Abstract:
The invention relates to a skating simulating exercise device including a force transmission means, which exponentially increases the amount of force required to spin a flywheel as the user approaches the limits of ovoid shaped boundaries, thereby eliminating abrupt stoppages and to simulate the digging in and pushing off actions in a real skating stride. The skating simulating exercise device also includes resistance to both rearward and lateral motion, which can be linked together to more effectively strengthen all aspects of a skater&#39;s motion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims priority from U.S. Patent Application No. 60/838,109 filed Aug. 17, 2006, which is incorporated herein by reference for all purposes. 
     
     TECHNICAL FIELD 
       [0002]    The present invention relates to an skating simulation exercise device, and in particular to a skating simulation exercise device, which accurately simulates both rearward and lateral aspects of the skating stride. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional training devices, which attempt to simulate the skating stride, such as those disclosed in U.S. Pat. No. 3,756,595 issued Sep. 4, 1973 to Hague; U.S. Pat. No. 5,284,460 issued Feb. 8, 1994 to Miller et al; and U.S. Pat. No. 6,849,032 issued Feb. 1, 2005 to Chu, require that the user is standing on the ends of rotating arms, which define a set and limited range of motion. 
         [0004]    Inertia and wind are the two primary elements of resistance in actual skating. It is not enough to simply replicate the mechanics of skating, a true skating machine must also have the feel of skating, which is only obtained by incorporating inertial resistance. Machines that employ weight stacks, hydraulic pistons or elastic cords for resistance lack this important inertial component. Regardless of how energetic the user&#39;s efforts on conventional machines each stroke will feel the same as the last, and there will never be any sense of building momentum, as in real skating. 
         [0005]    Alternative systems, such as those disclosed in U.S. Pat. No. 4,915,373 issued Apr. 10, 1990 to Walker; U.S. Pat. No. 6,786,850 issued Sep. 7, 2004 to Nizamuddin; and U.S. Pat. No. 7,014,595 issued Mar. 21, 2006 to Bruno, utilized tracks to define the range of motion of the user. 
         [0006]    Unfortunately, the user&#39;s skating stride, i.e. their stride path geometry, is defined by both rearward and lateral components, and does not always match that of the training device, therefore the user, while still exercising, is not strengthening their own skating stride when utilizing the above-identified training devices. 
         [0007]    World Patent Application No. WO2004/108229 published Dec. 16, 2004 in the name of Jadine discloses inline roller skates secured to the ends of cords, which are engaged with a flywheel, thereby enabling the user to practice his own skating stride. Unfortunately, the Janine device is totally free wheeling with no provision for an increasing gradient of resistance at either the end of the stride or at the outer limit of lateral motion so as to contain the user&#39;s stride path within a defined area and thereby prevent the user from losing control. 
         [0008]    An object of the present invention is to overcome the shortcomings of the prior art by providing a skating simulating exercise device, which enables the user to strengthen their own skating stride by providing an infinitely variable stride path geometry dictated by the user, which is contained within certain boundaries to ensure balance. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, the present invention relates to a skating simulating exercise device comprising: 
         [0010]    a frame; 
         [0011]    a resistance apparatus supported by the frame; 
         [0012]    first and second moveable foot supports for supporting a user&#39;s feet during forward and rearward movement; 
         [0013]    first and second pull cables fixed at first ends thereof to the first and second moveable foot supports, respectively, and to the frame at second ends; and 
         [0014]    first and second force transmission means interconnecting the first and second pull cables, respectively, with the resistance apparatus, whereby the resistance apparatus has an exponentially increasing resistance to rearward movement of the first and second foot supports by exponentially decreasing the amount of force transmitted to the resistance apparatus, while exponentially increasing the amount of force transmitted to the frame. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof, wherein: 
           [0016]      FIG. 1   a  is an isometric view of the skating simulation exercise device of the present invention; 
           [0017]      FIG. 1   b  is an exploded view of the device of  FIG. 1 ; 
           [0018]      FIG. 2  is a plan view of the skating surface of the device of  FIG. 1 ; 
