Hi, Lisa. I had the same debate with myself over the weekend, and decided to lower my weight when necessary in order to get in all of the reps. For me, the primary purpose of Meso #1 is to build endurance. Strength gains are secondary. Meso #1 is laying the foundation on which Meso's 2 & 3 will build.
Are you doing a 3 or 6 month rotation? I'm on week 4 of a 6-1/2 month rotation. With the longer rotation, I use the first time through to note what works & what doesn't, in terms of weight. The second time through, I apply what I've learned. Refering to previous workout cards ensures I don't go below what I lifted previously.
If I can get in all but one or two of the reps with good form, I'll leave the weight where it is. There have been a few moves where I failed at 8 of 15 reps, or could only get in 14 of 21, or had
really sloppy form. For those, I back off just enough to where I get in all or most of the reps, with the last few a struggle. Fortunately, most of my 1RM results have been accurate.
I wouldn't hesitate to slow your pace if it keeps you in proper form. I certainly do. As Cathe would say, you've got to make it work for
you.
Hope this helps.
