Abstract:
A lumbar extension machine is disclosed including a seat with an upright rotatable back member securable to a variable resistance module or statically secured to a load cell module. A lower body system is provide to optimize the exercise of the lower back by preventing movement and work by the hips and thighs. A pelvic restraint pad is located adjacent the seat and the seat is adjustable at the pad to insure that the iliac crest is properly located at the pad. An adjustable foot rest is provided to align the thigh with the seat angle after the seat height has been properly adjusted. The load cell provides strength testing to allow the clinician to determine relative strength and establish treatment parameters and monitor treatment progress and validate and quantify treatment results.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to methods and apparatus for the exercising and/or testing of muscles of the human body. More particularly, the invention relates to an exercise machine which has the ability to isolate and focus specifically on the lumbar extensor muscles and lumbar musculoskeletal system and apply selected and appropriate exercise intended to produce a specific, desired result. More particularly, the invention relates to a device which can also be used to test relative muscular strength/torque. 
   2. Related Information 
   There are numerous and various types of problems and conditions which are typically referred to as “low back pain.” There can be numerous and various causes and contributing factors which often result in chronic low back pain. Although there can be numerous causes and contributing factors which result in varied diagnostic findings, there is often at least one common symptom in most chronic low back pain situations. Below normal strength levels are a major factor in most instances of low back pain, especially if the incident develops into a chronic situation. Regardless if below normal strength levels were a cause or exacerbation, one positive step that can be taken to provide treatment and rehabilitation is to introduce properly applied therapeutic exercise. In most instances, low back pain produces a decrease in regular, meaningful physical activity. As muscular strength decreases due to disuse atrophy, the lumbar musculoskeletal system becomes weak and compromised which typically leads to pain and dysfunction. This cycle of deterioration becomes self perpetuating and often results in the low back pain sufferer becoming a candidate for surgery. Research and clinical studies indicate that many of the common forms of “low back pain” can be successfully treated and rehabilitated by the proper application of therapeutic exercise. 
   The present invention provides the apparatus and the basis to develop a treatment and rehabilitation program intended specifically to increase the strength of the lumbar musculature. The basic principal is to introduce an overload stimulus which, when properly applied in proper amounts and at proper intervals and for an appropriate period of time, duration, will produce a specific, desired response. The specific desired response is an increase in muscular strength. Research and clinical studies have established that an increase in strength is typically accompanied by other desired improvements: a decrease in perceived pain; restored structural integrity; improved functional ability and enhanced quality of life. The present invention has the ability to introduce or apply an effective overload stimulus by inducing fatigue. Fatigue results from physical exertion or work. In the rehabilitation process, the magnitude of the overload stimulus, work, is increased from session to session. An increase can be either an increase in resistance or an increase in the number of repetitions performed. Proper increases in work, overload stimulus, at proper intervals will produce an increase in the ability to perform that work. This assumes, of course, that other relevant considerations, such as overall health and nutrition are also positive and proper. In a rehabilitation environment, physical exertion, kinetic activity, can be referred to as prescribed therapeutic exercise. The present invention comprises various features and functions which allow the controlled application of therapeutic exercise. An important aspect of any treatment and rehabilitation apparatus or program is the ability to test. Test information is useful in determining current/existing strength levels, establishing treatment and rehabilitation parameters, monitoring treatment progress and quantifying treatment and rehabilitation results. 
   OBJECTS OF THE INVENTION 
   In light of the above it is an object of the present invention to incorporate some new and unique features and functions and some previously established features and functions into a device which collectively provide a broad range of efficacious options and alternatives for the treatment and rehabilitation of many common forms of spinal pathology. 
   A further object of the present invention is to provide novel and improved methods and apparatus for the application of appropriate exercise to specific muscles and/or a specific musculoskeletal system. 
   A further object of the present invention is to provide novel and improved methods and apparatus for testing of specific muscles and/or a specific musculoskeletal system. 
   A further object of the present invention is to provide novel and improved methods and apparatus for exercising specific muscles and/or muscle groups incorporating a novel and improved mechanism for providing resistance to muscle exertion during exercise. 
   A further object of the present invention is to provide novel and improved methods and apparatus for restraining the lower body to remove and/or limit lower body influence and participation in exercise and testing of the targeted muscles and/or muscle groups. 
   A further object of the present invention is to provide novel and improved methods and apparatus which positively affect the size, weight, complexity and operational efficiency of this device of the present invention. 
   SUMMARY OF THE INVENTION 
   To accomplish the above objects the present invention includes a device or apparatus having a seat assembly which effectively restrains the lower body and properly positions the pelvis against a pelvic restraint pad. Operatively attached to the seat assembly is a movement arm which pivots around an axis to allow effective exercising and/or testing of specific, targeted muscles and/or muscle groups. The movement arm is operatively connected to a variable resistance mechanism which provides selected, appropriate resistance against movement and muscular exertion by the subject/exerciser. Included in one preferred embodiment is the ability to test relative muscular strength/torque. Thus the lumbar extension machine of the present invention comprises: 
   (a) a seat assembly comprising;
         (i) a seat frame   (ii) a seat hingedly secured at the front to said seat frame;   (iii) a pelvic restraint pad secured to said seat assembly;   (iv) a pair of rotating cams rigidly connected by a rod and mounted underneath and transverse said seat adjacent said pelvic restraint pad such that when said rod is rotated the cams move the rear of said seat upward or downward;       

   (b) a movement arm assembly rotatably secured to said seat assembly, said movement arm assembly having an axis of rotation 
   (c) a variable resistance mechanism securable to said movement arm assembly through its axis of rotation, said variable resistance module comprising a free weight attached to an adjustable length lever arm by a series of pulleys and pulley belts one of said pulleys being rigidly attached to said rotatable back member through its axis of rotation; 
   (c) a load cell module statically securable to said movement arm assembly through its axis of rotation; 
   (d) a proximity sensor module mounted adjacent said movement arm assembly to count the repetitions of passage; 
   (e) a pair of handlebars extending from the upper end of said movement arm assembly; 
   (f) an adjustable lower body restraint system mounted on said seat assembly comprising;
         (i) a height adjustable foot rest connected to said seat frame, and   (ii) a pair of adjustable shin pad restraints connected to said seat frame;       

   (g) a pivoting resistance pad at the upper end of said movement arm assembly; and 
   (h) a pelvic restraint pad secured on said back member near said seat. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is an isometric view of the device incorporating one preferred embodiment of the present invention for testing and exercising the muscles of the lumbar spine. 
       FIG. 2  is an isometric view of the device of the present invention showing major elements and configurations, however, some parts omitted for clarity. 
       FIG. 3  is a side elevational view of the device of the present invention showing major elements and configurations, however, some parts omitted for clarity. 
       FIG. 4  is a front elevational view of the device of the present invention showing major elements and configurations, however, some parts omitted for clarity. 
       FIG. 5  is an isometric view of the seat assembly of the present invention showing the lower body restraint mechanism. 
       FIG. 6  is a side elevational view of the seat assembly of the present invention showing more details of the lower body restraint mechanism. 
