Patent Publication Number: US-7223213-B2

Title: Dual-direction pulley system

Description:
This application claims the benefit of related U.S. Provisional Application Ser. No. 60/402,327, filed on Aug. 8, 2002. U.S. Provisional Application Ser. No. 60/402,327 is hereby incorporated by reference. 
    
    
     FIELD OF INVENTION 
     This invention relates to pulley systems allowing resisted motion in two directions, for example in weight stack applications. More particularly, this invention is a dual-direction pulley system for use in a seated leg curl/leg extension station on a multi-station weight stack. 
     BACKGROUND 
     Leg extension and leg curl exercises typically have to be performed on separate machines due to the opposite motions required for each exercise. In a leg extension, the user extends his leg from a 90 degree position to a straight position. This exercise uses the muscles in the top, front (quadriceps) of the leg. In a leg curl, the user contracts his leg from a straight position to a 90 degree position. This exercise uses the muscles in the top, back (hamstring) of the leg. These two directions are opposite one another, and hence a leg curl and a leg extension have historically been performed on different pieces of equipment. 
     A combined leg extension/curl bench has been developed, which has only one direction of loaded cable extension. This means that the direction of tensioning the cable is in one direction only, requiring that the user sit and extend his leg (as described above), using one set of actuating pads with the front of his ankles/shins. To perform a leg curl, the user must reorient himself on the machine and lie down on his stomach and engage a second set of actuating pads with the rear of his ankles/calves. Again, this development loaded the cable system only when the cable was tensioned in one direction, thus requiring the user to change positions on the machine. Lying down also takes up quite a bit of space compared to sitting, and thus these benches are quite large. 
     A separate standing leg curl has been developed where the user exercises one leg at a time from a standing position. 
     What is needed in the art is a seated leg extension/curl station that allows loading of the cable in such a manner as to create resistance in opposite directions so a user can perform a seated leg curl and a seated leg extension without substantially changing the user&#39;s general position. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a dual-direction pulley system for resisting motion in two directions. One embodiment of the pulley system includes a first main pulley having an actuator attached thereto, and second and third main pulleys. A first cable is fixed to and wrapped at least part of the way around the first main pulley and is fixed to and wrapped at least part of the way around the second main pulley. A second cable is fixed to and wrapped at least part of the way around the first main pulley opposite from the first cable and is fixed to and wrapped at least part of the way around the third main pulley. A tensioner cable has one end wrapped at least partially around the second main pulley opposite of the first cable and has the opposite end wrapped at least partially around the third main pulley opposite of the second cable. A pulley arm is reactive to movement of either of the second or third main pulleys. The pulley arm is attached to a load mechanism, and movement of the actuator causes movement of the pulley arm to engage the load mechanism. A tensioner pulley may also be provided around which the tensioner cable is wrapped at least part way. 
     In another embodiment the dual-direction pulley system the actuator is angularly adjustable with respect to the first main pulley to permit multiple rest positions for the actuator. The angular adjustment of the actuator may be accomplished by a retractable pin that passes through an opening in the actuator and engages one of a plurality of openings in the perimeter of the first main pulley. A first catch may be provided on the second main pulley to engage the pulley arm upon movement of the actuator in a first direction. A second catch may be provided on the third main pulley to engage the pulley arm upon movement of the actuator in a second direction opposite to the first direction. The pulley arm may be pivotal about a common axis with the second and third main pulleys. A frame may be provided with at least one hollow member for mounting the first, second and third main pulleys such that the first and second cables are at least partially contained within the hollow frame member. In a further preferred embodiment a seat is provided such that a user can perform seated leg extensions by moving the actuator in a first direction and seated leg curls by moving the actuator in a second direction opposite to the first direction. The actuator may be a lever that includes a first pad and a second pad, wherein the second pad is eccentrically rotatably mounted to the lever in order to hold the leg of a user in place between the first and second pad during a leg curl exercise, and to accommodate legs of different sizes. 
