1. Field of the Invention
This invention relates generally to hand-held wrist, hand and forearm exercisers, and more particularly to a bi-directional torsion spring wrist, hand and forearm exerciser having a flat torsion spring centrally disposed within a pair of handgrip members that rotate relative to each other in opposed directions about a common longitudinal axis to subject it to a twisting torque force along its longitudinal axis and thereby produce resistance to relative rotation of the handgrip members.
2. Brief Description of the Prior Art
Hand-held wrist, hand and forearm exersize devices are known in the art. There are several patents which disclose wrist, hand and forearm exersize devices of various construction.
U.S. Pat. Nos. 3,717,338 issued to Hughes, U.S. Pat. No. 4,643,417 issued to Nieman, U.S. Pat. No. 4,046,727 issued to Wilkinson, and U.S. Pat. No. 5,776,034 issued to Stamler disclose hand-held wrist, hand and forearm exersise devices that utilize one or a pair of internal springs that function to apply an adjustable amount of pressure to a friction disk sandwiched between two opposed handgrips or to a pair of friction pads disposed at each end of the handgrips. The force resisting relative rotation between the handgrip members is produced by the frictional engagement of the disk or disks.
U.S. Pat. No. 4,095,789 issued to Mueller, and U.S. Pat. No. 4,591,151 issued to Hensley, disclose hand-held wrist, hand and forearm exercise devices that utilize one or a pair of coiled torsion spring members having opposed ends secured to opposed rotatable handgrips. These types of tension spring devices produce a different resistance force depending upon whether the rotation is tending to coil the spring tighter or to uncoil the spring.
U.S. Pat. No. 5,690,598 issued to Liang discloses a hand-held wrist, hand and forearm exercise device which utilizes a single compression spring sandwiched between two opposed handgrips which can be threadedly rotated toward or away from each other. The force resisting relative rotation between the handgrip members is produced by the outwardly biased spring engagement of the spring between the opposed handgrips, and the spring produces a greater biasing force when the handgrips are threaded toward each other and a smaller biasing force when threaded away from each other.
U.S. Pat. No. 4,155,547 issued to Savio et al discloses an exercise device for strengthening the wrist, forearm and elbow that utilizes two flat spring members disposed inside a pair of opposed handgrips. The flat spring members are disposed in parallel spaced relation laterally outward from the central longitudinal axis of the handgrips and are fixed at one end to one handgrip and their free ends extend through slots in a disk that is adjustably positioned along their length to vary their effective length. As described in detail hereinafter, the the parallel spaced apart springs of the Savio et al device do not actually twist about their longitudinal axis, but instead, tend to "revolve" about the central longitudinal axis of the device. Thus, the springs are subject to a bending force along their length which is in a lateral direction transverse to their width, rather than a torque force tending to twist them along their longitudinal axis.
The present invention is distinguished over the prior art in general, and these patents in particular by a hand-held bi-directional torsion spring wrist, hand and forearm exercise device having a pair of handgrip members rotatably joined together to rotate relative to each other in opposed directions about a common longitudinal axis, each sized and shaped to be gripped by a separate hand of a user to impart rotation thereof. An elongate flat rectangular spring member is disposed in the center of the handgrip members and has opposed ends secured to each handgrip member, respectively, and has a longitudinal axis coaxial with the common axis of the handgrip members. The spring member is subjected to a twisting torque force along its longitudinal axis upon relative rotation of the handgrip members in opposed directions to produce a resistive force against relative rotation of the handgrip members in opposed directions.