E-Series Back TrainerE Series Back Trainer The E Series Back Trainer from Gyronetics is ideal for effective deadweight training. You can strengthen your back muscles through hyperextension or back extension without any additional equipment. However, if you want something more intensive, you can also use a weight plate. In Depth Look at the E Series Back Trainer by Gyronetics The E Series Back Trainer stands on non slip feet and is equipped with practical supports.