the spine and pelvis during movement.
Core stability is a misunderstood term. Typically, the core is associated with the abdominal muscles groups and stability is associated with isometric or static strength. However, in actuality, the core consists of the abdominal muscles groups (transverse abdomens, internal obliques, external obliques, rectus abdomens), hip abductors/ adductors, hip flexors, the pelvic floor, and lumbar spine. In addition, it is lumbar spine that is primarily responsible for posture and stability providing the strength needed for stability especially utilized in dynamic sports.
Whenever a person moves, to lift something or simply to move from one position to another, the core region is tensed first. This tension is usually made unconsciously and in conjunction with a change in breathing pattern. An example to try is to sit in a chair and to reach forward over a table to pick up a cup. This movement is first accompanied by a tension in the core region of the abdomen and can be felt by placing one hand on the abdomen as the movement is made.
As the load increases the key muscles contract around the viscera, which are incompressible, to form a stable ball-like core region against which the forces are balanced in coordination with posture. In martial arts there is a saying that 'power is generated from the ground up' and core stability is necessary for the transfer of force and power from the ground across the body into any movement.
It is commonly believed that core stability is essential for the maintenance of an upright posture and especially for movements and lifts that require extra effort such as lifting a heavy weight from the ground to a table. Without core stability the lower back is not supported from inside and can be injured by strain caused by the exercise. It is also believed that insufficient core stability can result in lower back pain, poor posture and lethargy.
There is little support in research for the core stability model and many of the benefits attributed to this method of exercise have not been demonstrated. At best core stability training has the same benefits as general, non-specific exercise (see review by Lederman 09) and walking. Trunk or core specific exercise have failed to demonstrate preventative benefits against injuries in sports or to improve sports performance.
Although Lederman remains a figurehead skeptical favorable studies that exist to support the role of core stabilization in protecting the spine from unnecessary shifting and shearing of vertebral structures. The core stability model consists of passive and active stabilization structures as well as a third, often disregarded subsystem, called the neuromotor system. This vital system is required for the active structures such as muscles to provide preemptive or rather quick responses to the body's demands.
Training methods for developing and maintaining core stability include:
- Exercise ball, also known as a Swiss ball, stability ball, yoga ball, Pilates ball or fitness ball
Exercise for Strengthening of the Cervical, Thoracic and Lumbar Spine
The cervical, thoracic and lumbar spine is composed of a total of 24 presacral vertebrae and their main functions are to protect the spinal cord, provide an attachment site for many muscles of the body. They also function by distributing one’s bodyweight when standing upright. Many injuries to the spine occur as a result of vehicle accidents, falling, and sports and recreation. While it is impossible to prevent such events from happening, by increasing intra-abdominal pressure and strengthening the musculature in your back and the ability to keep a neutral spine, one is able to minimize preventable injuries like hernias, strains, and sprains.
Achieving a Neutral Spine
The spine is naturally curved in segments: cervical spine is curved inward or anteriorly (lordosis), the thoracic spine is curved outward or posteriorly (kyphosis), and the lumbar spine is curved inward or anteriorly (lordosis) (6). In order to ensure even distribution of stress on the spine, maintaining a neutral spine can maximize the support provided by these structures. A simple exercise that may require some practice is called the “Pelvic Tilt.” The individual is laying on their back with their knees bent and their feet flat on the floor. Next the individual will engage their abdominals in order to pull their lower back flat on the floor. This may be difficult for some at first so aim for holding this contraction for approximately 10–15 seconds for a total of 5 repetitions (3).
The correlation between having a significant amount of core strength and spinal health has been well documented by many studies in the past. Some of these studies were able to quantify the effects that antagonizing abdominal muscle had on stabilizing the lumbar spine by increasing the amount of intra-abdominal pressure to in order to maintain a straight lumbar spine and avoid rounding during physical activities  and using simple techniques such as the “Valsalva maneuver”. A simple exercise used to strengthen the abdominals (rectus abdominus, internal/external obliques, and transverse abdominus) is using the isometric or “static” hold known as the plank. The plank is simulates the need to resist movement rather than create it and when focusing on spinal stability this is exactly what we need. In order to execute the move one can begin in a pronated position and either support one’s self on their forearms or hands (like a pushup position). The objective of the movement is to keep the spine in proper alignment while keeping protracted shoulders and maintaining the spine in alignment. This can be done by remembering to keep a tight core as well as consciously contracting the glutes.
