Patent Publication Number: US-8968164-B2

Title: Exercise apparatus and method with sliding handle assembly

Description:
FIELD OF THE INVENTION 
     The present invention relates to an exercise apparatus and method with a slidable handle assembly, the apparatus and method being useful, in one example, for developing the muscles used during trunk rotation of a user in a standing position. 
     BACKGROUND 
     Physical exercise apparati have been designed in the past which enable a user to perform a variety of different exercises. A user, typically standing or sitting in front of the machine, pulls or pushes against various resistance mechanisms, such as a resistance cable attached to a weight stack. One particular exercise motion that is used in basically in every sport is known as trunk rotation, and comprises a combination of a hip rotation and a spinal rotation. For example, when a user swings a golf club or a baseball bat, or throws a football or a punch, a trunk rotation motion is required. Thus, it would be desirable to provide an exercise apparatus that develops the muscles utilized during such motion. 
     SUMMARY OF THE INVENTION 
     An apparatus and method are provided in accordance with the present invention in which a pair of opposing pulleys are slidably mounted over an elongated rod. The pulleys are interconnected by a pull cable having a hand grip at each end wherein a user grasps a respective one of the hand grips causing the associated pulley to slide along a length of the rod toward the opposing pulley, thus maintaining the moving pulley in substantial alignment with the longitudinal axis of the elongated rod. In this manner, a substantially upright (e.g., standing or kneeling) user grasping one hand grip and moving it away from the longitudinal axis of the elongated rod (e.g., across his upper torso while twisting his upper torso) can develop the muscles utilized during trunk rotation while maintaining a substantially constant torque about the user&#39;s spine during the exercise. This avoids the problems of the prior art apparatus and methods in which a pull cable may wrap around the user&#39;s trunk, which causes a significant reduction in torque around the spine. 
     In accordance with one embodiment of the invention, an exercise apparatus is provided comprising:
         an elongated rod mounted on a frame, the rod having a longitudinal axis and first and second ends;   a pair of pulleys each mounted on an associated sleeve that is slidably mounted on the elongated rod;   each of the pulleys being interconnected to a force resistance mechanism and adapted to be held in a stable rest position at respective ones of the first and second ends of the elongated rod;   the pulleys each comprising a respective pulley wheel, the pulleys being interconnected by a pull cable having opposing ends wound around and interconnecting the pulley wheels;   each end of the pull cable being interconnected to an associated hand grip;   the interconnection between the pulleys and the force resistance mechanism being arranged such that when the user grasps a selected one of the hand grips and moves the hand grip away from the longitudinal axis, the pulley associated with the selected hand grip is slidable along the longitudinal axis of the elongated rod under forcible resistance from the force resistance mechanism.       

     In one embodiment, wherein the ends of the elongated rod are adjustably mounted to the frame such that the longitudinal axis is adjustable to one of a plurality of fixed vertical positions of selectively variable height relative to a ground surface on which a user is disposed for performing an exercise. 
     In one embodiment, the pulleys are interconnected to the force resistance mechanism via a connector cable. 
     In one embodiment, the connector cable is interconnected to each of the sleeves on which the pulleys are mounted. 
     In one embodiment, the rod is adjustably mounted to the frame via a frame member that pivots with respect to the frame. 
     In one embodiment, the elongated rod is mounted to the frame such that the rod is stationary against rotation transverse to its longitudinal axis. 
     In one embodiment, the elongated rod is mounted to the frame such that the longitudinal axis of the rod is disposed generally parallel to the ground surface at all fixed vertical positions of the rod. 
     In accordance with another embodiment of the invention, a method of performing a muscle exercise comprises providing an exercise apparatus comprised of a frame stationary with respect to a ground surface on which a user is disposed for performing an exercise, an elongated rod mounted on the frame having a longitudinal axis and first and second ends, a pair of pulleys each mounted on an associated sleeve that is slidably mounted on the elongated rod, wherein each of the pulleys is interconnected to a force resistance mechanism and wherein the pulleys are interconnected by a pull cable having opposing ends each interconnected to an associated hand grip engageable by the user, the method further comprising:
         the user grasping a selected one of the hand grips and moving the selected grip away from the longitudinal axis of the rod with a degree of force sufficient to overcome the force resistance mechanism such that the pulley and sleeve associated with the selected hand grip slides along the longitudinal axis of the elongated rod.       

