Hi :)
I see what you mean about the muscles being tense. I've tried to fix them up here.
With the shoulders, i think it's because they had their arms raised in the refs i used and that made them look really bulgy. I've tried to fix it but if it still looks wrong i can try it again.

Another update. I've modified the overall body shape to be a bit more slim. It was looking to bulky in some places so I've toned them down now.

The picture....