LAT PULLDOWN EXERCISE MACHINE AND METHOD OF EXERCISE

Abstract: An apparatus (1) and method for performing a lat pull down exercise are disclosed. A user support (11) and a primary hinge (30) are mounted to a frame (10). A secondary hinge (32, 34) is mounted to the primary hinge (30). An arm (60) mounted to the secondary hinge (32, 34) has a handle (61) adapted to be grasped by the user. The two hinges permit the user to displace the handle (61) in either or both the longitudinal and lateral directions. The resistance means may include an incremental weight stack (70) operably engaged to the handle (61) by belts (39, 40) directed by self-aligning pulleys (270). The arms (60) may be connected such that both handles (61) move the same longitudinal and/or lateral distance. To use the exercise machine, a user selects a weight for exercise, adjusts a knee pad (12) and sits on a seat (11), grasps the handle (61) and pulls downward toward his shoulder, moving the handle (61) longitudinally and laterally as he so chooses, overcoming the resistance.

Description: LAT PULLDOWN EXERCISE MACHINE AND METHOD OF EXERCISE This is a continuation-in-part of an application filed March 1, 1995 assigned to the assignee of the present invention, entitled, "Rear Deltoid and Rowing Exercise Machine and Method of Exercising," Roy Simonson, inventor. Field of the Invention The invention relates to the field of exercise and physical rehabilitation equipment; in particular, to an apparatus and method for exercising the latissi us dorsi muscle. Background of the Invention It is often necessary or desirable for a person to exercise a particular muscle or group of muscles. For example, when a muscle is damaged, such as through injury or surgery, it is important to exercise the muscle to prevent atrophy and to strengthen the muscle for normal use. Further, people exercise healthy muscles to increase strength and to maintain an active and healthy lifestyle, as well as to improve their appearance. Various routines have been developed to exercise different muscle groups by forcing the muscles to contract and extend under a load, such as by moving a free weight or doing chin ups against the force of gravity or by moving a handle whose movement is resisted by an exercise machine. One such exercise to work the back muscles is known as a chin up. The exerciser grasps a fixed overhead bar or handle in a military or overhand grip and pulls himself upward against his bodyweight or against his bodyweight plus added weights. Even if done properly, this exercise may not permit a full range of exercise since the exerciser may only pull part way up and stop before the back muscles have contracted fully. When doing a chin up, the resistance provided by gravity is constant while the strength of the muscles varies over the range of motion. Consequently, the uscles are not fully loaded at each point over the range. During a chin up exercise, the hands seek to follow a curved path outward as the body is pulled upward. This path cannot be followed during a chin up because the hands are maintained at a fixed distance apart. To overcome these difficulties, lat pulldown machines have been developed that simulate the exercise movements of a chin up. In one apparatus marketed by the assignee of the instant application, a user exercises by pulling a grip bar down toward his shoulders. A seat and knee pad are mounted to a frame to position a user. A grip bar contains angled handles for gripping by a user. A cable connected to the middle of the grip bar operably connects the arms to a weight stack such that when a user pulls down on the grip bar, the weight stack is lifted and provides resistance to the exercise. The cable may be journaled over a variable radius cam to alter the distance the weight is displaced for a given distance of grip bar movement at a particular point in the range of motion. Consequently, the resistance to the movement of the handles can be varied to match the strength curve of the back muscles. While this apparatus has solved many problems associated with performing lat pulls with barbells and dumbbells, it does not permit the user to vary the distance between his hands while performing the exercise. In both the chin-up exercise and the traditional lat pull-down machine, it is difficult to isolate the latissimus dorsi muscles of the back because an exerciser tends to also use the bicep muscles of the arm. One solution is to use a wide hand placement, but this reduces the range of motion through which the latissimus dorsi are worked, because these muscles are already partially contracted in the starting position. Summary of the Invention It is therefore an object of this invention to provide an apparatus and method for performing a lat pull exercise in which the user can vary the distance between his hands while performing the exercise. It is another object of the present invention to provide an apparatus and method for performing a lat pull exercise in which a user can select the path of hand motion best suited for his particular anatomy and exercise goals. It is another object of the present invention to provide an apparatus and method for performing a lat pull exercise in which a resistance is provided against the lateral movement of a user's hands. It is another object of the invention to provide an apparatus and method for exercising that permits the use of a few heavy weight plates along with a fine tuning mechanism to provide resistance to the exercise. In accord with one aspect of the invention, an apparatus is provided for exercising the latissimus dorsi and back muscles of a user. A primary hinge is mounted to a frame. A secondary hinge is mounted to the primary hinge. An arm is mounted to the secondary hinge. A handle is mounted to the arm distal to the secondary hinge. The handle is adapted to be grasped and displaced by the user. Due to the orientation of the two hinges, the handle may be displaced in both a longitudinal direction and a lateral direction, as selected by the user. A means for resisting the displacement of the handle, preferably in both the lateral and longitudinal directions, is provided. The resistance means may include a weight stack operably engaged to the primary hinge. A second handle, arm and secondary hinge may be provided for the other hand so that the user may exercise both halves of his body. The arms may be connected such that both handles move the same longitudinal and/or lateral distance. In accord with another aspect of the invention, a method is provided for exercising with an apparatus having an arm pivotally mounted to a frame. A user selects a resistance for exercise and sits on a user support. The user grasps a handle mounted to the arm and pulls the handle down toward his shoulder, moving the handle longitudinally and laterally as he so chooses. The user overcomes resistance to the lateral movement of the handle and resistance to the longitudinal movement of the handle. The user may grasp a second handle with his other hand to exercise both halves of his body. The handles may be connected such that both handles move the same longitudinal and/or lateral distance. Brief Description of the Drawings FIG. 1 is a perspective view of an embodiment of a lat pull exercise machine of the present invention, in a rest position; FIG. IA is a schematic view of the hinge mechanism of the exercise machine of FIG. 1, in a plane IA-IA shown in FIG. 3B; FIG. IB is a schematic view of the hinge mechanism of an alternative embodiment of the exercise machine of the invention, in a plane corresponding to plane IA-IA shown in FIG. 3B; FIG. IC is a schematic view of the hinge mechanism of an alternative embodiment of the exercise machine of the invention, in a plane corresponding to plane IA-IA shown in FIG. 3B; FIG. 2 is a perspective view of the exercise machine of FIG. 1, with the arms extended; FIG. 2A is a partial cut-away side view of the transmission of the exercise machine of FIG. 1, showing the longitudinal stop; FIG. 3A is a side elevation view of the exercise machine of FIG. 1, in the rest position; FIG. 3B is a side elevation view of the exercise machine of FIG. 1 with the arms extended; FIG. 4 is a partial