Abordnet

Have been doing dumbbell bench press at home, just tried some machines at a gym. Used the Smith machine bench press with a weight that was easy to move up and down with arms extended. Was trying NOT to arch back to get the weight going but when moving the weight with bar close to chest felt like something in my back was being strained to the limit way before other muscles. Something just felt very biomechanically WRONG, like maybe the bench was too close to the bar at its lower limit of travel, even though there was room for me under the bar. Are back injuries a big risk benching on the Smith machine?  Or do I need to change my form or make a machine adjustment to take the load off my back?