Patent Publication Number: US-10765900-B2

Title: Weights system

Description:
DESCRIPTION OF INVENTION 
     This invention relates to a system of pulleys and weights, and in particular a system which delivers a variable amount of force to a user. 
     In order to improve strength and fitness, many people lift weights. When lifting weights a user may simply perform repetitions with free weights, or a user may perform repetitions with one of a myriad of different exercise machines in order to target one or more specific muscle groups. Exercise machines have an advantage over free weights in that they allow a user to perform weight lifting in a more safe, efficient and versatile manner. Typically, exercise machines allow users to perform repetitions against a constant resistance, which may operate via a cam mechanism that is fixed at the time of manufacture and is not modifiable by the user. 
     However, it recognised in the art that many users do not want to perform repetitions on exercise machines that provides a constant resistance throughout the repetition. It is advantageous for a user to be able to perform repetitions where the resistance provided by the exercise machine can vary throughout the repetition. This may be desirable, for instance, because a typical user is able to lower a much greater load than they can raise in a controlled manner. 
     Exercise machines that allow a user to vary the resistance applied throughout a repetition exist in the art. However, these machines are often oversized and complicated. 
     U.S. Pat. No. 5,356,360 discloses an exercise machine that uses a variable resistance cam to impart a variable resistance to a user performing a repetition. 
     Another example of an exercise machine known in the art is disclosed in EP 2316538. The exercise machine comprises a weight stack mounted within a moveable frame. The frame can pivot about its lower end so that its angle with respect to the vertical can be altered, such that the force imparted to a user may be varied during a repetition. 
     It is desirable to have an exercise machine that allows a user to vary the resistance applied throughout a repetition, but is not oversized or complicated when compared to an exercise machine that provides a constant resistance. 
     The present invention aims to address at least some of these problems. 
     The present invention relates to a system for imparting a variable user force to a user, the system comprising: a line guide arrangement, including at least one moveable line guide which may move in both directions along a linear axis; wherein a force arrangement is arranged to apply at least one internal force to the at least one moveable line guide, wherein the at least one internal force opposes the motion of the at least one moveable line guide in a first direction along the linear axis; a member with which the user may interact so that the user force is applied to the user through the member; a line, having a distal end and a proximal end, with the distal end of the line attached to the member, the line being continuously threaded around the line guide arrangement; the system further comprising a line adjustment arrangement, wherein: the line adjustment arrangement is attached to the line, or is connected to move a component of the line guide arrangement; when the line adjustment arrangement is in a locked mode, there is a first ratio between distance moved by the member and distance moved by the force arrangement; and the line adjustment arrangement is operable to remove/introduce line between an entry point and the member, or actively move the component of the line guide arrangement, to alter the ratio between distance moved by the member and distance moved by the force arrangement during movement of the member. 
     Preferably, the user force is proportional to the internal force and the user force may be varied by manipulating the line adjustment arrangement. 
     Preferably, the user performs a first motion when the member is moved in a first direction and performs a second motion when the member is moved in a second direction. 
     Preferably, the system is configured to apply a first mode of operation during the first motion and a second mode of operation during the second motion, wherein the line adjustment arrangement changes the length of line between the entry point and the member is in a different manner during the first and second modes of operation. 
     Preferably, the first or second mode of operation is such that the first or second motion may be performed without any active change in the length of the line between the entry point and the member being applied by the line adjustment arrangement. 
     Preferably, the system is configured to apply a third mode of operation when the member is stationary between the first and second motions, wherein the line adjustment arrangement changes the length of line between the entry point and the member. 
     Preferably, the system is configured to apply a fourth mode of operation when the member is stationary between the second motion and a further first motion, wherein the line adjustment arrangement changes the length of line between the entry point and the member. 
     Preferably, the third and/or fourth modes are configured such that, following the first and the second motions, the length of line in the system is the same as before the first motion. 
     Preferably, the line adjustment arrangement is able to adjust the length of the line in the system in a continuous manner. 
     Preferably, the line adjustment arrangement is able to adjust the length of the line in the system in a step-wise manner. 
     Preferably, in use, the internal force is applied by a mass within a gravitational field. 
     Preferably, in use, the internal force is applied by a rotor in an electromagnetic field. 
     Preferably, in use, the internal force is applied by the deformation of an elastic object. 
     Preferably, the line is a cable. 
     Preferably, the line is a belt. 
     Preferably, the line adjustment arrangement comprises a motorised spool or a winch. 
     Preferably, the line adjustment arrangement comprises a linear actuator. 
     Preferably, the line adjustment arrangement can be manipulated by the user, a third party, or both the user and the third party to change the length of line between the entry point and the member. 
     Preferably, the line adjustment arrangement can be manipulated through voice recognition to change the length of line between the entry point and the member. 
     Preferably, the line adjustment arrangement can be manipulated with a switch to change the length of line between the entry point and the member. 
     Preferably, the line adjustment arrangement can be manipulated through eye movement recognition to change the length of line between the entry point and the member. 
     Preferably, the system further comprises a measurement arrangement to measure movement of the member. 
     Preferably, the manipulation of the line adjustment arrangement is automated by a real-time system, the real-time system able to process at least the user force, the internal force and the length of line between the entry point and the member using a microprocessor. 
     Preferably, the manipulation of the line adjustment arrangement is automated by a real-time system, the real-time system able to process at least the user force, the internal force and the length line between the entry point and the member by mechanical means. 
     Preferably, the system is an exercise device. 
     The invention also provides a system for imparting a variable user force to a user according to any of the above. 
     The present invention may also relate to a system for imparting a variable movement force to an object or a user, the system comprising: a line guide arrangement, including a moveable line guide which may move in both directions along a linear axis; a force generator configured to apply a linear force to the moveable line guide, wherein the movement force moves the moveable line guide in a first direction along the linear axis or opposes the movement of the moveable line guide in a second direction along the linear axis; wherein the object or user is arranged to apply an object force to the moveable line guide, wherein the object force opposes the motion of the moveable line guide in the first direction along the linear axis or moves the moveable line guide in a second direction along the linear axis; a first line, which is coupled with the force generator and having an end attached to the line guide arrangement, so that the force generator can apply the linear force to the moveable line guide through the first line, and a second line, having a distal end and a proximal end, the second line being threaded around the moveable line guide, the distal end of the second line being attached to a line adjustment arrangement and the proximal end of the second line attached to a fixed point, wherein the line adjustment arrangement is operable to change actively the length of the second line such that the object or a user may move in the first direction or the second direction at a rate that is different to the rate of movement of the moveable line guide. 
     Preferably, the force generator comprises a motorised pulley. 
     Preferably, the object force is at least partially offset by a counterweight. 
     Preferably, the system is a lift mechanism. 
     The invention also provides a system for imparting a variable user force to an object or a user according to any of the above. 
    
    
     
       In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of a system for imparting a variable user force to a user according to an embodiment of the present invention; and 
         FIG. 2  is a schematic view of a system for imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 3  is a schematic view of a system for imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 4  is a schematic view of a system for imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 5  is a schematic view of a system for imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 6  is a schematic view of a system for imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 7  is a flow diagram showing the steps of imparting a variable user force to a user according to another embodiment of the present invention; and 
         FIG. 8  is a schematic view of a system for imparting a variable user force to an object according to another embodiment of the present invention. 
     
    
    
     The embodiment shown in  FIG. 1  comprises a first exercise machine  10  (only part of which is shown). The exercise machine  10  comprises a cable  11 , a first pulley  12 , a second pulley  13 , a third pulley  15 , a fourth pulley  16  and a fifth pulley  17 . These components are held in place by a frame  30 , which may take any suitable form. The cable  11  has a distal end attached to a handle  110 . In use, the user can grasp the handle  110  to perform an exercise. The cable  11  extends upwards from the distal end to pass over the first pulley  12 , which is preferably arranged at about head height. The first pulley  12  is vertically orientated and is rotatable about a first axis. The cable  11  extends downwards from the first pulley  12 , to pass under the second pulley  13 , which is preferably arranged at about waist height. The second pulley  13  is vertically orientated, is rotatable about a second axis and can move in both directions along a first, generally vertical linear axis. The second pulley  13  may be arranged to move along a vertical track (not shown), for example, to allow this motion to take place. 
     The cable  11  extends upwards from the second pulley  13  to pass over the third pulley  15 , which is preferably arranged at a similar height to the first pulley  12 . The third pulley  15  is vertically orientated and is rotatable about a third axis. The cable  11  extends away from the third pulley  15 , in a generally horizontal direction that is away from the first pulley  12  and the second pulley  13 , such that about a quarter of the surface of the third pulley  15  is in contact with the cable  11 , to pass over the fourth pulley  16 , which is preferably arranged at a similar height to the first pulley  12  and the third pulley  15 . The fourth pulley  16  is vertically orientated and is rotatable around a fourth axis. The cable  11  extends downwards from the fourth pulley  16 , to pass under the fifth pulley  17 , which is preferably arranged at about waist height. The fifth pulley  17  is vertically orientated, is rotatable about a fifth axis and can move in both directions along a second linear axis. Once again, the fifth pulley  17  may slide along a vertical track during this motion. 
     The cable  11  extends upwards from the fifth pulley  17 , with the proximal end of the cable  11  being attached to a bolt  19 . The bolt  19  is attached to the frame  30  of the exercise machine  10 . In another embodiment of the present invention, the bolt  19  is not present and the end of the cable  11  is welded directly to the frame  30  of the exercise machine. The cable  11  is continuously threaded around the first pulley  12 , the second pulley  13 , the third pulley  15 , the fourth pulley  16  and the fifth pulley  17 . A weight stack  14  is attached to the second pulley  13  and applies an internal force, in a first (i.e. downward) direction due to gravity, to the second pulley  13 . The weight stack  14  may be arranged to move along a vertical track (not shown), for example, to allow the weight stack to move in both directions along a first, generally vertical linear axis. 