cut-away view of the transmission of the exercise machine of FIG. 1 with the arms extended, in section IV-IV as shown in FIG. 6; FIG. 5 is top plan view of the exercise machine of FIG. 1 in the rest position; FIG. 6 is a front elevational view of the exercise machine of FIG. 1 in the rest position; FIG. 7 is a perspective view of an incremental weight stack for use with an exercise machine, including the exercise machine of FIG. 1; FIG. 8 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having hinge plates; FIG. 9 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a slider link; FIG. 10 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a cam link; FIG. 11 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having variable length links with resistance; FIG. 12 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a spring pulley linkage; FIG. 13A is a front elevational view of the weight stacks of an embodiment of the invention having an auxiliary weight stack; FIG. 13B is a side elevational view of the weight stacks of FIG. 13A; FIG. 14 is a partial schematic view of the hinge mechanism, arms and handles of an embodiment of the invention having incrementally adjustable handle resistance; FIG. 14A is a partial schematic view of the hinge mechanism, arms and handles of an embodiment of the invention having discrete degrees of resistance; FIG. 15 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having incrementally adjustable handle resistance; FIG. 15A is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having discrete levels of resistance; FIG. 16 is a schematic view of the hinge mechanism of an embodiment of the invention having torsion springs to resist lateral movement; FIG. 17 is a schematic view of the hinge mechanism, arms and handles of an embodiment of the invention having a pivoting handgrip; FIG. 18 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having large gears; FIG. 19 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a rack and pinion link; FIG. 20 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a belt and pulley link; FIG. 21 is a partial schematic view of the hinge mechanism, arms and handles of another embodiment of the invention having outward sliding hand grips; FIG. 21A is a partial schematic end view of the arms and handles of FIG. 21; FIG. 21B is a partial schematic end view of the arms and handles of an embodiment of the invention having angled handle rods; FIG. 21C is a partial schematic end view of the arms and handles of an embodiment of the invention having angled handle rods; FIG. 21D is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 21E is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 21F is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 22 is a partial schematic view of the hinge mechanism, arms and handles of an embodiment of the invention having inward sliding hand grips; FIG. 22A is a partial schematic end view of the arms and handles of FIG. 22; FIG. 22B is a partial schematic end view of the arms and handles of an embodiment of the invention having angled handle rods; FIG. 22C is a partial schematic end view of the arms and handles of an embodiment of the invention having angled handle rods; FIG. 22D is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 22E is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 22F is a partial schematic end view of the arms and handles of an embodiment of the invention having a handle rod resistance mechanism; FIG. 23 is a partial schematic view of the hinge mechanism, arms and handles of an embodiment of the invention having sliding handles with cable resistance; FIG. 23A is a partial detail perspective view of an arm and handle of the machine of FIG. 23; FIG. 24 is a partial schematic view of the hinge mechanism and arms of an embodiment of the invention having a pivoting bar linkage; FIG. 25 is a schematic view of the hinge mechanism of an embodiment of the invention having an adjustable arm angle; FIG. 26 is a cross-sectional view of a self-aligning pulley of the exercise machine of the invention; FIG. 27 is a cross sectional view of the pulley of FIG. 26, taken through section XXVII-XXVII; and FIG. 28 is another cross-sectional view of the pulley in the same section as FIG. 26, showing a misaligned frame. Detailed Description FIG. 1 is a perspective view of an embodiment of the lat pulldown machine 1 of this invention in the rest position. Unless otherwise noted, the structural components of the machine are a mild steel. A seat 11 is mounted to a frame 10. In the preferred embodiment, the frame is constructed of 1^ x 3 inch, 11 gauge rectangular steel tubing. A knee pad 12 is mounted on a support beam 14 in front of the seat by a knee pad rod 13. Preferably, the support beam 14 is located just forward of the seat 11. The knee pad 12 may be of an adjustable length, such as by means of a telescoping rod 13 held in position by a pin/detent connection 27, as is shown in FIG. 1. Other locking mechanisms known in the art could be employed as well. The adjustable-length knee pad rod allows users of varying stature to be comfortably positioned at the machine, thereby permitting a full range of motion. The seat and knee pad comprise a user support adapted to maintain the user in a comfortable position for exercising. As discussed more fully below, the user exercises by sitting in the seat with his legs beneath the knee pad, and pulling handles 61 from a rest position down towards the area outside his shoulders. Alternatively, the user can sit in the seat facing away from the knee pad, with his body weight retaining him in the seat. The handles are operably engaged, in a manner described below, to weight plates 23 (see FIG. 3) such that the weight plates must be lifted to displace the handles. Arms 60 are mounted to the frame by a hinge mechanism 50, including a primary hinge 30 and secondary hinges 32 and 34 (see FIG. 5) . The primary hinge 30 is mounted to the frame and is located in front of, and above, the seat 11. The primary hinge is disposed perpendicular to a vertical plane X-X (see top view of FIG. 5) extending through the center of the machine 1. As currently preferred, the primary hinge includes a primary bearing tube 31 (see FIG. 5) mounted on sealed bearings, such as model #87503 metric bearings manufactured by Fafnir, or an equivalent. The primary bearing tube 31 is rotatable about a primary axis 46 (see FIG. 5) which axis is disposed perpendicular to the vertical plane X-X extending through the center of the machine. While in the currently preferred embodiment the primary bearing tube is disposed at a distance in front of and above the front of the seat 11 (see FIG. 3A) , it could be located in another position and still practice the invention. In particular, the primary hinge could be positioned further away from or closer to the front of the seat to vary the resistance to the back muscles. Brackets 47 (see FIG. 5) are rigidly mounted to the primary bearing tube 31. The secondary hinges 32 and 34 are rotatably mounted to the brackets. The secondary hinges include the secondary bearing tubes 33 and 35 mounted to sealed bearings, such as model #87503 metric bearings manufactured by Fafnir, or an equivalent. The secondary bearing tubes are rotatable about secondary axes 48 and 49 (see FIGS. IA and 5) . The secondary hinge axes 48 and 49 are skew to the primary hinge axis 46; in other words, the secondary hinge axes are not parallel to the primary hinge axis. In the rest position (i.e., when no weight is being lifted) , the arms 60 are oriented upwards at about 60° from the horizontal (see FIG. 3A) , and the arms are approximately parallel to the vertical plane X-X extending through the center of the machine when viewed from above (see FIG. 5) , and from the front (see FIG. 6) . As discussed more fully below, the angular relationship of the primary hinge 30 to the secondary hinges 32 and 34 effects the resistance to handle movement. As currently preferred, that angular relationship is fixed. FIGS. IA, IB and IC are schematic views of the primary hinge and secondary hinges in plane IA-IA (see FIG. 3B) , wherein the secondary hinges are disposed at an angle A with respect to the