I know this belongs in fitness, but I know I will get some responses here

Anyone have any good stretching routines to increase your shoulder turn? Any sites they would recommend?

I have a lot of tightness in my lower back and I am making it a point to increase my shoulder turn during the off season here in PA. When I make a full turn, I hit the ball REALLY well. But it takes effort to make that full 90 degree turn.

Thanks!