Asymmetry in the human body, it’s normal!
Do you love symmetry? Well I do. I even use the phrase “symmetry is the key” a lot. But not when I’m at work. And as you may know, I work with people and watch them perform presses, squats, and more. But I almost never mention symmetry as an outcome or judgment. In this blog I’ll explain why I don’t pay attention that much to the symmetry of the human body.
I’m not symmetrical!
We at yourphysio.online hear the phrases, “I’m out of line”, “I’m not symmetrical”, “My shoulder blades aren’t moving the same”, “my back pain is coming from my longer leg” or “I have more internal rotation on one shoulder” daily. But do these things even matter? Is it so important to be symmetrical? Do your shoulders need to move the same? Is it so bad to have a little longer leg than on the other side? Well no. And that’s because your body isn’t symmetrical. Your heart is even on one side, your liver is on one side, and you only have one stomach. So if your body isn’t built symmetrically from the inside, why should it be from the outside?
Why we aren’t symmetrical
Let’s start with movement preference, most people are left or right-handed. There are some people who are a bit different and can write, throw balls, or can hit punches, with both left and right, but most of them have a preference for one side. So if you’re right-handed, you can imagine that you do certain things more with the right side. So this will already develop some differences between muscle volumes and probably the way your skeleton is leaning, hanging or turning towards one side.
Symmetry in sports
If we take a look at the shoulders of a baseball pitcher, for instance, the dominant shoulder side is in most cases a little depressed. And no the shoulder blade is not crying or sad. But a depressed shoulder blade means that the shoulder blade is hanging a little bit more down than the other side. It is even believed that the shape of the upper arm bone (humerus) is changing because throwing a ball places more stress on the arm. Soccer players have different side to side hip mobility, volleyball players have more strength on one side, and people who do hurdling have more flexion and extension in one leg. And that’s okay, because this is a normal and even functional variation to it’s sport. But this happens also during your daily live.
Symmetry in the nonsportive population
But these types of asymmetries can also happen in the regular nonsportive population. Think about working in one direction behind a counter, on an assembly line or always needing to talk to the person next to you at your desk job. A carpenter or painter will also develop anatomical changes. All because of a certain repetitive movement or movement preference. And chances are high that you will also develop some asymmetry, and that is perfectly fine.
Is asymmetry a factor for injuries?
But what does the evidence has to say about this? Let’s first start with the one I hear a lot, leg length difference as a reason for injuries. To answer the question of whether a leg length difference is a predictor for injuries we look at a study from Knudsen from 2005. They found that a leg length difference smaller than 20 millimeters isn’t a predictor for injuries. It seems that only from 20 millimeters on and also depending on your activity, inequality might become a problem. It has to be noted that only 1 in a thousand people actually has this size of discrepancy. So a leg length difference is probably not the issue. But what about a difference in shoulder movement?
If we talk about shoulder movement, we talk about scapular dyskinesis. Scapular dyskinesis means involuntary movements of the scapula or shoulder blade. And for many years physios thought that scapular dyskinesis is a predictor for shoulder pain or something we need to treat. But research shows that scapular dyskinesis is really common. A study by Hannah et al from 2017 found that 68% percent had some kind of scapular dyskinesis. And these participants were pain-free. So a different type of shoulder movement isn’t a predictor for shoulder pain or is directly linked to shoulder pain. But what about shoulder positioning?
If we take a look at the overhead athlete, a different type of shoulder position is also really common. A study by Manske and Ellebecker from 2013 looked at the shoulder position of the overhead athlete and found that the dominant shoulder is most of the time depressed, and the lower part of the scapula points a little bit out. This asymmetry is also common in the normal population.
Shoulder asymmetries we shouldn’t be ignoring
Not all shoulder asymmetries are something we should ignore. If you can’t lift your arm up and your shoulder blade is not moving or is moving like a wing on your back during your arm movement, there’s a small chance that there could be a neurological problem. Other asymmetries like a pointing collarbone after a fall or a strange-looking shoulder blade or upper arm after a fall can be a sign of a fracture.
But what about the spinal scoliosis, should we do something about that? Scoliosis is a side curve in the spine and affects people of all ages. An estimation of 8% of people over 25 years of age will have spinal scoliosis rising up to 68% of people over 60 years of age. So can we do something about it? Well, scoliosis can improve with treatment, especially in the younger population, but it is not usually a sign of anything serious and treatment is not always needed if it’s mild. But you can probably imagine that if your spine is leaning or curved towards one side, your shoulder blade is also hanging a little bit lower than on the other side. So the spinal scoliosis can result in a harmless asymmetry somewhere else.
But is it harmful? Well, in most cases spinal scoliosis is more a cosmetic deformity. But a child younger than 10 years of age should be referred to a specialist if the curve is greater than 10° or is greater than 20° in a patient 10 years of age or older. That doesn’t mean it is harmful, but it’s more that they can monitor the progression of scoliosis and can intervene when necessary. So not that harmful. Oh and remember that the fastest person on earth has spinal scoliosis. So spinal scoliosis doesn’t have to slow you down.
Alright, I hope that this blog helped you in understanding that symmetry doesn’t have to be the key. It’s normal to have scoliosis, to have one shoulder blade hanging more down, or to have a slightly longer leg or bigger foot than the other side. It’s normal to be different. And on that note, I want to end this blog. But if you’re, after reading this blog, still in doubt if you should be treating your asymmetry, consider booking an online consultation with us. We can check it for you.