           [0019]      FIG. 3   a  is a side view of a basic pull cable and guide cable arrangements of the device of  FIG. 1 ; 
           [0020]      FIG. 3   b  is a side view of an alternative pull cable and guide cable arrangements of the device of  FIG. 1 ; 
           [0021]      FIG. 4   a  is a side view of a preferred embodiment of the pull cable and guide cable arrangement of the device of  FIG. 1 ; 
           [0022]      FIG. 4   b  is a plot of resistance to foot movement vs. distance of foot movement of the device of  FIG. 1 ; 
           [0023]      FIG. 5   a  is an exploded view of the left foot support structure of the device of  FIG. 1 ; 
           [0024]      FIG. 5   b  is a side and top view of the first and second cylindrical sections of the left foot support of  FIG. 5   a;    
           [0025]      FIG. 5   c  is a side and top view of the first and second cylindrical sections of the right foot support similar to the left foot support of  FIG. 5   a;    
           [0026]      FIG. 5   d  is an isometric view of an alternative foot receiving structure of the device of  FIG. 1 ; 
           [0027]      FIG. 6  is an isometric view of the torso-supporting arm of the device of  FIG. 1 ; and 
           [0028]      FIG. 7  is a top view of the torso-supporting arm of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    With reference to  FIGS. 1   a  and  1   b , the skating simulation exercising device  1 , according to the present invention, includes a triangular frame  2  for mounting an inertial resistance apparatus, e.g. a flywheel  3 , and an optional torso-supporting arm  4 . Typically a smooth skating surface  5  is provided, which extends from the base of the frame  2 , but an existing surface can be used, if the device  1  is permanently set up proximate a suitably smooth surface. Left and right sliding foot supports  6  and  7  are connected on the ends of left and right pull cables  8  and  9 , respectively, and laterally confined by left and right guide cables  11  and  12 , respectively. The resistance of the flywheel  3  can be adjusted by the rotation of vent covers  10 , which regulate the amount of air that is passed through the vanes of the flywheel  3 . The use of the flywheel  3  enables the user to stride until the flywheel  3  reaches a certain speed, i.e. revolutions per minute, pause for a period of time, i.e. simulating gliding, while the flywheel  3  continues to rotate, and then continue striding with a certain amount of force that does not feel like starting from a dead stop, as with most exercising machines. 
         [0030]    Ideally the frame  2  is triangular including an opened framed base  2   a , an opened framed front leg  2   b  extending at an acute angle to the base  2   a , and an opened framed rear leg  2   c , extending at an acute angle from both the base  2   a  and the front leg  2   b.    
         [0031]    Although the resistance provided by the flywheel  3  is ideally suited for a skating simulating exercise device, connecting the flywheel  3  directly to the left and right foot supports  6  and  7  does not provide the user with the realistic sensation of digging in and pushing off with one foot while bringing the other foot forward to begin the next stride. 
         [0032]    With no boundaries to define and contain the range of lateral and rearward movement, the balance and control of the user is seriously compromised. Accordingly, the present invention provides a pull and guide cable system, which defines the boundaries of the skating stride of the left and right feet. With reference to  FIG. 2 , the two areas  15   a  and  15   b  defined by these boundaries are approximately ovoid in shape, with the broader curved end of each ovoid rearward of the user, accurately replicating the areas traversed by the feet during actual skating. The pull and guide cable systems provide an increasing gradient, e.g. exponential increase, of resistance at any point of approach of the user&#39;s feet to the boundaries of the defined areas  15   a  and  15   b , providing a firm, but resilient containment of the user&#39;s stride within the defined areas. 
         [0033]    Within the ovoid areas  15   a  and  15   b  defined by the pull and guide cable systems, the user&#39;s movement is not restricted to the skating stride, whereby during the power portion of the stride, the feet push in an arc back and to the side, and then return up the middle, as shown by arrows in  FIG. 2 . The freedom of movement provided by the present invention with the defined areas also enables the user to push straight back down the middle with the return portion of the stride to the outside, which is an alternative stride not like a skating stride, but is an equally viable exercise, i.e. in opposite direction to arrows in  FIG. 2 . Accordingly, the present invention offers an infinitely variable stride path geometry to the user, along with directional freedom of movement. 