     In a preferred embodiment an exercise apparatus is disclosed that provides resistance to movement in opposite directions. The exercise apparatus includes a frame, with an actuating lever pivotally mounted thereon. The actuating lever is suitable for engagement by a body-part of a user. The actuating lever will pivot in both a clockwise and a counterclockwise direction. A pulley system is connected between a load mechanism and the actuating lever to provide resistance to the rotation of the actuating lever in both the clockwise direction and the counterclockwise direction. The pulley system may include first, second, and third main pulleys. The first main pulley is connected to the second main pulley by a first cable. The first main pulley is connected to the third main pulley by a second cable. The second and third main pulleys are connected by a tensioning cable. The interconnection of cables achieves the result that rotation of the first main pulley causes corresponding rotation of the second and third main pulleys without slack being created in the cables. The actuating lever is preferably attached to the first main pulley such that rotation of the actuating lever initiates rotation of the first main pulley. The exercise apparatus may further include a pulley arm connected to a load. The second and third main pulleys are equipped with catches. The catch on the second main pulley engages the pulley arm when the first main pulley is rotated in a clockwise direction to provide resistance to movement of the first main pulley in the clockwise direction. The catch on the third main pulley engages the pulley arm when the first main pulley is rotated in a counterclockwise direction to provide resistance to movement of the first main pulley in the counterclockwise direction. 
     Accordingly, it is a primary object of the present invention to provide a dual-direction pulley system that provides resistance to movement of an actuator in a first direction and provides resistance to movement of the actuator in a second direction opposite to the first direction. 
     Other aspects, features and details of the present invention can be more completely understood by reference to the following detailed description in conjunction with the drawings, and from the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an exercise machine including a seated leg curl/extension machine utilizing the unique pulley system of the present invention. 
         FIG. 1B  is a side view of the seated leg curl/extension machine of the present invention situated in the end position for a leg curl exercise. 
         FIG. 2  is a partial rear view of the seated leg curl/extension machine of the present invention. 
         FIG. 3  is a partial top plan view of the frame and mast assembly of the pulley system of the present invention. 
         FIG. 4  is a partial perspective view of the frame and mast assembly of the pulley system of the present invention. 
         FIG. 5  is a schematic view of the dual-direction pulley system of the present invention. 
         FIG. 6  is an exploded perspective view of the pulley system of the present invention. 
         FIG. 7  is a side view of the seated leg curl/extension machine of the present invention in a rest position for a leg curl exercise. 
         FIG. 8  is a side view of the seated leg curl/extension machine of the present invention in an end position for the leg curl exercise. 
         FIG. 9  is a side view of the seated leg curl/extension machine of the present invention in a rest position for a leg extension exercise. 
         FIG. 10  is a side view of the seated leg curl/extension machine of the present invention in an extended position for the leg extension exercise. 
         FIG. 11  is an enlarged side view illustrating how the leg hold-down pad functions. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present inventive dual-direction pulley system is embodied in a seated leg curl/extension exercise machine, either independent from or designed as a portion of a multi-station weight machine. One such multi-station weight machine is the NS-700 by Nautilus, Inc. It is contemplated that this dual-direction pulley system can be embodied in other types of exercise equipment for the same or different exercises, or in load-transfer structures where dual-direction load transfers are required. 
       FIG. 1A  shows a multi-station weight machine  10  that incorporates the dual-direction pulley system  5  of the present invention. The weight machine  10  includes a weight stack  12  for providing resistance to various movements for exercises performed at the weight machine stations. In the embodiment shown in  FIG. 1A , the weight machine  10  includes a chest exercise station  11  with handles  14  for performing chest and arm exercises. Load cables  16  transmit the resistance of the weight stack  12  to the chest exercise station  11  to resist movement of the handles  14 . Additional stations could be added to the weight machine  10 . The chest exercise station  11  shown in  FIG. 1A  does not utilize the dual-direction pulley system, and will not be described in detail. 
