Works the upper and lower body simultaneously, while shredding the core muscles in the process. Programmable LCD console. By using air resistance, the effort you put in determines how hard the bike pushes back. Pedal harder for increased resistance, or rest your legs momentarily while you crank the arms for a military grade upper body and core workout! Its the bike that not only screams interval training, it allows you to switch the effort from upper body to lower body for an interval training stack that keeps your cardio vascular system working at capacity for the entire workout.