primary hinge. The preferred angle A is 70°, as explained below. The hinge mechanism 50 (see FIG. 1) operates to divide the resistance provided by the weight stack 23 into a longitudinal component and a lateral component. These separated components of resistance increase the effectiveness of the exercise and provide feedback to the user that encourages symmetrical exercise paths of the right and left hands. The secondary hinge angle A (see FIGS. IA, IB and IC) establishes the relationship of the lateral component to the longitudinal component. When the secondary hinge angle is 90°, as shown in FIG. IB, there is no lateral component. Rather, all the resistance is attributed to the longitudinal component. Consequently, in the configuration of FIG. IB the user can move the handles 61 laterally without lifting the weight stack 23 at all. Furthermore, the user can move one hand in the lateral direction without moving the other, and perceive no difference between the resistance applied to the left and right arms. Pulling the handles longitudinally, however, lifts the weight stack. Such a system may be desirable to allow the user to select independent, comfortable hand positions while performing a traditional (i.e., longitudinal resistance only) lat pulldown exercise. As the secondary hinge angle A is increased or decreased from 90° (as shown in FIGS. IA and IC) , a component of the weight stack resistance becomes attributable to the lateral component. In other words, lateral handle movement causes the weight stack to lift. As the secondary hinge angle A diverges more from 90°, the weight stack is lifted further for the same lateral handle movement. If the angle A is reduced below 90°, as shown in FIG. IA, the arms resist an outward movement of the handles; if the angle A is increased above 90°, the arms resist inward movement. With a secondary hinge angle A other than 90°, asymmetry between the position of the user's right and left hands during an exercise stroke will cause the user to feel asymmetric feedback from the machine. The typical user will naturally seek to distribute the load equivalently between the left and right sides. Consequently, a secondary hinge angle of more or less than 90° encourages the user to move his hands symmetrically. The more the secondary hinge angle A diverges from 90°, the more the user is encouraged to perform the exercise symmetrically. By providing lateral resistance, and by encouraging a symmetric stroke, the hinge mechanism 50 can make the exercise machine feel "stable" as perceived by a user. It has been found that in using a machine with a hinge angle A of 90°, the user perceives that the exercise stroke is unstable because lateral hand movement is unresisted. While this sensation is likely to be more pronounced in exercises requiring pushing, such as a chest press, it is significant in pulling exercise machines such as the present lat pulldown exercise machine. A machine with a hinge angle A other than 90° feels more stable to a user because it resists lateral movement and encourages a symmetrical stroke. The perception of stability increases as angle A diverges from 90°. The preferred secondary hinge angle of 70° (as shown in FIG. IA) has been found by experimentation to produce the most comfortable or natural pulling stroke. In particular, the relationship of lateral resistance to longitudinal resistance at this angle seems to provide an effective exercise for the muscles of the back. Further, sufficient lateral resistance is provided so that a user perceives the lat pulldown exercise as stable. Other secondary hinge angles could be selected for a machine based on the comfort, stability, muscular development or exercise goals of a particular group of users to emphasize the longitudinal or lateral resistance to the exercise. Referring again to FIG. 1, a bridge support 24 is mounted rigidly to a front beam 17 at the top of the frame 10. A support bracket 25 is rigidly mounted to the weight stack frame 3 and front beam 17. A transmission 41, including a rod 43, an eccentric cam 42 and a pulley 44 (see also FIGS. 2 and 4) , is rotatably mounted to the bridge support 24 and support bracket 25. A weight stack pulley 45 is mounted to the frame 3 and is aligned with the cam 42. Rails 18 (see also FIGS. 3 and 4) are also mounted to the weight stack frame 3. Weight plates 23 (see FIGS. 3 and 4) are slidingly mounted to the rails 18 to provide a resistance to the exercise. Springs 19 (see FIG. 3) may by positioned on the rails to absorb the shock of the weight plates as they are lowered onto a weight support bar 5 of the weight stack frame 3. Of course, other mechanisms for providing resistance, such as a friction, springs, elastic bands, pneumatic or electromagnetic resistance, or an air resistance fan could be employed (either alone or in combination) and still practice the invention. Additionally, free weights could be operably engaged to the arms 60 to resist the movement of handles 61. FIG. 2 is a perspective view of the apparatus of FIG. 1 showing the arms 60 pulled down in the longitudinal direction and spread apart in the lateral direction (i.e., not in the rest position) . An arm restriction strap 2 is connected between the arms 60 to prevent a user from overextending the arms in the lateral direction. Other alternative means, such as a spring or rope, could be similarly attached to perform the same function. Also, mechanical stops attached to the primary bearing tube or other components could be used to limit outward arm travel and still practice the invention. Handles 61 are pivotally mounted at the end of the arms 60 distal to the secondary bearing tubes 33 and 35. The pivotal mounting releases pressure from the user's wrist and provides a comfortable grip. Alternatively, other variable position handles, or a rope loop or looped strap, could be attached to the arm to permit the user a variable grip during the exercise stroke. FIG. 2A is a partial side view of the apparatus of FIG. 1, showing components related to the hinge mechanism. A lever 36 is mounted to the primary bearing tube 31. An arched stop bracket 54 is fixedly mounted to the front beam 17, and contains a rubber or elastomer stop 37 (see FIG. 3B) . The arched stop bracket 54 and stop 37 serves to limit the upward travel of the arms 60 by contacting the lever 36 when the arms 60 are in the rest position. The exercise machine 1 also preferably contains a bumper bracket 28 that is mounted to the lever 36 distal to the primary bearing tube (see FIGS. 5 and 6) . The bumper bracket 28 has rubber or elastomer bumpers 29 positioned to contact the arms 60. The bumper bracket 28 and bumpers 29 serve to limit the inward travel of the arms 60 both when the machine is in the rest position and during an exercise stroke. As the arms are brought together, such as in the rest position, the bumpers 29 engage the arms 60, preventing the arms from striking each other. In the rest position, the bumper bracket 28 operates to limit the lateral range of motion of the handles 61 and to define a lateral starting position (see FIGS. 5 and 6 showing the arms 60 in contact with the bumpers 29) . The bumper bracket 28 also prevents the arms 60, and thus the handles 61, from swinging too close together and possibly hitting each other. Referring again to FIG. 2A, a counterweight 20 is connected to the primary bearing tube 31 via an arched counterweight bracket 21. When the arms 60 are pulled down during an exercise stroke, the counterweight 20 moves up in a longitudinal direction in tandem with the weight stack 23 (see FIG. 4) . The counterweight 20 slightly preloads the exercise machine 1 so that the arms 60 remain in their starting position when the exercise machine is at rest, as shown in FIG. l. FIG. 3A is a side elevation view of the apparatus of FIG. 1 in the rest position, and FIG. 3B is a side elevation view with the arms 60 extended. A front leg 6 is disposed at about 60 degrees from horizontal, and a frame support leg 7 is disposed at about 83 degrees from horizontal. The pitch of the legs 6 and 7 could be altered to cause the arms 60 to be in a different position at rest, so that a user must sit up straighter or lean over more to