Patent Publication Number: US-2007123396-A1

Title: Exercise treadmill for pulling and dragging action

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This patent application is a continuation-in-part of U.S. patent application Ser. No. 11/289,916 having a filing date of 30 Nov. 2005 entitled Exercise Treadmill For Pulling And Dragging Action, which is incorporated herein in its entirety by this reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Technical Field  
      This invention relates to the general technical field of exercise, physical fitness and physical therapy equipment and machines and to the more specific novel technical field of a mechanically, electrically and electronically operated reverse treadmill machine designed to simulate a dragging or pulling motion when operated by the user.  
      2. Prior Art  
      Exercise, physical fitness and physical therapy equipment and machines are available in various configurations and for various purposes, and are available for all of the major muscle groups. The majority of such equipment and machines, especially in the exercise field, concentrate either on an aerobic or anaerobic workout or on areas of the body such as the legs, the hips and lower torso, the chest and upper torso, the back, the shoulders and the arms.  
      Exercise treadmills are well known and are used for various purposes, including for walking or running aerobic-type exercises, and diagnostic and therapeutic purposes. For the known and common purposes, the person on the exercise treadmill normally can perform an exercise routine at a relatively steady and continuous level of physical activity or at a variable level of physical exercise including varying both the speed and incline of the treadmill during a single session.  
      Exercise treadmills typically have an endless running surface extending between and movable around rollers or pulleys at each end of the treadmill. The running surface generally is a relatively thin rubber-like material driven by a motor rotating one of the rollers or pulleys. The speed of the motor is adjustable by the user or by a computer program so that the level of exercise can be adjusted to simulate running or walking.  
      The belt typically is supported along its upper length between the rollers or pulleys by one of several well known designs in order to support the weight of the user. The most common approach is a deck or support surface beneath the belt, such as a plastic or metal panel, to provide the required support. A low-friction sheet or laminate, such as TEFLON® brand of synthetic resinous fluorine-containing polymers, can be provided on the deck surface (or indeed can be the material of construction of the deck surface) to reduce the friction between the deck surface and the belt.  
      Many current exercise treadmills, especially the middle to upper level of exercise treadmills, also have the ability to provide a variable incline to the treadmill.  
      The incline is accomplished in one of two manners—either the entire apparatus is inclined or just the walking and running surface is inclined. Further, the inclination can be accomplished by either manual or power driven inclination systems, and can be accomplished either at the command of the user or as part of a computerized exercise regimen programmed into the exercise treadmill. An inclination takes advantage of the fact that the exercise effort, or aerobic effect, can be varied with changes in inclination, requiring more exertion on the part of the user when the inclination is greater.  
      To the best of this inventor&#39;s knowledge, known exercise treadmills are structured to allow the user to walk or run in a forward direction, with the belt traveling in a direction that simulates walking or running forward; that is, the belt runs across the top of the deck in a front to back motion. Additionally, to the best of this inventor&#39;s knowledge, the inclination mechanisms in known exercise treadmills are structured to allow the user to walk or run in a level or uphill inclination; that is, the front of the deck can be level with the back of the deck or can be raised relative to the back of the deck to simulate an uphill inclination. Further, to the best of the inventor&#39;s knowledge, the hand rails and hand controls in known exercise treadmills are structured to complement simulated forward motion.  
      However, the inventor is unaware of any specific exercise treadmill that is structured to allow the user to comfortably simulate a dragging or pulling motion; that is, a backwards walking motion either on a level plane or uphill. Additionally, the inventor is unaware of any specific exercise treadmill that has an adjustable weight resistance against dragging or pulling so as to simulate dragging or pulling of a load. A simulated dragging or pulling motion can be useful for exercising and developing different groupings of muscles and for providing an aerobic workout. Thus it can be seen that an exercise treadmill simulating a dragging or pulling motion would be useful, novel and not obvious, and a significant improvement over the prior art. It is to such an exercise treadmill that the current invention is directed.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is a new category of cardiovascular cross training device that addresses many needs not met with the current industry offering of treadmills, elliptical devices, stationary bicycles, and stepping devices. Backward walking is incorporated into the fitness and physical rehabilitation programs prescribed by many professional fitness trainers, physical therapists, sports medicine professionals and strength and conditioning professionals. Additionally, many athletes use weight loaded sled dragging (hand held horizontal load) to augment their lower body strength training as well as their overall aerobic and anaerobic conditioning programs. The present invention combines these features.  
      The muscle activity of the lower body is much greater in backward walking versus forward walking and the heart rate is elevated 30% to 35% higher over the same forward walking speed. Thus, a person can expend more energy in a shorter period of time walking backwards. Adding the additional load factor of a hand held horizontal resistance (dragging motion) and the energy expenditure and muscle loading to the lower body is increased. This increased energy output allows an individual to achieve and maintain their desired heart rate at a traction of the speed of any forward motion oriented exercise.  
      Further, the overall force of impact is reduced at a backward walk versus forward motion oriented exercises due to the reduced stride length, foot pattern contact and lower extremity kinematics pattern. The sheer force to the knees is reduced because the sheer force is reversed while walking backwards. Moreover, the range of motion of the knee joint is reduced to incorporating a nearly isometric pattern following contact compared to a more stressful eccentric loading. This can be very beneficial to the exercisers with knee joint injuries or those who experience knee pain during forward motion oriented exercises. Most knee joint injuries can even continue to heal during a backward walking training program. Hip joint stress is reduced during backward walking because the overall range of motion of the hip joint is reduced by incorporating greater hip flexation but much less hip extension.  
      During backward walking the hamstring muscles are stretched prior to activation and foot plant due to hip flexation. Given the prestretch, the load is not introduced until the weight bearing phase of the movement where the hamstring muscle is much more capable of accepting the load factors. Subsequently, it is more beneficial and less injury prone to add additional hand held horizontal resistance (dragging motion) to the ham string muscle in a backward walking motion. Therefore, during a backward dragging motion the user can achieve greater blood flow to and activation of the hamstring muscles at a slower walking speed than walking without the added load factor of the dragging motion.  
      The present invention is an exercise treadmill for simulating the dragging or pulling of an object on a level surface, up an incline or down a decline. The treadmill has a lower base housing the internal mechanical components, a pivot arm on which a hand controller is mounted, and a weight resistance means located within the lower base. In one embodiment, the weight resistance means can be operatively connected to the pivot arm via a cable. In another embodiment, the weight resistance means can be operatively connected to the pivot arm by lever, rods, or the like. In yet another embodiment, the weight resistance means can be operatively directly connected to the pivot arm. In still another embodiment, the weight resistance means can be directly attached to the pivot arm or to the connection between the pivot arm and the lower base. In another embodiment, the weight resistance means can be in operative communication with the pivot arm, yet not directly attached to or structurally connected to the pivot arm.  