       FIG. 7  is an isometric view of the height adjustable seat assembly of the present invention with the seat in the lowest position. 
       FIG. 7A  is an isometric view of the height adjustable seat assembly of the present invention with the seat in the highest position. 
       FIG. 8  is a front elevational view of the height adjustable seat assembly of the present invention showing the components and configuration. 
       FIG. 8A  is a side elevational view of the height adjustable seat assembly of the present invention showing the adjusting cam. 
       FIG. 9  is an isometric view of the shin pad restraint mechanism of the present invention showing the components and configuration. 
       FIG. 9A  is a side elevational view of the shin pad restraint mechanism of the present invention showing the components and configuration. 
       FIG. 10  is an isometric view of the adjustable footboard assembly of the present invention showing the components and configuration. 
       FIG. 10A  is a side elevational view of the adjustable footboard assembly of the present invention showing the components and configuration. 
       FIG. 11  is a side elevational view of the seat assembly and restraint mechanism of the present invention with a subject/exerciser positioned and restrained therein. 
       FIG. 12  is an isometric view of the movement arm assembly of the present invention showing major elements of the movement arm assembly and resistance pad. 
       FIG. 13  is a side elevational view of the seat assembly and movement arm assembly of the present invention showing relative configuration from flexed position to extended position. 
       FIG. 13A  is a side elevational view of the pivoting resistance pad of the present invention showing typical movement during use and operation. 
       FIG. 13B  is a side elevational view of the pivoting resistance pad of the present invention showing the components and configuration. 
       FIG. 14  is a side elevational view of the present invention showing the subject/exerciser in the two extreme positions. 
       FIG. 15  is a side elevational view of the test mode engagement mechanism of the movement arm assembly of the present invention showing components and configuration. 
       FIG. 15A  is an exploded view of the components of the test mode engagement mechanism of movement arm assembly of the present invention. 
       FIG. 16  is an isometric view of the resistance mechanism of the present invention showing major elements and components. 
       FIG. 17  is a side elevational view of the resistance mechanism of the present invention showing more details of the components and configuration. 
       FIG. 18  is an isometric view of the cam and camshaft assembly of the resistance mechanism of the present invention. 
       FIG. 18A  is an exploded view of the cam and camshaft assembly of the resistance mechanism of the present invention. 
       FIG. 19  is an isometric view of range of motion selector and resistance engagement assembly of the resistance mechanism of the present invention. 
       FIG. 19A  is an exploded view of the range of motion selector and resistance engagement assembly of the resistance mechanism of the present invention. 
       FIG. 20  is an isometric view of the variable resistance assembly of the resistance mechanism of the present invention. 
       FIG. 20A  is an exploded view of the variable resistance assembly of the resistance mechanism of the present invention. 
       FIG. 21  is an isometric view of the resistance selector assembly of the resistance mechanism of the present invention. 
       FIG. 21A  is an exploded view of the resistance selector assembly of the resistance mechanism of the present invention. 
       FIG. 22  is a side view of the variable resistance assembly of the resistance mechanism of the present invention showing operational range, configuration, relative theory and function. 
       FIG. 23  is a side view of a typical belt and pulley connection used in several places and configurations in the resistance mechanism. 
       FIG. 24  is an isometric view of the resistance mechanism of the present invention showing typical action, cycle and sequence of the resistance mechanism during use and operation. 
       FIG. 25  is an isometric view of the load cell assembly, strength testing component, of the present invention. 
       FIG. 26  is a side view of the load cell assembly of the present invention in the upright, test position showing components, configuration, relative theory and function. 
       FIG. 26A  is a side view of the load cell assembly of the present invention showing the engagement rod in three test positions. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   For a detailed description of the invention the reader is directed to the attached figures wherein like components are given like reference numerals for ease of reference. 
   Referring first to  FIGS. 1-4 , the lumbar extension device of the present invention is shown to comprise a seat assembly generally indicated at  100  and a movement arm assembly generally indicated at  200 , a resistance mechanism generally indicated at  300 , a load cell testing module generally indicated at  400  and a readout module generally indicated at  500 . Movement arm assembly  200  is operatively connected to both the resistance mechanism  300  and the seat assembly  100  at the indicated AXIS. The load cell testing module  400  is connected to both the resistance mechanism frame and the seat assembly frame and is positioned to allow engagement of a test mode configuration via test mode engagement generally indicated at  210 . The meter readout module  500  is mounted on top of the resistance mechanism frame and contains a repetition count meter and a torque indicator meter. An important element of this device is the axis of rotation of the movement arm and is referred to in all relevant views and FIGURES as the “AXIS” and is indicated with a centerline designation. 
   Referring to  FIG. 5 , the seat assembly, generally indicated at  100 , of the present invention is shown in an isometric view. There is a frame comprised of horizontal members  101 ,  102 ,  103 ,  104  and upright members  105 ,  106 ,  107 . Preferred frame material is 11 or 14 gauge steel square tubing. Frame member  104  is a solid flat bar and has apertures which mate and match with apertures of the resistance mechanism frame, generally indicated at  300 , to allow seat assembly to be securely attached to the resistance mechanism. Securely attached to vertical, upright members  105  and  106  are pillow block bearings  114  which allow and determined the appropriate location and fixation of the “AXIS.” Preferred bearings have an extended inner race with dual set screws. Also rigidly fixed to the upright members  105  and  106  is the pelvic restraint frame  113  which provides the firm and appropriate location and support of the pelvic restraint pad  112 . A firmly placed and fixed pelvic restraint is an essential element to provide proper lower body restraint and allow safe effective exercise and extension by the subject/exerciser. Also shown is the adjustable seat assembly, generally indicated at  120 , of the seat assembly of the present invention. Member  111  provides one of the supports which rigidly attach the adjustable seat assembly  120  and the shin pad restraint mechanism  130  to the seat assembly frame. The adjustable seat assembly is further explained and shown in  FIGS. 6 ,  7 ,  7 A,  8 ,  8 A. Also shown is the shin pad restraint mechanism, generally indicated at  130 , of the seat assembly of the present invention. The shin pad restraint mechanism is further explained and shown in  FIGS. 9 and 9A . Also shown is the adjustable footboard assembly, generally indicated at  140 , of the seat assembly of the present invention. The adjustable footboard assembly is further explained and shown in  FIGS. 10 and 10A . 
   Referring to  FIG. 6 , the seat assembly, generally indicated at  100 , of the present invention is shown in a side elevational view. Member  110   a  is part of the adjustable seat assembly frame. Member  108  is part of the seat assembly frame and also the housing for the shin pad restraint mechanism. Shown is basic frame configuration and components for the seat assembly of the present invention. 