     A leg station  18  for performing seated leg curls and leg extensions is also incorporated into the weight machine  10 . The leg station  18  incorporates the dual-direction pulley system  5  of the present invention. The exercise machine  10  is provided with a seat  20  and backrest  22 . Preferably the seat  20  and backrest  22  are padded for comfort. The seat  20  has a seat support bar  26  that is adjustable upward and downward within in seat support tube  24 . A seat pop-pin  28  engages one of a plurality of corresponding holes in the seat support bar  26  to hold the seat  20  in place. Similarly, the backrest supported by backrest support tube  30 , which engages backrest bar  32 . Backrest pop-pin  34  engages one of a plurality of corresponding holes in the backrest bar  32  to adjust the backrest forward and rearward. 
     As best seen in  FIG. 4 , a frame assembly  37  is the skeleton structure supporting the pulley system  5 , seat support tube  24 , and backrest support tube  30 . The frame structure includes a base  38  resting on a floor or support surface. A mast  40  is attached to the base  38  and extends upwardly therefrom. A seat frame  36  extends from the mast  40  at a point above the base  38 , and in the same direction as one side of the base  38 . This indicates the front end of the pulley system. Preferably, a cross-member (not shown) extends laterally outwardly from the seat frame  36  to support the seat  20 . The seat frame  36  also includes an elongated main seat frame member  42 . Preferably the frame  37 , and especially the main seat frame member  42 , is formed from rigid hollow tubes. A brace  44  helps support the main seat frame member  42 . Feet  46  provide lateral support for the seat frame  36 . 
     The mast  40  supports the seat frame  36 , backrest  22  and part of the pulley system. It also facilitates positioning pulleys above the user for use while seated, such as lat pull-downs and the like. These upper pulleys are not part of the instant inventive pulley system as described herein in the preferred embodiment. The arm handles and the bench-press handles do not form part of the instant inventive pulley system as described herein in the preferred embodiment. 
     A rear housing  48  (see  FIGS. 6–10 ) is formed around the base  38  from the mast  40  rearwardly to the rear end of the base  38 , and from the base  38  up to just above the seat frame  36 . Only one side of this housing is shown in  FIGS. 7–10  for clarity. 
     As best seen in  FIG. 1B , at the front end of the seat frame  36  is a lever arm  50  engaged by a user to activate the dual pulley system of the present invention for performing exercises. The lever arm  50  curves downwardly from a pair of brackets  52  (see  FIGS. 1A and 6 ) to which it is pivotally connected. The brackets  52  extend upwardly from the seat frame  36  to support the pivot structure, to which is attached a front pulley  54  and the curved lever arm  50 . The brackets are affixed to the main seat frame member  42 . The lever arm  50  and the front pulley  54  pivot together, as described in greater detail below. Roller pads  56 , or bottom pads, extend outwardly from either side of the bottom end of the lever arm  50 . These roller pads  56  are used for both leg curls and leg extension exercises. Leg hold-down pads  58 , or upper pads, extend outwardly from either side of the middle of the lever arm  50 . These pads  58  are used to engage the user&#39;s shins and firmly clamp the user&#39;s shins in place while performing a leg curl. The hold-down pads  58  are rotatably connected to the lever  50 , and are lockable with a locking clamp mechanism  60 . Preferably, a single axle runs through both pads  58  so that they rotate in unison, and are locked in unison. The pads  58  are eccentrically mounted on the axle in order that their rotation increases or decreases the gap between the hold-down pad  58  and the lower pad  56  at the user&#39;s discretion, in order to preferably firmly clamp the user&#39;s shin between the hold down pad  58  and the lower pad  56 . This is described in more detail below. 
