US Patent 10143884 Curved treadmill

A curved treadmill with a base having a physical exercise surface configured for rotating around a first roller and a second roller, converting the potential energy of the user on the physical exercise surface into rotational kinetic energy. A first coupling device operatively connects a first pulley to the first roller. The first coupling device allows the first pulley and the first roller to revolve if the rotational speed of the first roller is equal to or greater than the rotational speed of the first pulley, and prevents the first pulley and the first roller from rotating if the rotational speed of the first roller is less than the rotation speed of the first pulley.