   Referring to  FIG. 7 , the adjustable seat assembly, generally indicated at  120 , of the present invention is shown in an isometric view. The padded seat  121  is firmly and securely attached to the adjustable seat frame by hinges  124 . The adjustable seat frame members  109   a ,  109   b ,  110   a ,  110   b , are firmly and securely attached to frame member  111  and frame member  108  which is also the housing for the shin pad restraint mechanism  130 . Frame member  111  is firmly and securely attached to upright members  105  and  106  shown in  FIG. 5 . In this view, the seat  121  is shown in the lowest position. Positional adjustment, i.e. height, is accomplished by turning a knob  125  which rotates a shaft  123 . Securely attached and affixed to the shaft are two 3 lobe cams  122  which contact the underside of the padded seat  121 . 
   Referring to  FIG. 7A , the adjustable seat assembly, generally indicated at  120 , of the present invention is shown in an isometric view. In this view, the seat  121  is shown in the highest position. Appropriate seat adjustment, position, should be noted on subject/exerciser records for future use and pre-session setup. 
   Referring to  FIG. 8 , the components and configuration the adjustable seat assembly  120  of the present invention are shown in a front view. Two 3 lobe cams  122  are securely attached and affixed to the shaft  123  by a preferred means of roll pins  128 . Adjustment shaft passes through apertures in seat frame members  110   a  and  110   b  and shin pad restraint mechanism housing  108 . The shaft  123  is passes through and is supported by flanged bushings, bearings,  129  which are placed in frame members  110   a  and  110   b . Adjustable seat height, position, is achieved by rotating a knob  125  rigidly attached and fixed to the shaft  123 . A preferred knob is a lobed model which allows for easier and more positive rotation of the knob and assembly adjustment. A seat position indicator pin  126  is firmly attached and fixed to the shaft outside frame member  110   a.    
   Referring to  FIG. 8A , the adjustable seat assembly  120  of the present invention is shown in a detail view. Knob  125  may be rotated in either direction to select the appropriate seat height position. Seat height position is indicated by a pointer pin  126  and a decal/label  127  which is affixed to the outside of seat frame member  110   a  and around shaft  123 . The importance of seat height adjustment will become clear in following information and detail, see  FIG. 11 . 
   Referring to  FIG. 9 , the shin pad restraint assembly, generally indicated at  130 , of the present invention is shown in an isometric view. A suitable hand wheel  131 , preferably with knob, is rigidly attached and fixed to a long threaded shaft, screw  135 . The hand wheel end of screw  135  is machined to allow passage through a pair of flanged bushings, not shown, which are positioned in a housing block  134 . Flanged bushings allow positive, smooth axial rotation of screw to bring appropriate restraint force when the hand wheel  131  is rotated. Clockwise rotation of the hand wheel brings application of force, counter-clockwise rotation releases force. Screw  135  passes through threaded blocks  137  and  138  which are rigidly attached and fixed inside frame member  108 . Preferred material for threaded blocks is a low friction plastic such as NYLATRON which allows smooth, positive movement of restraint mechanism. Restraint pads  132   a  and  132   b  are firmly mounted and fixed on plates  133   a  and  133   b  which are firmly attached and fixed to shaft  133 . 
   Referring to  FIG. 9A , the shin pad restraint assembly, generally indicated at  130 , of the present invention is shown in a side elevational view. Pad mounting shaft  133 , passes through and is supported by a pair of flanged bushings, not shown, which are positioned in housing block  134 . Flanged bushings allow positive, smooth rotation of restraint pads  132   a  and  132   b  and pad shaft  133 . Shaft  133  is held in proper position by means of shaft collars  133 C. Threaded blocks  137  and  138  are also machined to receive and allow smooth passage of guide and stabilizer rod  136 . On one end, guide rod  136  is firmly attached and fixed inside housing block  134 . On the other end a shaft collar  139  is fixed to guide rod  136  to limit the travel of restraint mechanism. Combination of threaded screw  135  and guide rod  136  and both blocks  137  and  138  allows for firm, smooth and positive application of appropriate restraint force to subject/exerciser. The importance of proper restraint force application will become clear in following information and detail, see  FIG. 11 . 
   Referring to  FIG. 10 , the adjustable footboard assembly, generally indicated at  140 , of the present invention is shown in an isometric view. The footboard assembly is supported by a notched rack member  142 . The preferred material for this rack is solid aluminum. This rack member  142  is machined to receive a smooth guide bar  143  which is rigidly attached and fixed to rack  142  and extends out each side to provide a slide surface for smooth longitudinal movement of the footboard assembly. Preferred material for this bar is polished brass or stainless steel. Footboard  141  is rigidly attached and fixed to a housing block  144 . Rigidly attached and fixed to the housing block  144  are two grooved or slotted guide blocks  145   a  and  145   b  which are matched and machined to accept the protruding edges of the guide bar  143 . The preferred material for the guide blocks  145   a  and  145   b  is a low friction, yet strong plastic such as NYLATRON. The housing block is machined to accept handle  146  and pawl  147  which are pivotally mounted inside housing block  144  to allow upward movement and positioning of footboard  141  by a ratcheting action. Downward movement and footboard  141  positioning are achieved by manipulating the handle  146  and pawl  147 . 
   Referring to  FIG. 10A , the adjustable footboard assembly, generally indicated at  140 , of the present invention is shown in a side elevational view. The preferred angle of the footboard  141  is twenty-five degrees from horizontal. The preferred configuration should provide for and allow consistent angular relationships of lower body parts for the subject/exerciser regardless of body size or morphology. A position indicator pin  148  attached and fixed to guide block  145   a  indicates footboard position relative to a decal/label  149  attached to the rack member  142 . Notched rack member  142  is rigidly attached and fixed to frame member  108  by a pair of mounting tabs  108   a  and to the lower seat frame member  101  by another pair of mounting tabs  101   a . The importance of proper footboard positioning will become clear in following information and detail, see  FIG. 11 . 
   Referring to  FIG. 11 , the seat assembly, generally indicated at  100 , of the present invention is shown in a side elevational view with a subject/exerciser positioned and restrained therein. Shown are the major elements of this preferred embodiment of the seat assembly which allow and provide proper subject/exerciser position and lower body restraint. In order to effectively and safely apply therapeutic exercise to the lumbar extensor muscles, it is necessary to properly position the subject/exerciser and appropriately restrain the lower body to eliminate or limit influence and participation of the lower body on upper body exercise above the stabilized and immobilized pelvis. It is essential that the subject/exerciser be positioned so that the iliac crest is at or near the top of the pelvic restraint  112  so that in extension exercise the vertebrae are allowed to safely extend over the pelvic restraint  112 . The footboard  141  should be raised or lowered so that the subject/exerciser&#39;s thigh, femur, is approximately aligned with the padded seat  121 . A suitable restraint force should be applied by turning the hand wheel  131  in order to exert force to the shins through contact with the shin pads  132   a  and  132   b . The amount or degree of appropriate restraint force will likely change or vary from session to session or during a rehabilitation program. Appropriate seat adjustment and footboard position should be noted on subject/exerciser records for future use and pre-session setup. 