     The inventive pulley system is shown in  FIG. 4 , and includes from front to back (right to left on  FIG. 4 ) a front main pulley  54  having two tracks or cable grooves, a pair of single front guide pulleys  62 , a pair of single rear guide pulleys  64 , a pair of single rear main pulleys  66  (each having a single track) and a tensioner pulley  68 . In the embodiment shown in  FIG. 4 , the tensioner pulley is mounted to a tensioner bracket  75  on the frame  37 . Alternatively, the tensioner pulley may be mounted to the rear housing  48  (see  FIG. 6 ). A pulley arm  70  is pivotally attached at the pivot axis of the rear main pulleys  66 , and is freely pivotable with respect to the rear main pulleys  66 . Two main cables A &amp; B and a tensioner cable T are also included in the pulley system. 
       FIG. 5  shows a schematic of the unique dual-direction pulley system  5  of the present invention, and represents one embodiment of the present invention. In the dual-direction pulley system of  FIG. 5 , the front main pulley  54  is pivotally supported by a frame (not shown in  FIG. 5 ). There are two cable guides  72  formed at the perimeter of the front main pulley  54 , one for primary cable A and the other for primary cable B. The front end of primary cable A is fixed to the front main pulley by a pin, a releasable cable stop, or the like, and extends at least partially around the front of the pulley. Cable A then runs over a front guide pulley  62 A and a rear guide pulley  64 A for proper positioning (the two guide pulleys are not necessary in certain configurations, and additional guide pulleys may be necessary in other configurations) and extends to a rear main pulley  66 A, and is guided over at least a portion of the perimeter of the rear main pulley  66 A. The rear main pulley  66 A is pivotally supported by the frame (not shown in  FIG. 5 ). The rear end of cable A is fixed to the rear main pulley  66 A. 
     Similar to the routing of cable A, the front end of primary cable B is fixed to the front main pulley  54  by a pin, releasable cable stop, or the like, and extends at least partially around the rear of the pulley  54  (in this configuration, opposite the direction cable A is wrapped around the front main pulley). Cable B then runs over a front guide pulley  62 B and a rear guide pulley  64 B for proper positioning (the two guide pulleys are not necessary in certain configurations) and extends to a rear main pulley  66 B, and is guided over at least a portion of the perimeter of the rear main pulley  66 B. The rear main pulley  66 B is pivotally supported by the frame  37  (not shown in  FIG. 5 ). Rear main pulleys  66 A and  66 B are free to pivot independently from each other. The rear end of cable B is fixed to the rear main pulley  66 B. 
     With further reference to  FIG. 5 , one end of the tensioner cable T is run over a portion of and attached to the perimeter of rear main pulley  66 A and the other end is run over a portion of and attached to the perimeter of rear main pulley  66 B. Between its ends, the tensioner cable T is routed through a tensioner pulley  68 . Preferably, as shown in  FIG. 5 , the primary cables A, B are each connected over the top of the respective rear main pulleys  66 A,B, and the ends of the tensioner cable T are each connected around the bottom of each respective rear main pulley  66 A,B. As a result, the rotational motion of the main pulleys  54 ,  66 A, and  66 B is interconnected. Rotation of any one of the main pulleys  54 ,  66 A, or  66 B will cause a corresponding reactive rotation in the remaining two pulleys. This relationship is described in more detail below. More particularly, rotation of the front main pulley  54 , as for example by applying a force to actuator  50 , will cause a reactive rotation of the rear main pulleys  66 A,B. The force applied to the actuator  50  is effectively transmitted through the cables A, B to the rear main pulleys  66 A, B. Similarly, any resistance forces applied to the rear main pulleys  66 A,B will be transmitted through the cables A, B to the front main pulley  54  and the actuator  50 . 
     This system thus forms a closed-loop cable system, shown in  FIG. 5 , that creates reaction when the front main pulley  54  is rotated in either direction. For instance, when the front main pulley  54  is rotated clockwise to position  1 , cable B is pulled in tension a certain distance X, and creates slack in cable A of that same length. This movement of cable B in turn causes rear main pulley  66 B to rotate in a clockwise direction also the same amount X. The tensioner cable T then is also pulled in tension on rear main pulley  66 B and runs through the tensioner pulley  68  and causes the rear main pulley  66 A to rotate in a counterclockwise direction a distance X to take up the slack in cable A. 