      In operation, when a user steps onto the treadmill and grips the hand controller and starts belt moving, the user begins to walk or run in a simulated backwards direction relative to the hand controller, causing the user to pull on the hand controller. Alternatively, the treadmill may be set up to begin to move automatically at a speed and at an inclination according to a value entered from the hand controller. This pulling transfers to the pivot arm, as the hand controller is attached to the pivot arm, thus acting on the weight resistance means. As disclosed above, the action of the pivot arm on the weight resistance means can be by many means, such as cables, wires, rods, levers, or the like, directly or indirectly, and structurally attached or in cooperative communication.  
      The degree of weight resistance of the weight resistance means can be controlled by the user to simulate dragging or pulling a weight such that the exercise regimen is similar to walking or running backwards while dragging or pulling an object of a weight comparable to the setting of the weight resistance means. The higher the setting of the weight resistance means, the heavier the simulated object being pulled. In preferred embodiments, the weight resistance means can be an adjustable spring or hydraulic or pneumatic cylinder, a spring with a known spring constant or a hydraulic or pneumatic cylinder with a known resistance, a flexible rod with a known elastic modulus, or a frictional coupling with known coefficients of friction. Additional weight resistance means include direct current motors, direct current motors coupled with brake controllers, alternating current motors coupled with brake controllers, eddy current/electromagnetic resistance, and torsion springs directly connected to the pivot arm attachment site.  
      The invention also can be a combination of a conventional treadmill and the reverse dragging motion treadmill. To accomplish this, the hand controller and pivot arm can be set in a locked position for conventional treadmill operation and set in an unlocked position for reverse dragging operation. Further, the lower base housing the treadmill belt motor and the weight resistance means can be a relatively larger structure sitting under and supporting the invention or a relatively smaller structure from which the treadmill belt and platform extend. In the first instance, the elevation motor or means for raising and lowering the treadmill belt platform for incline and decline operation can be located within the lower base housing. In the second instance, the elevation motor or means can be located in a separate relatively smaller structure attached to the end of the treadmill platform opposite the end of the treadmill platform attached to the lower base housing.  
      Generally speaking, the internal mechanical components of the treadmill are similar to (or can be similar to or the same as) the internal mechanical components of known treadmills. The treadmill comprises an endless belt looped about rollers or pulleys so as to provide a platform on which the user can stand, walk and/or run. A deck below a portion of the belt supports the belt and the user. A belt motor cooperates with the belt and/or the rollers or pulleys to move the belt, thus creating a moving platform on which the user can walk or run for the exercise regimen. An incline motor cooperates with the platform, the deck, the rollers or pulleys or rear legs to incline the belt to simulate a hill.  
      These objects, and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art when the following detailed description of the preferred embodiments is read in conjunction with the appended figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of the invention.  
       FIG. 2  is a side view of the in invention operating in a flat position.  
       FIG. 3  is a side view of the invention operating in an inclined position.  
       FIG. 4  is a side sectional view of the invention showing the internal mechanical components.  
       FIG. 4A  is a side schematic of a tension spring-based weight resistance means suitable for the invention.  
       FIG. 4B  is a side schematic of a compression spring-based weight resistance means suitable for the invention.  
       FIG. 4C  is a side schematic of a first hydraulic or pneumatic cylinder-based weight resistance means suitable for the present invention.  
       FIG. 4D  is a side schematic of a second hydraulic or pneumatic cylinder-based weight resistance means suitable for the present invention.  
       FIG. 4E  is a top schematic of a flexible rod-based weight resistance means suitable for the present invention.  
       FIG. 4F  is a top schematic of a frictional coupling-based weight resistance means suitable for the present invention.  
       FIG. 5  is a top view of the base of the invention.  
       FIG. 6  is a top view of a representative hand control for the invention.  
       FIG. 7  is a side view of the representative hand control for the invention shown in  FIG. 6 .  
       FIG. 8  is a side view of the invention with an optional rear safety arm.  
       FIG. 9  is a side view of the invention with an optional rear step-off platform.  
       FIG. 10  is a side sectional view of the invention with an optional rear step-off platform showing an alternate configuration of the internal mechanical components.  
       FIG. 11A  is a side sectional view of the invention showing an alternate embodiment of a pivoting piston driven push drive weight resistance means in the resting position.  
       FIG. 11B  is a side sectional view of the invention showing an alternate embodiment of a pivoting piston driven push drive weight resistance means in the operating position.  
       FIG. 12A  is a side sectional view of the invention showing an alternate embodiment of a rigid cam shaped push drive weight resistance means in the resting position.  
       FIG. 12B  is a side sectional view of the invention showing an alternate embodiment of a rigid cam shaped push drive weight resistance means in the operating position.  
       FIG. 12C  is a schematic view of the rigid cam shaped push drive weight resistance means shown in  FIGS. 12A and 12B .  
       FIG. 13A  is a side sectional view of the invention showing an alternate embodiment of a direct axle drive resistance weight resistance means in the resting position.  
       FIG. 13B  is a side sectional view of the invention showing an alternate embodiment of a direct axle drive resistance weight resistance means in the operating position.  
       FIG. 13C  is a schematic view of the direct axle drive resistance weight resistance means shown in  FIGS. 13A and 13B .  
       FIG. 14A  is a side sectional view of the invention showing an alternate embodiment of a direct axle mounted spring resistance weight resistance means in the resting position.  
       FIG. 14B  is a side sectional view of the invention showing an alternate embodiment of a direct axle mounted spring resistance weight resistance means in the operating position.  
       FIG. 14C  is a schematic view of the direct axle mounted spring resistance weight resistance means shown in  FIGS. 14A and 14B .  
       FIG. 15  is a side sectional view of the invention showing an alternate embodiment of a direct drive tensile weight resistance means in combination with an alternately mounted pivot arm.  
       FIG. 16A  is a side sectional view of an embodiment of the invention shown in the drag operating position with a level platform.  
       FIG. 16B  is a side sectional view of an embodiment of the invention shown in the drag operating position with an inclined platform.  
       FIG. 16C  is a side sectional view of an embodiment of the invention shown in the drag operating position with a declined platform.  
       FIG. 17A  is a side sectional view of an embodiment of the invention shown in the forward ambulatory position with a level platform.  
       FIG. 17B  is a side sectional view of an embodiment of the invention shown in the forward ambulatory position with an inclined platform.  
       FIG. 17C  is a side sectional view of an embodiment of the invention shown in the forward ambulatory position with a declined platform. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring now to the appended figures, the invention will be described in connection with representative preferred embodiments.  FIG. 1  is a perspective view of the invention illustrating the relationship between the various major components of the device.  FIG. 2  is a side view of the invention showing a user operating the invention in a flat or level dragging or pulling simulation.  FIG. 3  is a side view of the invention showing a user operating the invention in an inclined dragging or pulling simulation.  FIG. 4  is a side sectional view of the invention showing a schematic of the internal mechanical components of the invention.  