   Referring to  FIG. 12 , the movement arm assembly, generally indicated at  200 , of the present invention is shown in an isometric view. The frame of the movement is formed by upright, vertical members  201  and  202 . Preferred material for frame members is 11 or 14 gauge steel square tubing. Members  203   a  and  203   b  and  204  form the frame to support the pivoting resistance pad  209  which is shown in greater detail in  FIG. 13 ,  13 A,  13 B. Two formed, shaped, handlebars  207   a  and  207   b  are rigidly attached and fixed to the frame by means of apertures in the upper ends of members  201  and  202 . On the bottom, lower end of member  201  there are rigidly attached and fixed two solid counterweights  208   a  and  208   b . The two counterweights offset the weight and mass of the movement arm assembly to allow a smoother and more balanced movement. Positioned at the precise AXIS alignment point on movement arm frame members  201  and  202  are two shafts  205   a  and  205   b . When the device is fully assembled, these two shafts  205   a  and  205   b  are journalled in the two pillow block bearings  114  rigidly attached and fixed to the upper ends of seat assembly frame members  105  and  106 , see  FIGS. 5 and 6 . On the other side of member  201  from shaft  205   b  is a machined collar  206  also aligned on the AXIS and rigidly attached and fixed to member  201  and shaft  205   b . This collar allows rigid connection to the cam shaft  342  which protrudes from the resistance mechanism, generally indicated at  300 . See  FIGS. 16 and 17 . For added strength and stiffness, member  201   b  is rigidly attached and fixed to members  201 ,  203   b  and counterweight  208   b . The test mode engagement mechanism, generally indicated at  210 , is shown with greater detail in  FIGS. 15 and 15A . 
   Referring to  FIG. 13 , the movement arm assembly, generally indicated at  200 , and the seat assembly, generally indicated at  100 , of the present invention are shown in a side elevational view. When the two assemblies are operatively connected at the AXIS, the movement arm can rotate clockwise or counterclockwise in a smooth, balanced manner. As the subject/exerciser moves from flexion to extension, the spine grows or elongates as the lumbar vertebral facet joints encounter each other. To avoid unwanted friction or rubbing between the resistance pad  209  and the subject/exerciser&#39;s back, the resistance pad  209  is mounted pivotally on movement arm frame member  204 . 
   Referring to  FIGS. 13A and 13B , the pivoting resistance pad  209  is shown in detail. A pair of mounting tabs are rigidly attached and fixed to frame member  204 . A resistance pad mounting bar  209   a  is rigidly attached and fixed to the back of resistance pad  209 . The resistance pad  209  is suitably connected in such a manner to allow upward movement of the resistance pad  209  to accommodate the growth or lengthening of the subject/exerciser spine and avoid unwanted friction or rubbing. Initial positional relationship of the subject/exerciser back and the resistance pad  209  is determined by a pair of stop bumpers, not shown. 
   Referring to  FIG. 14 , the range of motion movement of the present invention is shown in a side view. When properly positioned by the seat  121  and pelvic restraint pad  112  and properly restrained by the shin restraint pads  132   a  and  132   b  and footboard  141 , the subject/exerciser can rotate or move through all or any portion of an available eighty-five (85) degree range of motion. While the normal range of motion of the lumbar spine for an average, uninjured subject/exerciser is probably 70-75 degrees, several factors such as age, body morphology, overall condition, etc. can determine individual range of motion and end points, this device allows for an available 85 degree movement. Subject/exerciser should always be instructed and cautioned to only perform exercise through “their” greatest pain-free range of motion. 
   In all instances, any treatment or rehabilitation program or use of apparatus should be preceded by an appropriate physical examination and the program prescribed and monitored by a qualified medical professional. In all instances, the patient, subject, exerciser should be instructed to perform all exercise repetitions throughout “their” greatest pain-free range of motion. A repetition is considered to be a full range movement in a controlled, deliberate manner with good form and good pace. When exercising to fatigue is the goal, the session should cease when the subject/exerciser loses good form or good pace. When performing strength tests, the subject should be instructed to give their best, pain-free effort. Subject should slowly build to maximum effort and slowly release. Care should be taken and caution given against over-exertion and any action or effort which produces pain. Subject should be cautioned against tightly gripping the handlebars during any test or exercise procedures. Tightly gripping the hands can result in a significant increase in blood pressure during extreme physical exertion. 
   Referring to  FIG. 15 , the test mode engagement mechanism, generally indicated at  210  of the movement arm assembly of the present invention is shown in a side view. Mechanism is housed inside movement arm frame member  201 . There is a shaft  211  which is rigidly attached and fixed to a knob  212 . Engagement shaft  211  passes through and is positioned by a machined upper housing and guide block  213  and lower guide block  214 . Engagement shaft also passes through apertures in handlebar  207   b  inside member  201  and also through aperture in shaft  205   b  also inside member  201 . 
   Referring to  FIG. 15A , the parts and components of the test mode engagement mechanism, generally indicated at  210 , of the present invention are shown in an exploded view. Engagement shaft  211  is machined to accept knob  212 . Engagement shaft has a pair of grooves  211   a  and  211   b  which provide “engaged” and “disengaged” positions for test mode engagement mechanism  210 . Preferred material for engagement shaft is stainless steel. An upper housing and guide block  213  is machined to allow free passage of engagement shaft and also to contain and operatively apply a pair of position retainer balls  216  and a pair of position retainer springs  217 . A lower guide block  214  allows free passage of engagement shaft  211 . Preferred material for guide blocks  213  and  214  is a low friction plastic such as NYLATRON. A limit pin  215  is affixed in an aperture in shaft  211  to limit upward movement of test mode engagement shaft  211 . Test mode engagement mechanism is securely attached and fixed inside the movement arm frame member  201  by means of tamper resistant screws, not shown, which pass through apertures in member  201  wall and into upper guide block  213  and lower guide block  214 . 
   Referring to  FIG. 16 , the resistance mechanism, generally indicated at  300 , of the present invention is shown in an isometric view. (Some parts not shown for clarity) The resistance mechanism is housed in a frame structure generally indicated at  301 . Preferred material for frame members is 11 or 14 gauge steel square tubing. The major components of the resistance mechanism  300  are: the camshaft and cam assembly, generally indicated at  340 ; the range of motion selector and resistance engagement mechanism, generally indicated at  350 ; the resistance arc/lever assembly, generally indicated at  360 ; and the resistance selector mechanism, generally indicated at  370 . The AXIS is indicated at the protruding cam shaft  342  which operatively connects to the movement arm assembly collar  206 , see  FIG. 12 . The resistance mechanism  300  also rigidly and securely connects to the seat assembly  100  with bolts and lock washers through apertures on seat frame member  104 , see  FIG. 5 , at points  301   a  and  301   b  on resistance mechanism frame  301 . 