     In accordance with another embodiment of the invention, an exercise apparatus is provided comprising:
         an elongated rod mounted on a frame, the rod having a longitudinal axis and first and second ends;   a pair of pulleys each mounted on an associated sleeve that is slidably mounted on the elongated rod;   each of the pulleys being interconnected to a force resistance mechanism and adapted to be held in a stable rest position at respective ones of the first and second ends of the elongated rod;   the pulleys each comprising a respective pulley wheel, the pulleys being interconnected by a pull cable having opposing ends wound around and interconnecting the pulley wheels;   each end of the pull cable being interconnected to an associated hand grip;   the interconnection between the pulleys and the force resistance mechanism being arranged such that when the user grasps a selected one of the hand grips and moves the hand grip away from the longitudinal axis, the pulley associated with the selected hand grip is slidable along the longitudinal axis of the elongated rod under forcible resistance from the force resistance mechanism; and   the rod being mounted on the frame such that the longitudinal axis of the rod is disposed in a generally horizontal orientation.       

     In one embodiment, the rod is adjustably mounted to the frame on a pivot arm structure, wherein the arm structure rotates with respect to the frame for adjusting the height of the rod above a ground surface on which a user is disposed. 
     In one embodiment, the apparatus includes a pivot adjustment mechanism including a support plate mounted on the frame with a plurality of apertures disposed in a circumferential array for adjusting the rotable position of the arm structure with respect to the frame. 
     In one embodiment, the sleeves are each interconnected to the force resistance mechanism via a connector cable and the connector cable engages one or more pulley wheels mounted to the pivot arm structure. 
     In one embodiment, the connector cable is assembled together with the sleeve for free rotation independent of the sleeve around the elongated rod. 
     In one embodiment, the sleeve is mounted for rotation about the longitudinal axis of the rod. 
     In accordance with another embodiment of the invention, an exercise apparatus is provided comprising: 
     an elongated rod mounted on a frame having a longitudinal axis; 
     a pair of pulleys each mounted on an associated sleeve adapted to slide along the elongated rod; 
     a pull cable having opposing ends wound around and interconnecting the pair of pulleys, each end of the cable being connected to an associated hand grip; 
     each pulley being slidable together with its associated sleeve along the elongated rod via a user grasping the associated hand grip and moving the hand grip away from the longitudinal axis; and 
     wherein the sleeves are interconnected to a force resistance mechanism holding the sleeves at opposing ends of the elongated rod under a selected resistance force. 
     In one embodiment, the hand grip is rotatable with respect to its associated sleeve. 
     In one embodiment, the elongated rod has a longitudinal axis, the rod being mounted on the frame such that the rod is disposed in a generally horizontal orientation. 
     In one embodiment, the elongated rod is mounted on the frame such that the longitudinal axis is selectively adjustable to one of a plurality of fixed positions of selectively variable vertical distance relative to a ground surface on which the user is supported. 
     In one embodiment, the sleeves are each interconnected to a force resistance mechanism via a connector cable. 
     In one embodiment, the force resistance mechanism comprises a plurality of incremental force resistance elements that are selectively engagable by the user with the connector cable. 
     In one embodiment, each of the sleeves are assembled together with respective collars, the sleeves being mounted together with the respective collars for free rotation around the elongated rod, the collars being interconnected to a respective opposing end of a connector cable, the collars being assembled together with the sleeves for free rotation independent of the sleeves around the elongated rod. 