     A user force is applied by a user through the handle  110 . In practice, a user pulls the handle  110  to lift the weight stack  14 . The user exerts a force on the handle  110  in order to lift the weight stack  14  and in doing so, the handle  110  exerts an equal and opposite force on the user. In practice, the user will pull the handle  110  down to raise the weight stack  14  against gravity, and will then allow the handle  110  to rise, to lower the weight stack  14  again to complete one repetition of an exercise. 
     The exercise machine  10  further includes a second cable  32 , which (in this example) is entirely separate from the cable  11  discussed above. The second cable  32  is attached at a distal end to a winch  18  and is attached at a proximal end to the fifth pulley  17 . The winch  18  may be operated to rotate a drum (not shown) around which the second cable  32  is wound. The winch  18  may therefore increase or decrease the length of the second cable  32  that extends from the winch  18 . The winch  18  is placed generally below the fifth pulley  17 . The fifth pulley  17  has a sprung mechanism (not shown), which biases the fifth pulley  17  upwards and provides tension in the cable between the winch  18  and the fifth pulley  17 . When the amount of cable between the winch  18  and the fifth pulley  17  is increased, the fifth pulley  17  moves in an upwards direction, away from the winch  18 . When the amount of cable between the winch  18  and the fifth pulley  17  is decreased, the fifth pulley  17  moves in a downwards direction towards the winch  18 . 
     The third pulley  15  may comprise an entry point  29 . The entry point  29  is indicated by a dotted line and need not be a physical feature of the embodiment. There is an initial length of cable  11  between the entry point  29  and the handle  110 . By reducing the length of cable  32  between the winch  18  and the fifth pulley  17 , the fifth pulley  17  moves in the downwards direction which (in the absence of any other motion) decreases the amount of cable  11  between the entry point  29  and the handle  110 . By increasing the amount of cable between the winch  18  and the fifth pulley  17 , the fifth pulley  17  moves in the upwards direction, which increases the amount of cable  11  between the entry point  29  and the handle  110 . The second pulley  13  may (if the handle  110  is held still) be moved along the first linear axis in both directions by changing the amount of cable between the entry point  29  and the handle  110 . Assuming that the handle  110  is kept at a constant position, when the amount of cable between the entry point  29  and the handle  110  is decreased by reducing the amount of cable between the winch  18  and the fifth pulley  17 , the second pulley  13  will move in the upwards direction and when the amount of cable between the entry point  29  and the handle  110  is increased by increasing the amount of cable between the winch  18  and the fifth pulley  17 , the second pulley  13  will move in the downwards direction. 
     It will be understood that a different entry point could have been chosen than the point  29  indicated on  FIG. 1 . In general, it is preferred that the entry point is fixed with respect to the frame of the exercise machine  10 , and is also preferably a point or region through which the cable  11  passes during all phases of motion of the cable  11 . The length of cable  11  between the entry point  29  and the handle  110  is influenced by activation of the winch  18  during use of the exercise machine  10  or by the user moving the handle  110  during use of the exercise machine. 
     If an entry point is to be selected, it is important that a continuous length of cable extends from the entry point to the handle  110  (or, in other embodiments, to a different member with which the user interacts, such as a foot plate), and that the introduction or removal of cable at the entry point will move the weight stack  14  upwards or downwards if all other components of the exercise machine  10  are held in a stationary position. 
     The arrangement of components shown in  FIG. 1  is schematic, and in other examples the relative positions of the components may be different. It is also envisaged that machines embodying the present invention will have further support and/or shielding components, so that the machine is sturdy and moving parts are not exposed to users any more than necessary. These further components are not shown in the figures for purposes of clarity. 
     In use, the user interacts with the handle  110  and performs a first motion when the handle  110  is moved in a first direction and a second motion when the handle  110  is moved in a second direction, which will usually be generally opposite to the first direction. These movements may comprise a concentric user movement and an eccentric user movement. A concentric user movement is a movement where the user&#39;s muscle is contracting and an eccentric user movement is a movement where the user&#39;s muscle is extending. 
     When the user performs the first motion and moves the handle  110  through one unit of distance, the user will raise the weight by 0.5 units. The effective weight experienced by the user is one-half of the real weight of the weight stack  14 . 
     The embodiment shown in  FIG. 2  comprises a second exercise machine  20  (only part of which is shown). The exercise machine  20  comprises a cable  21 , a first pulley  22 , a second pulley  23  and a third pulley  25 , again held in place by a frame  30 , which may take any suitable form. The cable  21  has a distal end attached to a handle  210 . In use, the user can grasp the handle  210  to perform an exercise. The cable  21  extends upwards from the distal end to pass over the first pulley  22 , which is preferably arranged at about head height. The first pulley  22  is vertically orientated and is rotatable about a first axis. The cable  21  extends downwards from the first pulley  22 , to pass under the second pulley  23 , which is preferably arranged at about waist height. The second pulley  23  is vertically orientated, is rotatable about a second axis and (as before) can move in both directions along a first, generally vertical linear axis. 
     The cable  21  extends upwards from the second pulley  23  to pass over the third pulley  25 , which is preferably arranged at a similar height to the first pulley  22 . The third pulley  25  is vertically orientated and is rotatable about a third axis. The cable  21  extends downwards from the second pulley  23 , with the proximal end of the cable  11  being attached to a winch  28 . The cable  21  is continuously threaded around the first pulley  22 , the second pulley  23  and the third pulley  25 . 
     A weight stack  24  is attached to the second pulley  23  and applies an internal force, in a first (i.e. downward) direction due to gravity, to the moveable second pulley  23 . The weight stack  24  may be arranged to move along a vertical track (not shown), for example, to allow the weight stack to move in both directions along a first, generally vertical linear axis. A user force is applied by a user through the handle  210 . In practice, a user pulls a handle  210  to lift the weight stack  24 . The user exerts a force on the handle  210  in order to lift the weight stack  24  and in doing so, the handle  210  exerts an equal and opposite force on the user. In practice, the user will pull the handle  210  down to raise the weight stack  24  against gravity, and then lower the weight stack  24  again to complete one repetition of an exercise. 
     Where the cable enters the winch  28  may comprise an entry point. There is an initial length of cable  21  between the entry point and the handle  210 . The second pulley  23  may (if the handle  210  is held still) be moved along the first linear axis by changing the amount of cable between the entry point and the handle  210 . Assuming that the handle  210  is kept at a constant position, when the amount of cable between the entry point and the handle  210  is decreased, the second pulley  23  will move in the upwards direction and when the amount of cable between the entry point and the handle  210  is increased, the second pulley  23  will move in the downwards direction. 
     A difference between the embodiment shown in  FIG. 1  and the embodiment depicted in  FIG. 2  is the arrangement of the winch  18 ,  28 . The second cable  32  of  FIG. 1 , which is connected to the winch  18 , is not directly connected to the handle  110 . The arrangement of  FIG. 1  is likely to provide a smoother change in effective cable length as the winch  18  is attached to a fifth pulley  17 , and a lower amount of stress is put on the third pulley  15  when compared to the embodiment shown in  FIG. 2 . The embodiment shown in  FIG. 2  has two fewer pulleys and as a result is a simpler and more cost efficient arrangement. 
     The embodiment shown in  FIG. 3  comprises a third exercise machine  40  (only part of which is shown). The exercise machine  40  comprises a cable  41 , and first to tenth pulleys  58 ,  59 ,  42 ,  43 ,  45 ,  46 ,  47 ,  53 ,  54   55 . These components are held in place by a frame  50 , which may take any suitable form. The cable  41  has a distal end attached to a handle  410 . In use, the user can grasp the handle  410  to perform an exercise. The cable  41  extends from the distal end to pass in-between the first and second pulleys  58 ,  59 , which are attached to a bogey  56 . The first and second pulleys  58 ,  59  are vertically orientated, with the second pulley  59  being generally directly above the first pulley  58 , and are independently rotatable about respective first and second axes. The bogey  56  is attached to the frame  50  and may move vertically along a range of motion, preferably from a height corresponding to a user&#39;s ankles to about the user&#39;s head height and the bogey  56  may be temporarily fixed at an attachment point (or any of a series of spaced-apart attachment points) so that a user may use the handle  410  at a preferred height. The cable  41  extends upwards from the bogey  56 , to pass over a third pulley  42 , which is preferably arranged at about head height. The third pulley  42  is vertically orientated and is rotatable about a third axis. 
     The cable  41  may have a rubber ball or a similar stop element (not shown) attached close to the distal end of the cable  41 . The rubber ball may be located in-between the handle  410  and the bogey  56 , such that if the handle  410  is removed from the distal end of the cable  41 , the distal end of the cable  41  cannot pass through the first and second pulleys  58 ,  59 . 
     The cable  41  extends downwards from the third pulley  42 , to pass under the fourth pulley  43 , which is preferably arranged at about waist height. The fourth pulley  43  is vertically orientated, is rotatable about a fourth axis and can move in both directions along a first, generally vertical linear axis. The fourth pulley  43  may be arranged to move along a vertical track (not shown), for example, to allow this motion to take place. 
     The cable  41  extends upwards from the fourth pulley  43  to pass over the fifth pulley  45 , which is preferably arranged at a similar height to the third pulley  42 . The fifth pulley  45  is vertically orientated and is rotatable around a fifth axis. The cable  41  extends away from the fifth pulley  45 , in a generally horizontal direction that is away from the third pulley  42  and the fourth pulley  43 , such that about a quarter of the surface of the fifth pulley  45  is in contact with the cable  41 , to pass over the sixth pulley  46 , which is preferably arranged at a similar height to the third pulley  42  and the fifth pulley  45 . The sixth pulley  46  is vertically orientated and is rotatable around a sixth axis. The cable  41  extends downwards from the sixth pulley  46 , to pass under the seventh pulley  47 , which is preferably arranged at about waist height. The seventh pulley  47  is vertically orientated, is rotatable around a seventh axis and can move in both directions along a second linear axis. Once again, the seventh pulley  47  may slide along a vertical track during this motion. 