       FIGS. 4A through 4F  show several illustrative weight resistance means suitable for use with the invention.  FIG. 4A  is a side schematic of a spring-based weight resistance means suitable for the invention, such as a spring with a known spring constant in tension.  FIG. 4B  is a side schematic of a compression spring-based weight resistance means suitable for the invention, such as a spring with a known spring constant in compression.  FIG. 4C  is a side schematic of a first hydraulic cylinder-based weight resistance means suitable for the present invention, such as a hydraulic cylinder with known or adjustable resistance, in which the resistance is created by pulling the piston rod out of the hydraulic cylinder.  FIG. 4D  is a side schematic of a second hydraulic cylinder-based weight resistance means suitable for the present invention, such as a hydraulic cylinder with known or adjustable resistance, in which the resistance is created by pushing the piston rod into the hydraulic cylinder.  FIG. 4E  is a top schematic of a flexible rod-based weight resistance means suitable for the present invention, such as a rod with a known elastic modulus.  FIG. 4F  is a top schematic of a frictional coupling-based weight resistance means suitable for the present invention, such as a combination of elements having known coefficients of friction.  
       FIG. 5  is a top view of the base of the invention illustrating the relative positioning of various components of the invention.  FIG. 6  is a top view of a representative hand control for the invention showing various features that can be included on the hand control.  FIG. 7  is a side view of the representative hand control for the invention shown in  FIG. 6 .  FIG. 8  is a side view of the invention with an optional rear safety arm to help prevent the user from inadvertently stepping off the rear of the invention.  FIG. 9  is a side view of the invention with an optional rear step-off platform on which the user can step if exiting the invention from the rear.  FIG. 10  is a side sectional view of the invention with an optional rear step-off platform showing an alternate configuration of the internal mechanical components illustrating the relationship between the various major components of the device.  
       FIGS. 11 through 15  show several additional illustrative weight resistance means suitable for use with the invention.  FIGS. 11A and 11B  are side sectional views of the invention showing a pivoting piston driven push drive weight resistance means in the resting and operating positions respectively.  FIGS. 12A and 12B  are side sectional views of the invention showing a rigid cam shaped push drive weight resistance means in the resting and operating positions respectively, with  FIG. 12C  showing a schematic view of the rigid cam shaped push drive weight resistance means.  FIGS. 13A and 13B  are side sectional views of the invention showing a direct axle drive resistance weight resistance means in the resting and operating positions respectively, with  FIG. 13C  showing a schematic view of the direct axle drive resistance weight resistance means.  FIGS. 14A and 14B  are side sectional views of the invention showing a direct axle mounted spring resistance weight resistance means in the resting and operating positions respectively, with  FIG. 14C  showing a schematic view of the direct axle mounted spring resistance weight resistance means.  FIG. 15  is a side sectional view of the invention showing an alternate embodiment of a direct drive tensile weight resistance means in combination with an alternately mounted pivot arm.  
       FIGS. 16 and 17  show alternative embodiments of a combination treadmill and reverse dragging treadmill and having a more compact lower housing body.  FIGS. 16A through 16C  are side sectional views of an embodiment of the invention shown in the drag operating position with a level platform, an inclined platform, and a declined platform, respectively.  FIGS. 17A through 17C  are side sectional views of an embodiment of the invention shown in the forward ambulatory position with a level platform, an inclined platform, and a declined platform, respectively.  
       FIG. 1  is a perspective view of one embodiment of the invention illustrating the relationship between the various major components of the device. Treadmill  10  has a lower base  12  housing the internal mechanical components of treadmill  10 .  
      Projecting upwardly from base  12  is pivot arm  14  on which hand controller  16  is mounted. Pivot arm  14  can comprise one, two, or more pivot arm sections. As illustrated in  FIG. 1 , pivot arm  14  comprises two pivot arm sections, upper pivot arm  14 A and lower pivot arm  14 B, such that pivot arm  14  is self-aligning for users U of different heights and body builds. Additionally, the use of a two-part pivot arm  14 , or a multi-part pivot arm  14 , provides for a more biometrically acceptable pulling motion and to position pivot arm  14  as far away from user U (shown in  FIGS. 2, 3 ,  8  and  9 ) as possible to avoid incidental and unwanted contact with pivot arm  14 . Further, the use of a two-part pivot arm  14 , or a multi-part pivot arm  14 , can be more comfortable to user U. First mounting means  28  pivotally attaches upper pivot arm  14 A to lower pivot arm  14 B.  
      Hand controller  16  is mounted on the end of upper pivot arm  14 A distal from lower pivot arm  14 B, which also is proximal to user U when user U is in the correct position for operating the treadmill  10 . Second mounting means  30  attaches hand controller  16  to upper pivot arm  14 A and can be a static or motionless connection, with hand controller  16  rigidly connected to upper pivot arm  14 A, or a dynamic or moving connection, with hand controller  16  movably connected to upper pivot arm  14 A, such as in a two-dimensional pivoting or three-dimensional joystick configuration. The combination of pivot arm  14  and hand controller  16  provides user U with a means of support either during the entire exercise period or for an initial period until user U has assimilated himself or herself to the speed of the treadmill. The combination of first mounting means  28  and second mounting means  30  allows desired motion of pivot arm  14  and hand controller  16  relative to user U.  
      Alternatively, there can be two pivot arms  14 , one for each hand of user U. If two pivot arms  14  are used, the controls on hand controller  16  can be on one or the other of pivot arms  14 , or split between the two pivot arms  14 . Further, the use of two independent pivot arms  14  can simulate the arm-swinging motion that normally occurs during walking or running, which may be advantageous to user U, or can be lined together.  
      Hand controller  16  can include electronic controls and information displays that typically are provided on exercise treadmills for purposes such as adjusting the speed and incline of treadmill  10 , the time user U has been operating treadmill  10  and/or the time left in a set exercise regimen, user&#39;s U heart rate, the simulated load being dragged or pulled, on and off buttons, and an emergency off button, and other functions, as will be discussed later in connection with  FIGS. 6 and 7 . Various step off platforms, such as side step offs  22 , front step offs  24  and rear step-offs  26 , can be included in various configurations both to allow user U easy access to the treadmill  10  and to provide safety platforms for user U to step off treadmill  10  onto a non-moving platform, as will be discussed later in connection with  FIG. 5 . Attached to lower pivot arm  14 B and extending between lower pivot arm  14 B and a weight resistance means  46  shown in more detail in  FIG. 4  is weight resistance cable  18 .  
      In normal operation, user U will step onto belt  20  and grasp hand controller  16 , positioning himself or herself generally centrally on belt  20  so as to face the hand controller  16 . As belt  20  begins to move, as will be discussed later, user U will start a rearward walking or running motion towards the rear of treadmill  10 , with belt  20  moving accordingly, such that user U will remain generally in the same position centrally on belt  20  as treadmill  10  is operating. Alternatively, treadmill  10  may be set up to begin to move automatically at a speed according to a value entered from hand controller  16 . The pace of the walking or running motion may be increased or decreased depending upon the speed of belt  20 . The speed of belt  20  can be controlled by the adjustment of the controls on hand controller  16 , along with the adjustment of the inclination of treadmill  10  and other functions and features, as will be discussed later in connection with  FIGS. 6 and 7 . Belt  20  also can comprise two belts, one for each foot, as an alternative.  
       FIG. 2  is a side view of the invention showing user U operating the treadmill  10  in a flat or level dragging or pulling simulation. In this position, user U is simulating a level surface dragging or pulling motion and is walking or running backwards and pulling on hand controller  16 , and thus pulling against weight resistance means  46 .  
