Exercise treadmill with selectable running surface

An exercise treadmill includes a frame, an endless belt, and a motor assembly for guiding the belt between front and rear ends of the frame while a user walks or runs on the belt. An impact absorbing assembly is supported beneath a region of the treadmill belt impacted by the user's feet when the user walks or runs on the belt. The assembly has physical properties that serve to define degrees of damping or springiness of the belt in the region impacted by the user. A control system including a user interface is coupled to the absorbing assembly, and the system is configured and operative to vary the physical properties of the assembly in response to an output from the user interface. The region of treadmill belt impacted by the user's feet then simulates a desired one of a number of different surfaces entered by the user on the interface.