Abstract:
A total body exercise machine including a fixed seat and longitudinal frame members on which travel a footrest slide carriage and a handle slide carriage. A tensile element coordinates movement of the slide carriages in opposite directions at a constant speed ratio. In the preferred embodiment resistance to slide carriage movement is provided by one or more friction brakes coupled to a slide carriage by a pivot frame oriented at an acute angle to the longitudinal frame member on which the carriage travels. The brake thereby provides more resistance in one direction of travel the other, and the magnitude of resistance is controlled by a small static force bearing on the pivot frame. In one embodiment a logic controller electronically controls this small static force by means of a force feedback loop to simulate a kinesthetic flywheel effect and to reduce shock loading. Additional means are provided to record, transmit, and receive data from a remote data processing device which aggregates and summaries such data in a user accessible medium.

Description:
FIELD OF INVENTION  
         [0001]    This invention relates to exercise devices which provide total body resistance to action of both extension and flexion muscle groups.  
         BACKGROUND OF THE INVENTION  
         [0002]    The importance of exercise in maintenance of human health is well established in the prior art. The primary benefits include cardiovascular conditioning, strength development, and flexibility development. For cardiovascular conditioning the most efficient exercises are so-called total body type in which oxygen is metabolized throughout the body, so total oxygen uptake is not limited by fatigue in any individual muscle group. For strength development efficiency requires convenient means to vary loads in both directions. Development of flexibility requires that an exercise be performed a wide range of motion. Also established in the prior art is the value of a so called kinesthetic momentum effect in providing an enjoyable continuous exercise.  
           [0003]    In the prior art many total body exercisers providing a kinesthetic momentum effect only offer significant resistance in one direction, for example rowing machines utilizing a one-way clutch to drive a flywheel. They provide extension resistance in the legs but minimal flexion resistance, and vice-versa in the arms. Several devises which do provide extension and flexion resistance employ pivoting frame members, including Bolf (U.S. Pat. No. 5,9913,752) and Scott (U.S. Pat. No. 5,178,599). These however do not provide a kinesthetic momentum effect or a wide range of motion. Others, such as Olschansky et al. (U.S. Pat. Nos. 5,145479 and 5,284,462) utilized foot and/or hand driven rotary crank means, which also do not provide a wide range of motion. Oter extension/flexion devices, such as Krukowski (U.S. Pat. No. 4,628,910) do not provide total body exercise. Mastropaolo (U.S. Pat. No. 3,572,700) describes a devise providing total body extension/flexion exercise over a wide range of motion which utilizes a sliding carriage for supporting the body and a one-way clutch means for switching direction of load which is not integral to the load means.  
         Objects and Advantages  
         [0004]    The object of the present invention is to provide a device for total body exercise which may be performed over a wide range of motion with provision for independent control of load over a wide range in both extension and flexion directions. A further object is to provide a device with a fixed seat so that work done by the upper body is independent of work done by the lower body. Another object is to provide a load control means which provides both a means to reduce shock loads at the beginning of each phase of operation and a simulated kinesthetic momentum effect not requiring a mechanical energy storage means such as a flywheel. Another object is to provide a load control means which provides an integral capability of measuring work output so that it may be economically recorded and summarized. A final object of the invention is to provide a device providing the above benefits which may be economically manufactured. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 shows a top perspective view of the exerciser.  
         [0006]    [0006]FIG. 2 a  is a side view of the exerciser in a beginning body position with components removed to show detail of power transmission.  
         [0007]    [0007]FIG. 2 b  is another side view of the exerciser in an ending body position with components removed to show detail of power transmission.  
         [0008]    [0008]FIG. 3 a  shows a perspective view of the footrest subassembly with manual resistance adjustment.  
         [0009]    [0009]FIG. 3 b  shows another perspective view of the footrest subassembly with manual resistance adjustment.  
         [0010]    [0010]FIG. 3 c  is a detail view of the manual resistance adjustment subassembly.  
         [0011]    [0011]FIG. 3 d  is a side view of the footrest subassembly with components removed to show arrangement of manual resistance subassemblies.  
         [0012]    [0012]FIG. 4 a  is a detail view of the automatic resistance adjustment subassembly.  
         [0013]    [0013]FIG. 4 b  is another detail view of the automatic resistance adjustment subassembly.  
         [0014]    [0014]FIG. 4 c  is a side view of the footrest subassembly with components removed to show arrangement of the automatic resistance adjustment subassembly.  
         [0015]    [0015]FIG. 5 a  shows the handle subassembly isolated from the exerciser with handles in the operating position.  
         [0016]    [0016]FIG. 5 b  is a detail view of the exerciser with handles in their storage position.  
         [0017]    [0017]FIG. 6 shows a perspective view of the exerciser in a vertical standing position with the handles and the display in their respective storage positions.  