       FIG. 3  is a side view of the invention showing user U operating the treadmill  10  in an inclined dragging or pulling simulation. In this position, user U is simulating an inclined uphill dragging or pulling motion and is walking or running backwards and uphill and pulling on hand controller  16 , thus simultaneously pulling against weight resistance means  46  and moving uphill. As will be discussed later in connection with  FIG. 4 , hand controller  16  and pivot arm  14  via first mounting means  28  and second mounting means  30  allow the appropriate motion of pivot arm  14  hand controller  16  relative to user U for self-alignment and for proper and comfortable operation of treadmill  10 .  
      The use of one or more pivot points such as first mounting means  28  and second mounting means  30  allows the various sections of pivot arm  14  to pivot relative to each other and to user U, resulting in a self-aligning feature. Further, as pivot arm  14  is pivotally attached to base  12 , there is another degree of movement for event greater alignment of pivot arm  14  relative to user U. For example, as user U grasps hand controller  18 , user U can move hand controller  18  upwards and downwards, and towards or away from user U, so as to place hand controller  18  in a position most comfortable to user U. Further, as the pivot points are freely pivotable, hand controller  18  in effect self-aligns to an appropriate position relative to user U simply upon being grasped by user U. The addition of additional pivot points, such as by making pivot arm  14  multi-sectional, can enhance this self-aligning feature.  
      As can be seen in  FIG. 3 , base  12  can comprise a separate support platform  32  and belt platform  34 . In such a configuration, the main support for treadmill  10  along with belt motor  40  (shown in  FIG. 4 ), incline motor  42  (shown in  FIG. 4 ) and weight resistance means  46  (shown in  FIG. 4 ) preferably are located in support platform  32 , whereas belt  20  and belt movement means (disclosed in connection with and shown in  FIG. 4 ) preferably are located in belt platform  34 . Alternatively, each of the above disclosed elements can be located as desired in either support platform  32  or belt platform  34  by the engineer of ordinary skill in the art. In such a configuration, the inclination of belt  20  is accomplished by incline motor  42  raising belt platform  34  relative to support platform  32 , in a manner well known in the art.  
      Alternatively, base  12  can comprise a single platform. In such a configuration, all of the above disclosed elements, namely the main support for treadmill  10 , belt motor  40  (shown in  FIG. 4 ), incline motor  42  (shown in  FIG. 4 ) and weight resistance means  46  (shown in  FIG. 4 ), are located in base  12 . In such a configuration, the inclination of belt  20  is accomplished by incline motor  42  raising the rear end of base  12  relative to the front end of base  12 , in a manner well known in the art.  
       FIG. 4  is a side sectional view of the invention showing a schematic of the internal mechanical components of the treadmill  10 . Generally speaking, because the internal mechanic components of the treadmill  10  are similar to (or can be similar to or the same as) the internal mechanical components of known treadmills, the internal mechanical components will be discussed in general terms. Treadmill  10  comprises an endless belt  20  looped about rollers or pulleys  36 . Rollers or pulleys  36  are rotatably secured within base  12  such that belt  20  can continuously travel about rollers or pulleys  36 . Located between rollers or pulleys  36  and within the endless loop of belt  20  is deck  38  for supporting the top run  20 A of belt  20 .  
      Specifically, as when user U steps on belt  20 , belt  20  is pressed against deck  38  to support user U. Belt motor  40  cooperates with belt  20  and/or rollers or pulleys  36  to move belt  20 . Incline motor  42  cooperates with belt platform  34 , deck  38 , rollers or pulleys  36  or rear legs  44  to incline belt  20 . Weight resistance means  46  cooperates with pivot arm  14  via cable  18 . Cable  18  can be of any structure, such as a rope, a chain, a belt; monofilaments, braided wires, and other suitable equivalents, that allow a transfer of force between pivot arm  14  and weight resistance means  46 , and is not limited to a standard cable.  
      A representative drive assembly for belt  20  is schematically illustrated in  FIG. 4 . Front roller or pulley  36 A is rotatably mounted within base  12 , such as on axle  48 .  
      Rear roller or pulley  36 B is rotatably mounted within base  12 , such as on axle  50 . Axles  48 ,  50  typically are secured to a frame portion of base. Front roller or pulley  36 A and rear roller or pulley  36 B are positioned substantially parallel to each other. Belt  20  is looped around rollers or pulleys  36  so as to allow belt  20  to move continuously about rollers or pulleys  36 , thus forming upper run  20 A and lower run  20 B. User U steps on belt  20  during normal operation of treadmill  10 , causing belt  20  to bend under the weight of user U. Belt  20  is supported for a portion of its length, and for a substantial portion of upper run  20 A, between rollers or pulleys  36  by deck  38 . To reduce friction between the underside of upper run  20 A and the top surface of deck  38 , a low friction material can be applied to the top surface of deck  38  or the underside of belt  20 , or both. Alternatively, deck  38  can be constructed of a low friction material. Deck  38  preferably is rigidly secured within base  12  or belt platform  34 . This configuration is known in the treadmill art.  
      In the illustrative example shown in  FIG. 4 , rear roller or pulley  36 B is rotated by belt motor  40 , such as by fan belt  54  or by a direct drive (not shown), during normal operation of treadmill  10 . Belt motor  40  is mounted within base  12 . Rear roller or pulley  36 A is rotated by belt motor  40 . As discussed in more detail later, the speed at which rear roller or pulley  36 A is rotated can be controlled by a microprocessor (not shown) through belt motor  40 . The speed is adjustable from controls on hand controller  16 . With this arrangement, it is therefore possible to vary the speed of belt  20  during the exercise regimen. This configuration is known in the treadmill art.  
      In the illustrative example shown in  FIG. 4 , an inclination mechanism is provided to permit inclination of deck  38 . Specifically,  FIG. 4  illustrates three different and separate inclination mechanisms. Preferably, only one inclination mechanism is used, but three are shown as alternatives to each other. If desired, two or more inclination mechanisms can be used in the same machine, with each being used independently from or in conjunction with each other. The three different lift mechanisms are a leg lift, comprising incline motor  42  and rear legs  44 , and two different belt platform  34  lifts, comprising lift motor  42  and a means for lifting belt platform  34 . Each of these three lift mechanisms are known in the treadmill art. In the leg lift, incline motor  42  is connected to rear legs  44 . Actuation of incline motor  42  causes the lifting of the entire base  12  relative to rear legs  44 . This causes treadmill  10  to pivot upwards about front legs  52 , thus raising the rear of treadmill  10  relative to front legs  52 , causing an incline in the entire base  12 . In the first belt platform  34  lift, belt motor  40  is supported within belt platform  34 . Incline motor  42  is connected to belt platform  34 , such as by supports  56 . Actuation of incline motor  42  causes the lifting of belt platform  34 , including belt motor  40  and the accompanying drive mechanics. In the second belt platform  34  lift, belt motor  40  is not supported within belt platform  34 , but is supported within support platform  32 . Incline motor  42  is connected to belt platform  34  or axle  48 , such as by supports  58 . Actuation of incline motor  42  causes the lifting of belt platform  34 , with belt motor  40  and the accompanying drive mechanics remaining below in support platform  32 . The degree of inclination chosen by user U is adjustable from controls on hand controller  16 . With this arrangement, it is therefore possible to vary the inclination of belt  20  during the exercise regimen. This configuration is known in the treadmill art.  
