You call it middle dog? That's interesting! We call that one melting heart or anahataasana, which I love the name of! I used to find it so hard, but I love it now - that feeling of the heart melting to the floor and opening up through the upper thoracic spine. So goooooodddddd. I can't do urdhva dhanursasana though - I just have NEVER been able to do it! That's okay, bridge is fine for me, I just really concentrate on the purpose of the pose, bringing my shoulder blades together and opening up through the rib cage. Ah damn, no I'm talking about yoga I have to go and do it!