         [0018]    [0018]FIG. 7 a  shows a functional layout of electrical components in the automatic resistance adjustment subassembly.  
         [0019]    [0019]FIG. 7 b  is a flowchart of logic used in the automatic resistance adjustment subassembly to control resistance within each phase of operation.  
         [0020]    [0020]FIG. 7 c  is logic sequence describing operation of the automatic resistance adjustment subassembly during an entire workout. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    First referring to FIG. 1, a footrest subassembly  100  is slidably mounted on a first frame member  50   a  and a handle subassembly  300  is slidably mounted on a second frame member  50   b . Frame members  50   a  and  50   b  are supported at a first end by a pair of supports  52   a  and  52   b . Frame members  50   a  and  50   b  are supported at their opposite end by a support  62 . As seat  58  is mounted on a first end of supports  52   a  and  52   b . The opposite end of supports  52   a  and  52   b  connect to a base member  54 . At a first end of base member  54  are attached a first set of floor bumpers  62   a  not shown and a first dolley wheel  56   a . At the opposite end of base member  54  are attached a second set of floor bumpers  62   b  and a second dolley wheel  56   b . Integral to seat  58  are alternate floor bumpers  60   a  and  60   b . A tensile element  64  links footrest subassembly  100  to handle subassembly  300  in a manner further described below with reference to FIG. 2 a  and FIG. 2 b.    
         [0022]    Now referring to FIG. 2 a  and FIG. 2 b , in which support  52   b  is removed for clarity, tensile element  64  attaches to a pin  68  mounted between supports  52   a  and  52   b . Tensile element  64  then runs substantially parallel to frame member  50   a  to where it turns about a pulley  72   a  rotatably mounted to footrest subassembly  100 . Pulley  72   a  is concentric to but here concealed by wheel  106   b  designated below. From pulley  72   a  tensile element  64  then runs back again substantially parallel to frame member  50   a  to where it turns about a pulley  66   a  which is rotatably mounted between supports  52   a  and  52   b . From pulley  66   a  tensile element  64  then runs substantially parallel to frame member  50   b  to where a clamp  70  connects it to handle subassembly  300 . From clamp  70  tensile element  64  then continues substantially parallel to frame member  50   b  to where it turns about a pulley  66   b  rotatably mounted within support  62 . Tensile element  64  then returns substantially parallel to frame member  50   a  to a pulley  72   b  rotatably mounted to footrest subassembly  100 . Pulley  72   b  is concentric to but here concealed by wheel  106   d  designated below. From pulley  72   b  tensile element  64  then runs back again substantially parallel to frame member  50   a  to where it terminates at a tension bracket  74  which is adjustably linked to support  62 .  
         [0023]    The positions of footrest subassembly  100  and handle subassembly  300  indicated in FIG. 2 a  reflect the respective positions of a user&#39;s feet and hands at the beginning of the exerciser&#39;s “drive” phase. The positions of those subassemblies indicated in FIG. 2 b  reflect the end of the drive phase which begins the exerciser&#39;s “recovery” phase, which returns them to their FIG. 2 a  positions. During both phases of motion handle subassembly  300  slides along frame member  50   b  in the opposite direction from and for substantially twice the distance that footrest subassembly  100  slides along frame member  50   a.    
         [0024]    Now referring to FIG. 3 a  and FIG. 3 b , which show the preferred manual resistance adjustment embodiment of the exerciser, footrest subassembly  100  includes a footrest support housing  102  within which are suspended a pair of manual resistance adjustment subassemblies  170  and  172  pictured in FIG. 3 c.    
         [0025]    Further referring to FIG. 3 a  and FIG. 3 b , a set of upper wheels  104   a  and  104   b  rotate on an axle  105   a  which is positioned within a first end of housing  102  so wheels  104   a  and  104   b  may roll on the top surface of frame member  50   a . Similarly a second set of upper wheels  104   c  and  104   d  rotate on an axle  105   b  which is positioned within a second opposite end of housing  102  so wheels  104   c  and  104   d  may also roll on the top surface of frame member  50   a . Likewise a group of lower wheels  106   a ,  106   b ,  106   c , and  106   d  is rotatably mounted within housing  102  where they may roll on the bottom surface of frame member  50   a . Pulley  72   a  designated above is rotatably mounted concentric to and between lower wheels  106   a  and  106   b . Pulley  72   b  designated above is rotatably mounted concentric to and between lower wheels  106   c  and  106   d . Also mounted within housing  102  are a set of anti-friction pads  108   a ,  108   b ,  108   c , and  108   d , located where they may contact the side surfaces of frame member  50   a . A set of access holes  110   a,    110   b,  and  112  pierce both opposing sides of housing  102 . A support rod  124  projects from both sides of housing  102  and supports a left footboard  120   a  and a right footboard  120   b . Footboard  120   a  is further fastened to housing  102  by a screw  126   a  and footboard  120   b  is further fastened to housing  102  by a screw  126   b  not shown. Pivotably mounted to rod  124  is a left Bootstrap  122   a  and a right Bootstrap  122   b . A display device  130  is mounted to resistibly pivot about axle  105   b . In this embodiment display  130  shows elapsed time, drive/recovery cycles per minute and total cycle count. A switch not shown connects to display  130  and detects the change in rotation direction of wheels  104   c  and  104   d  to signal drive/recovery cycle frequency.  