     The cable  41  extends upwards from the seventh pulley  47 , to pass over the eighth pulley  53 , which again is preferably arranged at about waist height. The eighth pulley  53  is vertically orientated and is rotatable around an eighth axis. The cable extends downwards from the eighth pulley  53  to pass under the ninth pulley  54 , which is preferably arranged at or around about foot height. The ninth pulley  54  is vertically orientated and is rotatable around a ninth axis. The cable  41  extends away from the ninth pulley  54  in a generally horizontal direction that is towards the third pulley  42  and the first pulley  58 , such that about a quarter of the surface of the ninth pulley  54  is in contact with the cable  41 , to pass under the tenth pulley  55 , which is preferably arranged at a similar height to the ninth pulley  54 . The tenth pulley  55  is vertically orientated and is rotatable around a tenth axis. The cable  41  extends upwards from the tenth pulley  55  to meet the bogey  56  at an attachment point  57 ; the proximal end of the cable  41  is attached to the attachment point  57 . In another embodiment of the present invention, the attachment point  57  may not be present and the end of the cable  41  is welded directly to the bogey  56  of the exercise machine. 
     The cable  41  is continuously threaded through the channel created by the first pulley  58  and the second pulley  59 , and is continuously threaded around the third pulley  42 , the fourth pulley  43 , the fifth pulley  45 , the sixth pulley  46 , the seventh pulley  47 , the eighth pulley  53 , the ninth pulley  54  and the tenth pulley  55 . A weight stack  44  is attached to the fourth pulley  43  and applies an internal force, in a first (i.e. downward) direction due to gravity, to the fourth pulley  43 . The weight stack  44  may be arranged to move along a vertical track (not shown), for example, to allow the weight stack to move in both directions along a first, generally vertical linear axis. 
     A user force is applied by a user through the handle  410 . In practice, a user pulls the handle  410  to lift the weight stack  44 . The user exerts a force on the handle  410  in order to lift the weight stack  44  and in doing so, the handle  410  exerts an equal and opposite force on the user. In practice, the user will pull the handle  410  away from the bogey  56  to raise the weight stack  44  against gravity, and will then move the handle  410  towards the bogey  56  to lower the weight stack  44  again to complete one repetition of an exercise. 
     The exercise machine  40  further includes a second cable  52 , which (in this example) is entirely separate from the cable  41  discussed above. The second cable  52  is attached at a distal end to a winch  48  and is attached at a proximal end to the seventh pulley  47 . The winch  48  may be operated to rotate a drum (not shown) around which the second cable  52  is wound. The winch  48  may therefore increase or decrease the length of the second cable  52  that extends from the winch  48 . The winch  48  is placed generally below the seventh pulley  47 . The seventh pulley  47  has a sprung mechanism (not shown), which biases the seventh pulley  47  upwards and provides tension in the cable between the winch  48  and the seventh pulley  47 . When the amount of cable between the winch  48  and the seventh pulley  47  is increased, the seventh pulley  47  moves in an upwards direction, away from the winch  48 . When the amount of cable between the winch  48  and the seventh pulley  47  is decreased, the seventh pulley  47  moves in a downwards direction towards the winch  48 . 
     The fifth pulley  45  may comprise an entry point. There is an initial length of cable  41  between the entry point and the handle  410 . By reducing the amount of cable between the winch  48  and the seventh pulley  47 , the seventh pulley  47  moves in a downwards direction which (in the absence of any other motion) decreases the amount of cable  41  between the entry point and the handle  410 . By increasing the amount of cable between the winch  48  and the seventh pulley  47 , the seventh pulley  47  moves in the upwards direction, which increases the amount of cable  41  between the entry point and the handle  410 . The fourth pulley  43  may (if the handle  410  is held still) be moved along the first linear axis in both directions by changing the amount of cable between the entry point and the handle  410 . Assuming that the handle  410  is kept at a constant position, when the amount of cable between the entry point and the handle  410  is decreased, the fourth pulley  43  will move in the upwards direction and when the amount of cable between the entry point and the handle  410  is increased, the fourth pulley  43  will move in a downwards direction. 
     In use, the user interacts with the handle  410  and performs a first motion when the handle  410  is moved in a first direction and a second motion when the handle  410  is moved in a second direction, which will usually be generally opposite to the first direction. These movements may comprise a concentric user movement and an eccentric user movement. As discussed above, a concentric user movement is a movement where the user&#39;s muscle is contracting and an eccentric user movement is where the user&#39;s muscle is extending. 
     A difference between the embodiments shown in  FIGS. 1 and 2  and the embodiment depicted in  FIG. 3  is the addition of a bogey  56 . The bogey  56  allows a user to adjust the height of the handle  410 . An advantage of the arrangement shown in  FIG. 3  is that the user can adjust the height of the handle  410  in order to perform different exercises. 
     The embodiment shown in  FIG. 4  comprises a fourth exercise machine  60  (only part of which is shown). The exercise machine  60  comprises a first cable  61 , and first to eleventh pulleys  68 ,  69 ,  62 ,  63 ,  64 ,  65 ,  66 ,  73 ,  74 ,  77 ,  78 . These components are held in place by a frame  81 , which may take any suitable form. The first cable  61  has a distal end attached to a handle  610 . In use, the user can grasp the handle  610  to perform an exercise. The first cable  61  extends from the distal end to pass in-between the first and second pulleys  68 ,  69 , which are attached to a bogey  70 . The first and second pulleys  68 ,  69  are vertically orientated, with the second pulley  69  being generally directly above the first pulley  68 , and are independently rotatable about respective first and second axes. The bogey  70  is attached to the frame  81  and may move vertically along a range of motion, preferably from a height corresponding to a user&#39;s ankles to about the user&#39;s head height and the bogey  70  may be temporarily fixed at an attachment point (or any of a series of spaced-apart attachment points) so that a user may use the handle  610  at a preferred height. The first cable  61  extends upwards from the bogey  70 , to pass over a third pulley  62 , which is preferably arranged at about head height. The third pulley  62  is vertically orientated and is rotatable about a third axis. 
     The first cable  61  may have a rubber ball or a similar stop element (not shown) attached close to the distal end of the first cable  61 . The rubber ball may be located in-between the handle  610  and the bogey  70 , such that if the handle  610  is removed from the distal end of the first cable  61 , the distal end of the first cable  61  cannot pass through the first and second pulleys  68 ,  69 . 
     The first cable  61  extends downwards from the third pulley  62 , to pass over a fourth pulley  63 , which is preferably arranged at about chest height. The fourth pulley  63  is vertically orientated and is rotatable about a fourth axis. 
     The first cable  61  extends downwards from the fourth pulley  63 , such that about a quarter of the surface of the fourth pulley  63  is in contact with the cable, to pass under the fifth pulley  64 , which is preferably arranged vertically below the fourth pulley  63 . The fifth pulley  64  is vertically orientated and is rotatable about a fifth axis and can move in both directions along a first, generally vertical linear axis. 
     The first cable  61  extends upwards from the fifth pulley  64 , to pass over a sixth pulley  65 , which is preferably arranged in a position that is in-between the bogey  70 , the fourth pulley  63  and the fifth pulley  64 . The sixth pulley  65  is vertically orientated and is rotatable about a sixth axis. 
     The first cable  61  extends downwards from the sixth pulley  65 , to pass under a seventh pulley  66 , which is preferably arranged at about foot height and vertically below the third pulley  62 . The seventh pulley  66  is vertically orientated and is rotatable about a seventh axis. The first cable  61  extends upwards from the seventh pulley  66  to meet the bogey  70  at a first attachment point  67 . In another embodiment of the present invention, the first attachment point  67  may not be present and the end of the first cable  61  is welded directly to the bogey  70  of the exercise machine. 
     At a first end, a member  71  is attached to the fifth pulley  64 . The member  71  extends vertically downwards from the fifth pulley  64 . At a second end, the member  71  is attached to an eighth pulley  74 , which is preferably arranged in the same vertical plane as the fourth  63  and fifth  64  pulleys. The eighth pulley  74  is vertically orientated and is rotatable about an eighth axis and can move in both directions along a first, generally vertical linear axis. At the distal end of the member  71  to which the eighth pulley  74  is attached, is a second attachment point  72 . 
     A second cable  79  extends downwards from the second attachment point  72 , to pass under a ninth pulley  73 , which is preferably arranged in the same vertical plane as the fourth  63 , fifth  64  and eighth  74  pulleys. In another embodiment of the present invention, the second attachment point  72  may not be present and the end of the second  79  cable  61  is welded directly to the bogey  70  of the exercise machine. The ninth pulley  73  is vertically orientated and is rotatable about a ninth axis and can move in both directions along a first, generally vertical linear axis. 
     The second cable  79  extends upwards from the ninth pulley  73 , passes over the eighth pulley  74  and extends downwards towards a tenth pulley  77 , which is preferably arranged at about foot level. The tenth pulley  77  is vertically orientated and is rotatable about a tenth axis. 
     The second cable  79  extends upwards from the tenth pulley  77  to pass over an eleventh pulley  78 , which is preferably arranged at head height. The eleventh pulley  78  is vertically orientated and is rotatable about an eleventh axis. The cable extends in a downwards direction from the eleventh pulley  78  and is attached at a distal end to a winch  80 . The winch  80  may be operated to rotate a drum (not shown) around which the second cable  79  is wound. Preferably, the winch  80  is generally below the eleventh pulley  78  and at foot level. 
