Abstract:
A weight lifting machine provides an instantaneous variable resistance, which can be adjusted manually during a workout routine or through a program, which has been selected by the user prior the workout routine. The weight lifting machine includes a pair of guides and a stack of weights which are slidably mounted on the guides and movable along the guides from a rest position to an elevated position. The weight lifting machine also includes a selector member and a lift member. Each of the weights includes an opening to receive the selector member. The openings are aligned to define a transverse passage through the stack of weights to allow the selector member to couple to each of the weights in the stack. The selector member includes a plurality of couplers which are adapted to instantaneously couple to and decouple from respective weights of the stack of weights. The lift member, which is coupled to the selector member, is adapted to permit a user of the weight lifting machine to pull and thereby raise the weights coupled to the selector member from their respective rest positions to their respective elevated positions. In preferred form, the couplers comprise electromagnetic couplers, with each of the electromagnetic couplers being adapted to be selectively energized and de-energized for coupling to and decoupling from a respective weight in the stack of weights.

Description:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to a weight lifting machine and, more particularly, to a weight lifting machine which permits the user to select a sequence in which the weight is increase or decreased at various intervals during the workout routine or permits the user to adjust the weight during the workout routine without dismounting the machine. 
     Conventional weight lifting machines comprise a frame which includes a pair of spaced apart generally vertical tracks with a plurality of weights and a carriage movably mounted on the tracks. The carriage typically includes a select post or bar which extends through the central portions of the weights and is manually coupled to one or more of the weights to increase or decrease the weight coupled to the carriage. Typically, the weights are coupled to the select bar by a removable pin which extends through the weight and through a corresponding aperture in the select bar. The carriage also is connected to a cable on the distal end of which is connect a handle bar, with the cable being supported on the frame by a pair of pulleys. Therefore, when the user of the machine pulls on the handle bar the carriage moves up the tracks, with the resistance being a function of the number of weights that are coupled to the carriage. In order to vary the weight on the carriage, and therefore the resistance for the user of the machine, the user of the machine must return the carriage to the starting position and relocate the pin either to reduce the number of weights attached to the select bar or increase the number of weights attached to the select bar. 
     In some machines the adjustment requires the user to demount the machine. Furthermore, the adjustment requires a break in the routine and may prevent the user from reaching his or her optimal workout. As it is known in the weight lifting art, the key to obtaining maximum muscle building is to push the muscle beyond its normal everyday demands. Since muscle can recover some of its strength in a short duration, the user of the exercise machine may not achieve his or her maximum fatigue point when his or her exercise routine includes pauses when for example the user needs to change the weight. 
     More recently, exercise devices have incorporated variable resistance capabilities which allow the user of the exercise machine to maximize his or her benefits from the machine. For example, in U.S. Pat. No. 5,037,089 to Spagnuolo weights are selected by mechanical actuators which are controlled by the user of the exercise machine. The mechanical actuator includes a solenoid and a pin, which is held in place by a spring. When the solenoid is energized, the pin is withdrawn from the weight which reduces the resistance for the user of apparatus. The solenoids are controlled by a module which includes a microprocessor which permits the user of the equipment to increase or decrease the weight as desired. However, these actuators still rely on pins extending into and out of the selector bar. Therefore, the decoupling and coupling is not instantaneous. Moreover, there may be increased potential for jams, which result from misalignment of the pins with the select bar. Because these type of jams can not be manually fixed, there is an even greater potential for interruption. 
     Accordingly, there is a need for a weight lifting machine which allows the user of the machine to instantly vary the resistance during a workout and, further, to choose a preprogrammed workout, which does not include transition delays associated with the pin couplers. 
     SUMMARY OF THE INVENTION 
     Accordingly the present invention provides a weight lifting machine which includes a at least one guide and a stack of weights which are slidably mounted on the guide and movable along the guide from a rest position to an elevated position. The weight lifting machine also includes a selector member and one of a lift cable and a lift bar. Each of the weights includes an opening to receive the selector member. The openings are aligned to define a transverse passage through the stack of weights to allow the selector member to couple to each of the weights in the stack. The selector member includes a plurality of couplers which are adapted to instantaneously couple to and decouple from respective weights in the stack of weights, and the lift cable, which is coupled to the selector member, is adapted to permit a user of the weight lifting machine to pull the lift cable or the lift bar and thereby raise the weights coupled to the selector member from their respective rest positions to their respective elevated positions. 
