Greg performs a Concentration Curl during STS March 19, 2008 by Cathe Friedrich Greg performs a Concentration Curl during STS Meso #2 – Back & Biceps. Categories: Behind The Scenes, Blog, STS, STS Mesocycle #2Tags: cathe, concentration curl, exercise dvd, exercise dvds, fitness dvd, fitness dvds, hypertrophy, mesocycle 2, STS, workout dvd, workout dvds Leave a Comment Related PostsLast Day to Pre-Order is Aug 31stAugust 26, 2011Understanding Your ATP Energy CycleJuly 6, 20115 Stretching Mistakes You’re Probably MakingMay 20, 2018