Pilates

I got a groupon and signed up for 5 Pilates classes. The first class went well, and it was arms, but I have to modify a lot because I have bad shoulders. The next day I was a little tight, but ok. I am pretty protective of my shoulder after years of dealing with it.

Then Monday was my second class and wow.. I came home and said, "It didn't seem strenuous." I do still think my shoulders are not great for it.. BUT MAN, on Tuesday, I went to get up from my chair and OUCH, my waist and core was WORKED.. funny! Even today, when I went for my normal weight lifting session, my abductors were saying, "ooo girl.. we are being worked."

My question is if I keep at it, even though I have weak tendons in my shoulder, will it get easier as my core get stronger will my arms do less of the work..

Thanks for any information :)