         [0026]    Manual resistance adjustment subassemblies  170  and  172  are identical in the preferred embodiment of the exerciser. Depicted in FIG. 3 c , they include a friction pad  180  mounted on a brake bracket  182  which is in turn is pivotably suspended by a pin  184  which connects lower portions of a link plate  186   a  and an identical link plate  186   b . Upper portions of link plates  186   a  and  186   b  are connected by a pin  188 . Upper portions of link plates  186   a  and  186   b  also contain holes  190   a  and  190   b  respectively. Pivotably mounted on pin  188  is an inverted U-shaped bracket  192  from which projects a thumb screw  194 . Interior to bracket  192  thumb screw  192  passes through a compression spring  196  and then threads into a nut  198  which is restrained from turning by the sides of bracket  192 .  
         [0027]    [0027]FIG. 3 d  shows the arrangement of manual resistance adjustment subassemblies  170  and  172  in footrest subassembly  100  in the manual resistance adjustment embodiment of the exerciser. Footboards  120   a  and  120   b  and footstraps  122   a  and  122   b  are here removed for clarity. Subassembly  170  is positioned so that axle  105   a  of footrest subassembly  100  passes through holes  190   a  and  190   b  of subassembly  170 , with pin  188  of subassembly  170  oriented towards the center of housing  102 . Taken together, pin  184 , link plate  186   a , link plate  186   b , and axle  105   a  form a pivot frame coupling bracket  182  to housing  102 .  
         [0028]    An acute angle “A” between the contact surface of friction pad  180  when in contact with frame member  50   a  and a plane containing the axes of axle  105   a  and pin  184  (the plane of said pivot frame) of subassembly  170  is equal to 50 to 80 degrees. Manual resistance adjustment subassembly  172  is positioned so that axle  105   b  of footrest subassembly  100  passes through holes  190   a  and  190   b  of subassembly  172 , with pin  188  of subassembly  172  also oriented towards the center of housing  102 , so pin  188  of subassembly  172  is adjacent to pin  188  of subassembly  170 . An acute angle “B” between the contact surface of friction pad  180  when in contact with frame member  50   a  and a plane containing the axes of axle  105   b  and pin  184  of subassembly  172  is equal to 50 to 80 degrees. In the preferred embodiment angles “A” and “B” are both equal to 67 degrees. In both subassemblies  170  and  172 , thumb screw  194  bears against the exterior surface of housing  102 . Pin  184  of subassembly  170  and pin  184  of subassembly  172  are located to allow their removal through access holes  110   a  and  110   b  respectively, in order to service friction pad  180  of both subassemblies  170  and  172 .  
         [0029]    One skilled in the art will recognize that the optimum angle for angles A and B is a function of the coefficient of friction of the material selected for brake pad  180 . For a given adjustment subassembly, if such angle is too large that subassembly will effectively lock itself to frame member  50   a . As such angle decreases a more powerful spring  196  is required to generate a given level of working resistance. A more powerful spring would then raise the minimum friction level which can be generated by that subassembly.  
         [0030]    [0030]FIG. 4 a  and FIG. 4 b  depict complimentary views an automatic resistance adjustment subassembly  200 , which contains the same friction pad  180  mounted on brake bracket  182  pivotably suspended by pin  184  as in subassemblies  170  and  172 . Here pin  184  connects to a link bracket  206  which in turn connects to an axle  208 . A pair of wheels  210   a  and  210   b  rotate on axle  208 . Also mounted on axle  208  is a strain gauge  212  incorporating a rear hole  213 . An electrical generator  214  sidably attached to link bracket  206  has a pair of drive wheels  216   a  not shown and  216   b . A compression spring  218  exerts a force from link bracket  206  against generator  214  so that drive wheels  216   a  and  216   b  bear against wheels  210   a  and  210   b  respectively. A force exerting device  220  is mounted at the end of link bracket  206  opposite pin  184 . In the preferred embodiment force exerting device  220  is a push type solenoid. The distance between force exerting device  220  and axle  208  is greater than the distance between axle  208  and pin  184  to leverage the effect of force exerting device  220 . Also mounted on link bracket  206  is circuit board  222  containing a heart rate receiver  224  which receives a signal from a heart rate transmitter  225  not shown worn by the user, and a controller  232 . Circuitry connecting the above components is not shown but will be described with reference to FIG. 7 a.    