       FIG. 4  also schematically illustrates an example weight resistance means  46  for the treadmill  10 . Weight resistance means  46  is operatively connected to pivot arm  14  via cable  18 . Cable  18  can be directed around one or more pulleys  60  to prevent cable  18  from becoming entangled in the internal mechanical components of treadmill  10 . Specifically, cable  18  is attached to lower pivot arm  14 B, travels around pulley or pulleys  60  if necessary, and attaches to weight resistance means  46 . In operation, when user U grips hand controller  16  and starts belt  20  moving, user U begins to walk or run in a simulated backwards direction relative to hand controller  16 , causing user U to pull on hand controller  16 . This pulling transfers to pivot arm  14 , as hand controller  16  is attached to pivot arm  14 , thus pulling on cable  18 , which in turn pulls on weight resistance means  46 .  
      The degree of weight resistance can be controlled by user U. In the lowest setting, it can be possible for user U to pull pivot arm  14  all the way to a stop (not shown) preventing pivot arm from moving any farther. At such a setting, user U would be simulating dragging or pulling little or no weight and the exercise regimen would be similar to walking or running backwards, and pivot arm  14  would provide user U with stability. In other settings, weight resistance means  46  can be set high enough to prevent user U from pulling pivot arm  14  all the way to the stop (not shown). At such settings, user U would be simulating dragging or pulling a weight and the exercise regimen would be similar to walking or running backwards while dragging or pulling an object of a weight comparable to the setting of the weight resistance means  46 . The higher the setting of the weight resistance means  46 , the heavier the simulated object being pulled. The degree of weight resistance chosen by user U is adjustable from controls on hand controller  16 . With this arrangement, it is therefore possible to vary the weight resistance being dragged or pulled during the exercise regimen.  
      In preferred embodiments, weight resistance means  46  can be an adjustable spring or hydraulic cylinder, a spring with a known spring constant or a hydraulic or pneumatic cylinder with a known resistance, a flexible rod with a known elastic modulus, or a frictional coupling with known coefficients of friction. Each of these elements is known in the art. As discussed later, the weight resistance means  46  can be of many different forms, known or future developed, preferably so long as weight resistance simulating dragging or pulling is provided.  
       FIGS. 4A and 4B  illustrate adjustable springs or springs with known spring constants.  FIG. 4A  illustrates the use of spring  70  in tension. Although adjustment mechanism  72  is shown, a spring of known spring constant can be used without adjustment mechanism  72 . First end  70 A of spring  70  is attached to base  12  and second end  70 B of spring  70  is attached to cable  18 . In tension, pulling on cable  18  in the direction of arrow P would stretch spring  70 , placing it in tension. A spring of known spring constant can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U. The use of adjustment mechanism  72  inserted at strategic positions between coils of spring  70  also can be used to adjust the simulated resistance weight.  
       FIG. 4B  illustrates the use of spring  70  in compression. Although adjustment mechanism  72  (not shown in  FIG. 4B ) can be used, a spring of known or unknown spring constant can be used with adjustment mechanism  72 . First end  70 A of spring  70  is attached to base  12  via attachment arms  74  and second end  70 B of spring  70  is attached to cable  18 . In compression, pulling on cable  18  in the direction of arrow P would compress spring  70 , placing it in compression. A spring of known spring constant can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U. The use of adjustment mechanism  72  inserted at strategic positions between coils of spring  70  also can be used to adjust the simulated resistance weight.  
       FIGS. 4C and 4D  illustrate hydraulic or pneumatic cylinders with known resistance. As hydraulic and pneumatic cylinders operate on the same general principle,  FIGS. 4C and 4D  will be discussed in connection with hydraulic cylinders;  
      however, the same discussion applies to pneumatic cylinders.  FIG. 4C  illustrates the use of hydraulic cylinder  76  in pulling configuration. Hydraulic cylinder  76  is attached to base  12  and piston rod  78  is attached to cable  18 . Pulling on cable  18  in the direction of arrow P pulls piston rod  78  out of hydraulic cylinder  76 , with the fluid within hydraulic cylinder  76  providing resistance. The use of a hydraulic cylinder with known or adjustable resistance, in which the resistance is created by pulling piston rod  78  out of hydraulic cylinder  76 , can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  
       FIG. 4D  illustrates the use of hydraulic cylinder  76  in pushing configuration. Hydraulic cylinder  76  is attached to base  12  via attachment arms  74  and piston rod  78  is attached to cable  18  via attachment arms  74 . Pulling on cable  18  in the direction of arrow P pushes piston rod  78  into hydraulic cylinder  76 , with the fluid within hydraulic cylinder  76  providing resistance. The use of a hydraulic cylinder with known or adjustable resistance, in which the resistance is created by pushing piston rod  78  into hydraulic cylinder  76 , can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  
       FIG. 4E  illustrates the use of flexible rod  80 . At least one end of rod  80  is attached to base  12  and a middle section or another end of rod  80  is attached to cable  18 . Pulling on cable  18  in the direction of arrow P would flex rod  80 , producing a combination of compression forces and tension forces in rod  80 . A flexible rod or rods of known elastic modulus can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  
       FIG. 4F  illustrates the use of friction members  82 ,  84  in pulling configuration. First friction member  82  is attached to base  12  and second friction member  84  is attached to cable  18 . Pulling on cable  18  in the direction of arrow P pulls second friction member  84  against first friction member  82 , providing frictional resistance. The use of friction members with known or adjustable coefficients of friction, in which the frictional resistance is created by pulling second friction member  84  against first friction member  82 , can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  
      Other weight resistance means  46  include electromagnetic braking, eddy current mechanisms, direct and alternating current motors including coupled with brake controllers, weight stacks, resistance bands, spring-powered reels, pneumatic, air resistance, and water paddles. Each of these other weight resistance means  46  are known and can be adapted for this invention without undue experimentation. Further, other weight resistance means are suitable for use in this invention, including known and future developed weight resistance means.  
      A comparison of the position of pivot arm  14  in  FIG. 2  versus  FIG. 4  shows how pivot arm  14  can move. Pivot arm  14  is shown in the at rest position in  FIG. 4 , and in the operational position in  FIG. 2  and in the ghost lines in  FIG. 4 . Pivot arm  14  can pivot between the at rest position and a fully extended position, and the position of pivot arm  14  during operation is dependent on user U. Stops (not shown) prevent pivot arm  14  from moving past the at rest position in one direction of motion and the fully extended position in the opposite direction of motion. Further, a comparison of the position of belt  20  in  FIGS. 1, 2  and  4  versus  FIG. 3  shows how belt  20  can incline. Belt  20  is shown in the level position in  FIGS. 1, 2  and  4  and in the inclined position in  FIG. 3  and the ghost lines of  FIG. 4 . Belt  20  (specifically belt platform  34  or base  12 ) can incline between the level position and the fully inclined position, and the inclination of belt  20  is dependent on user U.  
