Cathe, Cedie and Robert doing a Barbell Curl during the filming of STS Meso #2 – Back and Biceps. You will do Barbell Curls with various exercise techniques during the four week mesocycle #2 including Back-Off Sets. Back-off sets work because your muscle fibers are already stimulated from the previous heavy weight sets you just finished. This will trick your muscles into working harder than normal. Always make sure to reduce your weights by 40 percent from the previous set whenever you do a Back Off set in this program.