Symmetry and Asymmetry in Yoga
Excerpted from Your Upper Body, Your Yoga
By Bernie Clark
January 19, 2024
Symmetry is often sought by yoga teachers and students. Many teachers demand their students exhibit the same range of motion in a pose on both sides of the body, and if a student is unable to go as far on one side, then the other side is deliberately held back from expressing its range of motion until the first side can catch up. This makes symmetry into dogma: an ideal that can never be reached in all cases. Frankly the dogma of symmetry is not functional. Are you slavishly devoted to symmetry at all costs, or are you open to a more nuanced, functional approach?
Mountain Pose, as shown above, is sometimes called Samastitihi, or “equal standing” pose. The stated intention is to make both sides of the body appear equal or symmetric. Symmetric can be defined as having identical halves; hold a mirror to one side of an object, and in the reflection, you will see an identical copy of the side hidden by the mirror. To determine symmetry, an axis of comparison must be chosen. We are not symmetric front to back (when viewed in the side plane); we are not symmetric from top to bottom (when viewed in the frontal or side plane); but we are approximately symmetric from side to side (when viewed in the frontal plane). This supposition of frontal plane symmetry is not even skin deep, though, for not only are we not symmetric beneath the skin—we have three lobes of the lungs on our right side but only two on our left side, as just one example—but we are not even superficially symmetric. The right side of our face is not a mirror image of the left side. Since perfect symmetry is an ideal not found in real life, perhaps rather than seeking symmetry in our yoga practice, a better goal is to seek balance.
Balance can be defined as having elements that are equal and proportioned or as being in a steady equilibrium. The first definition has echoes of symmetry, but the second has a functional quality. It is in this latter sense that I will use the word. Consider the classic taijitu, or yin and yang symbol, shown in figure 1. The right side is darker than the left. The top is brighter than the bottom. There is no symmetry, but it is balanced and displays a great harmony among its elements. The yin elements are in harmony with the yang elements. Like this symbol, you are not symmetric. And that is okay! You do not need to be fixed unless you are also unbalanced.
To quote Leslie Kaminoff, noted yoga teacher and co-author of Yoga Anatomy, “To be in balance is to develop a healthy relationship between your asymmetries.” He offers the example of resting in Shavasana at the end of a yoga practice (see figure 2), allowing your arms and legs to be symmetrically arranged as perceived by a teacher or some other outside observer. He suggests that you notice how this arrangement feels on the inside. Do your proprioception and interoception agree that you are symmetric, or do you feel slightly off? Do you feel balanced in this shape? If not, what changes would you like to make to achieve the feeling of harmony between left and right, top and bottom?1
Your dominant arm is probably larger and stronger than your non-dominant arm; this does not mean that you have to use your dominant arm less and your non-dominant arm more. Similarly, one leg is probably stronger than the other. That is normal and natural. Which athletes would sacrifice strength and range of motion in one limb simply because the other limb is different? They have learned to perform optimally, not just despite of these asymmetries but because of them. This is not limited to humans: over 68% of vertebrates have a dominant side, thus a preference for asymmetry.2 Again and again we will find that asymmetries do not always have to be “fixed”; often, they are intentionally trained and developed. To be optimally functional, we require not perfect symmetry but an easy facility in movement with our asymmetries, or in other words, balance. A right-handed person has learned how to be balanced when throwing with her right hand; she doesn’t topple over because her right arm is stronger than her left. Her motions are fluid and graceful. She adapts and is in balance, thanks to her training.
IT’S COMPLICATED: The many definitions of asymmetry
Asymmetry can be defined as having your right side of your body appear different to your left side (or vice versa). You are not symmetric. Simple, right? Not so fast! Clinicians want to know more than the bold fact that you are not perfectly symmetric; they want to understand why you are not symmetric. Is your asymmetry minor or major? Will it lead to postural changes that can impair function? Has some physical instability created the asymmetry, or has asymmetry created the instability? Both are possible.
Asymmetries can be classified in many ways. They can be considered fixed or flexible. A fixed asymmetry describes an asymmetry that is in the nature of the bones, which cannot be altered. One femur may be longer than the other. You cannot change the shape and size of your bones, outside of surgery or some disease or condition. (Figure 3 shows several examples of how asymmetry in the acetabulum (hip socket) affects the positions of the legs and feet.) A flexible asymmetry can be changed, through retraining of movement patterns, braces or exercises. Perhaps you adopted the habit of slightly flexing one knee more than the other, creating an asymmetry. This could be changed and is thus a flexible asymmetry. Recently, the term fixed asymmetry has fallen out of favor because many supposedly fixed asymmetries can be changed; they were not truly fixed. Instead, two new terms have been adopted: correctable asymmetries and non-correctible asymmetries. In general, a truly fixed or non-correctible asymmetry will not become worse if no therapy is invoked, nor can it be corrected. If the asymmetry is not truly fixed and is actually a flexible or correctible asymmetry, then the condition may get worse without some intervention.3 (However, it must once again be pointed out that “may” does not mean “will,” and not all asymmetries are problems or will lead to future problems. Many asymmetries are benign or even helpful.)
So far, we have been considering only the physical appearance of asymmetry. But asymmetry can arise in many other ways that are not apparent through a casual glance: there can be differences from one side to the other in strength, movement patterns, range of motion, and muscle size and volume.4 One study evaluated 14 asymmetric variables in sprinters and found no correlation between the level of asymmetries and performance.5 Clearly, these asymmetries did not need to be corrected.