       FIG. 5  is a top view of the base of the invention illustrating the relative positioning of various components of treadmill  10 . Front step offs  24  run across at least a portion of the front of base  12  on either side of pivot arm  14 . Side step offs  22  run at least a portion of the length of base  12  from front to rear of treadmill  10 . Rear step offs  26  are not shown in this embodiment. Step off surfaces  22 ,  24 ,  26  provide a surface upon which user U can step onto before, during or after belt  20  begins to move. Slot  86  is where cable  18  enters base  12 . Hole  88  is where pivot arm  14  enters base  12 . Pivot arm  14  is pivotally attached within base  12  via a known type of connection (not shown).  
       FIG. 6  is a top view of a representative hand controller  16  for the invention showing various features that can be included on the hand controller  16 .  FIG. 7  is a side view of the representative hand controller  16  for the invention shown in  FIG. 6 . A number of visual displays can be included on hand controller  16  including time display  90  that displays the elapsed time of an exercise regimen or the time remaining in a count down for an exercise regimen, heart rate display  92  that shows the heart rate of user U assuming a heart rate monitor is being used and treadmill  10  include the features of heart rate monitoring, incline display  94  representing the incline of belt  20  in degrees or other units, load display  96  representing the load or weight being dragged or pulled, and speed display  98  representing how fast user is moving. Such displays are known in the treadmill art.  
      Additional displays can include a mile display to display the simulated distance raveled by user U during the exercise regimen, a calorie display to display the current rate of user U calorie expenditure or the total calories expended by user U during the exercise regimen. Further, hand controller  16  can include an input key pad with which user U can communicate with a microprocessor that operates treadmill  10  so as to operate treadmill  10  as well as set the parameters for exercise regimens. Also included on hand controller is or can be on-off buttons, emergency stop button  100 , increase buttons  102  to increase a parameter, decrease buttons  104  to decrease parameters, and other functional input devices. All of these are known in the treadmill art. Further, hand grips  106  also can comprise input means (not shown) for reading user&#39;s U heart rate, as is known in the art.  
      Treadmill  10  utilizes a known microprocessor (not shown) or other suitable electronic controller to control and operate the various features of the invention. For example, the speed of belt motor  40 , and hence the speed of belt  20 , is controlled by the microprocessor or other suitable electronic controller. Further, the inclination of belt  20  also is controlled by the microprocessor or other suitable electronic controller. Additionally connected to the microprocessor or other suitable electronic controller are the various display and other elements  90 ,  92 ,  94 ,  96 ,  98 , 100 , 102 , 104  (and others, if present) of the hand controller  16 . For the sake of simplicity, the signals are transmitted to and from the microprocessor or other suitable electronic controller to the hand controller  16  displays  90 ,  92 ,  94 ,  96 , 98  (and others, if present), and are operatively connected to the switches  100 , 102 , 104  (and others, if present) and the specific elements, such as belt motor  40 , incline motor  42 , and weight resistance means  46 . Again, the use of this type of microprocessor or other suitable electronic controller is well known in the treadmill art.  
       FIG. 8  is a side view of the invention with an optional rear safety arm  108  to help prevent user U from inadvertently stepping off the rear of treadmill  10 . Rear safety arm  108  can comprise pad  110  attached to upright  112 , upright  112  being attached to base  12 . Optionally, a second controller (not shown) can be located on rear safety arm  108  or pad  110 . Such a second controller could be used to operate treadmill  10  in a more conventional manner as a forward walking treadmill. With such a configuration, user U would in effect be standing on belt  20  facing rearward towards rear safety arm  108  with the motion of belt  20  allowing forward walking and control of treadmill  10  would be accomplished via second controller.  
       FIG. 9  is a side view of the invention with an optional rear step-off  26  platform on which user U can step if exiting treadmill  10  from the rear. Optional side step offs  22  are the most preferable step off features, with optional front step offs  24  also being preferable due to pivot arm  14  pivoting forward in the at rest position. Rear step offs  26  are optional and provide an additional measure of safety.  FIG. 9  also shows treadmill  10  in an inclined operational position using belt platform  34  and support base  32 .  
       FIG. 10  is a side sectional view of the invention with an optional rear step-off  26  platform showing an alternate configuration of the internal mechanical components illustrating the relationship between the various major components of the device.  FIG. 10  is similar to  FIG. 4  in this regard, but with the shape of the rear of base  12  altered to accommodate rear step off  26 .  
      Now that the cable embodiment of the invention has been disclosed, various other embodiments of the invention will be disclosed in connection with  FIGS. 11-17 . As can be seen, other embodiments of the invention are contemplated having various types of weight resistance means  46  and various types of connections between pivot arm  14  and weight resistance means  46 . Following are only several illustrative examples. As the general aspects of treadmill  10  have been disclosed above, the following disclosure will be limited to disclosures of the alternate structures and operational connections between pivot arm  14  and weight resistance means  46  to avoid being overly repetitive.  
       FIGS. 11-14  show side sectional views of the invention showing a schematic of the internal mechanical components of the treadmill  10 . As above, treadmill  10  comprises an endless belt  20  looped about rollers or pulleys  36 . Rollers or pulleys  36  are rotatably secured within base  12  such that belt  20  can continuously travel about rollers or pulleys  36 . Located between rollers or pulleys  36  and within the endless loop of belt  20  is deck  38  for supporting the top run  20 A of belt  20  such that when user U steps on belt  20 , belt  20  is pressed against deck  38  to support user U. A belt motor ( 40 , but not shown in  FIGS. 11-14 )  40  cooperates with belt  20  and/or rollers or pulleys  36  to move belt  20 . An incline motor ( 42 , but not shown in  FIGS. 11-14 ) cooperates with belt platform  34 , deck  38 , rollers or pulleys  36  or rear legs  44  to incline belt  20 .  
      In the illustrative example shown in  FIGS. 11-14 , rear roller or pulley  36 B is rotated by belt motor ( 40 , but not shown in  FIGS. 11-14 ) such as by fan belt  54  or by a direct drive (not shown), during normal operation of treadmill  10 . Belt motor ( 40 , but not shown in  FIGS. 11-14 ) is mounted within base  12 . Rear roller or pulley  36 A is rotated by belt motor ( 40 , but not shown in  FIGS. 11-14 ). The speed at which rear roller or pulley  36 A is rotated can be controlled by a microprocessor (not shown) or other suitable electronic controls through belt motor ( 40 , but not shown in  FIGS. 11-14 ). The speed is adjustable from controls on hand controller  16  making it possible to vary the speed of belt  20  during the exercise regimen.  
      In the illustrative examples shown in  FIGS. 11-14 , a simple incline mechanism  300  is shown in which a lever leg  302  is rotated by an incline motor ( 42 , but not shown in  FIGS. 11-14 ) to raise and lower motor housing  304 . Actuation of incline motor ( 42 , but not shown in  FIGS. 11-14 ) causes the rotation of lever leg  302  in the desired direction, thus raising or lowering motor housing  304  and belt platform  34 , thus causing the decline or incline, respectively, of belt platform  34 . The degree of inclination chosen by user U is adjustable from controls on hand controller  16  making it possible to vary the inclination of belt  20  during the exercise regimen.  