         [0031]    [0031]FIG. 4 c  shows footrest subassembly  100  equipped with the above automatic resistance adjustment subassembly  200 , representing the automatic resistance adjustment embodiment of the exerciser. In footrest subassembly  100  footboards  120   a  and  120   b  and footstraps  122   a  and  122   b  are here removed for clarity. In this embodiment automatic resistance adjustment subassembly  200  replaces both manual adjustment subassemblies  170  and  172  of the manual adjustment embodiment. Here subassembly  200  links to housing  102  where axle  105   a  passes through hole  213  of strain gauge  212 . Also incorporated in footrest subassembly in this embodiment are a pair of bumpers  250   a  and  250   b  which occupy the holes in housing  102  through which thumb screw  194  of subassemblies  170  and  172  passed in the manual adjustment embodiment. A battery  252  connects to circuit board  222  and generator  214  by connectors and wires not shown. Projecting from display  130  is an antenna  254  for communication with a remote computer  256  not shown. Pin  184  of subassembly  200  is located to allow its removal through access hole  110   a  in order to service friction pad  180 . Access hole  112  allows cleaning of the rolling surfaces of wheels  210   a  and  210   b  and drive wheels  216   a  and  216   b . An acute angle “C” between the contact surface of friction pad  180  of subassembly  200  when in contact with frame member  50   a  and a plane containing the axes of axle  208  and pin  184  of subassembly  200  is equal to 50 to 80 degrees. In the preferred embodiment angle “C” is equal to 64 degrees.  
         [0032]    Now referring FIG. 5 a  and  5   b,  handle subassembly  300  consists of a left grip  302   a  and a right grip  302   b  mounted on the first ends of a left tube  304   a  and a right tube  304   b . The second opposite end of tube  304   a  features a 90 degree bend after which it is rotatably mounted in a pivot block  306   a  with freedom to rotate about an axis D. Likewise the second opposite end of tube  304   b  may rotate in a pivot block  306   b  about an axis D′. Pivot blocks  306   a  and  306   b  in turn rotate within a housing  308  about an axis E and an axis E′ respectively. Mounted within housing  308  are a pair of parallel support panels  310   a  and  310   b  which support a set of wheels  312   a  and  312   b  positioned so they may roll on the top surface of frame member  50   b . Another set of wheels  314   a  and  314   b  are positioned so they may roll on the bottom surface of frame member  50   b . Also mounted on housing  308  opposite wheels  312   a  and  312   b  are a group of anti-friction pads  316   a ,  316   b , and  316   c  located to contact the top surface of frame member  50   b . Mounted below these pads and opposite wheels  314   a  and  314   b  are another group of anti-friction pads  318   a  not shown,  318   b  not shown, and  318   c  not shown located to contact the bottom surface of frame member  50   b.  Also supported by support panels  310   a  and  310   b  are a group of anti-friction pads  320   a  not shown,  320   b ,  320   c , and  320   d  not shown located to contact the left and right side surfaces of frame member  50   b . Clamp  70  is mounted on top of housing  308  located to connect to tensile element  64 .  
         [0033]    [0033]FIG. 5 a  shows handle sub-assembly  300  with handles  304   a  and  304   b  deployed in their operating position. FIG. 5 b  shows handle sub-assembly  300  with handles  304   a  and  304   b  rotated about axes D, D′, E and E′ into their storage position.  
         [0034]    [0034]FIG. 6 shows the exerciser in a vertical storage position supported by dolley wheels  56   a  and  56   b  and alternate floor bumpers  60   a  (not shown) and  60   b . Here handles  304   a  and  304   b  are in their storage position and display  130  is rotated about the axis of pin  105   b  to a storage position where it does not project through a plane defined by the tops of seat  58  and support  62 .  
