I started my humble music career as a Suzuki violinist, beginning at the age of 6. While there are many useful and important things I learned in my early training, standing position was one that has posed confusion as I've aged. Let me explain a bit more, for those non-violinist or violists out there.
When one learns beginning violin, often one is told to turn the feet out and step the left foot forward. I learned this way, and stood this way for a long time. (Over 15 years, at least). A few years ago, I started noticing that in yoga, pilates, and weight training, we were told to have both feet pointing forward, at least sometimes. I instead wondered, why do I always turn my feet out when I play, and does it actually serve me? I have since started experimenting with this concept.
So what's the big deal? Our feet naturally point forward or with a minimal turnout, and you may already remember that when you walk with your feet extremely turned out, there are potential consequences for foot, knee, and hip issues. (In addition, when feet point forward rather than externally rotated, the musculature of the foot is better able to support the body in standing and walking, and the ankle joint is able to articulate more fully.) From a biomechanical perspective, I don't understand why music educators have been teaching students to externally rotate their hips while standing, and I definitely don't understand why one foot needs to be in front of the other. I just don't. (Who decided this was a good idea?) However, I don't only care about the feet, but I care also about what is happening in the hips too. When one hip is perpetually externally rotated (left hip), we can exaggerate that asymmetry out of the practice room, and in our daily walking, standing, and movement lives, even if we don't intend to. That means that one set of external hip rotators is constantly working more than the other set, which can affect the muscles, bones, and connective tissue over time. What does that mean?
Side note, I came to this conclusion because of certain issues I was having in my hip, and that I was seeing in other colleagues of mine. Here are some of my personal symptoms, which may or may not be yours:
1. My left hip has consistently turned out more than my right, whether I'm in music mode, standing, cooking, walking, running, etc. This can simply manifest as the foot turning out, at least in appearance. Both hips want to turn out in standing though. I've been working on gently bringing the legs back to neutral, and found that to be helpful.
2. This in turn can cause my left external rotators of the hip and the low back muscles to be unruly. (Muscles include my gluteus medius, TFL, Quadratus lumborum, and the iliotibial band of fascia.
3. I also have the beginnings of a baby bunion on my left foot which may be impacted by the external rotation of the hip.
4. From a combination of asymmetrical music-making, left side dominance, and a host of other things, my entire left side is loads tighter (less range of motion from sole of the foot up to the shoulder!) than my right, which means that I sometimes have back pain and other issues on just the left side.
So what's the solution? Start to get curious. It's also important to remember that correlation does not imply causation- my left hip/back issues aren't inherently caused by the turn out, but I would venture to say that the perpetual external rotation has impacted things. I will say that my pain has diminished exponentially since I've been doing pilates and other movement activities that have challenged my hip range of motion and stability.
-How do you stand when you're playing? Where are your feet, knees, and pelvis? What sort of shoes do you normally wear? How might those be affecting your lower body?
-How do you teach your students to stand? If you have a specific way of teaching stance, why do you teach what you do?
-Try standing differently. Maybe feet closer together, more parallel, right leg in front, both legs in the same orientation...give yourself permission to experiment, and perhaps that will change how you teach.
-Do you sit when you practice at home, and if so, what are your legs doing?
-If you photograph yourself (or video) while playing, what does your standing look like in context?
-Do your feet turn out when you walk/run/play/sit/etc? Start experimenting with changing that setup gradually and see if it changes how you feel. It can have ramifications all around the lower body, specifically feet/knees/hips/spine, but maybe affects other aspects as well.
Playing an instrument requires movement within the body- it's not meant to be a static endeavor, but repeating the same position in perpetuity for twenty plus years may not be the best.