US Patent 7195584 Exercise apparatus for resistance training

Exercise apparatus for resistance training includes a first disk rotational about an axis, a second disk axially aligned with the first disk and resisting rotation about the axis, and a resiliently deformable coupling coupled between the first and second disks and tensionable in a spiral about the axis upon rotation of the first disk about the axis, such that rotation of the first disk about the axis tensions and stretches the coupling along a spiral and is resisted by the second disk.