US Patent 10561884 Manual treadmill and methods of operating the same

A manually operated treadmill is provided that includes a frame having a front end and a rear end positioned opposite the front end; a front shaft rotatably coupled to the frame proximate the front end; a rear shaft rotatably coupled to the frame proximate the rear end; a plurality of bearings coupled to the frame; a running belt supported by the plurality of bearings, wherein the running belt includes a curved running surface; and a safety device coupled to at least one of the front shaft and the rear shaft, wherein the safety device is structured to substantially prevent rotation of at least one of the front shaft and the rear shaft in a first rotational direction while permitting rotation of the at least one of the front shaft and the rear shaft in a second rotational direction opposite the first rotational direction.