     In one form, the couplers comprise electromagnetic couplers, with each of the electromagnetic couplers being adapted to be selectively energized and de-energized for coupling to and decoupling from a respective weight in the stack of weights. 
     In other forms, the lift cable or the lift bar is coupled to a handle, which the user can grasp to move a selected weight or weights from the rest position to the elevated position. The machine preferably includes a frame, which supports the lift cable or the lift bar and the guide. For example, the lift cable may be supported on the frame by at least one pulley. Furthermore, the frame may include a seat on which the user may sit when using the machine. 
     In yet further forms, the machine preferably includes a control module, which is electrically coupled to each of the electromagnetic couplers. The control module provides electrical current to the electromagnetic couplers for selectively energizing the electromagnetic couplers to respective weights on the stack of weights. Furthermore, the machine may include a sensor for detecting when at least one of the weights has been lifted from its respective rest position to its respective elevated position to determine the number of repetitions that have been completed, with the sensor being in communication with the control module and providing input into the control module. 
     As will be understood from the foregoing, the weight lifting machine of the present invention provides for instantaneous changes in resistance. Furthermore, the present invention allows the user the machine to pre-select or pre-program a workout routine and yet provide the user with a manual override option. Moreover, by provide remote control of the coupling and decoupling of weights to the selector member, the exercise machine can be reconfigured as desired to optimize the mechanical arrangement of the lift cable and the like. 
     These and other objects, advantages, purposes and features of the invention will become more apparent from the study of the following description taken in conjunction of the drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation of the weight lifting machine of the present invention; 
     FIG. 2 is a side elevation of the weight lifting machine of FIG. 1; 
     FIG. 3 is a rear elevation view of the weight lifting machine of FIG. 1; 
     FIG. 4 is an enlarged partial fragmentary elevation of a stack of weights illustrating electromagnetic couplers mounted to a selection rod for selectively coupling a respective weight to the selection rod; 
     FIG. 5 is a side elevation of the selection rod with the electromagnetic couplers mounted thereto; 
     FIG. 6 is a schematic circuit diagram illustrating a control circuit for the electromagnetic couplers; 
     FIG. 7 is an enlarged view of an input control module for the control circuit; 
     FIG. 8 is a flow chart of the control circuit for the weight lifting machine; 
     FIG. 9 is a side elevation of a second embodiment of the weight lifting machine of the present invention; 
     FIG. 10 is a side elevation of a third embodiment of the weight lifting machine of the present invention; 
     FIG. 11 is a side elevation of a fourth embodiment of the weight lifting machine of the present invention; and 
     FIG. 12 is a side elevation of a fifth embodiment of the weight lifting machine of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a weight lifting or exercise machine  10  is shown which includes a frame  12  that supports a pair of generally vertically oriented guide rods or rails  14  and  16  on which a stack of weights  18  and a carriage  22  are moveably mounted. As will be described in more detail below, the individual weights  20  of stack  18  are selectively coupled and decoupled from carriage  22  to increase or decrease the resistance for the user of machine  10 . 
     Carriage  22  comprises a base member  23  which includes a pair of spaced apart bushings or bearings  23   a  and  23   b , for example linear bearings. Bushings  23   a  and  23   b  define transverse passages through base  23  and guide carriage  22  on guide rods  14  and  16 . Mounted to base  23  of carriage  22  is a lift member or lift cable  24 . Lift cable  24  is secured at one end  24   a  to carriage  22  by a coupler  24   b , including for example a threaded coupler, and secured to a handle  25  at a second end  24   b . Lift cable  24  extends from carriage  22  upwardly through frame  12  and over a pair of spaced apart cable pulleys  26  and  28  which position handle  25  over a workout bench or seat  30 . In this manner when handle  25  is pulled downwardly, carriage  22  and any weights  20  which are coupled to carriage  22  move up guide rods  14  and  16 , with the resistance on the handle being a function of the number of weights coupled to the carriage  22 . 