   Referring to  FIG. 17 , the resistance mechanism, generally indicated at  300 , of the present invention is shown in a side elevational view. The mechanism is contained in a steel tubular frame  301 . Most moving parts and components are mounted, journalled with bearings, on machined shafts  302   a, b, c, d, e . Preferred material for shafts is stainless steel. Shafts and components are mounted with appropriate nuts, blots and washers through apertures on frame members. Camshaft and cam assembly, generally indicated at  340 , are explained in detail in  FIGS. 18 and 18A . Camshaft  342  is also the AXIS and entry point of movement, motion and force from the movement arm assembly, generally indicated at  200 . Camshaft and cam assembly  340  are mounted near the vertical middle and horizontal rear of the resistance mechanism. Camshaft and cam assembly  341  are connected to the range of motion selector and resistance engagement mechanism by belt  321 . The range of motion selector and resistance engagement mechanism, generally indicated at  350 , is mounted, journalled with bearings, on shaft  302   a  at the same horizontal position and somewhat forward of the cam assembly  340 . The range of motion selector and resistance engagement mechanism, generally indicated at  350  is explained in detail in  FIGS. 19 and 19A . The range of motion and resistance engagement mechanism  350 , is connected by belt  322  to a 7 inch diameter pulley  303   a . A 5 inch diameter pulley  303   b  is connected rigidly and concentrically with the 7 inch pulley  303   a , journalled with bearings on shaft  302   b . Pulley  303   b  is connected by belt  323  to the resistance selector mechanism, generally indicated at  370 . The resistance selector mechanism  370  is explained in detail in  FIGS. 21 and 21A . The resistance selector mechanism  370  is attached operatively to the resistance arc/lever, generally indicated at  360 . The resistance selector mechanism  370  can selectively traverse the arc portion of the resistance arc/lever  361  relative to a radius point at the forward and middle edge of the lower 5 inch pulley  303   b . The resistance arc/lever  361  is rigidly and concentrically connected with 7 diameter inch pulley  362   a  (not shown see  FIGS. 20 and 22 ) and spacer  362   b  (not shown see  FIGS. 20 and 22 ), journalled with bearings on shaft  302   c . The resistance arc/lever, generally indicated at  360 , is shown in detail in  FIGS. 20 and 20A . The resistance arc/lever assembly  360  is connected by belt  324  to another 5 diameter inch pulley  304   b . Pulley  304   b  is connected rigidly and concentrically with a 10 inch diameter pulley  304   a , journalled with bearings on shaft  302   d . Pulley  304   a  is connected by belt  325  to a 5 inch pulley  305   b  not shown (see  FIG. 22 ). Pulley  305   b  is connected rigidly and concentrically with another 10 inch diameter larger pulley  305   a , journalled with bearings on shaft  302   e . Pulley  305   a  is connected by belt  326  to dead weight  306 . Dead weight  306  travels vertically by means of a guide block  306   a , not shown. Guide rods  307   a  and  307   b  pass through apertures in guide block  306   a  and allow free and easy movement of dead weight  306  during exercise or use. Preferred belt material is a super strong, non-stretch material such as KEVLAR. Preferred method for mounting and/or attaching belts to pulleys is shown in  FIG. 23 . A means for adjusting and positioning the resistance arc/lever  361  is provided by a bolt and lock/jam nut at  308 . A means for supporting resistance arc/lever  361  during resistance selection is provided by two round rollers  309   a  and  309   b , not shown in this view. A means for aligning and synchronizing both pulleys of the range of motion selector and resistance engagement mechanism  350  is provided by a solid steel bar  310  rigidly attached and fixed to the resistance mechanism frame  301 . A means for connecting AC electric power to the device is provided by and electrical inlet at  311 . 
   Referring to  FIG. 18 , camshaft and cam assembly, generally indicated at  340 , of the resistance mechanism, generally indicated at  300 , of the present invention is shown in an isometric view. Camshaft  342  and plate  343  and cam  341  are rigidly connected. Each end of camshaft  342  is journalled in pillow block bearings  346  which are rigidly attached and fixed to the resistance mechanism frame  301 . Preferred bearings have an extended inner race with dual set screws. Range of motion limit/stop bumpers  347   a  and  347   b  are also mounted on resistance mechanism frame  301 . Range of motion limit/stop members  344   a  and  344   b  are mounted on plate  343  and determine and limit movement of the movement arm assembly. See  FIG. 14 . The protruding end of the camshaft  342  is machined and has threaded apertures to allow rigid and secure connection to the shaft collar  206  of the movement arm assembly. See  FIG. 12 . Camshaft and cam assembly  340  are shown at the flexed position or zero degrees of extension. 
   Referring to  FIG. 18A , camshaft and cam assembly, generally indicated at  340 , of the resistance mechanism, generally indicated at  300 , of the present invention is shown in an exploded view. A camshaft  342  is rigidly attached and fixed to a plate  343 . Plate  343  has apertures which allow range of motion limit/stop members  344   a  and  344   b  to be rigidly attached and fixed from the reverse side by means of flush mount screws/bolts  344   c . Plate  343  also has equally spaced apertures concentrically aligned around camshaft  342 . Through apertures in plate  343 , cam  341  is rigidly connected and fixed with bolts  341   a  and washers  341   b  into threaded apertures in cam  341  matching those in plate  343 . A notch  341   b  is machined into the cam edge to allow the placement of a tension adjuster  345  for the belt  321  which connects to the range of motion selector and resistance engagement mechanism, generally indicated at  350 . Tension adjuster comprises a block  345  threaded to receive an adjustment screw  345   a . Block  345  is held in place by side plates  345   b  and  345   c . Plates  345   b  and  345   c  are securely attached and fixed to cam  341  by means of bolts  345   d  washers  345   e  and nuts  345   f  through apertures in cam  341 . Turning screw  345   a  in or out can adjust the tension on belt  321 , not shown. Preferred material for camshaft  342  and plate  343  is stainless steel. Preferred material for cam  341  and adjuster block  345  is a strong, rigid plastic such as PVC or NYLATRON. The cam has a specific ratio of 1.4:1 to provide a continuous perceived resistance through the entire range of motion of the exerciser/subject. The axis of rotation of the cam should be on the AXIS to maintain constant synchronization with the movement arm regardless of the range of motion selected or performed. 
   Referring now to  FIG. 19 , the range of motion selector and resistance engagement mechanism, generally indicated at  350 , of the resistance mechanism, generally indicated at  300 , of the present invention is shown in an isometric view. The desired or appropriate range of motion is selected and the resistance is engaged by means of a selector and engagement pin  352  and knob  352   d  rigidly and operatively connected to the engagement pulley  351   a . The engagement pulley  351   a  and selector pulley  351   b  are each mounted on pairs of bearings, not shown in this view, which are journalled on shaft  302   a . Both the engagement pulley  351   a  and selector pulley  351   b  are 10 inches in diameter and bearing mounted and free wheeling until they are engaged or connected by means of the selector/engagement pin  352 . Appropriate position of engagement pulley  351   a  and tension on belt  321  connected to cam  341 , is achieved by a counterweight  355  rigidly connected and fixed to engagement pulley  351   a . Proper alignment between the engagement pulley  351   b  and the selector pulley  351   b  is achieved by means of alignment bars  353  and  354 , not shown in this view, which have an adjustment screw  353   a  with lock/jam nut  353   b . Proper alignment and adjustment of these components are essential to the smooth, efficient operation and use of this mechanism. 
