Beginner’s Guide to Spine Biomechanics: The Art of Injury Prevention
Ian McIntosh B.S. (future) D.C.
Hello there Stone Strength Systems (S3) community and other internet go’ers! My name is Ian McIntosh, I am a soon-to-be graduate of Logan University with a Doctor of Chiropractic degree and a current Personal trainer at S3. I am a Saint Louis native (Go Blues & Cardinals) with a passion for all things strength training, spinal biomechanics and performance. As a former college football player, I know my way around the weight room, however, I believe the importance of proper spinal biomechanics during a workout was under emphasized in many ways. Unfortunately, I learned this lesson the hard way – while training in the off season I sustained a multi-level disc injury in my lower back. During my rehabilitation process I began seeing a Chiropractor who not only taught me the importance of proper spine mechanics but ultimately cultivated my interest in becoming a Chiropractor. As a former athlete with a passion for working out combined with an interest in spinal health, I am here to spread the importance of spinal biomechanics in your workout in order to help you achieve a better workout while also reducing the risk of injury to your back.
In order to understand how spinal biomechanics affect your workout, it is important to first understand the types of forces that act on your spinal column as well as some basic anatomy. First, we will start with an explanation of the various types of forces applied to the spin. Compressive forces happen all day long due to gravity, activities such as walking or running, and muscular contractions.[i] By contrast, tension forces play a small role on the spine. For example, when you bend forward the front of the spine is resisting being compressed whereas the back of the spine is resisting the torsion force of being pulled apart. [ii]* Torsion forces are applied by actively rotating the torso, called “torsion movement”, or trying to rotate the body while keeping the torso still which is called “torsion moment”. While torsion forces are a common force leading to low back injury, there are many ligaments and bones working to prevent excess torsion forces. [iii] Lastly, shearing forces are the most common with weight-lifting. Every time a kettlebell swing, deadlift, lunge, squat or sit up is performed there are shear forces acting on the spine. Even though the spine can resist shear forces and stabilize itself, repetitive shear forces are likely to injure the ligamentous structures of your spine.[iv] Thus, proper exercise selection and load management are essential for the health of your spine
Another important topic in understanding spinal biomechanics is basic human anatomy. The spine is made up of 24 vertebral bodies. The vertebral bodies have a complex connection of vertical and horizontal fibers inside their hard outer bone, called “trabeculae”, that aid in the strength of the bone and resist the various forces I described above.[v] It should be noted that in some medical conditions, like Osteoporosis, there is a major loss of these supporting trabecular fibers which can put you at risk for compression fractures.[vi] While this might sound scary, it is well documented that physical activity, strength training and other movements can increase bone density and quality to prevent these fractures.[vii] Which is why training with a professional who understands the different forces affecting the spine and how the specific tissues adapt is very important. Lastly, it is important to understand the function of the discs of the spine. The disc is made up of a bundle of connective tissue fibers that surround a gel-like substance. This liquid encasing creates a hydraulic pressure system that is tough enough to resist compressive loads between the vertebra but is also flexible enough to allow movement.[viii] If there is injury to the disc caused by excessive force, then there will be spinal instability and a proper rehabilitation program is necessary.[ix] This is another reason why consulting an expert in spine biomechanics and rehabilitation is crucial for minimizing the risk of injury to the spine while weightlifting.
Luckily, the human body has evolved in such a manner that supports a wide variety of movements and activities. A gymnast can perform a back bend and touch her head to her ankles with the same anatomy that allows a power lifter to squat 1000lbs. Each sport creates specific demands which enables the body to produce an equal and appropriate adaptation.[x] Shear forces are extremely important while weightlifting. Research shows repetitive shear force, such as reaching end range flexion and extension, with moderate load can be problematic to the spine.[xi] Making a beginner to weight lifting start immediately with Olympic weight lifting, high repetition exercises such as burpees or kettle bell swings, and end range flexion exercises, like sit ups, is a recipe for low back pain. The spine is a complex guy-wire system, meaning, it has muscles oriented in all directions to provide 360 degrees of support. The muscles that surround the spine function to bear compressive load and resist spinal motion. These core muscles, when properly braced, increase the lumbar spine stability which allows the movement to occur in other joints, such as the ball and socket joints of the hip and shoulder.[xii] One muscle that should receive more credit and appreciation in spinal health is the quadratus lumborum. Research shows that the more load is applied to the spine the more this muscle is activated.[xiii] This muscle can also be trained with loaded carry style exercises. Therefore, walking with weight, either in your hand or on your back, should be incorporated into your training regime if you want to maximize your core stability. So, with that being said, many things need to be taken into consideration when programming a workout. The workout should be tailored to the various features of each individual, such as training age, functional capacity, injury history and more, in order to minimize the risk of harm and maximize the benefit.