     Referring to FIGS. 1-3, frame structure  12  includes a pair of horizontally spaced front and back base members  34  and  36  which are interconnected by opposed side base members  38  and  40 . Frame structure  12  further includes front and back upper members  42  and  44  which are similarly interconnected by opposed side upper members  46  and  48  and which are further interconnected to base members  32 ,  34 ,  36 , and  38  by a plurality of column members  50 ,  52 ,  54 , and  56 , which form a rigid frame and support guide rods  14  and  16 . Guide rods  14  and  16  are mounted to upper members  46  and  48  by a transverse cross member  58  which extends between upper members  46  and  48  on one end and are similarly mounted to base members  38  and  40  by a lower transverse member  60  which extends between lower base members  38  and  40 . Pulleys  26  and  28  are respectfully rotatably supported on frame  12  by a cantilever support member  62  which is mounted to upper members  42  and  44 . Pulleys  26  and  28  are rotatably mounted on member  62  by pins  26   a  and  28   a , respectively, which extend through transverse holes  62   a  provided in member  62 . It can be appreciated, in this manner at least the location of pulley  26  can be adjusted to accommodate different weight lifting configurations. 
     As best seen in FIGS. 1 and 2, seat  30  is positioned forwardly of frame  12  and is supported from a vertical intermediate frame member  64  which is secured to front base member  34 . Seat  30  is preferably supported from vertical member  64  by a braced cantilever member  66 . In addition to seat  30 , exercise machine  10  may include a leg restraint  33 . Leg restraint  33  is positioned forward of seat  30  so that the user can restrain himself or herself from lifting off seat  30  when working out with a weight that exceeds his or her own body weight. Restraint  33  includes a pair of cylindrical padded members  33   a  and  33   b  which are rotatably mounted on a tubular member  35  which is similarly mounted to vertical support or member  64  by a cantilever member  68 . Preferably, both seat  30  and restraint  33  are adjustably mounted to vertical support  64  to accommodate users of different height and proportions. In this manner, when a user is seated on seat  30 , the user may position his or her legs under restraint  33  and pull on handle  25  which in turn pulls on carriage  22  by way of lift cable  24 . As described previously, the amount of resistance depends on the number of individual weights  20  that are coupled to carriage  22 . 
     As best seen in FIG. 4, carriage  22  includes downwardly depending selection rod or member  65  in which a plurality of electromagnetic couplers  70  are positioned or mounted. In preferred form, selection rod  65  includes a plurality of cavities  71 , which can be milled, cast or formed from welded components forming selection rod  65 , in which electromagnetic coils  71   a , which form electromagnetic coupler  70 , are held in a respective cavity  71  by an adhesive, such as an epoxy potting material. Referring to FIGS. 4 and 5, selection rod  65  extends through central openings  72  provided in weights  20  and includes a respective electromagnetic coupler  70  for each individual weight  20  in stack  18  so that each weight can be individually and selectively coupled to selection rod  65 . Given the high tensile force, on the order of 1200 lbs, of the individual electromagnetic couplers  70 , only one exposed side or face  70   b  of electromagnetic couplers  70  are needed to hold the respective weights  20 . However, it should be understood that more than one side of electromagnetic couplers  70  may be exposed for holding the respective weights. Alternatively, electromagnetic couplers  70  may be mounted to selection rod by conventional means, such as fasteners or the like. 
     Electromagnetic couplers  70  are energized or de-energized through a control circuit  75 , shown in FIG. 6, which will be more fully described below. In this manner, each respective electromagnetic coupler  70  can be individually activated or deactivated to couple to or decouple from its respective weight  20  in stack  18  to increase or decrease the weight coupled to carriage  22 . Furthermore, the weights are instantaneously coupled or decoupled which eliminates any transition time between changes in the resistance. Consequently, the user of the weight lifting machine can work to his or her optimum fatigue point without resting. 
     As best seen in FIG. 6, control circuit  75  includes a control center  76 , which in turn includes a processor such as a microprocessor, and preferably a memory storage device, an AC to DC converter  78 , a manual input control  80 , such as a manual drop switch, and a proximity sensor  82 . In the illustrated embodiment, converter  78  is supported in a housing  85  which is mounted to frame  12  on column member  52 . Converter  78  is electrically coupled to a 110-volt AC power drop  88  through conventional wiring. Housing  85  includes a wire chase or harness  90  through which electrical wires extend from housing  85  to weight stack  18 . Wires  70   a  extend along frame  12  or in the frame&#39;s ( 12 ) tubular members  52 ,  46 , and  58  to housing  85  where they exit from housing  85  through wire chase  90 . Wire chase  90  preferably extends through base  23  of carriage  22  and down through selection member  65  to electrically couple each electromagnetic coupler  70  to control center  76 . 