   Referring now to  FIG. 19A , the range of motion selector and resistance engagement mechanism, generally indicated at  350 , of the resistance mechanism, generally indicated at  300 , of the present invention is shown in an exploded view. The engagement pulley  351  is machined to receive a pair of insert bearings  356   a  and  357   a . The outside bearing  356   a  has and extended inner race and dual set screws and a snap ring. The engagement pulley  351   a  is machined to accept the selector/engagement pin  352 . Large diameter pin lug/hub  352   a  is housed in an aperture in housing block  352   c  and an aperture  352   b  in the engagement pulley  351   a . The selector pin  352  and selector pin housing block  352   c  are rigidly connected to the engagement pulley  351   a  by two flush mount bolts  352   e . A knob  352   d  is attached to the threaded end of the selector/engagement pin. The selector/engagement pin  352  moves freely and efficiently in the housing block  352   c  and the matched aperture  352   b  in the engagement pulley  351   a . Preferred material for the selector/engagement pin is stainless steel. Proper position and alignment are achieved by an alignment bar  353  which is rigidly attached and fixed to engagement pulley  351   a  by two bolts  353   c . Precise adjustment and alignment are achieved by adjusting a bolt  353   a  and locking it in position with a lock/jam nut  353   b . Proper position and tension of the connecting belt  321  is achieved by the placement of a counterweight  355  on the lower portion of engagement pulley  351   a  by two bolts  355   a . The selector pulley  351   b  is machined to receive a pair of insert bearings  357   b  and  356   b . The outside bearing  356   b  has an extended inner race with dual set screws and a snap ring. The selector pulley  351   b  is machined with apertures  351   c  to receive the end of the selector/engagement pin  352 . The apertures  351   c  are spaced and positioned in four degree increments and allow range of motion selection from zero “0” to eighty-four degrees. Proper position and alignment with the engagement pulley  351   a  and selector/engagement pin  352  is achieved by an alignment bar  354  which is rigidly attached and fixed to the selector pulley by two bolts  354   c . Precise adjustment and alignment are achieved by adjusting bolt  354   a  and lock/jam nut  354   b . Preferred material for engagement pulley  351   a  and selector pulley  351   b  is a strong, rigid plastic such as PVC or NYLATRON. 
   Referring now to  FIG. 20 , the resistance arc/lever assembly, generally indicated at  360 , of the resistance mechanism, generally indicated at  300 , of the present invention is shown in an isometric view. A suitably broad range of resistance levels is provided by means of an arc/lever  361  properly positioned and configured to provide variable resistance from a low level at the far end, farthest from shaft  302   c , of the arc/lever to a much higher level at the closest end of the arc lever. The shape and dimension of the arc/lever  361  is determined by the radius point found somewhere near the front middle edge of the small pulley  303   a  mounted in the lower portion of the resistance mechanism  300 , see  FIG. 17 . The resistance selector mechanism, generally indicated at  370 , can operatively connect to the resistance arc/lever  361  by means of 26 equally spaced and positioned apertures  361   a . The resistance selector mechanism is shown in and explained detail in  FIGS. 21 and 21A . In essence, the resistance mechanism  300  is selectively activated and operated by either a long or short lever. The configuration and operation of the resistance arc/lever  360  and resistance selector mechanism  370  are shown and explained in  FIG. 22 . The resistance selector mechanism travel limits are determined by stops  363   a  and  363   b  mounted at either end of the aperture pattern  361   a  on the arc/lever  361 . The arc/lever  361  and pulley  362   a  and spacer  362   b , not shown in this view, are mounted on bearings, not shown in this view, which are journalled on shaft  302   c.    
   Referring now to  FIG. 20A , the resistance arc/lever assembly, generally indicated at  360 , of the resistance mechanism of the present invention is shown in an exploded view. Arc/lever  361  is machined to receive an insert bearing  364   a  with an extended inner race with dual set screws and a snap ring. The arc/lever  361  is also machined with 26 equally spaced apertures  361   a  to accept the end of resistance selector pin  372 , see  FIG. 21A . Resistance selector mechanism stops  363   a  and  363   b  are rigidly attached and fixed to arc/lever  361  by bolts  363   c  and washers  363   d . Preferred material for arc/lever is solid 0.50″ plate aluminum. Spacer  362   b  is machined to receive an insert bearing  365 . Pulley  362   a  is machined to receive an insert bearing  364   b  with an extended inner race with dual set screws and a snap ring. Preferred material for pulley  362   a  and spacer  362   b  is a strong, rigid plastic such as PVC or NYLATRON. Arc/lever  361  and spacer  362   b  and pulley  362   a  are rigidly and concentrically connected through matching apertures by bolts  366  and washers  367  and nuts  368 . Arc/lever  361  and spacer  362   b  and pulley  362   a  are mounted on bearings journalled on shaft  302   c.    
   Referring now to  FIG. 21 , the resistance selector mechanism, generally indicated at  370 , is shown in an isometric view. The resistance selector mechanism  370  can smoothly and accurately traverse the arc portion of the arc/lever  361  and select and operatively connect to any of the twenty-six apertures  361   a  and thus establish a lever which activates the resistance mechanism  300 . The length of the lever determines the dynamics and effective resistance encountered when force is applied through the movement arm  200  by the subject/exerciser. The resistance selector mechanism comprises two plates  371   a  and  371   b  and contain rollers and spacers, not shown in this view, which maintain proper and accurate alignment of mechanism and selector pin  372  and arc/lever apertures  361   a , see  FIG. 20A . The selected resistance level is shown through a “sight hole”, aperture  371   f , which reveals the alphabetical designation A-Z, see  FIG. 22 . The actual force of the resistance is carried/handled by two radial bearings  379 , housed in the resistance selector mechanism, see  FIG. 21A . The selector pin  372  only maintains selection and position. The resistance selector mechanism  370  is connected to the lower pulley  303   b , see  FIG. 22 , by a belt  313 . Proper tension and adjustment of this portion of the resistance mechanism  300 , is achieved by means of an adjustment member  375  with left/right threads. This adjustment member  375  operatively connects to blocks  374  and  376 . Proper adjustment and position are achieved and maintained with lock/jam nuts, see  FIG. 21A . 