     Similarly, when the front main pulley  54  is rotated counter-clockwise to position  2 , cable A is pulled in tension a certain distance Y, and creates slack in cable B of that same length. This movement of cable A in turn causes rear main pulley  66 A to rotate in a clockwise direction also the same amount Y. The tensioner cable T then is also pulled in tension on rear main pulley  66 A and runs through the tensioner pulley  68  and causes the rear main pulley  66 B to rotate in a counterclockwise direction a distance Y to take up the slack in cable B. 
     A catch  76  (such as a flange, pin, bent member, or other protrusion) extends from the side of each rear main pulley  66 A and  66 B to engage the pulley arm  70  when that particular rear main pulley is rotated clockwise (according to  FIG. 5 ). As a catch  76  rotates clockwise with the rear main pulley  66  on which it is formed, it engages the pulley arm  70 , which in turn actuates the load mechanism to create the resistance at the lever  50 . For instance, when the lever  50  in  FIG. 5  is rotated toward position  1 , cable B is tensioned, and as described above, causes rear main pulley  66 B to rotate in a clockwise direction. The catch  76 B on rear main pulley  66 B then engages the pulley arm  70 , which in turn actuates the load  12 . What also happens is that the tensioner cable T is pulled around rear main pulley  66 B in the clockwise direction, causing rear main pulley  66 A to rotate counterclockwise, thus moving the catch  76 A on rear main pulley  66 A away from the pulley arm  70 , and at the same time taking up the slack created in cable A by the movement of the lever  50  to position  1 . The catch  76  can have an adjustable surface on it, such as a set screw, to fine-tune the engagement position between the flange  76  and the pulley arm  70 . 
     When assimilated into a weight stack system, the lever arm  50  that moves the front main pulley  54  is the lever arm  50  to which the roller pads  56 ,  58  are attached (see  FIG. 4 ). Also, the pulley arm  70  may be pivotally attached to the pivot axis of rear main pulleys  66 A and  66 B (or a pivot axis effectively concentric with the pivot axis upon which each of the rear main pulleys  66 A and  66 B are attached). It is not necessary that that pulley arm  70  pivot about the same axis as the rear main pulleys  66 A and  66 B. By sharing the same axis as the rear main pulleys  66 A and  66 B, the mechanical advantage of the catch  76  pressing against the pivot arm  70  remains constant. If a nonlinear load actuation was desired a different pivot point could be selected for the pulley arm  70 . This would result in the catch  76  sliding along the pulley arm  70  as the pulley arm  70  and rear main pulley  66 A rotate, resulting in a varying mechanical advantage for the catch  76 . It should also be noted that rather than a single pulley arm  70 , separate pivot arms could be provided for each rear main pulley  66 A and  66 B. If desired, different loading reactions could be created for each pulley arm by choosing different pivot points. 
     It should also be understood that while the pulley system  5  has been described in terms of a front and rear orientation, there is no necessary limit on how the pulleys are arranged. For example, the front main pulley  54  could be called a first main pulley, the rear main pulley  66 A could be called a second main pulley, and the rear main pulley  66 B could be called a third main pulley. It is not necessary to locate the second and third main pulleys rearwardly from the first main pulley, nor even to make the second and third main pulleys coaxial. Certain efficiencies result from the preferred arrangement, but it is not a required arrangement. 
     In  FIG. 4 , the pulley arm  70  is H-shaped (see also  FIG. 6 ), with the bottom two legs each attached to the pivot axis of the respective rear main pulley  66 A,B. The top of the pulley arm  70  is operably connected to a load mechanism  78 , such as a weight stack, as is known in the art. In the embodiment shown a loading cable L is fixed to the frame  37  at one end, and extends through a pulley arm pulley  86 , and then routed through a series of pulleys to the weight stack  12 . Other load mechanisms, such as resilient bands or rods, may also be used. 
     In this way, the lever  50  can be moved in either direction under load (caused by the catch  76  on each of the rear main pulleys  66 A,B causing the pulley arm  70  to actuate the load mechanism  12 ), allowing opposite direction rotation (dual-directions) of the pulley  54  to be used easily and efficiently. 
