Breathing in Urdhva Dhanurasana
I realize it is worth making a small note on breathing in Urdhva Danurasana.
Because of the position of the arms and what that does to the chest, ribcage and upper back, and the arch in the spine and what that does to the whole breathing mechanism, if you want to be deep in this pose, it is worthwhile to breath softly in a relaxed manner. The spine and ribcage are in such a deep position that there is no room for them to give the breathing mechanism extra volume in breathing, and the abdomen is being stretched as well so there is not much space to give there. The result is that if you tried to breath too deeply in the pose it would result in tension and strained breathing which is not what you want. Slow relaxed breaths that are a length and depth that feels natural and comfortable to the body would help you open deeper into this pose than trying to breath deeply would. The strain from deeper breathing could actually prevent you from opening as much and could make the whole posture feel strained and less beneficial.