   Referring now to  FIG. 21A , the resistance selector mechanism, generally indicated at  370 , of the present invention is shown in an exploded view. Plates  371   a  and  371   b  are machined to allow the placement of radial bearings  379  and guide spacers  377  and spacers  378  and hanger straps  373   a  and  373   b  to be assembled in such a manner as to provide a rigid unit which allows smooth and positive movement along the arc portion of the arc/lever  361 . The top two radial bearings  379  provide smooth travel and also to support and handle the force exerted by the subject/exerciser and movement arm assembly  200 . The lower radial bearing  379 , acts to maintain proper position, alignment and allow free and smooth travel by the resistance selector mechanism  370  on the machined upper and lower surfaces of the arc/lever  361 . The front plate  371   a  is machined to allow mounting of a housing block  372   b  which houses and supports the selector pin  372 . The selector pin  372  is machined on one end to allow insertion into size matched apertures  361   a  on the arc/lever  361 . The other end of the selector pin  372  is machined to connect selector knob  372   c . A shoulder section  372   a  of the selector pin  372  travels in size matched apertures in housing block  372   b  and plate  371   a . Housing block  372   b  is rigidly connected to plate  371   a  by means of two flush mount bolts  372   d  through apertures in plate  371   a . Plates  371   a  and  371   b , bearings  379 , guide spacers  377 , spacers  378  and hanger straps  373   a  and  373   b  are rigidly and operatively connected by means of bolts  371   c , washers  371   d  and nuts  371   e . Suspended from the other end of hangers straps  373   a  and  373   b  are the connection and adjustment components of the resistance selector mechanism  370 . The upper adjustment block  374  is machined to accept one end of the adjustment member  375  which has left/right threads to allow easy tension adjustment of connecting belt  313 , see  FIG. 22 . The lower adjustment block  376  is machined to accept the other end of adjustment member  375 . The proper adjustment and/or tension of the mechanism  370  is maintained by means of lock/jam nuts  375   a  and  375   b . The upper adjustment block  374  is operatively connected to the hanger straps by means of a bolt  374   a , washers  374   b  and a nut  374   c . The lower adjustment block  376  is operatively connected to belt  313  by means of a bolt  376   a , washers  376   b  and a nut  376   c . Preferred material for the plates  371   a  and  371   b  and housing block  372   b  and adjustment blocks  374  and  376  is aluminum. Preferred material for selector pin  372  and hanger straps  373   a  and  373   b  is stainless steel. Preferred material for guide spacers  377  and spacers  378  is NYLATRON. 
   Referring now to  FIG. 22 , the resistance selector mechanism, generally indicated at  370  and the arc/lever assembly, generally indicated at  360 , of the present invention are shown in a side view. The amount of resistance provided by the resistance mechanism  300  of this device is determined primarily by the length of the lever used to lift the dead weight  306 . The arc/lever  361 , which acts as a lever arm, is rigidly connected to pulley  362   a  and by belt  324  to the small pulley  304   b  which is rigidly and concentrically connected to pulley  304   a  and by belt  325  to the small pulley  305   b  which is rigidly and concentrically connected to pulley  305   a  and by belt  326  to dead weight  306 . In effect, the arc/lever  361  is connected to the dead weight  306 . However, by virtue of the physics involved the effective weight or value of the dead weight has been increased considerably. The basic theory of lever and fulcrum dictate that the effective weight or resistance which exists at the arc/lever  361  is significantly greater than the actual weight or resistance inherent in the dead weight  306 . When assembled and adjusted, the arc/lever  361  is “loaded” by means of the dead weight being suspended slightly above the base frame. The precise position is determined and maintained by means of an adjusting bolt  308  with lock/jam nut which is fixed to a frame member, angle, of resistance mechanism frame  301 . This allows for a more consistent and immediate response to motion or movement generated by the subject/exerciser through the movement arm assembly, generally indicated at  200 , not shown in this view. Proper “loading” of the dead weight is achieved by means of the connection of belt  326  to the dead weight  306  which occurs at connector strap/clamp  306   a . The effective length of the lever used to engage the resistance is determined and selected by the resistance selector mechanism, generally indicated at  370 . Any one of twenty-six available positions, lengths, may be selected. The selected position is displayed in the “sight hole” aperture  371   f . An A-Z decal/label  361   b  is affixed to the arc/lever  361 . KEVLAR is the preferred material for the belts in this device. There is little, if any, perceptible give or stretch in this material. Once properly assembled and the system is “loaded” and the belts have seated, there will be little, if any, need for future adjustment. 
   Referring now to  FIG. 23 , the typical design and construction of the various pulleys, spacers and components used in this device of the present invention are shown in this view. Also shown are the typical attachment/connection means used in this device. Pulley  331  represents typical center aperture  331   a  machined to accept insert bearings, not shown. Bearings are press-fit into aperture which allows grouping various size pulleys together on the same shaft, not shown. Concentrically and equally spaced around the center aperture are four smaller apertures  331   b  which allow bolts, washers and nuts, not shown, to be used to group various size pulleys together as a unit. The size and pattern of the center aperture  331   a  and the four smaller apertures is the same and typical for all pulleys, spacers and components of this device unless otherwise indicated. Most pulleys, indicated typically as  331 , have a flat surface  331   c  machined on one quadrant which is offset forty-five (45) degrees from the alignment of the four small apertures  331   b . The flat surface area  331   c  is machined with threaded apertures  331   d , to accept two bolts  333 . There is a metal belt/strap clamp  332  with apertures which match the spacing of the threaded apertures  331   d  of the flat surface  331   c . Matching apertures are punched in the ends, where indicated, of the various KEVLAR belts used in the device of the present invention. Bolts  333  and washers  334  pass through the belt/strap clamp  332  and the various belts, indicated as  320 , and are suitably threaded into the threaded apertures  331   d . Suitable force, torque, is applied to firmly and securely attach belts  320  to the various pulleys indicated as  331 . Various size pulleys, spacers and components are assembled and utilized in various combinations and configurations in the device of the present invention. 