     In one embodiment, the connector cable has opposing ends interconnected to respective ones of the sleeves, the connector cable having a portion intermediate the opposing ends engageable with the force resistance mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of an apparatus according to the present invention, including an upright frame, an adjustable support arm structure pivotally mounted on the frame, and a rod attached to the arm structure shown in one of a plurality of fixed horizontal positions with left and right handle bracket assemblies slidably mounted thereon; 
         FIG. 2A  is a partial schematic perspective view of the pull handle and resistance cable assemblies of the  FIG. 1  apparatus, showing a user doing an exercise with the support arm structure and rod in a central horizontal position; 
         FIG. 2B  is a partial schematic perspective view similar to  FIG. 2A , showing a user doing an exercise with the support arm structure and rod pivoted to a lowered position; 
         FIG. 3A  is a partial schematic view of the pull handle and resistance cable assemblies of  FIG. 2 , showing the apparatus at rest; 
         FIG. 3B  is a schematic view similar to  FIG. 3A  showing the apparatus in use with the right hand handle being extended and the active weight stack being raised; 
         FIG. 3C  is a schematic view similar to  FIG. 3A  showing the apparatus in use with the left hand handle being extended and the active weight stack being raised; 
         FIG. 4  is a right side elevational view of the apparatus of  FIG. 1  showing the support arm structure in a central horizontal position in solid lines, and the arm structure in full vertically up and full vertically down positions in phantom lines; 
         FIG. 5  is a top plan view of the apparatus of  FIG. 1  in use with the right hand handle being extended; 
         FIG. 6  is a fragmentary detailed perspective view of the left hand handle assembly in use; 
         FIG. 7  is a cross-sectional plan view of the left hand handle assembly taken along line  7 - 7  of  FIG. 6 ;  FIG. 7A  is a cross-sectional view similar to  FIG. 7  but showing an alternate embodiment of handle assembly; 
         FIG. 8  is an exploded perspective view of the left hand handle assembly of  FIG. 7 ; 
         FIG. 9  is a schematic cross-sectional view of the left hand handle assembly taken along line  9 - 9  of  FIG. 7  with the arms in a horizontal position; 
         FIG. 10  is a schematic view similar to  FIG. 9  but showing the support arm structure pivoted to a lowered position; and 
         FIG. 11  is a schematic view similar to  FIG. 9  but showing the support arm structure pivoted to a raised position. 
     
    
    
     DETAILED DESCRIPTION 
     One embodiment of the apparatus of the present invention will now be described, which is meant to illustrate and not limit the scope of the claimed invention. Other embodiments and variations will be apparent to the skilled person and are intended to be included with the scope of the appending claims. 
     For ease of description, the left and right side frame elements and left and right side rotatable arm/handle assemblies are generally referred to as sub-elements a (left) and b (right) and are given the same reference number. The apparatus is essentially symmetrical with each of the left and right side frame, rotatable arm/handle assemblies, cable and pulley assemblies being the same. Thus, in some instances the sub-assembly only on one side will be described, it being clear from the drawings and reference numbers that the other side sub-assembly is the mirror image. 
       FIG. 1  is an overall view of an exercise apparatus  10  according to one embodiment of the invention. The apparatus includes a generally upright frame  11  which rests on a horizontal ground surface  2 . The frame includes a lowermost base member  14 , a vertical support structure  22  that includes an adjustable weight stack  150 , and a C-shaped pivoting arm structure  50  adjustably mounted on the frame  11  for lowering or raising a front horizontal rod  12  extending between the two front ends of the C-shaped arm structure  50 . A pair of left and right handle bracket assemblies  60   a ,  60   b  with respective left and right hand grips (e.g., handles)  90   a ,  90   b  are slidably mountable on the rod  12  for engagement by a user. When a user, standing in front of the machine  10 , pulls the handle of on one of the handle assemblies, that handle will move (extend) toward the user as the associated handle bracket slides across the rod  12  in the direction of the opposing handle bracket. This sliding motion will be further described in the following detailed description and accompanying figures. 
     As shown in  FIGS. 1-7 , the rod  12  comprises an elongated cylindrically shaped rod having a longitudinal axis LA, the rod being mounted on the frame such that the longitudinal axis is disposed generally horizontally relative to the ground surface plane P 2  which supports the frame and a user. 
     The apparatus  10  includes a base member  14  disposed generally parallel and adjacent to the horizontal plane P 2  of the ground surface  2 . The base  14  includes left and right elongated feet members  15   a ,  15   b , joined by a cross bar  17 . At the ends of each foot are mounting pads  16  with holes for bolting the front and rear ends of the feet to the ground surface  2  to maintain the machine in a stationary position. On top of the central cross bar  17  there is mounted a central vertical column or support  22  including a vertically-disposed housing  23  that encloses a weight stack  150 . The housing includes left and right end supports (e.g., hollow tubes)  24   a ,  24   b  that are joined by a top support (e.g. hollow tube)  25 , along with a front cover  26  and a rear cover  27  that define a central cavity  28  in which the weight stack resides. An elongated vertical opening  29  in the front cover  26  provides access to an adjustable pin  154  for selecting a number of weights in the stack to be attached to a connector (resistance) cable, thereby adjusting the amount of force required by the user to extend the pull handle assemblies  60   a ,  60   b.    