Asymmetry can also be defined as the absence of symmetry. But there are many types of symmetry. The simplest form is bilateral symmetry, which is the form of symmetry of most concern to therapists, clinicians and yoga teachers. This is sometimes referred to as reflection symmetry: one side is the mirror reflection of the other side. However, reflection symmetry can arise even in cases where bilateral symmetry is not present. There are other forms of symmetry gathered under the umbrella term complex symmetry. These involve transformations around multiple axes. A five-petalled flower is not bilaterally symmetric, but it does possess rotational symmetry. Rotating the flower by 72° returns it to its original presentation. Other complex forms of symmetry include translational symmetry and spiral symmetry.6
In the study of the shape of the human form, a science called geometric morphometrics, three kinds of asymmetry have been defined: fluctuating asymmetry, directional asymmetry and antisymmetry. These terms are not applied to an individual but rather to a whole population.7 In these cases, the development of asymmetry is the result of several biological processes. Fluctuating asymmetry refers to the difference or deviation a single individual has when compared to the average of the whole population. For example, the distance between the left and right eyes to the bridge of the nose may be equal when averaged across the whole population, but in any one individual, one eye may be further away from the bridge of the nose than the other eye. Directional asymmetry refers to consistent differences between sides, such as the location of our internal organs. For example, our right lung has three lobes, compared to two lobes in our left lung. Directional asymmetry is widespread in the animal world.8 Anti- symmetry refers to consistent asymmetries that can occur on either the left or the right side. For example, humans have a dominant arm that makes them asymmetric, but for some people, the dominant arm is on the right side, while for others, it is on the left.
IT’S IMPORTANT: Reconsidering symmetry
What is the point of seeking aesthetic symmetry if the cost is a loss of balance and harmony?
Let’s go back to the basics: Why are you doing yoga? What are your intentions? If your goals include regaining and maintaining optimal health, striving for a perfectly symmetric appearance is not going to serve you well. We are all asymmetrical to varying degrees, and yet the vast majority of us are still fully functional. Our side-to-side differences have developed over the decades of our lives. A few hours a week with a yoga strap and some blocks is not going to reverse bony asymmetries. If we have truly dysfunctional asymmetries, we should seek assistance from a trained therapist, but we should not expect our yoga practice to change us. However, it may still feel nice to work our two sides differently. If a student has slight scoliosis, they may choose to stretch the tight side longer than the loose side. They may choose to strengthen a weak area more than a strong one. They will do this because it feels good, but not in the expectation that they are going to significantly change the shape of their bones.
Use your yoga practice to address the soft-tissue differences that your asymmetry creates, but realize that this is a never-ending process. And that’s okay! Paul Grilley uses the analogy of bathing. Bathing will not prevent you from getting dirty in the future. You will still need to bathe throughout your life. You cannot bathe just once or twice and think you are done forever. Similarly, you will need to continue to work on the soft-tissue differences that arise due to the asymmetry of your bones, because your bones are not going to change. That’s life.
Sometimes, it may not be appropriate to place yourself in a symmetric shape. Is the desire to have both feet symmetric in Mountain Pose (Tadasana) worth making the femurs in the hip socket asymmetric? It is easy to see the feet in a yoga pose and make an aesthetic judgment about how well you are doing the posture; but do you know what you are doing to the knees or hips? That is much harder to see. If your intention is to establish and maintain balance and harmony in the body, then how you look while you are in a pose should be, at best, secondary to how you feel while in the pose. At worst, how you look, the aesthetic of the pose, is irrelevant. Avoid the dogma of symmetry. Focus on the feeling of balance and ease before worrying about how you look. If you are a yoga teacher, teach your students to pay attention to their inner experience before making any outward alignment adjustments. Look beyond the aesthetics to the functional requirements of each student’s body.
To learn more about how asymmetry affects your yoga practice, check out the book, Your Upper Body, Your Yoga.
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[1] See Leslie Kaminoff and Amy Matthews, Yoga Anatomy, 2nd edn. (Champaign, IL: Human Kinetics, 2011).
[2] See F. Ströckens, O. Güntürkün, and S. Ocklenburg, “Limb Preferences in Non-Human Vertebrates,” Laterality 18.5 (2013): 536–75, doi:10.1080/1357650X.2012.723008.
[3] See Laurie Watanabe, “Asymmetry in Balance,” Mobility Management (September 1, 2017), https://mobilitymgmt. com/Articles/2017/09/01/Asymmetry.aspx?Page=2.
[4] See Cary Groner, “Implications of Asymmetry in the Treatment of Injured Athletes,” Lower Extremity Review (February 2018), https://lermagazine.com/article/implica- tions-of-asymmetry-in-the-treatment-of-injured-athletes.
[5] See T. Haugen, J. Danielsen, D. McGhie, O. Sandbakk, and G. Ettema, “Kinematic Stride Cycle Asymmetry Is Not Associated with Sprint Performance and Injury Prevalence in Athletic Sprinters,” Scandinavian Journal of Medicine and Science in Sports 28.3 (2017), doi: 10.1111/sms.12953.
[6] See C.P. Klingenberg, “Analyzing Fluctuating Asymmetry with Geometric Morphometrics: Concepts, Methods, and Applications,” Symmetry 7.2 (2015): 843–934, https://doi. org/10.3390/sym7020843.
[7] See Laura Manthey and Stephen D. Ousley, “Geometric Morphometrics,” in Zuzana Obertová, Alistair Stewart, and Cristina Cattaneo (eds.), Statistics and Probability in Forensic Anthropology (London: Academic Press, 2020).
[8] See Klingenberg, “Analyzing Fluctuating Asymmetry.”