Thus, the key takeaways in regard to spine biomechanics and training are:
- Consult a trained expert in spinal biomechanics before stepping into the gym.
- Start slow. Muscle, bone and connective tissue all have to adapt to the new load placed upon them and having a beginner step into the gym and immediately lift heavy weight and do advance barbell movements like Olympic lifting is a bad idea.
- Understand the forces that are acting on the spine and how they can either create damage or promote injury resiliency.
Most importantly, if you are interested in hands-on personal training that is safe for your spine, sign up to train with me at stonestrengthsystems.com. I can help you with proper exercise programming, weight loss, low back pain, muscle gain, joint pain and much more.
[i] M Rathore, K Sharma, Manisha B, A Siddiqui, S Trivedi, A focused Review-Thoracolumbar Spine: Anatomy, Biomechanics and Clinical Significance, (April 2014), https://www.researchgate.net/profile/Mrithunjay_Rathore2/publication/281442403_A_Focused_Review_Thoracolumbar_Spine_Anatomy_Biomechanics_and_Clinical_Significance/links/55e7391008aeb6516262dcd3/A-Focused-Review-Thoracolumbar-Spine-Anatomy-Biomechanics-and-Clinical-Significance.pdf?origin=publication_detail
[ii] A Duncan, A Ahmed, The role of axial rotation in the etiology of unilateral disc prolapse. An experimental and finite-element analysis,
[iii] A Barbir, Karolyn E, C Iatridis, Effects of Torsion on Intervetebral Disc Gene Expression and Biomechanics, Using a Rat Tail Model, (April 2011), Spine https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3061235/
[iv] S Gallagher, W Marras, Tolerance of the lumbar spine to shear: A review and recommended exposure limits, (Dec 2012), Clinical Biomechanics https://www.clinbiomech.com/article/S0268-0033(12)00183-0/fulltext
[vi] G Osterhoff, E Morgan, P Augat, Bone Mechanical properties and changes with osteoporosis, (June 2016), Injury, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4955555/
[vii] A Rebucci, Lirani-Galvan, M Lazaretti-Castro, Physical approach for prevention and treatment of osteoporosis, Endocrinology & Metabolism, (2010), https://www.scielo.br/scielo.php?pid=S0004-27302010000200013&script=sci_arttext&tlng=en
[viii] Adams, Bogduk, Burton, Dolan, The Biomechanics of Back Pain, p.11, Churchill Livingstone Elevier
[x] Purslow peter, The structure and functional significance of variations in the connective tissue within muscle, Comp Biochem Physiol A Mol Integr Physiol, (Dec 2002), https://pubmed.ncbi.nlm.nih.gov/12485685/
[xi] Cholewicki J, McGill S, Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain, Clinical Biomech, (Jan 1996), https://pubmed.ncbi.nlm.nih.gov/11415593/
[xii] Cholewicki J, Juluru K, Radebold A, Panjabi M, McGill S, Lumbar spine stability can be augmented with an abdominal belt and/or instead intra-abdominal pressure, European Spine Journal, (1999), https://pubmed.ncbi.nlm.nih.gov/10552322/
[xiii] McGill S, Juker D, Kropf P, Quantitative intramuscular myoelectric activity of quadratus lumborum during a wide variety of tasks, Clin. Biomech., (April 1996), https://pubmed.ncbi.nlm.nih.gov/11415616/
Juker D, McGill S, Kropf P, Seffen T, Quantitative intramuscular myoelectric activity of lumbar portion of psoas and the abdominal wall during a wide variety of tasks,