     In the present embodiment, the rod  12  on which the slidable handle bracket assemblies  60   a  and  60   b  are mounted, forms one side of a rectilinear pivot arm structure  50 . This is by way of example only, as other mechanically rigid support structures can be used for pivotably mounting the rod  12  to the frame  11 . In this embodiment, the arm structure  50  includes left and right side arms  52   a ,  52   b  each joined at their rear ends to opposite ends of a transverse rear arm  51 , wherein all three arms and the front rod  12  lie in a single horizontal plane P 50  that in  FIG. 1 , is substantially parallel to the ground surface plane P 2 . This is referred to herein as the middle or central position, also illustrated (in use) in  FIG. 2A . With the pivot arm  50  in the middle position, the front rod  12  is in the same horizontal plane P 50  as the arm structure  50 , parallel to the ground surface plane, and the rod  12  is disposed roughly three feet above the ground surface plane P 2 . This central position provides easy access by a user standing in front of the machine  10  and rod  12  for engaging and grasping the handles  90   a ,  90   b  in order to pull on the handle(s) and as a result slide the handle bracket(s) across the rod  12  (as shown in  FIG. 2A ). 
     To vary the direction of extension and range of motion of the user, the arm structure  50 , including left and right side arms  52   a ,  52   b  and supporting rod  12 , can be pivoted about a generally horizontal axis A which is disposed parallel to the ground surface plane P 2 . Pivoting the arm structure  50  clockwise about the axis A enables the user to raise the front rod  12  upwardly, so that the handle assemblies are now further away from the ground surface  2  (e.g., about five feet above the ground  2 ) than in the middle position, while still maintaining the rod  12  in a plane substantially parallel to the ground surface plane P 2 . Alternatively, pivot arm  50  can be pivoted in the opposite direction (counterclockwise), lowering the rod  12  so that the handles are now closer to the ground (see  FIG. 2B ), and a user  4  disposed in front of the machine now will pull upwardly on the handles. Again, the rod  12  is always maintained in a substantially horizontal plane parallel to the ground surface plane P 2 , but the distance from the ground surface plane varies depending on the pivoted position of arm structure  50  on frame  11 . 
       FIG. 2A  illustrates the cooperation of multiple pulley cable assemblies during use, including two handle pulley assemblies  70   a ,  70   b  engaging opposite ends of the pull cable assembly  68  and a connector (resistance) cable assembly  30  engaging the weight stack. Relevant portions of these assemblies are shown in  FIG. 2A  where a user  4  is performing an exercise with the support arms  52   a ,  52   b  in a horizontal middle position (same as  FIG. 1 ). The pull cable assembly  68  is directly engaged by the user; it includes a pull cable  80  having a left end  81  engagable with the left slidable handle bracket  60   a , and a right cable end  82  engagable with the right slidable handle bracket  60   b . The left and right handle brackets  60   a ,  60   b  are initially disposed at opposing left and right ends  13   a ,  13   b  of the rod  12  (prior to use, as shown in  FIG. 1 ). When a user grasps the grip  91   b  of right handle  90   b  and pulls it toward himself, as shown by arrows A 1  in  FIG. 2A , the right handle bracket  60   b  is caused to slide across the rod  12  toward the left handle bracket  60   a , the latter being fixed in position on the left hand end  13   a  of rod  12  by its engagement with the resistance cable assembly  30  attached to the weight stack  150 . 