         [0035]    [0035]FIG. 7 a  illustrates the electrical and data connections employed by automatic resistance adjustment subassembly  200 . Generator  214  transmits electrical power when driven by wheels  210   a  and  210   b  to controller  232  which in turn transmits a non-reversing charging current to battery  252 . Controller  232  measures the power output from generator  214 , which is proportional to both the speed of rotation of generator  214  and, by common rolling contact with wheels  210   a  and  210   b , the speed of linear displacement of the entire footrest subassembly  100  with respect to frame member  50   a . Strain gauge  212  measures the force resisting the linear displacement of footrest subassembly  100  with respect to frame member  50   a  and passes this information to controller  232 . The means to convert analog signals from generator  214  and strain gauge  212  into digital form are integral to controller  232 . Using the above displacement and force inputs controller  232  then calculates the energy expended by the user in moving housing  102  with respect to frame member  50   a  during a predefined iteration time interval. Subject to control objectives described below, controller  232  then controls the amount of force which force exerter  220  applies against link bracket  206  when pushing away from bumper  250   b . Battery  252  supplies operating power to controller  232  and display  130 , and well as the excitation energy used by force exerter  220 . By tending to pivot about axle  208  link bracket  206  magnifies the force applied by exerter  220  and brings it to bear as a normal force acting through brake bracket  182  and brake pad  180  against frame member  50   a . Subject to the coefficient of friction of brake pad  180 , this normal force controls the predominant component of the above resisting force measured by strain gauge  212 . The remaining lesser components of the resisting force measured by strain gauge  212  represent the force required to drive generator  214  and other friction forces generated by the exerciser&#39;s other moving parts. Controller  232  accumulates and stores in memory data representing user energy expenditure during successive time intervals.  
         [0036]    Further referring to FIG. 7 a , heart rate transmitter  225  transmits data to heart rate receiver  224 . In the preferred embodiment transmitter  225  is carried in a chest strap worn by the user in the known way, and signal transmission is by magnetic resonance. Receiver  224  then relays heart rate data to controller  232  where it is accumulated and stored in memory.  
         [0037]    Periodically controller  232  passes data representing user energy expenditure, operating cadence, and user heart rate to display  130 , where it is displayed graphically and/or numerically in appropriate units during the workout. At the end of each workout session this data is then relayed to remote computer  256  by antenna  254  where it is recorded in a database format in digital storage media. Using this user workout data computer  256  then prepares reports documenting user fitness levels. Antenna  254  also can receive communications from remote computer  256 , for example of new workout programs, which antenna  254  then passes to controller  232 . Also integral to display  130  are buttons which communicate with controller  232  with which the user can manually initiate, define, modify, and terminate workout programs.  
         [0038]    The long term control objectives of controller  232  consist of managing entire workout programs, including: (1) Drive and recovery resistance balanced according to relative muscle group strength with work load adjustment to maintain target user heart rate, (2) Switch between (a) high drive/low recovery resistance and (b) low drive/high recovery resistance when controller  232  senses power drop due to user fatigue, (3) Balanced low resistance steady state aerobic work, (4) Balanced high resistance strength training work, (5) Balanced with alternating high/low resistance intervals, (6) Repeating pattern of balanced low resistance, followed by high resistance on drive only, followed again by balanced low resistance, followed by high resistance on recovery only. The means by which controller  232  executes these workout programs are described below.  
         [0039]    The short term control objectives of controller  232  relate to managing resistance within a single operating phase (drive or recovery). These include: (1) Reduction of dynamic shock loading at the beginning portion of each operating phase, and (2) Creation of a desirable kinesthetic momentum or flywheel effect during the remaining portion of each phase.  
         [0040]    [0040]FIG. 7 b  is a flow chart illustrating how controller  232  achieves these short term objectives on either a drive or recovery phase. A step  402  assigns zero value to a variable “XB” representing the linear displacement of subassembly  100  during a prior iteration interval. A step  404  assigns zero value to a variable “XC” representing the cumulative linear displacement of subassembly  100  since the beginning of the current drive or recovery phase. In a pause  406  controller  232  pauses for an iteration interval “TI”. A step  408  records a value “XA” representing the linear displacement of subassembly  100  during pause  406 . A step  410  provides workout program data either stored in controller  232  memory, previously input directly by the user or previously transmitted from remote computer  256 . A data element  412  provided by workout program  410  is an inertial factor “I” representing acceleration of a virtual mass to generate the above momentum effect. Another data element  414  provided by workout program  410  is a drag factor “D” representing a drag force proportional to displacement XA. A third data element  416  provided by workout program  410  is a constant force value “FC” representing a constant component of the force applied by force exerter  220 . A calculation step  418  is an equation of motion which then computes an output force “F” based upon I, D, and FC, assuming the common time interval TI. Here the first term “I*(XA-XB)” represents the virtual mass times its acceleration. In the second term “D*XA 3 ” the quantity XA is raised to the third power to better simulate a viscous resistance.  
         [0041]    Further referring to FIG. 7 b , controller  232  acts to reduce shock loading in a step  420 , a step  422 , and a step  424 . Step  420  increments XC by the current value of XA. Step  422  retrieves from memory a soft start distance “XS”. Step  424  proportionally reduces the value of F to the extent XC is less than XS. In the preferred embodiment XS is equal to two inches. In a step  426  Controller  232  then applies output force F to exerter  220 . A step  428  then retrieves from memory a glide factor “G” which is a scalar quantity representing the rate at which the virtual mass slows down during interval TI due to external drag. A step  430  then calculates a new value for XB equal to G times the current value of XA. In this way, during each such iteration, in calculation step  418  the XA value represents current iteration displacement and the XB value represents prior iteration displacement adjusted by glide factor G. Finally in a step  432  controller  232  returns to step  406  if the current phase or workout is not over.  
