I've lifted heavier on the second time around, but I did STS back-to-back (with only one week off between rounds). I don't know if that makes a difference or not.
However, I can also tell you that when I started Meso 1 again, I couldn't believe how tough it seemed! (Push-ups! Pull-ups! Yikes!)
I had a question for you ladies who have completed STS and started again. When you started Meso 1 again did you find you lifted heavier then the first time you completed Meso One? Lori