     More specifically, the right handle bracket  60   b  includes a slidable sleeve (e.g., tube)  62   b  having a central bore  63   b  which slidably engages the outer cylindrical surface of rod  12 . A pulley housing  71   b  attached to slidable tube  62   b  mounts a pulley wheel  76   b , over which a pull cable  80  can be pulled (by a user) while the wheel rotates. At the right end  82  of pull cable  80 , a stop ball  83   b  is provided that prevents the pull cable from being pulled out of the handle bracket  60   b  when the user pulls on the opposing handle  90   a . The right end  82  of cable  80  is attached by a metal ring  84   b  to a Y-shaped handle frame  92   b . A grip  91   b  is supported across the open ends  94   b  of the Y-shaped frame  92   b , wherein an opening  93   b  between the grip and Y-shaped frame allows the user&#39;s fingers to be inserted for grasping the grip  91   b . The opposing end  95   b  of the Y-frame  92   b  has an aperture which receives the ring  84   b  for connecting the stop ball  83   b  between the handle  90   b  and pull cable  80 . 
     The right handle bracket assembly  60   b  further includes a tabbed collar  130   b  attached to the slidable tube  62   b  for connecting the handle bracket  60   b  to the resistance cable assembly  30 . More specifically, a first end  32  of resistance cable  31  is attached to the tab portion of the collar  130   b . The resistance cable  31  extends from collar  130   b  around four right side pulley wheels  35   b - 38   b , and then around a central pulley  42  which is attached to the weight stack  150 . The opposing left end  33  of resistance cable  32  is similarly engaged with the left handle bracket  60   a  and a mirror image pulley assembly with four pulley wheels, and ultimately engages the same central pulley wheel  42  engaged with the same common weight stack  150 . Thus, in the present embodiment, a single resistance cable assembly  30  connects the left and right slidable handle brackets  60   a ,  60   b , while a separate pull cable assembly  68  similarly connects the left and right handle brackets  60   a ,  60   b , and together the two separate cable assemblies  30  and  68 , which each engage the left and right slidable handle brackets  60   a ,  60   b , enable the resistance training motion and exercises illustrated in the figures. 
     Returning to  FIG. 2A , when a user  4  grasps the right handle  90   b  (shown in phantom lines in its initial position) and pulls the handle  90   b  toward himself while moving away from the machine  10 , thereby extending the right handle away from the rod  12 , he pulls against the resistance set by the resistance cable assembly  30  which is attached to a select number of weights in the weight stack  150 . Here, an adjustable pin  154  selects the upper 5 weights in the stack as a desired resistance level; while the user pulls on the right handle these upper 5 weights rise upwardly along the parallel guide rods  152  of the weight stack. As a result the right handle bracket  62   b  slides to the left on the rod  12 , allowing the pull cable  80  to extend further toward the user while the user continues to exert sufficient force to overcome the selected weight resistance  151  (upper 5 weights of the stack). The left handle bracket  60   a  remains stationary with respect to the frame  11 , the stop ball  83   a  preventing the pull cable  80  from disengaging with the left handle bracket, and the resistance cable  31  attached to the left handle bracket resisting the force on the pull cable  80  exerted by the user pulling on the right handle.  FIG. 2A  includes a series of arrows A 2  that illustrate the movement of the resistance pull cable  31  around the various pulley wheels, including the right front side wheel  35   b , right rear side wheel  36   b , right central lower wheel  37   b , right central upper wheel  38   b , and the common wheel  42  attached to the weight stack. In  FIG. 2A  the rod  12  is in the middle position, parallel to the ground plane P 2 , and here about 3 feet above the ground surface. 
     In contrast,  FIG. 2B  shows the pivot arm structure  50  rotated counterclockwise about axis A to a lowermost position, wherein the rod  12  is now horizontally aligned in a plane PL much closer to the ground plane  2 , here a minimum of about 45 inches above the ground. In this position, the user pulls upwardly on the right handle  90   b , again overcoming the resistance of the selected weights in the weight stack, similar to  FIG. 2A . This adjustability of the height at which the rod  12  is positioned and thus the position at which the handle bracket assemblies are provided, enables a wide range of motion for the user exercising with this single apparatus.  FIG. 4  shows in phantom lines a third uppermost position in which the pivot arm structure  50  is pivoted in the opposite direction (clockwise) about axis A, causing the rod  12  to be raised above the middle position, to an uppermost position, in a horizontal plane about five feet above the ground surface. The adjustment mechanism for the pivot arm structure is described below, and may include additional positions between the uppermost and lowermost positions. 
