When being trained as a movement professional our first introduction to health and ideal movement patterns is often associated with symmetry.
There are limitations to viewing movement being only ideal when symmetry is present, or subscribing to the concept that there is only an ideal way to complete an exercise.
Why Movement Can Never Be Symmetrical
If you were to dissect the body deep enough to the organs it is easy enough to see that the layout of all the structures inside our gut and chest are not symmetrical. In fact most of the organs themselves are not even symmetrical.
The heart beats in a rotation, and our lungs fill up at different times.
It would be unrealistic to think that we could bend, compress, expand in exactly the same way on both sides of our body. There will always be one side that’s easier to do a task on than the other. Even if you were to look at the brain it’s not symmetrical. They are two hemispheres of the brain, and both of them are specialized for different tasks.
If symmetry is not observed anywhere else in the body, then should we really prioritize trying to achieve symmetry when teaching people to move?
There is a dichotomy to this idea though because having movement variability, and being able to distribute workloads by changing shapes through the body is important. Egregious differences between one side and the other is commonly a sign for intervention, however we should never expect to have both sides of the body fully operating the same.
Let’s go over a couple of examples.
Case #1: Shoulder flexion PROM (lying on the table)- Right= 180 deg. Left= 140 deg. This individual is a cross fit athlete.
Case #2: Same measurements, but this individual is a right handed baseball pitcher.
In case 1, I’m concerned about the severity of the asymmetry in shoulder flexion. This individual participates in a sport requiring a lot bilateral movement, and much of it overhead. While I’m sure watching them workout looks fine, they must be using a strategy that consistently requires compression on one side more than the other. If they don’t passively have the ROM, then they have to be achieving the range from somewhere else especially during a bilateral overhead movement.
In case 2 I’m not as concerned or surprised. While I think the lack of shoulder flexion is something to monitor and program for in the athlete’s training, it is a phenomenon that occurs as a natural adaptation from being a good baseball pitcher. Pitching is not a symmetrical motion, so we shouldn’t except the body to move or look symmetrical off the mound either.
In summary: Do we need to intervene when someone is asymmetrical? That’s a big… it depends.