   Referring now to  FIG. 24 , the typical operational action, cycle and sequence of the resistance mechanism, generally indicated at  300 , of the present invention is shown/illustrated in an isometric view with arrows to indicate motion and direction. Movement (action, motion, force) is introduced into the resistance mechanism  300  through the camshaft  342 , which is operatively connected to the movement arm assembly  200 , not shown in this view. All movement inside the resistance mechanism  300  is conditioned by the cam  341 . The cam  341  is rigidly connected to the camshaft  342  which is rigidly and operatively connected to the movement arm assembly  200 . The placement and position of the cam  341  is critical in that it always (constantly) maintains proper relationship and synchronization with the movement arm assembly  200  regardless of movement arm position throughout the range of motion. This cam is designed to accommodate the differences in the established strength levels inherent in the lumbar musculoskeletal system from the flexed position, zero degrees of extension, to the extended position which might be as much as 75 degrees or more. An important factor in the design and use of the cam is that it “flattens” or levels the perceived level of resistance experienced by the subject/exerciser throughout the performed range of motion. By positioning the cam at this input point, ahead of the actual resistance, all movement and resistance are properly timed or synchronized regardless of movement arm position. The range of motion available in the device of the present invention is eight-five (85) degrees. Range of motion stops or limits, not shown in this view, are placed at approximately zero and eighty-five degrees. As the camshaft and cam assembly  340 , see  FIGS. 18 and 18A , rotates in a clockwise motion, an operatively connected belt  321 , which is operatively connected to the engagement pulley  351   a  of the range of motion selector and resistance engagement mechanism  350 , see  FIGS. 19 and 19A , said belt pulls the engagement pulley  351   a  in a clockwise motion. The movement arm assembly  200  and the camshaft and cam assembly  340  and the engagement pulley  351   a  are all operatively connected and allowed to “freewheel” and provide little or no resistance to movement when not engaged or connected by means of the selector and engagement pin  352  to the selector pulley  351   b . When the selector pulley  351   b  is engaged and connected by means of the selector and engagement pin  352 , the selector and engagement mechanism  350  also turns in a clockwise motion when movement is initiated by the subject/exerciser by means of the movement arm assembly  200 , not shown in this view. As the selector pulley  351   b  rotates in a clockwise motion, an operatively connected belt  322 , which is operatively connected to a lower pulley  303   a , said belt is connected in such a manner to produce a counter-clockwise motion. Pulley  303   a  is rigidly and concentrically connected to a smaller pulley  303   b , see  FIG. 17 . As pulley  303   b  rotates in a counter-clockwise motion, an operatively connected belt  323 , which is operatively connected to the resistance selector mechanism  370 , see  FIGS. 21 and 21A  is pulled downward. The resistance selector mechanism  370  allows selection of any one of twenty-six levels of resistance available by means of 26 apertures in the arc/lever  361  of the arc lever assembly  360 , see  FIGS. 20 and 20A . When the resistance selector mechanism  370  is engaged and connected at the appropriate resistance level by means of the resistance selector pin  372  to the resistance arc/lever  361 , said lever is pulled downward and rotates counterclockwise on its axis. The resistance arc/lever  361  is rigidly and concentrically connected to pulley  362   a . As pulley  362   a  rotates in a counter-clockwise motion, an operatively connected belt  324 , which is operatively connected to a small pulley  304   b , said belt is connected in such a manner to produce a counter-clockwise motion. Pulley  304   b  is rigidly and concentrically connected to a larger pulley  304   a , see  FIG. 17 . As pulley  304   a  rotates in a counter-clockwise motion, an operatively connected belt  325 , which is operatively connected to a small pulley  305   b , said belt is connected in such a manner to produce a clockwise motion. Pulley  305   b  is rigidly and concentrically connected to pulley  305   a , see  FIG. 17 . As pulley  305   a  rotates in a clockwise motion, an operatively connected belt  326 , which is securely connected to dead weight  306 , said belt pulls upward, lifting weight which provides resistance to movement initiated by the subject/exerciser by means of the movement arm assembly  200 . 
   An important aspect and consideration of any exercise machine design is the factor of inertia. A low or short travel distance of the resistance weight is desirable. Inertia results from speed and distance relative to the actual weight itself. Less weight moving at slower speeds and shorter distances develops less inertia. With the device of the present invention, different diameter pulleys are connected and share the same axis, in essence, they become a lever and a fulcrum. When used in series and carefully configured and connected they can act to multiply the weight or force factor inherent in the dead weight. Thus the actual weight of the machine itself and the weight actually moved during use and operation are decreased significantly while still maintaining an appropriate level of effective/perceived weight or resistance. The actual travel distances or movement by the various components of the resistance mechanism are also an important consideration. The amount of motion or movement input through the movement arm and the range of motion selected and the resistance level selected determine the actual motion or movement inside the resistance mechanism. As a result of this design, the greatest vertical travel distance of the dead weight which is produced by a full range movement of the movement arm is slightly less than nine inches. The greatest travel distance or movement occurs when the greatest resistance “Z” is selected at the position or aperture closet to the axis of rotation of the arc/lever. The least travel distance or movement of the dead weight is at the lowest resistance at the farthest position form the axis of rotation of the arc/lever. At the position of least resistance “A”, a full range movement, eighty-five degrees, produces a vertical movement of the dead weight of less than four inches. Less weight, slower speed and shorter distance results in less unwanted inertia being developed during use and operation of the device of the present invention. 
   Referring now to  FIG. 25 , the load cell assembly, generally indicated at  400 , of the device of the present invention is shown is an isometric view. The frame support  403  for the load cell assembly  400  is machined from solid aluminum bar stock. The load cell  401  is rigidly connected to the frame support  403  by a bolt  401   a  and a lock/jam nut, not shown. Preferred load cell is an Interface Model SML-1000. The load cell  401  is operatively connected by a threaded shaft, not shown, to an arc member  402  which has three machined slots  402   a  which allow three different test positions. The machined bottom surface of arc member  402  sits on the horizontal member of the frame support  403 . Preferred material for arc member is stainless steel. The load cell  401  is connected by potted cable to a meter, readout  501 , generally indicated at  500  and mounted atop the resistance mechanism, generally indicated at  300 . Preferred meter is a Red Lion—Model PAX S. The meter is programmed to retain peak torque registered during test procedures. Although the load cell  401  and meter  501  are capable of detecting very small increments of force or torque, the system is programmed to display force or torque in tenths of a foot pound. The movement arm assembly  200  can operatively connect or engage the arc member  402  by means of the test engagement shaft  211  of the test mode engagement mechanism  210 , see  FIGS. 15 and 15A . Also housed in the load cell assembly  400  is a proximity sensor  404 . Preferred sensor is a Turck Model Q25-AP6X. In the exercise mode, the sensor  404  detects, displays and counts repetitions performed by the subject/exerciser. The sensor  404  is connected by potted cable to a meter, readout  502 , generally indicated at  500 . Preferred meter is a Red Lion—Model PAX C. Both meters can be quickly and easily reset to “zero” prior to any test or exercise session. Meters are housed in a formed stainless steel cabinet  503  assembled with tamper resistant screws. 
   Referring now to  FIG. 26 , the load cell test assembly, generally indicated at  400 , of the device of the present invention is show in a side view. In the preferred configuration of the device of the present invention, the load cell test assembly  400  is positioned opposite and equally distant from the AXIS from the resistance pad  209  of the movement arm assembly  200 . When engaged and operatively connected the device of the present invention allows for meaningful static testing of the subject&#39;s relative lumbar extension strength. In the test mode and at the selected test position, the subject is instructed to slowly build force by pushing their upper back against the resistance pad  209 . The subject is instructed to slowly build to an honest, maximum exertion. Care should be taken and caution given to only expend or exert pain-free effort. Subject should avoid any quick, jerky motion or effort. Test effort should be developed and released in a slow, controlled manner. Relative test positions are indicated by a label/decal  405  affixed to the resistance mechanism frame. In many instances, subjects might be tested in only one position. When a one position only test is used, most often the test will be conducted at the middle, upright neutral position. 
   Referring now to  FIG. 26A , the load cell test assembly, generally indicated at  400 , of the device of the present invention is shown in a side view. The movement arm assembly  200  can be maneuvered to any of three test positions. Each test position is separated by 16 degrees. To engage a test position, the movement arm  200  is maneuvered to the appropriate position and the engagement shaft  211  is lowered, pushed into the appropriate arc member slot  402   a . Test engagement mechanism  210  has a position retainer system which maintains the test mode position or the exercise position, see  FIGS. 15 and 15A . 
   The foregoing description of the invention has been directed to a particular preferred embodiment of the present invention for the purposes of explanation and illustration. It will be apparent to those skilled in the art that many modifications and changes in the apparatus may be made without departing from the scope and spirit of the invention. It is therefore intended that the following claims cover all equivalent modifications and variations as fall within the scope of the invention as defined by the claims.