       FIGS. 3A-3D  illustrate the coordinated motion of the pull cable assembly  68  and the resistance cable assembly  30  in use. These figures show a top view of the cable assemblies, with the arm structure  50  supported in the middle horizontal position (same as in  FIG. 1 ). 
       FIG. 3A  shows the pull cable  68  and resistance cable  30  assemblies respectively in solid lines, with the support arm structure  50  shown in phantom lines. Here the handles  90   a ,  90   b  are in an initial position, each located at the respective left and right ends  13   a ,  13   b  of the rod  12 , respectively. The weight stack is at rest. 
       FIG. 3B  is similar to  FIG. 3A  but now shows the right handle  90   b  being extended away from the machine  10 , i.e., being pulled by the user (not shown) in a generally leftward direction (arrow A 4 ), causing the right sliding bracket  60   b  to slide toward the left end of  13   a  the rod  12 . The arrows A 4  illustrate the respective motions of the pull cable  80  and the resistance cable  31  over the respective pulleys. 
       FIG. 3C  is a mirror image of  FIG. 3B , showing the effect of pulling on the left handle  90   a , and the respective movements (arrows A 5 ) of the pull cable  80  and resistance cable  31  over the pulleys. 
       FIG. 4  is a side elevational view of the apparatus of  FIG. 1  showing in solid lines the pivot arm structure  50  in the horizontal middle position (in plane P 50 ).  FIG. 4  shows in phantom lines the rod  12  in an uppermost position, wherein the handle bracket is disposed near the top end of the vertical frame  11 , and in an opposing lowermost position in which the rod  12  is disposed near the lowermost end of the frame (near the base member  14 ). The base  14  sits generally horizontal and adjacent to the ground plane P 2 , and the central support column  22  is vertically disposed above the base  14 . Trusses  19   a  and  19   b  rigidly support the central support column  22  in an upright vertical position with respect to the base  14 . About half-way up the vertical support  22 , the pivot arm structure  50  is disposed at a height H 1  in the horizontal plane P 50 . The right pulley housing  71   b  and handle  90   b  are in a relaxed position extending vertically downward, from the plane P 50 . 
     The arm structure  50  is pivotally mounted to the upright frame  11  by rotable joints  156  (see  FIGS. 1 ,  4  and  5 ). A releasable pin  168  is positionable in one of a series of user selectable apertures  171  disposed about the radius of a support plate  170  of the height adjustment assembly  160  for selectively adjusting and positioning the longitudinal axis LA of the rod  12  in any one of a plurality of fixed vertically variable (height) positions relative to a ground surface plane P 2 . As shown,  FIG. 4 , the longitudinal axis LA of rod  12  can be selectively fixed at any one of a plurality of different vertical distances or heights including middle H 1 , uppermost H 2  and lowermost H 3  positions, relative to the ground plane P 2 . The rod  12  can be fixed at many other heights (varying vertical distances) above the ground plane P 2  depending on the predetermined number and location of fixing apertures  171  provided on the pivot or height adjustment assembly  160 . The apertures define the multiple pivotable positions of the support arm structure  50  on the upright frame  11 . 
       FIG. 5  shows a top view of the apparatus of  FIG. 1  in use wherein a user (not shown) is pulling on the right handle assembly  60   b . The right handle bracket  60   b  is shown sliding across the rod  12  to the left, as previously described. The pull cable  80  extends from the right handle  90   b , through the right handle bracket  60   b , across a portion of the rod  12 , into the left handle bracket  60   a  and ending at the left handle  90   a . The resistance cable  31  extends from the right handle bracket  60   b  around the right front side pulley wheel  35   b , around the right rear side pulley wheel  36   b , around the right central pulley wheels  37   b - 38   b , and into the central housing  23  (where it further extends around the common wheel  42 , not shown) before exiting from the central housing  23  and extending over the left central pulley wheels  37   a - 38   a , the left rear side wheel  36   a , the left front side wheel  35   a , and terminating at the left handle bracket  60   a . The resistance pulley wheels are mounted in respective housings fixed to the pivot arm structure  50 . The upper and lower central pulley wheels  37 - 38  are mounted to a transverse arm  56  extending between the side arms  52   a ,  52   b  of the pivot structure  50 , with the resistance cable  31  disposed in a bore of the transverse arm  56 . A pair of counterweights  55   a ,  55   b  are attached to a rear transverse arm  51  of the pivot arm structure for counterbalancing the pivot arm structure  50 . A pair of diagonally disposed trusses  20   a ,  20   b  extending from the vertical support structure  22  support the transverse arm  56  and rotatable joints  156 . 