     A weight stack  76  is attached to the ninth pulley  73  and applies an internal force, in a first (i.e. downward) direction due to gravity, to the moveable ninth pulley  73 . The weight stack  76  may be arranged to move along a vertical track (not shown), for example, to allow the weight stack to move in both directions along a first, generally vertical linear axis. A user force is applied by a user through the handle  610 . A user pulls a handle  610  to lift the weight stack  76 . The user exerts a force on the handle  610  in order to lift the weight stack  76  and in doing so, the handle  610  exerts and equal and opposite force on the user. In practice, the user will pull the handle  610  away from the bogey  70  to raise the weight stack  76  against gravity, and will then move the handle  610  towards the bogey  70  to lower the weight stack  76  again to complete one repetition of an exercise. 
     The sixth pulley  65  may comprise an entry point. There is an initial length of first cable  61  between the entry point and the handle  610 . By moving the handle  610  away from the bogey  70 , the amount of first cable  61  between the entry point and the handle  610  is increased. By moving the handle  610  towards the bogey  70 , the amount of first cable  61  between the entry point and the handle  610  is decreased. By increasing the amount of cable between the entry point and the handle  610 , the fifth pulley  64  moves in the upwards direction which moves the member  71  and the eighth pulley  74  in the upwards direction also. This upwards movement of the eighth pulley  74  decreases the amount of cable between the eighth pulley  74  and the second attachment point  72 . The ninth pulley  73  may (if the winch  80  is locked) be moved along the first linear axis in both directions by changing the amount of cable between the entry point and the handle  610 . Assuming that the winch  80  is locked, when the amount of first cable  61  between the entry point and the handle  610  is increased, the ninth pulley  73  will move in the upwards direction and when the amount of first cable  61  between the entry point and the handle  610  is decreased, the ninth pulley  73  will move in the downwards direction. 
     As the ninth pulley  73  is attached to the weight stack  76 , the weight stack  76  will move up and down as the ninth pulley  73  moves. 
     As described below, the amount of work done by the user when moving the handle  610  may be varied by adjusting how much of the second cable  79  the winch  80  pays out when the user is performing a user action. 
     In use, the user interacts with the handle  610  and performs a first motion when the handle  610  is moved in a first direction and a second motion when the handle  610  is moved in a second direction, which will usually be generally opposite to the first direction. These movements may comprise a concentric user movement and an eccentric user movement. A concentric user movement is a movement where the user&#39;s muscle is contracting and the eccentric user movement is where the user&#39;s muscle is extending. 
     A difference between the embodiments shown in  FIGS. 1-3  and the embodiment shown in  FIG. 4  is that there is a first cable  61  and a second cable  79 , the two cable arrangements being connected by the member  71 . An advantage of such an arrangement is that the first cable  61  is threaded through fewer pulleys than the cable  11 ,  21 ,  41  attached to the handle  110 ,  210 ,  410  of the previous embodiments. As the first cable  61  is threaded through fewer pulleys, the pulleys impart a lower resistance when compared to the number pulleys through which the cable  11 ,  21 ,  41  of the embodiments shown in  FIGS. 1-3  is threaded and hence the exercise machine  60  feels more responsive than the exercise machines  10 ,  20 ,  40  shown in  FIGS. 1-3 . Furthermore, by isolating the winch  80  from the first cable  61 , the user is less able to perceive the operation of the winch  80  when compared to the embodiments of the present invention shown in  FIGS. 1-3 . If the winch  80  of the present embodiment employs a stepper motor, the advantage of isolating the winch from the user would be more pronounced. 
     The embodiment shown in  FIG. 5  comprises a fifth exercise machine  90  (only part of which is shown). The exercise machine  90  comprises a cable  91 , and first to eighth pulleys  101 ,  102 ,  92 ,  93 ,  95 ,  96 ,  97 ,  98 . These components are held in place by a frame  103 , which may take any suitable form. The cable  91  has a distal end attached to a handle  910 . In use, the user can grasp the handle  910  to perform an exercise. The cable  91  extends from the distal end to pass in between the first and second pulleys  101 ,  102 , which are attached to a bogey  100 . The first and second pulleys  101 ,  102  are vertically orientated, with the second pulley  102  being generally directly above the first pulley  101 , and independently rotatable around respective first and second axes. The bogey  100  is attached to the frame  103  and may move vertically along a range of motion, preferably from a height corresponding to a user&#39;s ankles to about the user&#39;s head height, the bogey  100  may be temporarily fixed at an attachment point (or any other series at spaced-apart attachment points) so that a user may use the handle  910  at a preferred height. The cable  91  extends upwards from the bogey  100 , to pass over the third pulley  92 , which is preferably arranged at about head height. The third pulley  92  is vertically orientated and is rotatable around a third axis. 
     The cable  91  may have a rubber ball or a similar stop element (not shown) attached close to the distal end of the cable  91 . The rubber ball may be located in between the handle  910  and the bogey  100  such that if the handle  910  is removed from a distal end of the cable  91 , the distal end of the cable  91  cannot pass through the first and second pulleys  101 ,  102 . 
     The cable  91  extends downwards from the third pulley  92 , to pass under the fourth pulley  93 , which is preferably arranged at about waist height. The fourth pulley  93  is vertically orientated, is rotatable about a fourth axis and can move in both directions along a first, generally vertical linear axis. The fourth pulley  93  may be arranged to move along a vertical track (not shown), for example, to allow this motion to take place. 
     The cable  91  extends upwards from the fourth pulley  93  to pass over the fifth pulley  95 , which is preferably arranged at a similar height to the third pulley  92 . The fifth pulley  95  is vertically orientated and is rotatable around a fifth axis. The cable  91  extends away from the fifth pulley  95 , in a generally horizontal direction that is away from the third pulley  92  and the fourth pulley  93 , such that about a quarter of the surface of the fifth pulley  95  is in contact with the cable  91 , to pass over the sixth pulley  96 , which is preferably arranged at a similar height to the third pulley  92  and the fifth pulley  95 . The sixth pulley  96  is vertically orientated and is rotatable around a sixth axis. The cable  91  extends downwards from the sixth pulley  96 , to pass under the seventh pulley  97 , which is preferably arranged at about foot height. The seventh pulley is vertically orientated and is rotatable around a seventh axis. 
     The cable  91  extends away from the seventh pulley in a generally horizontal direction that is away from the seventh pulley  97  and towards the third pulley  92 . The cable  91  passes under the eighth pulley  98  which again is preferably arranged at about foot height. The eighth pulley  98  is vertically orientated and is rotatable around an eighth axis. The cable extends upwards from the eighth pulley  98  and the proximal end is attached to a winch  99 . The winch  99  is attached to the bogey  100 . 
     The cable  91  is continuously threaded through the channel created by the first pulley  101  and the second pulley  102 , and is continuously threaded around the third pulley  92 , the fourth pulley  93 , the fifth pulley  95 , the sixth pulley  96 , the seventh pulley  97  and the eighth pulley  98 . A weight stack  94  is attached to the fourth pulley  93  and applies an internal force, in a first (i.e. downward) direction due to gravity, to the fourth pulley  93 . The weight stack  94  may be arranged to move along a vertical track (not shown), for example, to allow the weight stack to move in both directions along a first, generally vertical linear axis. 
     A user force is applied by a user through the handle  910 . A user pulls the handle  910  to lift the weight stack  94 . A user exerts a force on the handle  910  in order to lift the weight stack  94  and in doing so, the handle  910  exerts an equal and opposite force on the user. In practice, the user will pull the handle  910  away from the bogey  100  to raise the weight stack  94  against gravity, and will then move the handle  910  towards the bogey  100  to lower the weight stack  94  again to complete one repetition of an exercise. 
     The fifth pulley  95  may comprise an entry point. There is an initial length of cable  91  between the entry point and the handle  910 . The length of the cable  91  between the entry point and the handle  910  may be changed by operation of the winch  99 . By reducing the amount of cable between the winch  99  and the entry point, the amount of cable between the entry point and the handle  910  is also reduced. By increasing the amount of cable between the winch  99  and the entry point, the amount of cable between the entry point and the handle  910  is also increased. The fourth pulley  93  may (if the handle  910  is held still) be moved along the first linear axis in both directions by changing the length of the cable  91  between the entry point and the handle  910 . Assuming that the handle  910  is kept at a constant position, when the length of the cable  91  between the entry point and the handle  910  is decreased, the fourth pulley  93  will move in an upwards direction and when the length of the cable  91  between the entry point and the handle  910  is increased, the fourth pulley  93  will move in a downwards direction. The movement of the fourth pulley  93  will rise and lower the weight stack  94  accordingly. 
     As described below, the amount of work done by the user when moving the handle  910  may be varied by adjusting the length of the cable  91  that the winch  99  pays out when the user is performing a user action. 
     In use, the user interacts with the handle  910  and performs a first motion when the handle  910  is moved in a first direction and a second motion when the handle  910  is moved in a second direction, which will usually be generally opposite to the first direction. These movements may comprise a concentric user movement and an eccentric user movement. A concentric user movement is a movement where the user&#39;s muscle is contracting and an eccentric user movement is where the user&#39;s muscle is extending. 
     A difference between the embodiment shown in  FIG. 3  and the embodiment depicted in  FIG. 5  is the arrangement of the winch  99 . The winch  99  is connected directly to the bogey  100 . An advantage of attaching the winch  99  directly to the bogey  100  is that the exercise machine has two fewer pulleys and as a result is simpler and more cost efficient. 