grasp the handles 61, thereby changing the effect of the exercise. Such an effect can be achieved in part by altering the height of the knee pad 12 by sliding the rod 13 in the pin/detent mechanism 27. Thus, the legs 6 and 7 could be pitched at other angles and still practice the invention. FIG. 4 is a partial cut-away view of the transmission 41 taken from the side along line IV-IV of FIG. 6, when the arms are extended as shown in FIG. 3B. A rubber or elastomer stop 55 is mounted to the lever 36, along with a bumper bracket 28 (see FIG. 5) , discussed above. When the handles are moved longitudinally to the rest position, the stop 55 contacts the arched bracket 54 connected to the front beam 17, preventing the lever 36 from rotating any further, thereby limiting the longitudinal range of motion of the arms 60. A first belt 39 is attached at one end to the lever 36. The first belt is preferably KEVLAR® fabric. Other high- strength tethers could be used, however, and still practice the invention, which may include other high strength fabrics, cables, chains and ropes. A curved tip 56 may be mounted at the end of the lever 36 so that the belt 39 does not bend over a corner or sharp edge of the lever. Preferably, the belt is held on the lever by a pressure plate 57 that clamps the belt to the lever. Such a plate typically would be attached to the lever by bolts (not shown) , as is known in the art. The other end of the first belt 39 is attached to the pulley 44 using another pressure plate 57 and appropriate attachment means, such as bolts. In the rest position, the belt 39 is wound about the circumference of the pulley 44. A second belt 40 is attached at one end to the cam 42, again by a pressure plate 57. The second belt is also preferably KEVLAR® fabric or another high strength tether. The belt 40 then extends over a weight stack pulley 45 and a weight stack pulley pair 58 and is finally attached to the weight stack 23 (see also FIGS. 3 and 7) . As the user pulls down and out on the handles 61, the lever 36 rotates, causing the first belt 39 to unwind and rotate the pulley 44. As the pulley rotates, the rod 43 (see FIG. 5) and the cam 42 rotate as well. The pulley 44 and cam 42 are fixedly mounted to the rod 43 such that the pulley and cam rotate together. The rotation of the cam 42 pulls the second belt 40 over the weight stack pulley 45 and pulley pair 58, and thus lifts the weight stack as shown in FIG. 4. The eccentric shape of the cam 42 changes the effective resistance of the weight stack over the range of motion. The tension of the belt 39 pulling the lever 36 is directly proportional to the radius of the cam 42 at the point of tangency of belt 40. The cam profile is selected in a manner well-known in the art to match the force profile of an exercise stroke with the strength curve of the back muscles of a typical user. In addition, other configurations of weight stack pulleys could be used to practice the invention. FIG. 5 is a top view of the apparatus of FIG. 1 in the rest position. The handles 61 are tilted slightly outward from center line X-X in order to present a more comfortable grip to the user. FIG. 6 is a front view of the apparatus of FIG. 1 in the rest position. FIG. 7 is a perspective view of an incremental weight stack 70 for use with a selectorized exercise machine, such as the apparatus of FIG. 1. A flange or storage finger 73 (shown partly in phantom) is rigidly mounted to a flange 72, which in turn is attached to the frame 3 , such as by bolting. Slotted holes (not shown) may be provided in the flange 72 for height adjustment. The flange finger 73 extends proximate to the top weight plate 75. A stack or movement finger 74 is mounted to the top of the top weight plate 75. Incremental weights 76, having tracks such as axial bore 79 (shown in phantom) for receiving the fingers 73, 74, are slidingly mounted on the flange finger 73. When the weight stack is lowered (i.e., in the rest position) , the tips of the frame finger 73 and the stack finger 74 are adjacent, almost touching. The incremental weights can be moved from the flange finger to the stack finger as desired. The tips of the fingers 73 and 74 may be rounded to provide for a smooth transfer of the incremental weights 76. Rubber or elastomer bumpers 77 can be mounted to the fingers to restrict the movement of the incremental weights on the fingers. Preferably, both fingers are slanted up toward the tips at approximately 5° from horizontal. This angle retains the incremental weights on the respective fingers while permitting the weights to easily slide from one finger to the other. When the user lifts the weight stack, he also must lift any incremental weights on the stack finger. The incremental weight stack 70 permits use of heavy plates on the main weight stack 23. For example, each plate on the main stack may weigh 20 pounds. Each incremental weight may be 5 pounds. If three incremental weights are mounted to the flange finger, the user can select the appropriate resistance in five-pound increments by sliding the appropriate number of weights to the stack finger. This allows the user to finely adjust the resistance at any point throughout the weight stack. Furtner, the manufacturer will save costs in manufacturing and assembling an exercise machine with the incremental weight stack due to the labor saved using a smaller number of plates. To operate the apparatus of the present invention, a weight is selected on the main weight stack by placing a pin (not shown) in one of the holes 78, as is known in the art. A weight 76 from the incremental weight stack is selected, if desired, and moved onto the stack finger 74 (see FIG. 7) . The user adjusts the knee pad 12 to a position on the support beam 14 that is at a comfortable height. A user with longer legs will adjust the knee pad to a higher position to be at a comfortable distance from the handles 61 to just reach the handles when his arms are fully extended. With his feet resting on the floor, the user grasps a set of handles and pulls the handles out and down toward the seat. The movement of the handles causes the arms 60 to move which, in turn, cause the secondary bearing tubes 33 and 35 and the brackets 47 to move. The movement of the brackets cause the primary bearing tube 31 to rotate which, in turn, causes the lever 36 to rotate (see FIG. 4) . As the lever 36 rotates, the counterweight 20 rises and the first belt 39 is pulled, causing the pulley 44 to rotate. As the pulley 44 rotates, the rod 43 and cam 42 rotate, pulling on the second belt 40 which is journaled about the weight stack pulley 45 and weight stack pulley pair 58, and lifting the selected weight. The user then returns the handles to the initial position, thereby lowering the weight. When the user pulls the handles down (concentric action) , he overcomes the resistance provided by the weight. When the user returns the handles (eccentric action) , he succumbs to the resistance provided by the weight. A user exercises the latissimus dorsi muscles of the back by grasping the handles 61, and pulling downward in the longitudinal direction and outward in the lateral direction. When the handles are pulled outward, the secondary bearing tubes 33 and 35 are caused to rotate with respect to the brackets 47. In this exercise, the user keeps the arms raised and pulls the hands outward laterally at the beginning of the concentric portion (i.e., where the muscles contract against the load) of the exercise, and then down to the shoulders in an arcuate path. The user then returns the handles in an arcuate path towards each other and away from his shoulders during the eccentric portion (i.e., where the muscles extend under the load) of the exercise. In a traditional machine, this would not be possible. In the apparatus of the present invention, however, the hinge mechanism 50 allows such movement. The handle 61, and thus the arm 60, can be moved in a plane perpendicular to the corresponding secondary axis 48 or 49 (see FIG. 5) without encountering resistance from the weight stack because such movement requires only that the secondary bearing tubes 33 and 35 rotate. The primary bearing tube 31, and thus the lever 36, need not