Tonight's class went quite well. For most of the hour, I actually felt like I was participating, rather than fighting to keep up. That is a first for me. The last time I exercised was 3 days ago, and I think going into class fresh made it a lot easier.
I also made small progress on the transition between chatarunga and up dog. The postural muscles in my upper/mid back are definitely relaxing as I drop into chatarunga. By lowering all the way to the ground, resetting my back and shoulders, then pressing into up dog, I found I was able to get through the whole class without any shoulder pain from impingement. It felt great, much more comfortable. I need to figure out how to end up with my shoulders set correctly at the bottom of chatarunga, but until then, this is a nice interim solution.
I noticed my Manduka mat has started to become pliable. It has stopped fighting me when I roll it up after class, and I can feel myself sinking into the mat during class. The problems I was having with slipping have diminished quite a bit. It makes me happy that the mat is actually breaking in like the company promised.
Today it occurred to me that no matter how much I improve, the teacher is going to keep providing options to increase difficulty. It is a good reminder that the goal is to be present with my limits, not to do crazy awesome bending like a pretzel.