     The embodiment shown in  FIG. 6  comprises a sixth exercise machine  120  (only part of which is shown). The exercise machine  120  comprises a first cable  121 , a second cable  127 , a third cable  131 , first to third reels  123 ,  124 ,  125 , a guide wheel  126  and first to fifth pulleys  135 ,  136 ,  122 ,  129 ,  130 . These components are held in place by a frame  133 , which may take any suitable form. The first cable  121  has a distal end attached to a handle  1010 . In use, the user can grasp a handle  1010  to perform an exercise. The first cable  121  extends from the distal end to pass in between the first and second pulleys  135 ,  136 , which are attached to a bogey  134 . The first and second pulleys  135 ,  136  are vertically orientated, with the second pulley  136  being generally directly above the first pulley  135 , and independently rotatable around respective first and second axes. The bogey  134  is attached to the frame  133  and may move vertically along a range of motion, preferably from a height corresponding to a user&#39;s ankles to about the user&#39;s head height and the bogey  134  may be temporarily fixed at an attachment point (or any other series of spaced-apart attachment points) so that a user may use the handle  1010  at a preferred height. The first cable  121  extends upwards from the bogey  134 , to pass over a third pulley  122 , which is preferably arranged at about head height. The third pulley  122  is vertically orientated and is rotatable around a third axis. 
     The first cable  121  may have a rubber ball or a similar stop element (not shown) attached close to the distal end of the first cable  121 . The rubber ball may be located in between the handle  1010  and the bogey  134 , such that if the handle  1010  is removed from the distal end of the first cable  121 , the distal end of the first cable  121  cannot pass through the first and second pulleys  135 ,  136 . 
     The first cable  121  extends downwards from the third pulley  122 , to pass under the first reel  123 , which is preferably arranged at about chest height. The proximal end of the first cable  121  is attached to the first reel  123 , an extended length of cable is wrapped around the first reel such that multiple rotations (for example one, two, three, four or five rotations) may take place. The first reel  123  is vertically orientated, is rotatable around a fourth axis and is attached to a first end of a continuously variable transmission (not shown). Attached to the second end of the variable transmission, is a third reel  125 . 
     The third reel  125  is vertically orientated and is rotatable around the fourth axis. In between the first reel  123  and the third reel  125  is a second reel  124 . The second reel  124  is vertically orientated and is rotatable around the fourth axis. The second reel  124  is attached to the third reel  125  by a locking/free-wheeling mechanism (not shown). 
     The second cable  127  is attached at a proximal end to the third reel  125  and is wrapped around the third reel  125  a number of times (for example one, two, three, four or five times). and extends in a generally downwards direction passing by a guide wheel  126  attached at a distal end to a weight stack  128 . 
     A third cable  131  is attached to the second reel  124  at a proximal end and is wrapped around the second reel  124 , for example two, three, four times etc. The third cable  131  extends in a generally downward direction towards a fourth pulley  129 . The fourth pulley  129  is preferably arranged at about foot height. The fourth pulley is vertically orientated and is rotatable around a fifth axis. The third cable  131  passes around the fourth pulley  129  and extends in a generally upwards direction towards a fifth pulley  130 . The fifth pulley  130  is preferably arranged at a similar height to the third pulley  122 . The fifth pulley  130  is vertically orientated and is rotatable around a seventh axis. The third cable  131  passes over a fifth pulley  130  and extends in a generally downwards direction towards a winch  132 . The third cable  131  is attached to a proximal end to a winch  132 . The winch  132  may be operated to rotate a drum (not shown) around which the third cable  131  is wound. The winch  132  may therefore increase or decrease the length of the third cable  131  that extends from the winch  132 . The winch  132  is placed generally below the fifth pulley  130 . 
     A user force is applied by a user through the handle  1010 . A user pulls the handle  1010  to lift the weight stack  128  and in doing so, the handle  1010  exerts an equal and opposite force on the user. In practice, the user will pull the handle  1010  away from the bogey  134  to raise the weight stack  128  against gravity, and will then move the handle  1010  towards the bogey  134  to lower the weight stack  128  again to complete one repetition of an exercise. 
     In use, the user interacts with the handle  1010  and performs a first motion when the handle  1010  is moved in a first direction and a second motion when the handle  910  is moved in a second direction, which will usually be generally opposite to the first direction. These movements may comprise a concentric user movement and an eccentric user movement. 
     In this embodiment, when the user performs a concentric user movement, the locking/free-wheeling mechanism is set to free-wheeling mode (either manually by the user, or through the processor detecting the movement and switching automatically to this mode). The concentric user movement will cause the first reel  123  to rotate in a first direction, which in  FIG. 6  corresponds to a clockwise motion. The clockwise motion of the first reel  123  is passed through the continuously variable transmission and effects a movement in the same first direction in the third reel  125 . The rotation of the third reel  125  will cause the weight stack  128  to rise. 
     In this embodiment, when the user has finished the concentric user movement, the continuously variable transmission is now set to free-wheeling mode and the locking/free-wheeling mechanism is set to locked mode. If the winch  132  is required to alter the position of the weight stack  128 , the amount of third cable  131  is reduced or increased, which will cause the second reel  124  to rotate, the third reel  125  also will rotate and hence the weight stack  128  will move, without altering the length of first cable  121 . 
     In this embodiment, when the user performs an eccentric user movement, the continuously variable transmission is set to locked mode and the locking/free-wheeling mechanism is set to free-wheeling mode and hence the weight stack  132  may be lowered. 
     The fourth axis may comprise an entry point. There is an initial length of first cable  121  between the entry point and the handle  1010 . By moving the handle  1010  away from the bogey  134 , the amount of first cable  121  between the entry point and the handle  1010  is increased. By moving the handle  1010  towards the bogey  134 , the amount of first cable  121  between the entry point and the handle  1010  is decreased. By increasing the amount of first cable  121  between the entry point and the handle  1010 , the first reel  123  rotates in a first direction and hence the third reel  125  also rotates in the first direction. The rotation of the third reel  125  in the first direction decreases the amount of second cable  127  between the weight stack  128  and the third reel  125 . The weight stack  128  may (if the winch  132  is locked) be moved along a first linear axis in both directions by changing the amount of cable between the entry point and the handle  1010 . Assuming that the winch  132  is locked, when the amount of first cable  121  between the entry point and the handle  1010  is increased, the weight stack  128  will move in the upwards direction and when the amount of first cable  121  between the entry point and the handle  1010  is decreased, the weight stack  128  will move in the downwards direction. 
     A difference between the embodiments shown in  FIGS. 1-5  and the embodiment depicted in  FIG. 6  is the addition of first to third reels  123 ,  124 ,  125 , the continuously variable transmission and the arrangement of the first to third cables  121 ,  127 ,  131 . An advantage of such an arrangement is that the first cable  121  is threaded through fewer pulleys than the cable  11 ,  21 ,  41 ,  61 , attached to the handle  110 ,  210 ,  410 ,  610 ,  910  of the previous embodiments. As the first cable  121  is threaded through fewer pulleys, the pulleys impart a lower resistance when compared to the number pulleys through which the cable  11 ,  21 ,  41 ,  61 ,  91  of the embodiments shown in  FIGS. 1-5  is threaded and hence the exercise machine  120  feels more responsive than the exercise machines  10 ,  20 ,  40 ,  60 ,  90  shown in  FIGS. 1-5 . Furthermore, by isolating the winch  132  from the first cable  121 , the user is less able to perceive the operation of the winch  132  when compared to the embodiments of the present invention shown in  FIGS. 1-5 . If the winch  132  of the present embodiment employs a stepper motor, the advantage of isolating the winch  132  from the user would be more pronounced. 
     Other embodiments of the present invention may replace the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  (and bogey  56 ,  70 ,  100 ,  134  where appropriate) with any other member, such that the embodiments can be used to perform a wide variety of exercises. An example of a different member is a lever to allow the user to perform leg extensions. 
     An example of use of the exercise machines  10 ,  20 ,  40 ,  60 ,  90 ,  120  will now be described. 
     The user is likely to perform the concentric movement first, which, in the embodiments of  FIGS. 1 and 2  is pulling the handle  110 ,  210  downwards and in the embodiments of  FIGS. 3-6 , is moving the handle  410 ,  610 ,  910 ,  1010  away from the bogey  56 ,  70 ,  100 ,  134 . The exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  has means for monitoring the first motion and during the first motion, the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  applies a first mode of operation. 
     As the user performs the first motion, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may increase the amount of cable in the system, as part of the first mode of operation. If the user moves the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  through one unit of distance, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may increase the amount of cable in the system at a rate that is proportional to or commensurate with the rate at which the user moves the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 . In one example, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may introduce 0.5 units of cable  21 ,  32 ,  52 ,  79  (or in in the embodiment known from  FIG. 4 , second cable  91 , or in the embodiment known from  FIG. 6 , third cable,  131 ) into the system. This means that for every unit of increase in distance between the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  and the first pulley  12 ,  22 ,  42 ,  62 ,  92 ,  122 , the user will raise the weight by only 0.25 units (or in the embodiment known from  FIG. 6 , the distance that the user will raise the weight may be different, depending on the setting of the continuously variable transmission). 
     In this example, as the user performs the first motion, the weight lifted by the user appears to be less than if the first mode of operation was not applied. More particularly, the effective weight experienced by the user is half of the weight that would be experienced without the operation of the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  (or in the embodiment known from  FIG. 6 , the effective weight that the user will experience may be different, depending on the setting of the continuously variable transmission). 
     Ideally, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  tracks the user&#39;s movement quickly and in real time, to give an effective weight that is experienced by the user that is half of the real weight, regardless of how quickly the user moves the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 . The user&#39;s movement may be monitored in any suitable way, and some examples are given below. A sensor may be attached to the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6 , the third pulley  42 ,  62 ,  92 ,  122 ) and the sensor may be a rotational encoder. The sensor may detect the rate of rotation of the pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) and communicate this information to the winch in real-time. The pulley  12 ,  22  (or in the case of the embodiment known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) may, for example, have a marking or series of markings on it, which the sensor detects when the/each marking passes the sensor. The winch may take this information and apply a scaling factor in order to introduce cable into the system at a rate which is, at any moment, maintained in a pre-determined proportion to the rate at which the user is adding it to the system. 