rotate. However, as the handles are moved out from the center of the machine in any other plane, the secondary hinges 32 and 34 must revolve about the primary axis 46. This causes the primary bearing tube 31 to rotate. In effect, the primary bearing tube must rotate to compensate for the lateral movement of the handle. This causes the lever 36 to rotate and displace the weight stack, as described above. Thus the weight stack resists movement of the handles both vertically and outward. The hinge mechanism 50 permits movement of the handles 61 vertically (i.e., longitudinally) and outward (i.e., laterally) in a relationship selected by the user. Consequently, the user can grasp the handles and pull down and out in the natural arcuate path. Alternatively, the user can select another path to give the muscles a different workout. For example, the user may wish to pull directly downward, emulating the purely longitudinal motion of a traditional lat pulldown machine. The user may instead choose to pull his hands directly down, and then, at the end of the stroke, pull his hands out latitudinally while near his shoulder. The user may choose to pull his hands out latitudinally at the beginning of the stroke, and then pull down longitudinally. The user can even chose a "figure eight" path, moving his hands out, in, out and in again during the exercise stroke. Any combination of such movements can be accomplished with the machine of the present invention. It is believed that by following a natural C-shaped path with his hands, the user can exercise his latissimus dorsi muscles through essentially their full range of motion, by starting with the arms extended vertically, and finishing with the elbows down and back. This is not possible with either a chinup bar or a traditional lat pulldown machine. Furthermore, by spreading his arms to a wide handgrip early in the stroke, the user can emphasize the latissimus dorsi muscles, and reduce the effect of the biceps. The secondary hinge angle A is selected to present a combination of lateral resistance and longitudinal resistance that feels comfortable or natural to a typical user moving his hands in an arcuate path. The resistance overcome by the particular muscle group is determined, in part, by the selected path of the hands and the secondary hinge angle A. The double hinge mechanism 50 thus provides a fundamental advance over existing exercise machines by establishing a predetermined ratio of lateral to longitudinal resistance while encouraging left-to-right hand symmetry in the exercise stroke and allowing the user to select the path of the stroke and the muscle group emphasized. Since the secondary bearing tubes 33, 35 are both mounted to the primary bearing tube 31 at the same orientation, the hinge mechanism 50 encourages symmetrical movement of the handles 61. Such symmetrical movement, however, is not required. The user can move his hands through different paths during the same exercise stroke. While this configuration is currently the preferred embodiment of the invention, it may be advantageous in some situations to further couple the motion of the arms, as is done in several of the following additional embodiments. FIG. 8 is a schematic plan view of the hinge mechanism 80 and arms 81 of another embodiment of the invention. The secondary hinges 82 are shown disposed perpendicular to the primary hinge 83, although they may be oriented at other angles. Flanges 84 are pivotally mounted to each arm, such as by piano hinges 85. The flanges 84 are rotatably mounted to each other, such as by a knuckle joint 86. The arms and flanges constrain the knuckle joint to move within the plane of symmetry S-S between the arms. Since the linkage formed by the primary bearing tube 87, the arms and the flanges is symmetrical, the arms must translate the same amount laterally. Consequently, the arms (and thus the handles) are forced to move symmetrically. Alternatively, the hinges, flanges and knuckle joint may be constructed of a resilient material such as plastic, elastomer or rubber. For example, the knuckle joint may be a deformable rubber connector, or the hinges, flanges and knuckle may be a one-piece polymer part with reduced cross sections in the areas requiring flexure. Such embodiments encourage symmetric exercise strokes while permitting some left-to-right asymmetry. FIG. 9 is a schematic plan view of the hinge mechanism 90 and arms 91 of another embodiment of the invention. Again, the arms are operably engaged such that they must move symmetrically in the lateral direction. The secondary 92 hinges are again shown disposed perpendicular to the primary hinge 93, although other angles of attachment are possible. A slider rod 94 is fixedly mounted to the primary hinge 93. A slider ring 95 is mounted to the slider rod 94 and adapted to be displaceable along its length. Links 96 are pivotally mounted to the slider ring and to each arm 91. Consequently, as the arms are displaced laterally, the slider ring is caused to move along the slider rod. Due to their mutual connection to the slider ring, both arms are caused to move symmetrically about the secondary hinges. FIG. 10 is a schematic plan view of the hinge mechanism 100 and arms 101 of another embodiment of the present invention. The secondary hinges 102 are shown mounted perpendicularly to the primary hinge 103, although other attachment angles are possible. A barrel cam 104 having mirrored, grooved profiles 105 is mounted to the primary bearing tube 108 equidistant from both secondary hinges 102. The barrel cam is mounted for rotational movement. A rigid link 106 with a cam follower 107 is pivotally mounted to each arm. As an arm is moved outward, the barrel cam is forced to rotate about its axis, causing the other rigid link to force the other arm to move the same lateral distance. FIG. 11 is a schematic plan view of the hinge mechanism 110 and arms 111 of another embodiment of the invention. The secondary hinges 112 are shown mounted perpendicularly to the primary hinge 113, although other attachment angles are possible. An anchor 114 is rigidly mounted to the primary hinge between the secondary hinges 112. A variable length link 115 engages each arm 111 to the anchor. A resistance mechanism 116, such as a pneumatic, hydraulic, spring, elastic band, electrical or magnetic resistance, is operably engaged to the link 115 to resist any change is length. Consequently, the mechanism provides resistance to lateral movement of the arms 111 during the exercise stroke. Also, the resistance mechanism discourages quick, lateral movement of the arms. The mechanism 110 thus provides resistance to lateral movement both inward and outward, while encouraging a smooth stroke. FIG. 12 is a schematic plan view of the hinge mechanism 120 and arms 121 of another embodiment of the invention. The secondary hinges 122 are shown mounted perpendicular to the primary hinge 123. However, other orientations are possible. Branches 124 are fixedly mounted to the primary bearing tube 129. A pulley 125 is mounted on each branch and disposed in the same plane as its respective arm. Cables or belts 126 are attached to the arms 121, extend over the pulleys 125 and attach to a plate 127. The plate is attached to the primary bearing tube 129 by a resistance 128, which can be a spring, or can be another resistance device such as hydraulic, pneumatic, frictional or electromagnetic. As the arms are displaced laterally, the plate 127 is pulled from the primary hinge. This lateral movement is resisted by the resistance 128. The plate 127 could be journaled in a track, or mounted on rails, such that the orientation of the plate with respect to the primary hinge is fixed. Consequently, as one arm is displaced laterally, the other arm is free to rotate the same lateral distance. FIG. 13A is a schematic front elevation view of the weight stacks 130 of an embodiment of the invention including an auxiliary weight stack 131. FIG. 13B is a side view of the weight stack with the auxiliary weight stack. In this embodiment, the spring 128 shown in FIG. 12 is replaced by a cable or belt 132. A pulley 133 is mounted on or near the primary hinge to direct the cable or belt for