Strengthening back musculature
Simply by working to keep a neutral spine and remembering to increase intra-abdominal pressure before performing a movement that could compromise the spine, you are able to drastically decrease your risk for sustaining a back injury. If you were looking for ways to both strengthen and increase stability of the musculature of the spine one could perform various bodyweight exercises, one of them being what is known as the “contralateral bird-dog.” To perform this exercise, one will begin on their hands and knees with their palms flat and under their shoulders and their thighs directly under their hips. Next, while maintaining a neutral spine and a braced abdomen, the individual raises their right arm and left leg simultaneously forming a straight line with their spine as shown in figure 3 below. If possible hold this position for a total of 10 seconds on each side for 5 repetitions and once you are able to perform these, then you can add touching the contralateral (opposite) elbow to the knee.
While our brains are “wired for movement, not musculature”, we must learn to move properly utilizing proper biomechanics and ensuring our posture and alignment are in optimal positions to execute the task safely while minimizing the possibility of injury. If we can learn to remember to keep a neutral spine, increase intra-abdominal pressure, and we continue to strengthen the musculature of our back and core, we will live a pain free life.
- Inline citations
- Dr. Michael Yessis (2000). Explosive Running. McGraw-Hill Companies, Inc.; 1st edition. ISBN 978-0-8092-9899-0.
- Kriese M, et al Segmental stabilization in low back pain: a systematic review. Sportverletz Sportschaden. 2010 Mar;24(1):17-25. Epub 2010 Mar 16
- Rackwitz B, et al Segmental stabilizing exercises and low back pain. What is the evidence? A systematic review of randomized controlled trials. Clin Rehabil. 2006 Jul;20(7):553-67
- May S, Johnson R. Stabilisation exercises for low back pain: a systematic review. Physiotherapy.2008;94(3):179-189
- Ferreira PH, Ferreira ML, Maher CG, et al. Specific stabilisation exercise for spinal and pelvic pain: a systematic review. Aust J Physiother 2006;52:79–88
- Macedo LG, Maher CG, Latimer J et al 2009 Motor Control Exercise for Persistent, Nonspecific Low Back Pain: A Systematic Review PHYS THER Vol. 89, No. 1, January, pp. 9-25
- Lederman, E. The myth of core stability. Journal of Bodywork and Movement Therapies. 2009, doi=10.1016/j.jbmt.2009.08.001
- Smeets RJ. Do lumbar stabilising exercises reduce pain and disability in patients with recurrent low back pain? Aust J Physiother. 2009;55(2):138
- Childs JD, 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. Phys Ther. 2010 Jul 22
- Helewa A, et al., 1999. Does strengthening the abdominal muscles prevent low back pain--a randomized controlled trial. J Rheumatol. 26 (8), 1808-1815
- Nadler SF, et al., 2002. Hip muscle imbalance and low back pain in athletes: influence of core strengthening. Med Sci Sports Exerc. 34 (1), 9-16
- Hibbs AE, et al Optimizing performance by improving core stability and core strength. Sports Med. 2008;38(12):995-1008. doi:10.2165/00007256-200838120-00004
- "Vertebral column". Encyclopedia Britannica. Encyclopedia Britannica Online. Encyclopedia Britannica Inc., 2015. Web. 16 Feb. 2015 <http://www.britannica.com/EBchecked/topic/626589/vertebral-column>.
- Gardner-Morse, M., & Stokes, I. (1998). The Effects of Abdominal Muscle Coactivation on Lumbar Spine Stability. Spine, 23(1), 86-91.
- Goldish, MD, G., Quast, MD, J., Blow, MD, J., & Kuskowski, PhD, M. (1994). Postural Effects on Intra-Abdominal Pressure During Valsalva Maneuver. Arch Phys Mad Rehabil ,, Vol75, 324-327.
- Starrett, K., & Cordoza, G. (2013). Chapter title. In Becoming a supple leopard: The ultimate guide to resolving pain, preventing injury, and optimizing athletic performance (pp. 71). Las Vegas: Victory Belt Publishing.
- General references
- Anderson, Stephen A.; Calais-Germain, Blandine (1993). Anatomy of movement. Chicago: Eastland Press. ISBN 0-939616-17-3.
- Mel Cash. Pocket Atlas of the Moving Body: For All Students of Human Biology, Medicine, Sports and Physical Therapy. North Pomfret, Vt: Trafalgar Square Publishing. ISBN 0-09-186512-3.