     In this embodiment of the present invention, the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  has a distance ratio of 2 (or in the embodiment known from  FIG. 6 , the ratio may be different, depending on the setting of the continuously variable transmission). The distance ratio is the ratio between how far the user is required to move the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  to move the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  through a set unit of distance, compared to the distance through which the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  must be moved to move the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  through the same set distance if the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  is locked and performs no activity (and in the embodiment known from  FIG. 6 , the setting of the continuously variable transmission is locked). A distance ratio of two means that the user will have to move the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  through a distance that is twice the distance that the user would have to move the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  if the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  was locked in order to move the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  132  through a set unit of distance. 
     The exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  has means for detecting when the first motion has been completed. There are many ways to detect when the first motion has been completed and embodiments of the present invention are not limited to a specific means of detection. 
     Some embodiments of the present invention may comprise a sensor for detecting distance by which the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  has been moved by the user. The sensor may (as discussed above) be a rotational encoder and measure the rotational rate of the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) or one or more other pulleys. The sensor may alternatively monitor the length of cable that has passed the third pulley  15 ,  25  (or in the case of the embodiment known from  FIGS. 3, 5, 6  the fifth pulley  45 ,  95 ,  130 , or in the case of the embodiment known from  FIG. 4  the seventh pulley  78 ). This sensor may further comprise a memory and a processor. The sensor may have a value stored in the memory that represents a distance by which the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  has moved for the user to have finished the first motion. The sensor may retrieve the value from the memory and compare the value to the sensed distance. If the sensed distance is equal to or greater than the value stored in the memory, this indicates that the user has completed the first motion. In this embodiment, no other sensing means may be required. 
     Other embodiments of the present invention may comprise a sensor for monitoring the force that the user is applying to the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 . The sensor may comprise a strain gauge attached to the second pulley  13 ,  23  (or in the case of the embodiments known from  FIGS. 3, 5  the fourth pulley  43 ,  93  or in the case of the embodiment known from  FIG. 4 , the eighth pulley  73 , or in the case of the embodiment known from  FIG. 6 , the third reel  125 ) (or another part of the system), such that the strain gauge monitors the force applied to the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 . The sensor may further comprise a memory and a processor. The sensor may store a value in the memory, which represents the force applied to the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 . Taking information from other sensors in order to calculate the distance through which the weight stack has been moved, the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  may calculate the work done by the user during a repetition. 
     When the rate of change of force with respect to time is equal to zero (or is below a threshold value), the sensor may indicate that the user movement has stopped. However, this could merely indicate that the user has paused during a user motion, rather than that the user has finished a user motion. 
     In other embodiments of the present invention, in order to determine whether the user has completed the first motion, a number of sensors may be used in combination. 
     Taking the embodiment known from  FIG. 1  as an example, as the user performs the first motion, the winch  18  is locked and does not adjust the length of cable  11  in system. If the winch is locked, once the user has completed the first motion, the user will (in the embodiment shown in  FIG. 1 ) have lifted a weight through a distance that is half that of the increase in the distance between the handle  110  and the first pulley  12 . 
     A control unit detects when the user has completed the first motion. This may be detected (as described above) through a sensor attached to the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ), any other pulley, the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  or any other positions where movement of the cable may be detected. A first sensor may monitor whether a pulley has stopped moving. A second sensor may monitor the amount of cable  11 ,  21 ,  41 ,  91  (or in the embodiments known from  FIGS. 4 and 6 , the first cable  61 ,  121 ) that has passed over a pulley. The control unit may take inputs from these sensors and calculate once the user has finished the first motion. 
     In some embodiments, once the user has stopped moving, the user indicates that they have finished the first motion through the use of a switch on the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 . Alternatively, in other embodiments of the present invention, the user may use voice recognition, eye movement sensors instead of a switch, or the control unit may compare the amount of cable between the entry point and the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  to a standard distance and calculate the probability that the user has finished the first motion. 
     In this embodiment, there is a third mode of operation after the first. Once the user has performed the first motion, the control unit may send instructions to an indicator to display an indication to the user not to start the second motion, which may be an eccentric movement. Once the user has completed the first motion, the control unit may start the third mode of operation and instruct the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  to reduce the amount of cable  11 ,  21 ,  41 ,  91 , (or in the embodiment known from  FIG. 4 , second cable  79  or in the embodiment known from  FIG. 6 , third cable  131 ) in the system, thereby increasing the height of the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 . The exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  may calculate the increase in the height of the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  based on the distance ratio and instruct the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  to raise the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  to a height that the user would have lifted it to in the first motion if there had been no compensatory action provided by the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132 . 
     In other embodiments of the present invention, the winch may raise the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  to a height that is different from the position that the user would have lifted it to in the first motion if there had been no compensatory action provided by the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132 . The winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may raise the weigh stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 , to a height that is lower or higher than the user would have lifted it to in the first motion. An advantage of the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  moving the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  is that different distance ratios for the first and second motions may be achieved, including ratios that change as the user performs a number of repetitions. For example, the user may perform a set that comprises ten repetitions. Of the set comprising ten repetitions, the distance ratio may be a ratio of 2 for the first motion of the first five repetitions and the distance ratio may be a ratio of 4 for the first motion of the second five repetitions. 
     Once the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  has increased the height of the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  in the third mode of operation, an indication may be displayed to the user, indicating that the user may perform the second motion. In this example, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  provides no compensatory motion and is simply “locked”. In the second mode of operation. The user lowers the weight through a longer distance, for each unit of distance moved by the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  whilst performing the second motion than is the case whilst performing the first motion, so that the user effectively experiences a greater weight whilst performing the second motion. During the second motion, in this embodiment, there is a distance ratio of 1 (or in the embodiment known from  FIG. 6 , the user may use the continuously variable transmission to set a different distance ratio). 
     In other examples the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  performs a compensatory motion during the second phase, or indeed a motion that increases the effective weight experienced. 
     The control unit calculates once the user has finished the second motion. This may again be based on a sensor which detects once a pulley has stopped moving. In some embodiments, the control unit may receive an input from a sensor that measures how much cable has passed a pulley. 
     Once the second motion has finished, the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  is ready for the start of the first motion again for a new repetition. 
     After the second motion and before a further first motion, there may be a fourth mode of operation. Once the user has completed the second motion, the control unit may start the fourth mode of operation and instruct the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  to increase the amount of cable  11 ,  21 ,  41 ,  91 , (or in the embodiment known from  FIG. 4 , second cable  79 , or in the embodiment known from  FIG. 6 , third cable  131 ) in the system, thereby decreasing the height of the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 . It does not apply to the present example, but in some embodiments of the present invention, the user may finish the second motion and the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  may not be at the same position as when the user started the second motion. If this is the case, the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  may calculate the amount of cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , second cable  79  or in the embodiment known from  FIG. 6 , third cable  131 ) that needs to be introduced into the system in order lower the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  to ground level. 
     In some embodiments of the present invention, the user may perform the first motion or the second motion without the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  making any active adjustment to the length of cable in the system. 
     With reference to  FIG. 7 , controls can be provided to a user to control the ratio and the workout. 
     At step  301 , the user selects a setting that controls the amount of weight to be lifted. Alternatively, this may be permanently set, or indeed a traditional pin system may be provided to allow the user to select a number of weights in the stack to be lifted. Optionally, the user then selects whether to workout using a constant cam or an asymmetric cam (described in greater detail below) at step  302 . At step  303 , the user selects the distance ratio for the concentric user movement and (separately) the eccentric user movement. In this embodiment the user selects a ratio of 2 for the concentric user movement and a ratio of 1 for the eccentric user movement. 
     In this example, in order to provide a good level of monitoring and to increase the accuracy of the monitoring, the exercise machine takes five inputs from a plurality of sensors (there may be more than one sensor per input) and has a separate control unit, communicatively coupled to the plurality of sensors. The control unit takes a number of inputs, the external force applied by the user  304 , the tension at the first pulley  305 , the tension at the second pulley  306 , the tension at the third pulley  307 , the displacement of the second pulley  308  and the displacement of the handle  309 , that are communicated to the control unit and are stored in a memory of the control unit. The control unit retrieves from the memory a value representing how far the user will move the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  and then calculates the internal force that will be applied to the user, based on the ratio selected by the user. In other embodiments, the control unit may receive an input representing a unique ID associated with a user and can retrieve from a memory a value representing how far this user typically moves the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 . The control unit sends instructions to the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  based on these calculations. 
     At step  310 , the control unit calculates how much cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , second cable  79  or in the embodiment known from  FIG. 6 , third cable  131 ) the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132 , will need to remove from the system in order for a distance ratio of 2 to be achieved as the user performs the first mode of operation. The amount of cable to be removed from the system is communicated to the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  and the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  removes the cable from the system as the user performs the first motion. 
     The user performs the first motion and at step  313  the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  detects once the user has finished the first motion (as discussed above). At step  314 , the exercise machine performs the third motion and instructs the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  to reduce the amount of cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4  second cable  79  or in the embodiment known from  FIG. 6 , third cable  131 ) in the system, based on the distance ratio, thereby increasing the height of the weight stack  14 ,  24 ,  44 ,  79 ,  91 ,  121 . 
     At step  315 , the control unit calculates whether to start the second mode of operation and introduce more cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , second cable  79 , or in the embodiment known from  FIG. 6 , third cable  131 ) into the system as the user is performing the second motion. This may be based on the distance ratio indicated by the user in step  303 . 
     In other embodiments of the present invention, the user or a third party may indicate to the control unit that they have completed a first or second motion. This may be via a switch on any part of the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120 , (particularly a switch on the handle, or a foot switch) through voice recognition or by an eye movement sensor. The means of indicating to the control unit that the user has completed a first or second motion may be communicatively connected to the control unit through wired or wireless means. In other embodiments, an accelerometer may be attached to the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  and the accelerometer may be connected to the control unit by wired or wireless means. The control unit may use the input from the accelerometer in order to calculate when a user has started or finished a user movement. 