     Control center  76 , which also includes manually operational buttons as described below, is preferably mounted to a forward portion of frame  12  which is easily accessible by the user of the machine, for example column member  50 . Referring to FIG. 7, control center  76  preferably includes a touch pad having a plurality of buttons or touch pads  92  and  94  to increase or decrease the start weight, a pair of buttons or touch pads  96  and  98  to increase or decrease the drop weight, and a pair of buttons or touch pads  100  and  102  to increase or decrease the number of repetitions at which the drop weight occurs. Furthermore, control center  76  preferably includes an enter button  104  and a clear button  106  to start and to stop the sequence. Control module  76  also preferably includes a plurality of readouts  108 ,  110 , and  112  either in analog or digital form, for example LCDs, to indicate the starting weight, drop weight, and the number of repetitions before the drop is automatically executed, which is selected by the user. In this manner, the user of the weight lifting machine  10  may manually select a program of varying weights for each workout. In addition, control circuit  75  preferably includes manual drop switch  80  which allows the user to drop one weight at a time. Preferably, manual drop switch  80  comprises a foot switch, which is easily accessible by the user of the machine, as shown in FIGS. 2 and 3. Manual drop switch  80  may be used in lieu of an auto drop weight input into control center  76  or may be used to override control center  76 , for instance when the user has not yet reached the number of pre-set repetitions. In addition, control circuit  75  may include emergency drop switch  84 , which can be mounted on handle  25 , which provides for a quick release of all the weights  20  in the event of a cramp or other similar situations. 
     As best seen in FIG. 1, switch  80  may be coupled or mounted to base member  34  by a conduit  80   b  though which switch  80  is powered by conventional wiring. Conduit  80   b  may comprise a rigid conduit or a flexible conduit to permit repositioning of switch  80  as desired. Alternately, manual drop switch  80  can be located on handle  25 . Manual drop switch  80  is preferably coupled to control center  76  and optionally can provide an override of the program which has been input into control center  76 . 
     Referring again to FIG. 2, the respective electrical wiring  80   a ,  84   a , and  82   a  for manual drop switch  80 , emergency drop switch  84 , and proximity switch  82  are preferably harnessed and extend through framework  12  and are directed by the frame members of frame  12  to control module  76 . Optionally, frame members  34 ,  36 ,  38 ,  40 ,  42 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 , and  56  comprise tubular members, which are welded together or otherwise rigidly interconnected and provide a conduit for electrical wiring  80   a ,  82   a , and  84   a , which respectively electrically connect manual switch  80 , proximity sensor  82 , and emergency switch  84  to control center  76 . As described previously, electrical wiring  70   a  which couples electromagnetic couplers  70  to control center  76  are directed to control center  76  via wire chase  90 . 
     Proximity sensor  82  is supported on frame  12  by a transverse support member  94 , which extends between columns  52  and  54 . Proximity sensor  82  provides input to control center  76  and determines the number of repetitions that have been completed so that the microprocessor can initiate a change in the weight. Proximity sensor  82  is, therefore, preferably mounted above the starting position of stack  18  so that when a weight is lifted above sensor  82  the sensor detects a repetition. 
     In order to reduce the impact on frame  12  when weights  20  are lowered to their respective starting positions, rails  14  and  16  preferably include springs  120  interposed between the lowermost weight  20 ′ and transverse member  60 . 
     It should be understood from the foregoing that when a user is seated on bench  30 , the user may reach control center or module  76  to either select a preprogrammed sequence or select a program, which would provide a variable resistance over the duration of the workout, by using buttons  92 ,  94 ,  96 ,  98 ,  100 , and  102 . Furthermore, the user may use the manual drop switch  80  to manually drop the weight if the auto-drop sequence is not selected in control center  76 . 
     Furthermore, it should be understood that weight lifting machine  10  permits the user to adjust the sequence of the workout without releasing handle  25  and, furthermore, without moving from seat  30 , which is especially desirable for a new user or an occasional user who is unfamiliar with the resistance that best suited for him or her. In addition, by providing remote control of the couplers, the configuration of the seat, leg restraint, and handle may be optimized and provide for custom configurations. Thus, the configuration of the weight machine can be built in an optimal mechanical fashion rather than by the dictates or requirements of the weight stack. 
