On One Hand: An Unnatural MotionAccording to certified personal trainer Shelby Young, the Gazelle exercise machine does not allow the body its natural movements. "Though many feel the machine resembles an elliptical, it's hard to balance on the plates, there is no real regulation as to how far backward or forward the plates swing, which makes the body have large, awkward and unnatural movements."On the Other: Gentle on the JointsUnlike the treadmill or weight lifting, the Gazelle puts nearly no strain on the joints, more specifically ankle, hip and knee joints. The circular motion of the plates and arm bars allow fluid movement designed to get muscles warm without hurting joints.Bottom Line"There really aren't any results to be seen from using the Gazelle. If someone is recovering from a knee or foot injury, stay away from it as it's been known to reaggravate these injuries," said Young.