I have often been asked if there is an advantage to standing rather than sitting to play if you have that option.
I advocate alternating between one and the other when possible. It is true that when standing, musicians are more free to move around and change position, hence they are able to be more fluid. This is good. Static postures are the enemy. Any posture has a static component except when we are lying down and the static portion ( like holding up an instrument or a head that is leaning forward..) is the most important to evaluate in determining position, as it is the most taxing physically. Standing is not better necessarily, although chances are that our training was in a standing position and we are more accustomed to that and possibly more comfortable, and comfort and ease is the goal.
Of course there are musicians who, when playing in a standing position, might tend to lock their knees, perch on their toes, tense their calves or hamstrings, arch there back, or hunch shoulders and lean forward. ( ie I term it the "jazz look" a look that some people equate with really being "into" the music or looking very taken by their playing). These are similar problems that one encounters sitting.
It is essential whether playing seated or standing, that one maintains as neutral a position as possible. This means that one's body weight is on one's feet, shoulders are down and relaxed, head is erect ( not cocked, or leaning to the left or right, or dropped forward, and the chin does not jut out or forward); no turning or twisting of torsos, and there should be a normal lumbar curve in the lower back which we see if we stand normally.
When sitting to play, the most advantageous position, to ensure that the spine does not curve into a C curve, is to sit so that the knees descend downward from the pelvis. In other words the knees should be below the buttocks. ( this can be achieved by a variety of different ergonomic chairs which are now available and/or wedge shaped cushions and a myriad of lumbar cushions).
Feet should be flat on the floor although one leg can be more forward than the other, the torso should be erect ( not twisted or turned) and balanced, so there is a lumbar curve in the lower back. The shoulders should be square, relaxed and down. This erect ( but not arched) posture not only prevents spine damage, but also prevents the compression of internal organs and allows one to breathe normally. This of course is essential.
One needs to nourish the muscles and tendons, the brain and the organs with oxygen and blood flow that is constricted when there is tension. It is essential though, as with standing, that one is not "locked" into one position. We are trained to sit ( or stand) like statues and that builds up the static loading scenario. In my seminars, I demonstrate several Onstage Tricks (tm) which are small movements to ensure that tension does not build up. We must be conscious about releasing and letting go even for seconds. To MOVE is what is the most important- to uncurl arms, circle or roll shoulders, release hands and thumbs, to wiggle and adjust sitting, to let instruments and arms down for a few seconds.....etc
Lastly, whether a musician stands or sits, it is important to be aware that one does not to clench one's teeth, raise or lower wrists exaggeratedly, slam down fingers ,or squeeze thumbs. Instruments must fit the player. Adjustments should be done to make sure shoulder pads and chin rests are fitted appropriately, instruments are not too large, strings are not too high, instruments are in good repair and not "resistant" and bows are not too heavy.