         [0042]    [0042]FIG. 7 c  is a logic sequence which applies the short term methods described in FIG. 7 b  in the larger context of a complete workout. Here controller  232  manages output force F independently on the drive and recovery. A virtual mass generating drive momentum and a separate virtual mass generating recovery momentum have the effect of simultaneously moving in opposite directions. In this logic sequence workout programs are defined by the following variables:  
         [0043]    P=Workout program type  1 , 2 , 3 , 4 , 5 , or  6 ;  
         [0044]    ID=Inertial factor on drive, analogous to I of FIG. 7 b;    
         [0045]    IR=Inertial factor on recovery, analogous to I of FIG. 7 b;    
         [0046]    D(N)=Drag factor for drive N, scaled to reflect the force magnification resulting from the effect of angle C noted above, analogous to D of FIG. 7 b;    
         [0047]    R(N)=Drag factor on recovery N, analogous to D of FIG. 7 b;    
         [0048]    TEND=Total workout time;  
         [0049]    WEND=Total workout work.  
         [0050]    D(N) and R(N) are data series wherein a zero value indicates the end of the series. For example, workout type  5  is represented as: D(N)=(low value, high value, low value, low value, zero) and R(N)=(low value, low value, low value, high value, zero). Special forms for workout types  1  and  2  are described below. Other variables used in the FIG. 7 c  logic sequence are:  
         [0051]    DD=Current drive phase drag factor D(N)  
         [0052]    DR=Current recovery phase drag factor R(N)  
         [0053]    F=Control force applied by exerter  220 , as in FIG. 7 b    
         [0054]    FC=Base constant force, as in FIG. 7 b;    
         [0055]    G=Glide factor, as in FIG. 7 b;    
         [0056]    HR=Current user heart rate;  
         [0057]    FM=Force measured by strain gauge  212 , where (+) designates compression (drive) and (−) designates tension (recovery);  
         [0058]    N=Drive/recovery cycle count;  
         [0059]    TI=Iteration time interval, as in FIG. 7 b;    
         [0060]    TC=Time elapsed from beginning of workout;  
         [0061]    X 1 =Drive displacement during current iteration time interval, analogous to XA of FIG. 7 b;    
         [0062]    X 2 =Drive displacement during prior iteration interval, analogous to XB of FIG. 7 b;    
         [0063]    X 3 =Cumulative drive displacement from beginning of drive phase, analogous to XC of FIG. 7 b;    
         [0064]    X 4 =Recovery displacement during current iteration time interval, analogous to XA of FIG. 7 b;    
         [0065]    X 5 =Recovery displacement during prior iteration interval, analogous to XB of FIG. 7 b;    
         [0066]    X 6 =Cumulative recovery displacement from beginning of recovery phase, analogous to XC of FIG. 7 b;    
         [0067]    XS=Soft start distance, as in FIG. 7 b;    
         [0068]    WC=Work done in current drive/recovery cycle,  
         [0069]    WMAX=Work done in maximum work drive/recovery cycle;  
         [0070]    WT=Total work done since beginning of workout.  
         [0071]    Now referring to FIG. 7 c , a series of lines  500 ,  510 ,  520 ,  530 , and  540  assign a zero initial value to TC, WC, WMAX, X 2 , and X 5 . Setting X 2 =0 here is analogous to step  402  of FIG. 7 b . A line  550  sets N=1. A line  580  is the beginning of a drive/recovery cycle iteration loop setting WC=0. A line  585  resets N=1 if the series D(N) yields a zero value indicating end of series. A line  600  is the beginning of a drive phase iteration loop setting X 3 =0, analogous to step  404  of FIG. 7 b . At a line  605  controller  232  pauses for time interval TI, analogous to step  406  of FIG. 7 b . A line  610  reads the current value of FM. A line  615  then skips ahead to a line  700  if the user is in a recovery phase rather than a drive phase. A line  620  records X 1 , representing the linear displacement of subassembly  100  during the pause at line  605 , analogous to step  408  of FIG. 7 b . A line  625  then increments WC by the quantity FM*X 1 , representing the amount of work done during displacement X 1 . A line  630  retrieves a DD value from a subroutine at a line  900 , analogous to step  414  of FIG. 7 b . An equation  635  is the drive phase equation of motion analogous to step  418  of FIG. 7 b . A line  640  then increments X 3  by X 1 , analogous to step  420  of FIG. 7 b . A line  645  then implements the soft start feature of steps  422  and  424  of FIG. 7 b , so that if X 3  is less than XS then F is reduced by a factor X 3 /XS, but not to less than FC. Line  650  applies the resulting value of F to exerter  220 , analogous to step  426  of FIG. 7 b . While X 2  was initially set equal to zero at line  530 , a line  655  then sets X 2 =G*X 1 , a value which will apply in subsequent iterations through equation  635 , analogous to steps  428  and  430  of FIG. 7 b . Line  660  then sets X 5 =G*X 5 , having the effect of decelerating the recovery virtual mass during the drive phase. A line  665  skips to a line  850  if workout time has expired and a line  670  skips to a line  850  if workout work has expired. At a line  675  controller  232  then skips to a line  700  if the absolute value of FM is less than a minimum quantity, indicating the user is at a phase transition. A line  680  then returns to line  600  completing the drive phase iteration loop.  