     In the implementation of this pulley system in a leg extension/curl machine, the collar  82  can be moved around the perimeter of the front main pulley  54  using the handle  81  to provide the proper positioning of the lever  50  to allow for either leg extensions or leg curls. For instance, with reference to  FIGS. 7–10 , in  FIG. 7  the lever  50  is shown positioned to extend from approximately 11 o&#39;clock from the front main pulley  54  to facilitate the leg curl exercise. In  FIG. 9 , the lever  50  is shown positioned at approximately 8 o&#39;clock from the front main pulley  54  to facilitate the leg extension exercise.  FIGS. 8 and 10  show the end position for the leg curl and the leg extension, respectively. Note how in each of  FIGS. 8 and 10  the respective catches  76  on main pulleys  66 A and  66 B engage the pulley arm  70  to cause it to pivot and the load to be actuated. 
     The adjustment structure that allows the relative re-positioning of the lever  50  with the front main pulley  54  is a pop-pin mechanism  80 . A collar  82  extends around a central portion of the rim of the front main pulley  54 . Referring to  FIG. 7 , the lever  50  is attached to the collar  82 , and the collar  82  has an opening in it through which the pop-pin  80  selectively extends. A handle  81  is provided on the collar  82  to assist the user in gripping and adjusting the collar  82 , but is not required. The central portion of the outer rim of the front main pulley  54  has a series of apertures  84  formed therein for positioning the lever  50  for either leg curls or leg extensions. Preferably there are apertures  84  formed at varying angles to accommodate different exercises. Each aperture corresponds to a resting, or starting position, for the actuating lever  50  for an exercise, such as a leg curl or leg extension. For example in the preferred embodiment a first set of apertures is provided that correspond to a starting position for the leg curl exercise. These apertures are formed such that the lever  50  is maintained at approximately the 11 o&#39;clock position shown in  FIG. 7  to start the leg curl. More than one aperture is provided near this orientation to accommodate variances in anatomy and preference for starting position. Similarly, a second set of apertures is provided such that lever  50  is maintained at approximately the 8 o&#39;clock position of  FIG. 9  to start the leg extension exercise. As an example,  FIG. 6  shows a aperture  84  in the central rim of the front main pulley  54  for use in positioning the lever  50  for the leg curl exercise. 
     As seen in FIGS.  4  and  7 – 10 , the primary cables A, B run through the tubular seat frame member  42  in the preferred embodiment. In this fashion the cables A and B are hidden from view, and are protected. The cables A and B could be anywhere necessary to extend as needed to the rear main pulleys  66 . 
       FIG. 6  shows an exploded assembly view of a pulley system  5  according to the present invention. Working from front to rear (left to right in  FIG. 6 ), the first part of the assembly is the leg hold down locking clamp mechanism  60 , which includes a friction pad  88 , an adjustment handle  90 , a fastening screw  92 , and a screw cover  94 . The pop pin  80  is received through collar  82 , which is pivotally mounted on pivot shaft  96 , along with the lever arm  50  and the front main pulley  54 . The pop pin  80  will engage apertures  84  formed in the central portion of the front main pulley  54 . The pivot assembly mounted on bracket  52  includes bearings  98 , bushings  100 , step spacers  102 , shim washers  104 , lock washers  106 , button head screws  108 , and plastic finishing caps  110 . The front guide pulleys  62  are also mounted on the bracket  52 , generally beneath the front main pulley  54 . The front guide pulleys  62  rotate freely, and independently on bolt  112 . Cable lock pin  114  is used to fasten the main cables A &amp; B to the front main pulley  54 . Each of the cables A &amp; B has a loop formed in their end. The front main pulley  54  has openings through which the loops at the end of the cables A &amp; B extend, so that the cable lock pin  114  passes through the loops to retain the cables A &amp; B in place on the front main pulley  54 . C-clamps (or snap rings)  116  may be used to fasten the cable lock pin  114  in place. 