     A user may also perform initial first and second motions with a light weight, such as the lightest weight on the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  or, alternatively, an even lighter calibration weight, in order that the control unit can calibrate a range of motion. 
     Once the user has finished the second motion, the control system then calculates if an adjustment needs to be made to the amount of cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , second cable  79 , or in the embodiment known from  FIG. 6 , third cable  131 ) in the system before a further first motion is started, if an adjustment to the amount of cable  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , second cable  79 , or in the embodiment known from  FIG. 6 , third cable  131 ) in the system needs to be made, the control unit will instruct the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  to start a fourth mode of operation. In other embodiments, the control system provides instructions to the winch to adjust the amount of cable  11 ,  21 ,  41 ,  79 ,  91  (or in the embodiment known from  FIG. 4 , the second cable  79  or in the embodiment known from  FIG. 6 , the third cable  131 ) in the system whilst the user is performing the first motion. 
     In some embodiments, the control unit continuously monitors the performance of a user and dynamically alters the distance ratio for the first and second motions as the user is exercising. This ratio may be altered when the user is stationary between first and second motions or it may take place whilst the user is performing a first or a second motion. The distance ratio may also change as the user performs repetitions. For example, the distance ratio may require the user to work harder for the first five repetitions and may require the user to work in a relatively easy manner for the second five repetitions. This change in ratio may be programmable or, alternatively, the user may be able to select a change in ratio from a number of pre-set options or simply by outlining a desired ratio curve on a touch screen connected to the control unit. The control unit may also provide instructions to the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  or other means of providing the internal force, in order to adjust the internal force as the user is exercising. This adjustment of the internal force may take place when the user is stationary, between first and second motions or it may take place whilst the user is performing a first or a second motion. 
     Embodiments of the present invention may have an asymmetric cam in place of the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) or alternatively any other pulley. Other embodiments may present the user with a choice of a constant cam (i.e. a regular pulley) or the asymmetric cam in place of the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) or alternatively any other pulley. An advantage of using an asymmetric cam as opposed to a constant cam is that the shape of the cam can be tailored to a specific workout and how a user&#39;s muscles vary in strength and hence the effective generation of an external force when moving a weight through a repetition. 
     In some embodiments, the mode of operation may change during a first or second user motion. The advantage of being able to change the mode of operation is that the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  can replicate the action of an asymmetric cam. When performing a repetition with a standard pulley, the resistance provided by the exercise machine to the user&#39;s motion will be relatively constant. If an asymmetric cam is used, the resistance will not be constant. For example, if the asymmetric cam has a protrusion, it may take more work to move the cable over the protrusion than it takes to move the cable over a flat part of the cam profile. By changing the mode of operation during the first or second user motion, the exercise machine can remove and introduce cable into the system as the user is performing the repetition, as described above, this will change the effective weight experienced by the user and hence aid the user movement or provide more resistance to the user movement. This means that at different points of the first motion and the second motion the resistance to the user action may vary as it does with an asymmetric cam. 
     In embodiments of the present invention that use sensors to monitor the movement of the pulleys or the amount of cable in the system, the sensors may be RFID tags or other sensing means. In some embodiments, the RFID tags may comprise a sensor located adjacent to the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) and the cable  11 ,  21 ,  41 ,  91  (or in the embodiments known from  FIGS. 4, 6  the first cable  61 ,  121 ) may have markings at regular intervals along the cable. The sensor may monitor how quickly the markings move past the sensor and, in combination with information that describes the distance between the markings on the cable, may calculate how much cable has passed the sensor and hence how much cable is in the system and the RFID tag may communicate this to the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132 . In other embodiments, a rotational encoder may be attached to the RFID tag and the sensor may directly monitor the rotation of the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) or any other pulley in the system. The sensor may further comprise a processor and a memory and perform calculations as to how much cable is in the system, taking either the information regarding how much cable has passed the sensor or how may rotations the first pulley  12 ,  22  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ) has gone through and the sensor may perform these calculations locally. Alternatively, the sensor may simply communicate how quickly the markings pass the sensor to a remote processor and memory and the calculation may be performed remotely. 
     The sensors may further comprise a strain gauge. In the embodiment shown in  FIG. 1 , the strain gauge could be located between the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  and the second pulley  13 ,  23  (or in the case of the embodiments known from  FIGS. 3, 4, 5, 6  the third pulley  42 ,  62 ,  92 ,  122 ). The strain gauge would measure the downward force exerted on the strain gauge by the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  and this information may be communicated to the control unit such that the control unit can take into account the mass of the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  that the user is lifting. In some embodiments, such an arrangement may also be used to warn the user if no weights have been selected on the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  or if the pin securing the weights is missing. 
     The RFID tags may have unique identification codes such that the control unit can identify which RFID it is communicating with. The RFID tag or any other sensor may be powered by harvesting energy from the user movements or from an external energy source. The sensors may be battery powered in other embodiments. In some embodiments, the sensors may be powered by mains electricity. 
     In some embodiments of the present invention, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  only operates when the user is stationary, in other embodiments, the operation of the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may be in a step-wise manner. In other embodiments of the present invention, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  operates whilst the user is performing the first or second mode of operation, and this operation may be in a continuous manner. 
     The weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  may, as discussed above, comprise a single mass, which cannot be changed by the user. The weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  may comprise a number of masses, which the user can select in order to vary the internal force. The advantage of using the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  is that it provides an experience that a user may be familiar with, for example when compared to free weights, a standard cable machine or a standard body-part machine. The weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  and second pulley  13 ,  23  (or in the case of the embodiments known from  FIGS. 3 and 5  the fourth pulley  43 ,  93  or in the case of the embodiment known from  FIG. 4 , the eighth pulley  73 ) may be replaced by a rotor in an electromagnetic field in some embodiments of the present invention. In other embodiments of the present invention, the weight stack  14 ,  24 ,  76 ,  94 ,  128  and second pulley  13 ,  23  (or in the case of the embodiments known from  FIGS. 3, 5  the fourth pulley  43 ,  93  or in the case of the embodiment known from  FIG. 4 , the eighth pulley  73 ) may be replaced by an elastic object, and the internal force is produced by deforming the elastic object. Other methods for producing an internal force are contemplated. An advantage of using a rotor in an electromagnetic field to produce the internal force, is that the exercise machine may weigh less and be easier to move. An advantage of using an elastic object to produce the internal force is that an elastic object may be light, cheap to produce and easy to replace. 
     Any of the cables  11 ,  21 ,  41 ,  91  (or in the embodiment known from  FIG. 4 , the first and second cables  61 ,  79  or in the embodiment known from  FIG. 6  the first, second and third cables  121 ,  127 ,  131 ) may be replaced by a belt in some embodiments of the present invention. In other embodiments, a Kevlar reinforced cable or belt may be used. In further embodiments, a belt reinforced by metal wires may be used. An advantage of using a belt over a cable is that the load is spread more evenly over each individual pulley, potentially lengthening the life of the pulleys in the exercise equipment. 
     The winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may take the form of a motorised spool in some embodiments of the present invention. In other embodiments, a linear actuator may be used. In the exercise machine  10  shown in  FIG. 1 , a linear actuator could replace the winch  18  and the cable  32  and be attached directly to the fifth pulley  17 . In the embodiment known from  FIG. 1 , a linear actuator could have a similar effect to the winch  18  it is replacing and will move the fifth pulley  17 , such that the amount of cable between the third pulley  15  and the handle  110  is increased or decreased as required. 
     In the exercise machine  20  shown in  FIG. 2 , a linear actuator could replace the winch  28  and be attached to the cable  21 . In the embodiment known from  FIG. 2 , the linear actuator will have a similar effect to the winch  28  it is replacing and will increase and decrease the amount of cable between the third pulley  25  and the handle  210 . 
     In the exercise machine  40  shown in  FIG. 3 , a linear actuator could replace the winch  48  and be attached to the cable  52  and be attached directly to the seventh pulley  47 . In the embodiment known from  FIG. 3 , a linear actuator could have a similar effect to the winch  48  it is replacing and will move the seventh pulley  47 , such that the amount of cable between the fifth pulley  45  and the handle  410  is increased or decreased as required. 
     In the exercise machine  60  shown in  FIG. 4 , a linear actuator could replace the winch  80  and be attached to the second cable  79 . In the embodiment known from  FIG. 4 , the linear actuator will have a similar effect to the winch  80  it is replacing and will increase and decrease the length of the second cable  79  between the eleventh pulley  78  and the attachment point  72 . 
     In the exercise machine  90  shown in  FIG. 5 , a linear actuator could replace the winch  99  and be attached to the cable  91 . In the embodiment known from  FIG. 5 , the linear actuator will have a similar effect to the winch  99  it is replacing and will increase and decrease the length of the cable  91  between the eighth pulley  98  and the handle  910 . 
     In the exercise machine  120  shown in  FIG. 6 , a linear actuator could replace the winch  132  and be attached to the third cable  131 . In the embodiment known from  FIG. 6 , the linear actuator will have a similar effect to the winch  132  it is replacing and will increase and decrease the length of the third cable  131  between the fifth pulley  130  and the second reel  124 . 
     The advantage of using a motorised spool or a linear actuator is that they are different sizes and have different power to weight ratios than the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132 . This allows the exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  to be customised for the location in which it will be operated. 
