Arms overhead position & back extension

[Adam McCubbin]

I have been meticulously following the GST foundation one program and have seen significant improvements in mobility, strength and movement quality. Plus really enjoying it. 

I'm coming from years of powerlifting and weight training, so there are some limitations in some positions and movements at the moment. 

In particular my arm flexion overhead when seated, lying and standing. See attached picture below. Which stretch series do I need follow or any particular drills that can help? 

[Adam McCubbin]

Plus, this is my end range of back extension from this prone position.  I find this limites me in a number of the exercises.  

[Alessandro Mainente]

hI Adam i'm going to split my suggestion in 2 parts:

1) the suggested work is once a week the thoracic bridge course and the restore series more often;

2) my personal suggestion is to have a check with a PT so that you can understand where limitations are located since many groups can lead to similar posture modification.