       FIG. 5  also shows in greater detail the adjustment mechanism  160  for varying the pivot position of the arm structure  50 . A user (not shown) engages a finger lever  162  at one end of an adjustment cable  163 , the cable  163  extending through a central bore of the right support arm  52   b  and over a pulley wheel  165  mounted in the right end of transverse arm  56 ; the other end of the adjustment cable  163  is attached to a pin  168  for releasable insertion into one of the apertures  171  in the support plate  170 , for selecting (fixing) the respective pivot position of the arm structure  50 . 
       FIG. 6  is a fragmentary detailed perspective view of the left handle assembly  60   a  in use. When a user (not shown) pulls on the left handle  90   a  (not shown) connected to pull cable  80  in the direction of the arrow A 10 , the pull cable  80  rotates about pulley wheel  76   a  and is extended further from pulley housing  71   a  of the left handle bracket  60   a . The housing  71   a  includes two spaced apart parallel plates between which is defined a cavity  72   a  in which the pulley wheel  76   a  resides; the wheel is free to rotate in the cavity, being rotatably mounted between the opposing plates by a pin  75   a . The housing has an open end  74   a  from which the pull cable  80  extends, and an opposing second end  73   a  attached to the slidable tube or sleeve  62   a  of the left handle bracket  60   a . The tube or sleeve  62   a  has a central bore  63   a  which is slidable over rod  12 , as shown by the arrows. The tube or sleeve  62   a  is mounted on rod  12  by a bearing assembly  110   a  which is illustrated in  FIGS. 7-8 . Mounted on one end of the tube  62   a  is a tabbed collar  130   a ; the collar includes a tubular collar portion  131   a  concentrically disposed over and around the tube  62   a  (or an inwardly disposed distal tubular end  132   a  of the tube  62   a ), and a transverse arm  134   a  extending radially from the collar portion  131   a  and having at its opposing end a threaded connector  138   a  that secures the first distal end  33  of resistance cable  31  to the tube  62   a /collar  130   a . A snap ring  147   a  and washer  146   a  secure the collar  130   a  to the end of the tube  62   a . The collar  130   a  is freely rotatably mounted on and around the slidable tube  62   a  and bracket  60   a . Thus, both the bracket  60   a  and the collar  130   a  are freely rotatably mounted on and around the rod  12  for free rotation around the axis LA (see arrows A 11 ), the bracket  60   a  and collar  130   a  being independently freely rotatable around each other and the rod  12  axis LA. Also extending from tube  62   a  is a curved arm  101   a  having at its opposing end a counterweight  100   a  for counterbalancing the weight of the pulley housing  71   a , pulley wheel  76   a  and handle  90   a . This ensures that both pull cable  80  and resistance cable  31  lie in planes substantially parallel to rod  12  (e.g., in plane P 50  in the middle position). 
     As previously described, the left side support arm  52   a  has, adjacent its front end, a housing  39   a  for mounting the left front pulley wheel  35   a , and a pair of aligned apertures  58   a , through which the resistance cable  31  extends in parallel alignment with rod  12 . As a result, when a user pulls on the left handle  90   a , the pull cable  80  extends forwardly away from the frame  11 , typically in a forwardly and rightwardly direction (see arrow A 10 ), causing the pull cable  80  to rotate counterclockwise about wheel  75   a , pulling the sliding tube  62   a  and the attached resistance cable  31  to the right (arrow A 12 ) along rod  12 , to the extent the user&#39;s pull force can overcome the resistance set by the weight stack  150  to which the resistance cable  31  is attached. 