attachment to the auxiliary weight stack 131. Consequently, to move the arms laterally, the user must pull on the cable or belt, thereby lifting the auxiliary weight stack. The user thus has the freedom to select the resistance to the lateral movement of the hands. In another version of this embodiment, separate auxiliary weight stacks are provided to resist the lateral movement of each arm. FIG. 14 is a schematic front view of a hinge mechanism 140 of another embodiment of the present invention. The secondary hinges 142 are shown disposed perpendicular to the primary hinge 143, although other orientations could be used. Rigid members 144 are mounted to the primary hinge 143 and disposed in the plane of rotation of the arms 141 about the secondary hinges 142. A resistance means 145, such as a spring, is operably engaged to each arm 141 and its respective rigid member 144. The resistance means resists the lateral movement of the arm outward. The resistance means may be disposed at different points along the arm and the rigid member to vary the lateral resistance. The shape of rigid member 144 or the angle of attachment of the rigid member to the primary hinge 143 may be chosen to further define the resistance profile as means 145 is moved along the arm. The angle of attachment may further be adjustable. The resistance means 145 may be attached to both the arm 141 and the member 144 to operate in both tension and compression, providing bidirectional resistance to lateral arm movement. FIG. 14A shows another embodiment or the hinge mechanism 140 of FIG. 14, with the resistance means 145 comprising a set of springs 146, 147, 148 mounted to a ring 149. The ring is rotatably mounted to the rigid member 144 such that each spring can be indexed into contact with the arm 141. Each spring 146-148 has a different spring constant and thus provides a different resistance to the lateral movement of the arms. FIG. 15 shows the hinge mechanism 150 and arms 151 of another embodiment of the present invention. The secondary hinges 152 are shown disposed perpendicular to the primary hinge 153. A central member 154 is mounted to the primary hinge 153 between the secondary hinges and disposed in the same plane as the arms 151. The angles or shape of the central member may be adjustable. A resistance means 155, such as a spring, is operably engaged to each arm 151 and the central member 154. The resistance means 155 resists the lateral movement of the arm toward the central member. This results in resistance to the lateral displacement of the handles (not shown) toward the center. The resistance means 155 may be moved by the user to different points along the arm and the central member to vary the resistance. Alternatively, a single spring could be mounted to each arm, thereby connecting the arms. FIG. 15A shows the hinge mechanism 150 of FIG. 15 with an alternative resistance means. The resistance means in this embodiment comprises spring pairs 157 and 158 mounted to a ring 159. The ring is rotatable about the rigid member 156 such that a different spring pair may be indexed into contact with the arms. Each spring pair 157 and 158 has a different spring constant and thus provides a different resistance to the lateral movement of the arms 151. The ring 159 may be made displaceable along the length of the rigid member 156 to additionally vary the resistance to lateral movement of the arms 151. FIG. 16 is a front schematic view of the hinge mechanism 160 of another embodiment of the invention. The secondary hinges 162 are shown disposed perpendicular to the primary hinge 163, although other secondary hinge angles are possible. A torsion spring 164 is mounted to the primary hinge 163 near each secondary hinge 162 and operably engaged to the respective arm 161. The torsion spring resists the rotation of the arm about the secondary hinge. The torsion spring may be disposed to resist either inward movement of the arm or outward movement of the arm. FIG. 17 is a schematic bottom view of the hinge mechanism 170, arms 171 and handles 172 of another embodiment of the invention. The arms 171 are directly mounted to the primary hinge 173. The handles 172 are pivotally mounted to the arms and adapted to rotate about a handle peg 175 in a plane perpendicular to the arms. A spring 174, such as a torsion spring, or other resistance mechanism, may resist the rotation of the handle 172 about the handle peg 175. FIG. 18 is a schematic plan view of the hinge mechanism 180 and arms 181 of another embodiment of the invention. The secondary hinges 182 are shown mounted perpendicular to the primary hinge 183, although other attachment angles are possible and still practice the invention. A large spur gear 184 is fixedly mounted to each arm 181 and adapted to rotate about its respective secondary hinge 182. The teeth of the large spur gears 184 engage each other such that the arms are caused to rotate about their respective secondary hinges together. Consequently, the handles and the user's hands are displaced symmetrically with respect to a central vertical plane. In the case where the secondary hinges are not perpendicular to the primary hinge, the large spur gears could be replaced by bevel gears. FIG. 19 is a schematic plan view of the hinge mechanism 190 and arms 191 of another embodiment of the invention. The secondary hinges 192 are shown mounted perpendicularly to the primary hinge 193, although other attachment angles are possible. Gears or pinions 194 are attached to each arm 191 and adapted to rotate about the secondary hinges 192 with the respective arm. A rack 195 is operably engaged to the pinions 194, forming a "rack and pinion" system which causes the arms to rotate about their respective secondary hinges 192 symmetrically. Consequently, the arms 191 are forced to move the same lateral distance. FIG. 20 is a schematic plan view of the hinge mechanism 200 and arms 201 of another embodiment of the invention. The secondary hinges 202 are shown disposed perpendicular to the primary hinge 203. The secondary hinges could be disposed at other orientations. A sprocket or pulley 204 is mounted on each secondary hinge 202 and adapted to rotate with the respective arms 201. A chain or belt 205 is looped about the pulleys in a "figure eight" configuration, causing the arms to rotate symmetrically in the lateral direction. Alternately, two chain or belt segments could be used, each following an S-shape, to form the figure eight. The belt may be non-deformable and require completely symmetrical movement of the arms, or may be made of an elastic material which would permit the arms to rotate asymmetrically but would encourage symmetrical movement. FIG. 21 is a partial schematic plan view of the hinge mechanism 210, arms 211 and handles 212 of another embodiment of the invention. The arms are mounted directly to the primary hinge 213. The arms may be angled outward. Handle rods 214 are mounted at the ends of the arms distal to the primary hinge 213. A handle is slidingly mounted to each handle rod. The user is thus free to select the width of his hands during the exercise stroke, even changing the position of the hands. FIGS. 21A-21F show schematic end views of the hinge mechanism 210, in the plane 215 of the arms 211. As shown in FIG. 21A, the handle rod may be oriented within the plane of the arms, providing a neutral- resistance sliding motion of the handles 212. In this plane, the handle rod may be slanted up away from the arm, slanted down away from the arm or disposed horizontally. Further, the handles may be tilted backward from plane 215, as shown in FIG. 2IB, or tilted forward of plane 215, as shown in FIG. 21C, thereby resisting handle movement inward or outward respectively, as this movement raises the arms and acts against the resistance. As shown in FIGS. 21D, 21E and 21F, a resistance mechanism, such as springs 216-219, can be mounted to the handle rod 214 to oppose the movement of the handle 212 in the lateral direction. In the embodiment shown in FIG. 2ID, the resistance mechanism 216 opposes movement of the handles 212 outward. As shown in FIG. 21E, the resistance mechanism 217, 218 opposes movement of the handles 212 both inward and outward. As