To you play a musical instrument; you need to think in the most appropriated posture for the best musical performance and quality. Don´t have a general rule for the posture, but we need to find the best way to do it, where this don´t bring techniques difficulties, tension and performance difficulties, as the aesthetics while you play.
In the case of saxophone there´s basics rules of posture:
1. Let your arms relax, next to the body;
2. Don´t let your fingers pressing the keys, “pressing more the keys don´t make the sound flow”, mainly the low notes;
3. Try to play in the same way, sitting or standing, always with relaxed posture, without any tension in any part of your body. Your spine must be always straight, assisting your breathing;
4. Let your saxophone strap in the correct height, it can bring tension in your neck.
When you´re sitting don´t support your sax in the chair, let all the weight of your instrument in the strap. In the case of the baritone or the bass sax there a specific stand for playing as for the soprano sax has a specific strap.
Sax can be played next to the body, as between legs, with the exception of the soprano and baritone that must be played next to the body.
There´s a great variety of saxophones straps, find the best that fit to you.
If you´re reading a sheet, you must have a music stand, it will help your posture. Putting your sheet music above a chair, a coach will not bring good results to your spine and your neck, as increase the technique difficulty to play your instrument.
Let´s think that improving every detail of your posture while you play, the result will be a more soft music, you will have a more natural sound of your instrument, independently of the tempo and without tensions.
Greetings a good practice.