       FIG. 7  is a more detailed internal view of the left handle assembly of  FIG. 6 , taken along lines  7 - 7 , showing a cross section of the slidable tube  62   a , tabbed collar  130   a  and a bearing assembly  110   a  for mounting tube  62   a  on rod  12 . As shown and described below, the handle bracket  60   a  and slidable tube  62   a  are assembled together with the collar  130   a  in a manner such that the bracket  60   a /tube  62   a  and collar  130   a  are each rotatable independently of each other (arrow A 13 ) for free rotation around the longitudinal axis LA of the rod  12 . The bearing assembly includes a pair of left and right bearing sleeves  112   a ,  112   a  concentrically disposed about axis LA and on either side of a hollow cylindrical spacer  114   a ; together the sleeves and spacer are secured within the central bore  63   a  of tube  62   a , enabling the tube  62   a  to slide on the outer surface of rod  12  in both the left and right directions. A bearing retainer  118   a  and washer  116   a  are provided at each opposing end of the tube  62   a  for securing the bearing assembly within the tube bore  63   a . This same bearing assembly is further illustrated in the exploded perspective view of  FIG. 8 . 
     As further illustrated in  FIGS. 7-8 , the collar  130   a  includes a tubular collar portion  131   a  which is secured to the outer circumference of the tubular end  132   a  of tube  62   a  at one distal end  65   a  thereof, the collar being secured to the tube by a washer  146   a  and snap ring  147   a  such that the collar  130   a  and the bracket  60   a /tube  62   a  are longitudinally fixedly attached to each other and forced to travel or slide longitudinally along the axis LA together with each other. Extending transverse to the collar portion  131   a  is an arm or tab  134   a  having at its free end an aperture  136   a  through which the resistance cable  31  extends, and an adjacent threaded portion  138   a  which secures the first end  33  of resistance cable  31  to the left handle bracket  60   a . As previously described the handle bracket assembly  60   a  maintains both the pull cable  80  and resistance cable  31  in substantially parallel alignment with the rod  12  during use. 
     In an alternative embodiment shown in  FIG. 7A , the collar  130   a  on which the resistance cable  31  is mounted and the bracket  60   a  to which the handle pulley  76   a  is attached can alternatively be configured such that the collar  130   a  is mounted directly on the outside surface of the rod  12  via bearings that enable the collar  130   a  to rotate freely around and on the surface of the rod  12 . In such an embodiment, the sleeve or bracket  60   a  is preferably rotatably mounted on an outside surface of a tubular element of the collar  130   a  such that the bracket  60   a  is rotatable independently and freely around and on the collar  130   a.    
       FIGS. 9-11  show three schematic cross-sectional views of the left handle bracket assembly taken along line  9 - 9  of  FIG. 7 , with the left support arm  52   a  in three different positions.  FIG. 9  shown the support arm  52   a  in a middle position (in horizontal plane P 50 ). The rod  12  is shown in cross section within the bore of the bearing sleeve  112   a ; the bearing sleeve lies concentrically within the bore of tube  62   a . The bearing sleeve and tube can rotate clockwise and counterclockwise about the rod  12 . One end  33  of the resistance cable  31  is anchored to the arm  134   a  of  130   a . The counterweight  100   a  on arm  101   a  counterbalances the bracket housing  71   a  and pulley wheel  76   a , about which the pull cable  80  rotates. 
     In  FIG. 10 , the left support arm  52   a  has been rotated counterclockwise (see arrow A 14 , with respect to the position shown in  FIG. 9 ) to a lower position, such that rod  12  now lies in a horizontal plane closer to the ground surface  2 . In this position, a user will pull upwardly on pull cable  80  (see  FIG. 2B ). The left handle  90   a  (not shown) accommodates this upward pulling motion by pulley wheel  76   a  and pulley housing  71   a  being rotated clockwise (arrow  15 ) about rod  12 . As a result, the counterweight  100   a  is now shown at a lower position (closer to ground plane P 2 ), below the horizontal plane in which rod  12  resides. 
     Similarly,  FIG. 11  shows the left support arm  52   a  rotated clockwise (arrow A 16 ) in the opposite direction, placing rod  12  in a higher position. Now, a user pulls downwardly on pull cable  80 , causing the pulley wheel  67   a  and pulley housing  71   a  to rotate counterclockwise (arrow A 17 ) about rod  12 . As a result, the counterweight  100   a  is now positioned above the horizontal plane in which rod  12  resides. 
     While specific embodiments of the present invention have been shown and described, it will be apparent that many modifications can be made thereto without departing from the scope of the invention. Accordingly, the invention is not limited by the foregoing description.