         [0072]    A recovery phase iteration loop at a series of lines  700 - 780  corresponds numerically to the above drive phase iteration loop at lines  600 - 680 , except there is no line corresponding to line  615 . In the line  700 - 780  loop variables DD, X 4 , X 5 , and X 6  replace DR, X 1 , X 2 , and X 3 , and vice-versa, respectively. Line  760  sets X 2 =X 2 *G, having a reciprocal effect of decelerating the drive virtual mass during the recovery phase. The phase transition test at line  775  skips to a line  800 .  
         [0073]    For the case of workout program type  2 , line  800  sets WMAX equal to the highest value of WC generated since initialization or reset of WMAX=0. A line  805  then increments WT by WC. A line  810  then displays WC and HR for the just ended drive/recovery cycle. A line  815  records in memory the current TC, WC and HR value for later reporting. For workout types other than  1  and  2  a line  820  then increments N by 1. A line  825  marks the end of the drive/recovery cycle and returns to line  580  to begin the next cycle. At the end of the workout line  850  then displays all workout results on display  130 . Finally, a line  855  transmits those results to remote computer  256 .  
         [0074]    For workout programs other than type  1  and type  2  the subroutine beginning at line  900  goes to a line  950  and returns DD=D(N) and DR=R(N).  
         [0075]    In the special case of workout type  1 , workout drag factors are in the form D(N)=(base drag factor on drive, drag adjustment coefficient for drive, heart rate minimum) and R(N)=(base drag factor on recovery, drag adjustment coefficient for recovery, heart rate maximum). Here, if HR is greater than or equal to the heart rate minimum D( 3 ) and less than or equal to the heart rate maximum R( 3 ), then a line  905  returns DD=D( 1 ) and DR=R( 1 ). For heart rates below the minimum D( 3 ) value, a line  910  returns DD adjusted by factor D( 2 ) and the quantity D( 3 )AHR and DR adjusted by factor R( 2 ) and the quantity D( 3 )/HR. Similarly, for heart rates above the maximum R( 3 ) value, a line  915  returns DD adjusted by factor D( 2 ) and the quantity R( 3 )/HR and DR adjusted by factor R( 2 ) and the quantity R( 3 )/HR.  
         [0076]    Workout type  2  reverses drive and recovery intensity levels when user work output falls below defined threshold levels. In this case workout drag factors are in the form D(N)=(high value, low value, fatigue threshold percent) and R(N)=(low value, high value, zero). For this workout type, if WMAX=0, a line  930  goes to line  950 , indicating it is in an initial drive phase following WMAX initialization or reset. Then a line  935  also goes to line  950  if controller  232  is in the drive phase (FM&gt;0), so that intensity reversal only occurs following a complete drive/recovery cycle. Finally, in a line  940 , if WC is less than WMAX times threshold D( 3 ) the value of N switches from  1  to  2  and vice-versa to reverse drive and recovery intensity levels. Line  950  then returns DD=D(N) and DR=R(N).  
       Operation  
       [0077]    In its operating position the exerciser is supported by bumpers  62   a  and  62   b  and support  62 . The user sits on seat  58  and places his/her feet on footboards  120   a  and  120   b  within footstraps  122   a  and  122   b . The user&#39;s hands grasp grips  302   a  and  302   b . During the drive phase of operation the user extends his/her legs so footrest subassembly  100  moves away from seat  58  and pulls with his/her hands so handle subassembly  300  moves towards seat  58 . As noted above, handle subassembly  300  moves in the opposite direction and substantially twice the distance as footrest subassembly  100 . The drive phase employs the user&#39;s extension muscle groups in the legs and lower torso and flexion muscle groups in the upper torso and arms. The recovery phase is the reverse, so it employs the user&#39;s flexion muscle groups in the legs and lower torso (abdominals) and extension muscle groups in the upper torso and arms.  
