An exercise device for exercising a user's arms and upper body includes an endless belt of hingedly connected articulating panels guided in channels of a supporting frame. A pair of hand grip assemblies are slidably attached to the endless belt through a ratcheting mechanism that allows relative movement of the hand grip assemblies in a first direction while preventing said relative movement in a second direction. Movement of the endless belt may be retarded by a tensioning mechanism and completely ceased by a braking mechanism actuated by signals provided from first and second sensors provided on the supporting frame.