I think TW and Tuney have it right. Sounds like your ski muscles are more flexible allowing the other muscles in your shoulders and chest that are tighter to roll your shoulders forward. I think dumbbell flies,, push-ups, dips, pec cable machine and any thing else that will put a stretch on the front half of your upper body will help restore your shape. I spend a little time in the gym during the season and usually do supersets starting with a benching exercise and pull-ups. I alternate my grips on the pull-ups and usually do four sets. Yesterday I did 20 minutes on the stair climber, leg extensions and curls, inclined bench and pull-ups four sets of each then four sets of Arnold curls/military press. That is about it for lifting weights while skiing as far as quantities of sets go although I will change the exercises.  In addition, I try to run and cycle each a couple of times a week for cardio. I haven't settled on my offseason routine yet but I am sure it will be the addition of some more gym time each work-out starting on the rowing machine and ramping up my running for some road races and weight control.