Hey there, I work as a manager and personal trainer in gym so get people asking me this all the time, please please please do not buy one, they are a waste of money. You will not achieve anything from using one, firstly they will not raise your heart rate enough, secondly in natural movement, when do you ever move up down and sidways? Its like people that use x-trainers with the backwards movement, why, when do you ever go backwards for anextended period of time? You will gain pleanty more results from a treadmill or a stationary bike.