     Referring to FIG. 8, a computer program  125  may be preprogramed and stored in the control center memory storage device. Computer program  125  preferably includes an initial clear or start condition, in which all the electromagnetic couplers are de-energized. Then, the program  125  waits for a prompt from buttons  92  and  94  to select an initial or start weight. If no further input is given after the initial weight is selected, then a preprogramed set will start with the start weight remaining constant through the workout cycle, unless manual drop switch  80  is used. However, if a drop weight is selected by the user, then the program will wait to receive input from buttons  100  and  102  for the number of repetitions which indicates when the drop weight is to be decoupled from the selection rod. It should be understood to those having ordinary skill in the art that the program can be varied and modified to provide other options and variations. 
     Referring to FIG. 9, a second embodiment  210  of an exercise machine is shown. Exercise machine  210  includes a frame  212  which supports a pair of generally vertical oriented guide rods or rails  214  and  216  in which a stack of weights  218  and a carriage  222  are moveably mounted. Reference is made to the first embodiment for details of carriage  222  and its respective selection rod and electromagnetic couplers (not shown). In this embodiment, a lift member or lift cable  224  is secured at one end  224   a  to carriage  222  and secured to an ankle pad  225  and a second end  224   b . Cable  224  extends from carriage  222 , similar to that previously described in reference to the first embodiment, upwardly through frame  212  and over a pair spaced apart cable pulleys  226  and  228  and extends downwardly behind a third cable pulley  229  which is supported on frame  212  and positioned to align second end  224   b  of lift cable  224  and ankle pad assembly  225 . 
     Mounted to frame  212  is a seat  230 . Seat  230  is positioned above ankle pad assembly  225  which is pivotally mounted to seat  230  by a pivotal arm  231 . Preferably, ankle pad assembly  225  comprises a pair of cylindrical padded members  233   a  and  233   b  which are rotatably mounted on a tubular member  235 . Tubular member  235  is mounted to the end portion of pivotal arm  231  so that when a user is seated on seat  230 , the user&#39;s legs can extend behind cylindrical padded members  233   a  and  233   b  for positioning his or her feet behind the respective padded members  233   a  and  233   b . When the user extends his or her legs and pushes against padded members  233   a  and  233   b  with his or her respective feet or ankles, arm  231  pivots with a resistance that is a function of the number of weights  220  coupled to the selector rod and to carriage  222 . In this embodiment, both the control center  276  and a manual drop switch  280  may be mounted to frame  212  or seat  230  so that they are accessible and can be reached by the users hands. Reference is made to the first embodiment for preferred details of the control center and the control circuit. 
     Referring to FIG. 10, a third embodiment  310  of the weight lifting or exercise machine is illustrated. In this embodiment, exercise machine  310  comprises a rowing-type exercise machine and includes a frame  312  which is configured to provide an upper and lower body workout. Frame  312  includes a pair of generally vertically oriented guide rods or rails  314  and  316  on which a stack of weights  318  and a carriage  322  are movably mounted. Similar to the first and second embodiments, the individual weights  320  of stack  318  are selectively coupled and decoupled from carriage  322  to increase or decrease the resistance of the user of the machine  310  by energizing or deenergizing the electromagnetic couplers provided or formed on the selection rod of the carriage. 
     For further details of carriage  322  and its selector rod and electromagnetic couplers (not shown) reference is made to the first embodiment. Exercise machine  310  includes a lift member or lift cable  324 , which is secured at one end  324   a  to carriage  322  and secured to a handle  325  at a second end  324   b . Lift cable  324  extends from carriage  322  upward through frame  312  and over a pair of spaced apart pulleys  326  and  328  and downwardly behind a third pulley  329  which is mounted to a lower but forward portion of frame  312  and which positions handle  325  over a sliding seat  330 , for example a rowing seat. In this manner, when handle  325  is pulled outwardly from frame  312 , any weights  320  which are coupled to carriage  322  move up guide rods  312  and  314 , with the resistance on the handle being the function of the number of weights coupled to the carriage  322 . 