       Operation of Manual Resistance Adjustment  
       [0078]    In the manual resistance adjustment embodiment illustrated in FIG. 3 d , thumb screw  194  of adjustment subassembly  172  substantially controls resistance during the drive phase. Here, with reference to components of adjustment subassembly  172 , thumb screw  194  adjusts the force compression spring  196  applies to generate a small initial torque on link plates  186   a  and  186   b  which tends to rotate them about axle  105   b  so brake pad  180  is brought to bear against the underside of frame member  50   a . The orientation and magnitude of angle B greatly compound this initial torque in response to the user moving footrest subassembly  100  in the drive direction. This positive feedback effect occurs because the friction force transmitted through brake pad  180  during the drive phase acts in concert with that of compression spring  196 , thus further increasing the normal force on brake pad  180 , which in turn further increases the friction force itself. However during the recovery phase the friction force reverses direction and tends to rotate link plates  186   a  and  186   b  the other way so brake pad  180  is pulled away from frame member  50 , in opposition to spring  196  force. Therefor during the recovery phase friction force generated by adjustment subassembly  172  does not exceed that which results from spring  196  force alone.  
         [0079]    In similar fashion thumb screw  194  of adjustment subassembly  170  substantially controls resistance during the recovery phase. Here link plates  186   a  and  186   b  tend to rotate about axle  105   a  rather than  105   b , and the orientation and magnitude of angle A govern the positive feedback effect.  
         [0080]    Because the muscle groups used during the drive phase are typically stronger than those used during the recovery phase, a user typically sets adjustment subassembly  172  for higher resistance than subassembly  170 . At low levels this will provide a balanced total body workout for maximum cardiovascular benefit. However a user may wish to vary these settings in accordance with other training goals. For example, setting subassembly  170  for high resistance provides a strength training exercise isolating the abdominal muscles.  
       Operation of Automatic Resistance Adjustment  
       [0081]    Referring again to FIG. 4 c , in the automatic resistance adjustment embodiment of the exerciser subassembly  200  controls resistance during both the drive and recovery phases. Here the acute angle C faces in the same direction as angle B of manual resistance adjustment subassembly  172  in order to most efficiently provide more resistance during the drive phase than the recovery phase, in accordance with the relative strength of different muscle groups. An alternative embodiment of the exerciser may contain two subassemblies  200  facing in opposite directions as do subassemblies  170  and  172  in the manual adjustment embodiment. Controller  232  independently adjusts resistance during the drive and recovery phases. Here the action of force exerter  220  is analogous to spring  196  of the manual adjustment subassemblies. Controller  232  also functions to reduce startup shock loading at the beginning of each phase, provide a desirable kinesthetic momentum effect, and provide a drag force which simulates viscous resistance.  
       Alternative Embodiments  
       [0082]    While the above description of the exerciser illustrates its preferred embodiments numerous alternative methods and structures falling within the scope of the invention can be developed by those skilled in the art. Such alternative methods and structures include:  
         [0083]    A. The ratio of footrest subassembly  100  movement to handle subassembly movement may be other than 2:1.  
         [0084]    B. Exerter  220  may be a piezo-electric element rather than a solenoid.  
         [0085]    C. Some or all functions ascribed to controller  232  may reside in display  130 .  
         [0086]    D. The spring rate of spring  196  in manual resistance adjustment subassembly  170  may differ from that in subassembly  172 .  
         [0087]    E. In a lower cost embodiment, strain gauge  212  in automatic resistance adjustment subassembly  200  may be eliminated. In this case for calculation of work done FM would be defined as a empirical function F and workout program type  2  would be eliminated. Generator  214 &#39;s signal would be used to determine phase and phase changes.  
         [0088]    F. In a further automatic resistance adjustment embodiment, footrest subassembly  100  may comprise two automatic resistance adjustment subassemblies oriented to maximize resisting force in opposite directions as do manual resistance adjustment subassemblies  170  and  172  in the manual resistance embodiment.  
         [0089]    G. Glide factor G may be variably defined by alternative workout programs rather than constant.  
         [0090]    H. The equation of motion at lines  635  and  735  of FIG. 7 c  may be replaced by other functional means, for example a lookup table defining F as a function of X 1  and X 2  on the drive or X 3  and X 4  on the recovery.  
         [0091]    I. The drag term D*(XA) 3  at step  418  of FIG. 7 b . may raise XA (or X 1  at line  635  and X 4  at line  735  of FIG. 7 c ) to a power other than three.  
         [0092]    J. Resistance means mounted on handle subassembly  300 .  
         [0093]    K. Frame member  50   b  not parallel to frame member  50   a.    
         [0094]    L. Frame member  50   b  above frame member  50   a.    
         [0095]    M. Where pulley  66   a  may be driven by tensile element  64 , one skilled in the art may construct analogous resistance subassemblies opposing rotary motion of pulley  66   a.    
         [0096]    The scope of the invention should be determined by the appended claims and their legal equivalents rather than by the above examples.