Proper back tension is applied with the rhomboid muscles in your back. Your bow arm, release arm, and release hand should be totally relaxed. Apply a light amount of pressure to the trigger, (caliper, thumb, or pinky) after settling in to anchor point. Aim and start to squeeze your release arm shoulder blade towards your spine. Imagine sueezing an orange with your shoulder blade. The release will fire without you knowing when and your total release will be an explsion with a nice follow through.