You create back tension by locking your anchor and pushing forward with your bow arm . If you try this without a bow in your hand you will get a better feeling of the muscles between your shoulder blades working .On release if your fingers are angled down slightly & relaxed its a sign of backtension . There will be slight movement backwards but many people also exagerate this and try to kid themselves they have massive back tension , if fingers are pointing straight out and rigid , not so much happening . A good release is all in the front arm , its about creating a balance with your bow arm and drawing arm between your shouler blades , if one has more tension than the other - form collapses . I like the swing draw that John Schultz coaches in his video it sets up that balance well . regards Perry