     In some embodiments, the winch  18 ,  28 ,  48 ,  80 ,  99 ,  132  may include the control unit. The control unit may be communicatively coupled with a sensor or a plurality of sensors through wired or wireless means. In other embodiments of the present invention, the control unit that may communicate with external devices such as such as a smart phone, table device, smart watch, smart wristband, activity tracker or other devices. The data received by the control unit may be from sensors on one or more of the pulleys  12 ,  13 ,  15 ,  16 ,  17 ,  22 ,  23 ,  25 ,  42 ,  43 ,  45 ,  46 ,  47 ,  53 ,  54 ,  55 ,  58 ,  59 ,  62 ,  63 ,  64 ,  65 ,  66 ,  68 ,  69 ,  73 ,  74 ,  77 ,  78 ,  92 ,  93 ,  95 ,  96 ,  97 ,  98 ,  101 ,  102 ,  122 ,  129 ,  130 ,  135 ,  136 . This data may comprise information about the movement of the pulleys  12 ,  13 ,  15 ,  16 ,  17 ,  22 ,  23 ,  25 ,  42 ,  43 ,  45 ,  46 ,  47 ,  53 ,  54 ,  55 ,  58 ,  59 ,  62 ,  63 ,  64 ,  65 ,  66 ,  68 ,  69 ,  73 ,  74 ,  77 ,  78 ,  92 ,  93 ,  95 ,  96 ,  97 ,  98 ,  101 ,  102 ,  122 ,  129 ,  130 ,  135 ,  136 . Other embodiments of the present invention may include a sensor on the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128  and communicate to the control unit information about the internal force. Some embodiments may include sensors on the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010 , which communicate with the control unit. The data collected from the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  may include heart rate information. Other embodiments of the present information may collect information from the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  that indicates a hazardous situation, for example if the user has released the handle  110 ,  210 ,  410 ,  610 ,  910 ,  1010  whilst performing the first or second motions. 
     The control unit may comprise a microprocessor, RAM and a memory. The control unit may receive data from any of the sensors and store it in the memory. The control unit may retrieve data from the memory and perform calculations on the data. The output of calculations performed by the control unit may be used by the control unit to calculate whether a user is performing a first motion or a second motion. The control unit may calculate whether a user is performing a first motion or in the second motion. 
     The control unit may be communicatively coupled to a display device. This display device may display may display how many repetitions a user has performed, the heart rate of a user, a user calorie count or any other information that a user may require. The display device may be a touchscreen device and a user may be able to input information that is used by the control unit, for example a user weight or a user age. The user might input information about the internal force such that the user does not need to directly interact with the weight stack  14 ,  24 ,  44 ,  76 ,  94 ,  128 . In other embodiments, the control unit may be communicatively coupled with an external device such as a smart phone, table device, smart watch, smart wristband, activity tracker or other device. The user may be able to input information through an external device. The control unit may store information that a user has input in the memory. The control unit may retrieve the information that a user has input from the memory and perform calculations on it. 
     In some embodiments, the control unit may be able to track users through the use of a unique identification code. This may be a code that is input by a user through the display device or through an external device. Alternatively the external device may automatically provide the unique identification code, for example through the MAC address of the device, by storing a code after it has been input by a user or through other paring means. 
     The control unit of the present invention may be connected to a local network or a wider network such as the internet in order to upload information about users to a central server or through a distributed network. This information may be accessed by the user through different external devices and from a location that is different to that of the present invention. This information may be accessed by other exercise machines in the same location as the present invention or may be accessed by exercise machines in a different location to the present invention. The exercise machine  10 ,  20 ,  40 ,  60 ,  90 ,  120  may access such information in order to calculate the user force to impart to the user. 
     In other embodiments of the present invention, a system for tracking the user&#39;s movements in real time is not required. The cable may be introduced between the entry point and the member at a constant rate, when the user starts the first or second motion, in order to reduce the effective weight experienced by the user. The cable may continue to be introduced between the entry point and the member throughout the duration of the user performing the first or the second motion. Such an embodiment may require a system for detecting when the user starts or finishes the first and second motions or the user may indicate that they are about to start or finish the first or second motion through the use of a switch, voice recognition or eye movement sensors. The embodiment may also detect that a certain amount of cable has been introduced between the entry point and the member in order to establish when the user has finished the first or the second motion. The cable may alternatively be introduced between the entry point and the member at, for example, a first rate and a second rate. The change between the first rate and the second rate may be based on an amount of cable passing the entry point or the user indicating that they wish the rate to change. 
     Another embodiment of the present invention may be applied to an elevator/lift mechanism, as shown in  FIG. 8 .  FIG. 8  comprises an elevator mechanism  750 . The elevator mechanism  750  comprises a weight  709 , a first cable  710 , a second cable  706 , a first pulley  708 , a second pulley  705 , a third pulley  704 , a first member  707 , a second member  703 , a winch  702  and an elevator car  701 . These components are arranged in a lift shaft (not shown). The first cable  710  has a distal end attached to a weight  709 . The first cable  710  passes upwards from the weight  709  to pass over the first pulley  708 , which is preferably arranged at the top of the lift shaft. The first pulley  708  is vertically orientated and is rotatable about a first axis. A motor (not shown) powers the first pulley  708 . The first pulley  708  is grooved, such that it may grip the first cable  710  and move the first cable. The first cable  710  extends downwards from the first pulley  708  and the proximal end of the first cable  710  is attached to a first attachment point  711  at a distal end of the first member  707 . 
     Attached towards the proximal end of the first member  707  is a second pulley  705 . At the proximal end of the first member  707  is a second attachment point  712 . The first member  707  and the second pulley  705  may comprise a first unit, so that these components are fixed to each other and the distance between them does not vary. The first unit is vertically orientated and can move in both directions along a first, generally vertical linear axis. The first unit may be arranged to move along a vertical track (not shown), for example, to allow this motion to take place. 
     A third pulley  704 , a second member  703  and an elevator car  701  comprise a second unit, so that these components are fixed to each other and the distance between them does not vary. The third pulley  704  is attached near to the distal end of the second member  703 . The proximal end of the second member  703  is generally attached to the roof of the elevator car  701 . The second unit is vertically orientated and can move in both directions along a second, generally vertically linear axis. The second unit may be arranged to move along a vertical track (not shown), for example, to allow this motion to take place. The second unit is generally arranged vertically below the first unit. 
     A second cable  706  is attached at a distal end to the second attachment point  712 . The second cable  706  extends downwards from the second attachment point  712  and under the third pulley  704 . The third pulley  704  is vertically orientated and is rotatable about a third axis. The second cable  706  extends upwards from the third pulley  704  to pass over the second pulley  705 . The second pulley  705  is vertically orientated and is rotatable about a second axis. The second cable  706  extends downwards from the second pulley  705  and is attached at a proximal end to a winch  702 . The winch  702  is attached to the roof of the elevator car  701 . The winch  702  may be operated to rotate a drum (not shown) around which the second cable  706  is wound. The winch  702  may therefore increase or decrease the length of the second cable  706  that extends from the winch  702 . 
     The second cable  706  is continuously threaded around the third pulley  704 , over the second pulley  705  and into the winch  702 . 
     In some embodiments, the first pulley  708  is a grooved drive sheave. 
     In use, the winch  702  may be either in a locked mode or in an unlocked mode. 
     If the winch  702  is in the locked mode, then when the motorised first pulley  708  rotates in a first rotational direction, the counterweight  709  rises and the elevator car  701  is lowered. When the motorised first pulley  708  rotates in a second, opposite rotational direction, the counterweight  709  is lowered and the elevator car  701  is raised. Each rotation of the motorised first pulley  708  raises and lowers both the elevator car  701  and the counterweight  709  by a fixed amount. 
     If the winch  702  is in the unlocked mode, the length of the second cable  706  between the second attachment point  712  and the winch  702  may be increased or decreased as the elevator car  701  rises and lowers due to the movement of the motorised winch  708 . This will cause the elevator car  701  to move at a different rate to the counterweight  709 . 
     The advantage of such an arrangement is that the inertia imparted to the elevator car  701  can be varied. For example, when approaching a stopping point, in order to ensure the comfort of the users, it is preferable to impart a small amount of inertia to the elevator car  701 . However, in order to rapidly move the elevator car  701  up and down a lift shaft, a high amount of inertia is preferable. In order to balance these competing requirements, the winch  702  can increase or decrease the amount of second cable  706  as the elevator car  701  is moving. 
     In use, the elevator mechanism  750  may incorporate a first pulley  708  with a large inertia in order to move the elevator car  701  rapidly. However, when the elevator car  701  is approaching a stopping point, for example at a requested floor, a system with a low inertia is required. When the car is approaching a stopping point, the winch  702  may adjust the length of the second cable  706  in-between the winch  702  and the second attachment point  712 . By shortening or lengthening the length of the second cable  706 , the elevator mechanism  750  can make use of a low inertia system in order to make small adjustments to the position of the elevator car  701 . 
     In use, as the elevator mechanism  750  moves the elevator car  701  from a lower floor to a higher floor, the length of the first cable  710  between the first pulley  708  and the elevator car  701  is shortened. At the same time, as the elevator car  701  begins to move from the lower floor, the elevator mechanism  750  may lengthen the length of the second cable  706  in-between the winch  702  and the second attachment point  712  in order to reduce the acceleration experienced within the elevator car  701 . 
     As the elevator car  701  moves up the lift shaft, the elevator mechanism  750  may reduce the length of the second cable  706  in-between the winch  702  and the second attachment point  712 . 
     As the elevator car  701  approaches the higher floor, the elevator mechanism  750  may lengthen the length of the second cable  706  in-between the winch  702  and the second attachment point  712  in order to reduce the deceleration experienced within the elevator car  701 . 
     In a first mode of operation, the winch  702  may be set to a locked position by a control mechanism. In this mode of operation, the elevator car  701  moves at the same rate, but in the opposite direction to, the counterweight  709 , both of which are dependent on the rate of rotation of the first pulley  708 . 
     In a second mode of operation, the winch  702  may vary the length of the second cable  706  in-between the winch  702  and the second attachment point  712 . In this manner, the elevator car  701  moves at a different rate to the counterweight  709  and the rate of movement of the elevator car  701  is not solely dependent on the rate of rotation of the first pulley  708 . 
     When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 
     The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.