     Referring again to FIG. 10, secured to frame structure  312  is a seat frame  331 . Seat frame  331  supports sliding seat  330  and includes a foot restraint  332  so that when the user is seated on seat  330 , the user can lock his or her feet in position at the foot restraint while pulling on handle  325  such that the users can slide along seat frame  331  and move his or her legs from a folded position to a fully extended position to engage in a rowing exercise. 
     Referring to FIG. 11, a third embodiment  410  of weight lifting or exercise machine is illustrated. In this embodiment, weight lifting machine comprises a calf exerciser and includes a frame  412  with a foot rest  430  which is secured to a base member  432  of frame  412 . Frame  412  also includes a pair of generally vertically oriented guide rods or rails  414  and  416  in which a stack of weights  418  and a carriage  422  are movably mounted. The individual weights  420  of stack  418  are selectively coupled and decoupled from carriage  422  to increase or decrease the resistance of the user of the machine  410 , in a similar manner to that described in reference to the first embodiment. Therefore, reference to the first embodiment is made for further details of weights  420  and carriage  422  including its selector bar (not shown) and the control circuit which activates or deactivates the electromagnetic couplers on the selector bar. 
     Mounted to base  423  of carriage  422  is a lift member  424 , such as a lift cable, lift chain, or lift rod or bar. Lift member  424  is secured at one end to carriage  422  and pivotally secured at its second end to a lift arm  425 , which in turn is pivotally mounted to frame  412 . Mounted or secured to the free end of lift arm  425  is a shoulder pad  425   a . In this manner, a user of exercise machine  410  stands on foot pad  430  and places shoulder pads  425   a  on his or her shoulders. As the user pivots about his or her ankles, the user extends and contracts his or her calf muscles with a resistance that is a function of the number of weights  420  which are coupled to carrier member  422 . It should be understood that lift arm  425  preferably comprises a pair of spaced apart arm members, which are interconnected by intermediate transverse or bracing members  426 . Additionally, shoulder pad  425   a  may comprise a single shoulder pad with a cut-out for the users neck or may comprise two spaced apart shoulder pads, which would allow the user&#39;s neck to be positioned between the respective shoulder pads, as would be understood by those having ordinary skill in the art. 
     As best seen in FIG. 12, a fifth embodiment  510  of weight lifting or exercise machine is illustrated. In this embodiment, exercise machine  510  comprises a leg curl exercising machine and includes a frame  512  which supports a pair of spaced apart guide rails or guide rods  514  and  516  on which a stack of weights  518  and a carriage  522  are movably mounted. Individual weights  520  of stack  518  are selectively coupled and decoupled from carriage  522  to increase or decrease the resistance for the user of the machine by a plurality of electromagnetic couplers, as described in reference to first embodiment. 
     Mounted to base  523  of carriage  522  is a lift member or lift cable  524 . Lift cable  524  is secured at one end  524   a  to carriage  522  and secured at a second end  524   b  to a foot or ankle pad assembly  525 . Lift cable  524  extends upward through frame  512  and over a first pulley  526  supported on an upper member of frame  512  and then downwardly and outwardly below a second pulley  528  and third pulley  529 , which are respectively supported on a base member  532  of frame  512  and which direct cable  524  to ankle pad assembly  525 . 
     Frame  512  includes a bench or seat  530 , which may be releasably coupled to frame  512  or integrally formed or rigidly coupled to frame  512 . The user of machine  510  lays generally face downward with his or her legs extending beneath foot or ankle pad assembly  525 . Foot or ankle pad assembly  525  is mounted to a support arm  525   a , which is pivotally mounted to seat  530 . In this manner, when a user of the machine  530  lays face down on seat  530  with his or her legs extending below ankle or foot pad assembly  525 , the user can curl his or her legs to move foot pad assembly  525  from a first position wherein the users legs are fully extended to a second position wherein the users legs are curled. In this manner, the resistance experienced by the user is a function of the number of weights  520  which are coupled to the carriage  522 , as described in reference to the first embodiment. Preferably, seat  530  includes a hand restraint  533  which enables the user of exercise machine  530  to restrain his or her upper body movement during an exercise routine. 
     Furthermore, while various forms of the invention have been shown and described, other forms are being apparent to those skill in the art. It should be understood that the general concept of a stack a weights with a selection member with a plurality of individually selectively activated electromagnetic couplers can also be used in other weight lifting configurations. Therefore, the embodiment of the invention shown in the drawings is not intended to limit the scope of the invention which is instead defined by the claims which follows.