Patrick Huston describes how to get your shoulders in the correct position and therefore the right back tension for your shot
Q. Can you describe how to get your shoulders in the correct position and therefore back tension functioning in the shot?
Getting correct back tension is something which every recurve archer is aiming towards. Back ‘tension’ is not actually the correct phrase (despite it being the one everybody uses). We should actually be aiming to have the muscles in the back active but not tense. However, this does take a long time to achieve properly. The rear shoulder blade should be as far round behind the front shoulder as you can. I recommend coming into your anchor point from about four inches away from your face laterally – that is, from towards the archer in front of you. This allows your scapula to move in a rotational motion rather than trying to make rotation from a straight line.
The front shoulder should be pushing forward powerfully into the bow using your lats and pectoral muscles. This is often neglected by many archers but is very important. I recommend leaning against a wall and pushing yourself away from it with your arm out to your side. Try to push as far away as you can – this is the position and feeling you should have with your front shoulder.