shown in FIG. 21F, the resistance mechanism 219 opposes movement of the handles 212 inward. The resistance mechanisms 216-219 may be further supplemented by inclining the handle rods 214 as shown in FIGS. 21B and 21C. FIG. 22 is a front elevation view of the hinge mechanism 220, arms 221 and handles 222 of another embodiment of the invention. The arms 221 are mounted directly to the primary hinge 223. Preferably, the arms are angled outward. Handle rods 224 are mounted at the ends of the arms distal to the primary hinge and disposed on the interior side of the arms. A handle is slidingly mounted to each handle rod. The user is thus free to select the width of his hand position during the exercise stroke, and to vary the position of the hands throughout the exercise pattern. As shown in FIGS. 22A, 22B and 22C, the handle rod may be oriented within the plane 225 of the arms 221, or angled rearward from or forward of plane 225, to provide neutral, inward or outward resistance, respectively, to handle movement. As shown in FIGS. 22D, 22E and 22F, a resistance mechanism, such as springs 226-229, can be mounted to the handle rod to oppose the movement of the handle in the lateral direction. As shown in FIG. 22D, the resistance mechanism 226 opposes movement of the handles 222 outward. As shown in FIG. 22E, the resistance mechanism 227, 228 opposes movement of the handles 222 both inward and outward. As shown in FIG. 22F, the resistance mechanism 229 opposes movement of the handles 222 inward. The resistance mechanisms 226-229 may be further supplemented by inclining the handle rods 224 as shown in FIGS. 22B and 22C. FIG. 23 is a schematic front view of the hinge mechanism 230, arms 231 and handles 232 of another embodiment of the invention. The arms are mounted directly to the primary hinge. The arms may be angled outward. Handle rods 234 are mounted at the ends of the arms 231 distal to the primary hinge 233 and disposed on the exterior side of the arms. The handle rod may be oriented at a horizontal plane, tilted up away from the arm, or tilted down away from the arm. A handle 232 is slidingly mounted to each handle rod 234. A cable 235 is engaged to each handle and is directed, for example, by pulleys 236, 237, and 238 up to the primary hinge 233 and down to an auxiliary weight stack (see FIGS. 13A and 13B) such that the user may select the resistance to be provided to lateral movement of the arms. As shown in FIG. 23A, a detail view of the handle, the cable 235 is preferably disposed within the handle rod 234 and arm 231 to decrease the chance of the user contacting the cable. The handle rods 234 may alternatively be mounted to the interior side of the arm to provide resistance to inward motion of the arms. Further, the movement of the cables alternatively may be resisted by springs, friction, pneumatic, electric or magnetic resistance or other resistance mechanisms. FIG. 24 is a schematic plan view of the hinge mechanism 240 and arms 241 and 248 of another embodiment of the invention. A single secondary hinge 242 is mounted perpendicular to the primary hinge 243. An extension 244 is attached to one of the arms 241 opposite the secondary hinge. A pivot plate 245 is slidingly and pivotally mounted at its center 247 to the primary hinge 243. The extension 244 is pivotally mounted to one end of the pivot plate 245. A rigid link 246 is pivotally mounted to the other end of the pivot plate 245 and to the other arm 248. A four-bar linkage is created by the extension 244, the portion of the second arm 248 near the primary hinge, the rigid link 246 and the pivot plate 245. Lateral displacement of one of the arms causes lateral displacement of the other in the opposite direction, via the four bar linkage. FIG. 25 is a partial schematic view of the hinge mechanism 250 of another embodiment of the present invention that permits the user to select the orientation of the secondary hinges to the primary hinge, respectively. Since the orientation of the secondary hinge to the primary hinge controls the resistance ratio of longitudinal to lateral resistance, the user can employ this embodiment to select a resistance ratio best suited to his exercise needs. The secondary hinges 251 (left secondary hinge only is shown) are mounted to the primary hinge 252 by a variable position rod 253. The arm 254 is mounted to the secondary hinge 251 by U-shaped member 255 which, in turn, is rotatably mounted to the secondary hinge. The orientation of the secondary hinge 251 to the primary hinge 252 is maintained by the engagement of notched or serrated surfaces 256 and 257 mounted to the secondary hinge and the primary hinge. To vary the orientation of the primary hinge to the secondary hinge, the notched surfaces are removed from engagement, such as by loosening a locking mechanism 258 such as a wing nut or cam lock. Once disengaged, the secondary hinge may be rotated to a desired position. The locking mechanism 258 is then tightened, engaging the notched surfaces and locking the secondary hinge in position with respect to the primary hinge. Preferably, both secondary hinges are disposed at the same orientation with respect to the primary hinge such that both arms will require the same force to be displaced laterally. FIG. 26 is a cross sectional view of a self-aligning pulley 270 for use with an exercise machine, such as the lat pulldown machine of FIG. 1. The pulley is designed to align itself with the belt when either the frame or the belt is not perfectly aligned. Such a self-aligning pulley may be substituted for the traditional pulley used as the weight stack pulley 45 in the apparatus shown in FIGS. 1 to 6. FIG. 27 is a cross sectional view of the pulley 270 of FIG. 26, taken through section XXVII-XXVII. The self- aligning pulley 270 has a hub 277 mounted to a bearing 273. As shown in FIG. 26, a channel 278 having side walls 279 and a bottom 280 is disposed at the circumference of the hub 277 and adapted to accept a belt 281. In use, the belt should lie flat against the bottom of the channel. These elements are conventional. In the self-aligning pulley 270 of FIG. 26, a shaft 271 having a novel design is mounted to the frame 272. The shaft 271 is preferably made from a mild tool steel such as SAE 1018. A bearing 273 is mounted over the shaft such that it is disposed symmetrically about the center of the shaft. The center of the shaft has a crowned portion 274 that presents a convex surface to the bearings. Spacers or locking rings 275 are disposed at the ends of the shaft 271 to prevent the bearing from slipping off the shaft. Alternatively, the shaft could be formed with integral flanges at each end. Wave washers 276, preferably made of hardened steel having some compressibility, are mounted to the shaft and disposed between each spacer 275 and the bearing 273. The wave washers bias the bearing away from the spacers and, thus, operate to urge the bearing toward the center of the convex surface. Other centering devices, such as O-rings, could be substituted for the wave washers. While the self-aligning pulley 270 is shown in FIG. 26 mounted to a cylindrical portion of frame 272, which is fitted to an internal diameter of the shaft 271, the frame could alternatively have bores fitted to the external diameters of the spacers 275 and still practice the invention. FIG. 28 is a cross sectional view of the self-aligning pulley 270 shown correcting for a misalignment. As shown, the frame 272 is misaligned from a horizontal axis 282. However, this apparatus would work equally well if the belt 281 were misaligned. If a traditional pulley were used, the belt 281 would ride, at least in part, on the side wall 279 of the channel 278. When the misalignment is severe, or over long periods of use, the belt would have a tendency to ride up over the side wall 279 completely, such that the belt would be completely out of the channel. The self- aligning pulley, however, compensates for misalignment by tilting about a plane extending through the center of the pulley. When misaligned, the belt 281 exerts a force on the pulley 270 that overcomes the bias of the wave washers 276 and causes the bearing 273 to slide over the crowned portion 274, resulting in the tilting of the pulley. The tilting of the pulley maintains the belt 281 in a flat position against the bottom 280 of the channel. The crowned portion 274, which is a surface of rotation, preferably maintains the pulley in a symmetrical position with respect to the center of the shaft so that the pulley will tilt, rather than simply slide. By compensating for belt misalignment, the self- aligning pulley 270 reduces maintenance costs by minimizing edge wear on the belt 281 and by reducing side loads on the bearing 273. Furthermore, the self-aligning pulley can reduce manufacturing costs by permitting increased alignment tolerances without sacrificing belt life and smoothness of operation. The foregoing is in no way a limitation on the scope of the invention which is defined by the following claims:

Claims: I claim: 1. An apparatus for exercising comprising: a frame having a front end and a rear end; a seat mounted to the rear end of the frame; a knee pad mounted to the frame and disposed in front of and above the seat; a primary bearing tube rotatably mounted to the frame which primary bearing tube is rotatable about a primary axis and disposed above the knee pad; a bracket rigidly mounted to the primary bearing tube; a secondary bearing tube rotatably mounted to the bracket which secondary bearing tube is rotatable about a secondary axis wherein the primary axis and the secondary axis are skew; an arm rigidly mounted to the secondary bearing tube; a handle mounted to the arm distal to the secondary bearing tube; a weight slidingly mounted to the frame; a lever mounted to the primary bearing tube; and a tether having a first end and a second end wherein the first end is attached to the lever and the second end is attached to the weight. 2. The apparatus of claim 1 further comprising a self- aligning pulley system mounted to the frame wherein the tether is journaled over the pulley system between the lever and the weight. 3. The apparatus of claim 1 wherein the weight is slidable from an initial position to a raised position further comprising a fine tune adjustment comprising: a first finger having a tip mounted to the frame proximate to the weight; and a second finger having a tip mounted to the weight wherein the tips are adjacent when the weight is in the initial position. 4. A method for exercising the latissimus dorsi muscles of a user with an apparatus having a primary hinge mounted to a frame, a secondary hinge mounted to the primary hinge, an arm mounted to the secondary hinge, a handle mounted to the arm distal from the secondary hinge and a resistance mechanism operably engaged to the primary hinge, the method comprising: grasping the handle at a position above the user; pulling down the handle; selecting a path of handle motion having a lateral motion component and a longitudinal motion component; rotating the primary hinge; and overcoming the resistance provided by the resistance mechanism. 5. The method of claim 4 wherein the step of pulling down the handle includes rotating the secondary hinge. 6. The method of claim 5 wherein the step of rotating the secondary hinge causes the primary hinge to rotate. 7. The method of claim 4 wherein the step of overcoming the resistance comprises: overcoming resistance to the lateral motion component; and overcoming resistance to the longitudinal motion component. 8. The method of claim 4, further comprising the step of facing the primary hinge before grasping the handle. 9. The method of claim 4, further comprising the step of facing away from the primary hinge before grasping the handle. 10. An apparatus for exercising the muscles of the back of a user comprising: a frame having a front end and a rear end; a seat mounted to the frame at the rear end; a knee pad mounted to the first end of the frame and disposed above and in front of the seat; a primary hinge mounted to the frame at the front end and disposed above the seat which primary hinge is rotatable about a primary axis; a secondary hinge mounted to the primary hinge which secondary hinge is rotatable about a secondary axis; an arm mounted to the secondary hinge wherein the arm can be displaced from an initial position; a handle mounted to the arm distal to the secondary hinge such that the handle is disposed above the knee pad when the arm is in the initial position; and means for resisting the displacement of the arm. 11. The apparatus for exercising of claim 10 wherein the secondary hinge is a first secondary hinge, the arm is a first arm and the handle is a first handle, further comprising: a second secondary hinge mounted to the primary hinge; a second arm mounted to the second secondary hinge; and a second handle mounted to the second arm distal to the second secondary hinge. 12. The apparatus of claim 11 further comprising means for constraining the movement of the arms such that the first arm and the second arm move symmetrically. 13. The apparatus of claim 10 wherein the resistance means comprises a weight connected to the frame and slidable from an initial position to a raised position further comprising a fine tune adjustment including: a first finger having a tip mounted to the frame proximate to the weight; and a second finger having a tip mounted to the weight wherein the tips are adjacent when the weight is in the initial position. 14. The apparatus of claim 10 wherein the resistance means comprises a tether connecting the primary hinge to a displacable weight further comprising a self-aligning pulley mounted to the frame wherein the tether is journaled over the self-aligning pulley between the primary hinge and the weight. 15. An apparatus for exercising the latissimus dorsi muscles of a user by resisting displacement of the user's limb comprising: a frame; means for engaging the user's limb such that downward displacement of the user's limb causes displacement of the engagement means; means for mounting the engagement means to the frame directly above the user for rotation about at least two axes; a weight stack displacably mounted to the frame; and means for connecting the engagement means to the weight stack such that downward displacement of the engagement means causes displacement of the weight stack. 16. An apparatus for exercising the latissimus dorsi muscles of a user comprising: a frame; a seat mounted to frame; a knee pad mounted to the frame disposed in front of and above the seat; a primary hinge mounted to the frame; a left secondary hinge mounted to the primary hinge; a left arm mounted to the left secondary hinge; a right secondary hinge mounted to the primary hinge; and a right arm mounted to the right secondary hinge. 17. The apparatus of claim 16 further comprising: a right flange rotatably mounted to the right arm; a left flange rotatably mounted to the left arm; and a knuckle joint rotatably connecting the right flange to the left flange. 18. The apparatus of claim 16 further comprising at least one weight connected to at least one arm. 19. The apparatus of claim 16 further comprising at least one weight connected to the primary hinge. 20. The apparatus of claim 19 wherein the weight is connected to the primary hinge by a belt extending over a self-aligning pulley. 21. The apparatus of claim 16 wherein the left secondary hinge is rotatably mounted to the primary hinge at a first selected orientation and the right secondary hinge is rotatably mounted to the primary hinge at a second selected orientation. 22. The apparatus of claim 21 further comprising a first toothed plate mounted to the left secondary hinge and a second toothed plate mounted to the primary hinge. 23. The apparatus of claim 16 further comprising: a slide rod mounted to the primary hinge; a slide ring mounted to the slide rod and adapted to slide along the length of the slide rod; a left link pivotally mounted to the left arm and rigidly mounted to the slide ring; a right link pivotally mounted to the right arm and rigidly mounted to the slide ring; and a weight operably engaged to the primary hinge for resisting rotation of the primary hinge.

Inventors: SIMONSON ROY, SIMONSON, ROY
Applicants: LUMEX, LUMEX, INC.
Application year: 1996
Main classification: A63B21
IPC codes: A63B21, A63B23