       FIGS. 11-15  schematically illustrate additional examples of weight resistance means  46  for the treadmill  10 . Each of these additional weight resistance means  46  are operatively connected to pivot arm  14  via what is considered a direct means, meaning in this specification, a means not comprising a length of cable  18 . However, as disclosed above, the degree of weight resistance can be controlled by user U. For example, in the lowest setting, it can be possible for user U to pull pivot arm  14  all the way to a stop  200  preventing pivot arm  14  from moving any farther. In other settings, weight resistance means  46  can be set high enough to prevent user U from pulling pivot arm  14  all the way to stop  200 . The higher the setting of the weight resistance means  46 , the heavier the simulated object being pulled. The degree of weight resistance chosen by user U can be adjustable from controls on hand controller  16 . With this arrangement, it is therefore possible to vary the weight resistance being dragged or pulled during the exercise regimen.  
       FIG. 11A  is a side sectional view of the invention showing an alternate embodiment of a pivoting piston driven push drive weight resistance means  46  in the resting position with pivot arm  14  resting against stop  200 .  FIG. 11A  illustrates the use of hydraulic cylinder  310  in pushing configuration. Hydraulic cylinder  310  is pivotally attached to base  12  and piston rod  312  is pivotally attached directly to pivot arm  14 . In this configuration, pivot arm  14  is pivotally attached to base  12  at a position below where piston rod  312  is attached to pivot arm. Pulling on pivot arm  14  pushes piston rod  312  into hydraulic cylinder  310 , with the fluid within hydraulic cylinder  310  providing resistance. The use of a hydraulic cylinder  310  with known or adjustable resistance in which the resistance is created by pushing piston rod  312  into hydraulic cylinder  310  is known and can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  FIG. 11B  is a side sectional view of the invention showing the alternate embodiment of a pivoting piston driven push drive weight resistance means  46  in the operating position.  
       FIG. 12A  is a side sectional view of the invention showing an alternate embodiment of a rigid cam shaped push drive weight resistance means  46  in the resting position with pivot arm  14  resting against stop  200 .  FIG. 12A  illustrates the use of a cam shaped resistance arm  320  in combination with a resistance source  322 . Cam arm  320  is pivotally attached to base  12  and resistance source  322  is attached to base  12  at a position somewhat removed from cam arm  320 . Cam arm  320  is operationally connected to resistance source  322  via a flexible or rigid drive connector  326 , or directly if the mechanics permit. As shown in  FIG. 12 , resistance source  322  is an electric motor acting against the rotation caused by connector  326 , as disclosed below, and connector  326  is a belt. Alternatively, resistance source  322  can be a spring or a torsion rod or the like. Roller wheel  324  is rotatably attached to pivot arm  14  at a position corresponding approximately to where cam arm  320  contacts pivot arm  14  in the resting position. In this configuration, pivot arm  14  is pivotally attached to base  12  at a position below where roller wheel  324  is attached to pivot arm  14 . Pulling on pivot arm  14  pushes roller wheel  324  against cam arm  320  thus causing cam to rotate about cam axle  328 . As connector  326  is operationally attached to cam arm  320  proximal to cam axle  328 , this rotation causes the rotation of connector  326 , which acts upon resistance source  322 , with resistance source  322  providing resistance. The use of a resistance source  322  with known or adjustable resistance of this type is known and can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  FIG. 12B  is a side sectional view of the invention showing the alternate embodiment of the rigid cam shaped push drive weight resistance means  46  in the operating position.  FIG. 12C  is a more detailed schematic view of the rigid cam shaped push drive weight resistance means  46  shown in  FIGS. 12A and 12B .  
       FIG. 13A  is a side sectional view of the invention showing an alternate embodiment of a direct axle drive resistance weight resistance  46  means in the resting position with pivot arm  14  resting against stop  200 . The embodiment shown in  FIG. 13A  is similar in function to the embodiment shown in  FIG. 12A , but without the use of a cam arm  320 . In the embodiment shown in  FIG. 13A , axle drive pulley clutch  330  is attached to or at the base of pivot arm  14  at a position corresponding to where pivot arm  14  is pivotally attached to base  12 . Resistance source  332  is attached to base  12  at a position somewhat removed from axle drive pulley clutch  330 . Axle drive pulley clutch  330  is operationally connected to resistance source  332  via a flexible or rigid drive connector  336 , or directly if the mechanics permit. As shown in  FIG. 13 , resistance source  332  is an electric motor acting against the rotation caused by connector  336 , as disclosed below, and connector  336  is a belt. Alternatively, resistance source  332  can be a spring or a torsion rod or the like, or an eddy current/electromagnetic. In this configuration, pivot arm  14  is pivotally attached to base  12  at a position generally corresponding to where axle drive pulley clutch  330  is attached to pivot arm  14 . Pulling on pivot arm  14  causes axle drive pulley clutch  330  to rotate about pulley axle  338 . As connector  336  is operationally attached to axle drive pulley clutch  330  proximal to pulley axle  338 , this rotation causes the rotation of connector  336 , which acts upon resistance source  332 , with resistance source  332  providing resistance. The use of a resistance source  332  with known or adjustable resistance of this type is known and can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  FIG. 13B  is a side sectional view of the invention showing the alternate embodiment of the direct axle drive weight resistance means  46  in the operating position.  FIG. 13C  is a more detailed schematic view of the direct axle drive weight resistance means  46  shown in  FIGS. 13A and 13B .  
       FIG. 14A  is a side sectional view of the invention showing an alternate embodiment of a direct axle mounted spring resistance weight resistance means  46  in the resting position with pivot arm  14  resting against stop  200 . In the embodiment shown in  FIG. 14A , direct axle spring  340  is attached to or at the base of pivot arm  14  at a position corresponding to where pivot arm  14  is pivotally attached to base  12 . Direct axle spring  340  in this embodiment is the resistance source. In this configuration, pivot arm  14  is pivotally attached to base  12  at a position generally corresponding to where direct axle spring  340  is attached to pivot arm  14 . Direct axle spring  340  is a torsion and/or compression spring or pair of springs attached at one end to, or ultimately to, base  12  and at another end to pivot arm  14 . Pulling on pivot arm  14  causes direct axle spring  340  to twist (helically) about direct axle spring axis  348 , which provides torsional or compressional resistance, depending on which direction direct axle spring  340  is being twisted. The use of a direct axle spring  340  with known or adjustable resistance of this type is known and can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U.  FIG. 14B  is a side sectional view of the invention showing the alternate embodiment of the direct axle mounted spring resistance means  46  in the operating position.  FIG. 14C  is a more detailed schematic view of the direct axle mounted spring weight resistance means  46  shown in  FIGS. 14A and 14B .  
