US Patent 11590377 Manually powered treadmill

A manually powered treadmill includes a frame; a first rotatable element coupled to the frame; a second rotatable element coupled to the frame; a plurality of bearings coupled to the frame; a running belt at least partly supported by the plurality of bearings, where at least a portion of the running belt defines a curved running surface; and a safety device coupled to at least one of the first rotatable element and the second rotatable element. The safety device is structured to substantially prevent rotation of the at least one of the first rotatable element and the second rotatable element in a first rotational direction and permit rotation of the at least one of the first rotatable element and the second rotatable element in a second rotational direction opposite the first rotational direction.