If you’ve been around sports for any amount of time, you’re probably aware that your body is not perfectly symmetrical. Perhaps your left foot pronates a bit more than your right, or maybe your left shoulder is a little higher than your right. We all have these types of asymmetries and despite what you may read online, in magazines, or even what you might be told in running stores, asymmetries are normal. As both a personal trainer and endurance sports coach, I’ve worked with hundreds of clients over the years and do you know how many were perfectly symmetrical? Zero.
The body is an amazing machine in that it naturally compensates for changes in symmetry. This has been demonstrated by how the foot and ankle alter their mechanics to account for changes in footwear – most notably a breakdown due to wear. While the body can adapt to changes in symmetry, if the changes or more specifically, the degree of asymmetry is too large, injury can occur. This is likely exacerbated by increased intensity and, or volume.
SHOULDERS AND HIPS
When body mechanics are discussed in regard to running, the areas most often discussed are the feet/ankles (neutral, pronation, supination), foot strike (rearfoot, forefoot, midfoot) arm swing (elbow angle, degree of arm swing) and upper body position (sway back, vertical, forward lean).
The area that is often missing is hip and shoulder rotation. Before we get into this, it’s critical to understand that body parts do not function in isolation. Rather, the body works as a whole unit. This is commonly referred to as the ‘kinetic chain.’
In regard to running, the hips and shoulders rotate in opposite directions. This is the result of the spine counter-rotating, as is noted in the illustration below.
Used with Permission from Erik Dalton
Counter rotation of the spine stores energy when the shoulders and hips are rotated farthest from each other and the energy is released to counter-rotate the spine in the opposing direction – thus, allowing the hips and shoulder to rotate in the other direction. A good example of this is twisting a coil spring in opposite directions. The more the spring is twisted, the greater the amount of energy is stored. When the spring is released, the energy uncoils the spring. In other words, the origin of movement in respect to running gait comes not from the legs, but from the spine. This is termed, the ‘Spinal Engine Theory‘ and was developed by Dr. Gravovetsky.
TRANSVERSE PLANE ASYMMETRY
When the hips and shoulders twist (rotate) to the left and right, they are moving in the transverse plane.
If one shoulder or hip is rotated in the transverse plane substantially more in one direction than the other, it will likely affect a runner’s form. The degree of hip and shoulder rotation directly relates to the amount of hip extension and flexion a runner has. For example, if a runner’s hips are rotated excessively to the left, it will likely equate to the left leg having more hip extension than the right. This will also likely cause the knee of the left leg to over-extend prior to the foot strike to compensate for the overly rearward rotated hip. This can cause hamstring issues (left leg) due to excessive knee/leg extension.
As a non-clinician, it’s best to leave any formal assessment to a professional, such a physical therapist. The cause of a hip/shoulder asymmetry could be from any number of things (ex: scoliosis) that may or may not be able to be corrected and more importantly, may or may not negatively affect performance. However, if you notice that your shoulders and, or hips are substantially rotated more in one direction than the other in the transverse plane, it’s strongly advised to get this evaluated by a trained professional.
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Knapik J.J, Feltwell D, Canham-Chervak M. “Evaluation of injury rates during implementation of the Fort Drum Running Shoe Injury Prevention Program” U.S. Army Center for Health Promotion and Preventive Medicine Report. 12-MA-6558-01, Aberdeen Proving Grounds, MD; 2001
Kong P.W., Candelaria N.G., Smith D.R., “Running in new and worn shoes: A comparison of three types of cushioning footwear”. Br J Sports Med 2009; 43(10): 745-749.
Gracovetsky S. “Is the lumbodorsal fascia necessary?” J Bodyw Mov Ther. 2008 Jul;12(3):194-7. doi: 10.1016/j.jbmt.2008.03.006. Epub 2008 May 16.
http://erikdalton.com/spinal-engine-vs-the-pedestrian-theory-of-locomotion/. Retrieved August 13, 2014.