       FIG. 15  is a side sectional view of the invention showing an alternate embodiment of a direct drive tensile weight resistance means  46  in combination with an alternately mounted pivot arm. The embodiment shown in  FIG. 15  is similar in function to the embodiment shown in  FIG. 11 , but with the hydraulic cylinder  310  being attached to pivot arm  14  at a position below where pivot arm  14  is attached to base  12 .  FIG. 15  illustrates the use of hydraulic cylinder  310  in pulling configuration. Hydraulic cylinder  310  is pivotally attached to base  12  and piston rod  312  is pivotally attached directly to pivot arm  14 . In this configuration, pivot arm  14  is pivotally attached to base  12  at a position above where piston rod  312  is attached to pivot arm  14 . Pulling on pivot arm  14  pulls piston rod  312  out of hydraulic cylinder  310 , with the fluid within hydraulic cylinder  310  providing resistance. The use of a hydraulic cylinder  310  with known or adjustable resistance in which the resistance is created by pushing piston rod  312  into hydraulic cylinder  310  is known and can be used to provide a basis for determining the simulated resistance weight being dragged or pulled by user U. In this configuration, the slot or hole through which pivot arm  14  passes through the structure of base  12  can be reduced or eliminated.  
       FIGS. 16 and 17  show alternative embodiments of a combination treadmill and reverse dragging treadmill and having a more compact lower housing body  12 , a belt platform  34  extending from a proximal end operationally connected to the lower body housing  12 , to a distal end on which an incline mechanism  300  is attached. To operate the invention as a conventional treadmill, belt motor  40  causes belt  20  to travel in one direction and to operate the invention as a reverse treadmill, belt motor  40  is reversed and causes belt  20  to travel in the other direction. In each of the illustrative embodiments shown in FIGS.  16  and, the treadmill  10  is shown with the cable  18  embodiment; however, it should be noted that the alternative non-cable  18  embodiments also can be configured as shown in each of  FIGS. 16 and 17 . These alternative embodiments are to show that the invention can be manufactured in various configurations. For example, in the configurations shown in  FIGS. 16 and 17 , belt platform  34  can be structured to be raised or folded vertical so as to provide a smaller footprint for storage.  
       FIGS. 16 and 17  also show a pivot arm  14  structured more like the conventional control console of a conventional treadmill. More specifically, pivot arm  14  is a unitary structure rather than the two- or multi-piece structure disclosed above. With such a configuration, pivot arm  14  can give user U a more conventional feel and can comprise the more conventional features and placement of features that user U may be used to. Although in the dragging mode one-piece pivot arm  14  may pivot slightly more downward than two-piece pivot arm  14 , the difference can be made slight or negligible with common engineering solutions, such as adjusting the angle at which pivot arm  14  is attached to lower base housing  12 , including a telescoping device allowing the handhold portion of pivot arm  14  to be raised or lowered, and the like. Alternatively, pivot arm  14  as shown in  FIGS. 16 and 17  also can be a two- or multi-piece structure with the hand console  16  being pivotally or hingedly attached to the upper end of pivot arm  14 .  
       FIG. 16A  is a side sectional view of an embodiment of the invention shown in the drag operating position with a level belt platform  34 . In this embodiment, belt motor  40  is located within lower housing body  12 , along with weight resistance means  46 , but incline motor  42  is located in incline motor housing  304  at the distal end of belt platform  34 . Lever leg  302  also is located in operational proximity to incline motor  42  and incline motor housing  304 .  FIG. 16B  is a side sectional view of the embodiment of the invention shown in  FIG. 16A  in the drag operating position but with an inclined belt platform  34 .  FIG. 16C  is a side sectional view of the embodiment of the invention shown in  FIG. 16A  in the drag operating position but with a declined platform. Similarly,  FIG. 17A  is a side sectional view of embodiment of the invention shown in  FIG. 16A , but in the forward ambulatory position with a level belt platform  34 .  FIG. 17B  is a side sectional view of the embodiment of the invention shown in  FIG. 17A  in the forward ambulatory position but with an inclined belt platform  34 .  FIG. 17C  is a side sectional view of the embodiment of the invention shown in  FIG. 17A  in the forward ambulatory position but with a declined belt platform  34 .  
      The invention also can comprise additional optional features. For example, the invention can comprise a safety mechanism to prevent user U from speeding up the movement of belt  20  due to the weight resistance of the weight resistance means  46 , and from speeding up the movement of belt  20  to a speed faster than what is shown on the hand controller  16  speed display  98 . In other words, treadmill  10  can further comprise a means for preventing belt  20  from running out from under user U should either user U move too fast relative to belt  20  or belt  20  move too fast relative to user U. This also would help prevent the force of user&#39;s U foot plant from undesirably increasing the speed of belt  20 . Clutches attached to belt  20  or axles  48 ,  50  can be used, among other known mechanisms. For another example, the step offs  22 ,  24 ,  26  optionally can be and preferably are of a substantial width to allow for a wider platform for user U to step onto or step off of treadmill  10 . Side rails and kill switches also can be used. Heart rate monitors can be used, and the microprocessor, or other suitable electronic controllers, can be configured to allow for heart rate monitoring and for the adjustment of belt  20  speed and incline and the level of weight resistance to maintain a desired heart rate.  
      In stark contrast to known treadmills, the present invention accomplishes a different exercise regimen than an aerobic walking or running workout. Initially, belt travels in the opposite direction than the belt on known treadmills to provide the basis for the dragging or pulling motion. Further, the use of a weight resistance means  46  in combination with a walking or running motion in general and a backwards walking or running motion in particular provides a more complex exercise regimen. It has been found that the combination of walking or running backwards in conjunction with the simulation of dragging or pulling a load provides a useful aerobic and/or anaerobic work out and can strengthen various muscles and muscle groups, specifically leg muscles and the gluteus maximus and also possibly arm, chest, shoulder and back muscles.  
      Other alternatives and embodiments can comprise one or more of the following features. The treadmill drive motor assembly and incline assembly can be positioned at either end, or in the middle, of the base. The hand controller can be wireless and connected to the weight resistance means with a flexible connection, such as wire or polymer cable and, in such an alternative embodiment, the pivot arm would not be necessary. The pivot arm can pivot on the top portion of the lower base housing and extend into the lower base housing to connect to the weight resistance means, as in  FIG. 15 , or can be pivotally connected to the bottom of the lower base housing, as in  FIG. 12 . The belt platform can incline and decline in both directions, providing incline or decline resistance for both conventional treadmill operation and for reverse treadmill operation. The pivot arm and/or the hand console can have a docking or fixed position for forward walking, for storage, and for greater safety in getting on and off of the treadmill. Additionally, the invention can have more common features including the ability to incline and decline at various or continuous degree settings and a belt that moves at various or continuous speeds. Further, there can be two or more pivot arms (or support members, uprights or pylons), with each pivot arm or the equivalent being a one-, two- or multi-piece structure with the hand console being pivotally or hingedly attached to one or more of the pivot arms or the equivalent.  
      While the invention has been described in connection with certain preferred embodiments, it is not intended to limit the spirit or scope of the invention to the particular forms set forth, but is intended to cover such alternatives, modifications, and equivalents as may be included within the true spirit and scope of the invention as defined by the appended claims.