     The rear pivot assembly is pivotally connected to the rear housing  48 . The rear main pulleys  66 A,B are separated by a spacer  118 , and are pivotally mounted on rear pivot shaft  116 . Bearings  120  and spacers  122  are provided between the rear main pulleys  66 A and  66 B and the pulley arm  70 . Another set of bearings  124  and spacers  126  are provided between the outward facing surfaces of the pulley arm  70  and the inward facing surfaces of the rear housing  48 . The pulley arm  70 , and rear main pulleys  66 A,B are thereby freely rotatable on the rear pivot shaft  116 . Catches  76  are mounted on the outward facing sides of the rear main pulleys  66 A,B. In the embodiment shown, each catch  76  takes the form of a flange  128 , which extends generally perpendicularly from the side of the pulley  66 A,B, and a set screw  130 . In this embodiment, it is the set screw  130  that actually contacts the pulley arm  70  when the rear main pulleys  66 A,B rotate in the proper direction (counterclockwise as seen in  FIG. 6 ). 
     The tensioner pulley  68  is mounted on a bracket  132  by a bolt  136 . The tensioner pulley bracket  132  is mounted to the rear housing  48  via threaded bolt  134 . The amount of tension in cable T can be adjusted by turning the threaded bolt  134  to shorten or lengthen the amount of offset from the rear housing  48 . 
     As best seen in  FIG. 11 , each hold-down pad  58  extending off the lever  50  is rotationally mounted to the lever, as mentioned above. Each substantially cylindrical hold-down pad  58  is mounted eccentrically to its rotational axis so that when a person&#39;s leg is positioned between the lower pad  56  and the hold-down pad  58 , the hold down pad can be rotated to snugly contact the person&#39;s shin (it is used only for the leg curls, and is not used for the leg extensions).  FIG. 11  shows in phantom lines a users leg and the rotation of the hold-down pad  58  to accommodate the leg. Once a user&#39;s leg is in place, the position of the hold-down pad  58  is fixed to prevent it from rotating about the axle  138  by a locking clamp mechanism  60  including a friction pad  88  (or similar other similar mechanism such as a set screw) attached to the lever arm  50  (see elements  88 ,  90 , and  92  in  FIG. 6 ). The friction pad  88  engages the common axle  138  extending through both hold down pads  58  to fix their position. Alternatively, any other type of fixing mechanism could be used if the hold-down pads  58  were not on a common axle since the locking clamp mechanism  60  is mounted at a location between the inner ends of the hold-down pads  58  (at the lever arm  50 ). The hold-down pad  58  has a cushion that is rotationally fixed to the axle, whether it is a common axle for both sides, or an individual axle for both sides. This is to keep the pad  58  from rotating on the axle  138  during use, which would adversely affect its performance. There needs to be constant contact between the hold-down pad  58  and the user&#39;s leg in order for the leg curl exercise to feel right. In order to facilitate this it is preferred that the hold-down pad  58  be soft and have a somewhat tacky or slip-resistant outer texture. An outer cover could be used on the pad  58  which could rotate around the pad  58  in order to prevent excessive rubbing between the user&#39;s leg and the hold-down pad  58 . 
     The front main pulley  54  could be a dual pulley that is structured so that each of the two pulleys are rotationally connected together to turn together. The rear mechanism could be positioned below the seat of the embodiment shown in  FIG. 4  with the proper modifications. Cables mean any tension transmitting means, such as chain, rope, belts, etc. Pulleys could include sprockets or other mechanisms ways by which a cable is re-directed and creates some displacement by rotation or the like. The dual-direction pulley system could easily be adapted for use with other pairs of exercises that have matching movements in opposite directions, such as biceps curls and triceps extensions, or, lower back extensions and abdominal crunches. 
     Presently preferred embodiments of the present invention and many of its improvements have been described with a degree of particularity. The previous description is of preferred examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is defined by the scope of the following claims.