I've noticed in most of the leg work, we are using all dumbbells, with the exception of some of the deadlifts. The dumbbell squats feel different to me than the barbell squats, so that I can understand, by why for lunges? It is easier on my hands to hold a barbell on my shoulders than to hold 2 heavy dumbbells. I did switch to lighter dumbbells and the vest for disc 14 which seemed to help. Is there a reason to use DBs instead of the BB for lunges? It is also easier to hold a barbell for leg presses than to try to hold on to the thick ends of a heavy DB.