         [0034]    The basic principle of the pull cable system is illustrated in  FIGS. 3   a  and  3   b , in which each pull cable (only left pull cable  8  shown) is passes under a fixed roller  13 , has a bend formed therein by being passed over a reciprocating pulley  14 , and directed to a fixed point  16 , whereby the fixed roller  13 , the reciprocating pulley  14  and the fixed point  16  form the vertices of a triangle. The fixed point  16  can be the end of the pull cable  8  or  9 , or a point through which the pull cable  8  or  9  passes over before being fixed to the frame  2 . A motion converting chain  17  is connected to the reciprocating pulley  14 , and extends around a sprocket  18 , which is connected to an axle of the flywheel  3 . The other end of the chain  17  is fixed at a point  19  via a return spring/elastic  21 . 
         [0035]    During use, ignoring the effect of lateral motion, rearward motion of the left foot support  6  pulls on the left pull cable  8 , which forces the pulley  14  to move downwardly, decreasing the size of the triangle until the left pull cable  8  is substantially straight, with the pulley  14  in alignment between the fixed roller  13  and the fixed point  16 . As the pulley  14  moves downwardly, the mechanical advantage of the left pull cable  8  on the pulley  14  decreases exponentially, and the force required to move the left foot support  6  follows an increasing gradient e.g. exponentially increases, until a point limited by the strength of the left pull cable  8 , in which the left pull cable  8  is substantially pulling directly on the frame  2 , e.g. via fixed point  16 . As the pulley  14  moves downwardly, the chain  17  rotates the sprocket  18 , thereby rotating the flywheel  3  and transferring the rearward motion of the left foot support  6  to the flywheel  3 , i.e. the flywheel  3  provides resistance to rearward movement. The return spring  21  biases the pulley  14  back into the raised position as the left foot support  6  is returned to the forward position. The sprocket  18  is mounted on a roller clutch enabling force to be applied to the flywheel  3  while the left cable  8  is being pulled rearward, but enabling the sprocket  18  to freewheel when the left cable  8  is returning to the forward position. The identical mechanisms are provided and the identical processes are repeated as the right foot support  7  is moved rearward pulling on the right pull cable  9 . 
         [0036]    In the basic embodiment illustrated in  FIG. 3   a , the left and right guide cables  11  and  12  have only some elasticity or spring biasing  40 , e.g. bungee cord, forcing them back to a rest position, with the ends thereof fixed to the frame  2 . If low tension, high elasticity spring cables are used for both the pull and guide cables  8 ,  9 ,  11 , and  12 , the aforementioned alternative stride style would result, which is enhanced by the lack of lateral movement restraint. 
         [0037]    In the alternate embodiment, illustrated in  FIG. 3   b , the left and right guide cables  11  and  12  travel around a pulley  49  to a mechanical linkage  50  on the left pull cable  8 , whereby lateral displacement of the left foot support  6  applies a pulling force on the left guide cable  11 , which applies a pulling force on the left pull cable  8  via the mechanical linkage  50 . Accordingly, the pulling force on the left pull cable  8  translates the pulley  14  downwardly applying a portion of the pulling force to the flywheel  3  via the chain  17 , but at the same time decreasing the mechanical advantage of the left pull cable  8  on the pulley  14 . As above, both the rearward and lateral motion of the left and right foot supports  6  and  7  apply force to the flywheel  3 , and provide the gradually increasing gradient, e.g. exponentially increase, of resistance. 
         [0038]      FIG. 3   b  illustrates a more advanced principle, in which the force of lateral motion is imparted to the flywheel  3  through the connection and interaction of each guide cable  11  and  12  with its associated pull cable  8  and  9 , respectively, as hereinafter discussed. Identical principles are at work in both stride length, i.e. rearward, control and range of lateral motion control. Just as pull cable  8  defines a triangle with vertices at fixed point  16 , reciprocating pulley  14 , and the fixed roller  13 , so too, guide cable  11  (controlling lateral motion) together with part of pull cable  8 , defines a smaller triangle with vertices at fixed point  16 , cable link point  50 , and fixed roller  49 . The application of lateral force to left foot support  6 , tensions guide cable  11 , which results in a pulling downward of cable link point  50 , tensioning pull cable  8 , and thereby pulley  14 , imparting the energy of that lateral movement to the flywheel  3 . 
         [0039]    Note that the smaller triangle undergoes the same leverage dynamics as a result of lateral movement of left foot support  6 , as does the larger triangle as a result of rearward movement of the left foot support  6 . As cable link point  50  is pulled down, the angular changes in the smaller triangle results in a decreasing, e.g. exponentially, mechanical advantage and consequently an increase in the gradient, e.g. an exponential increase, to the resistance of lateral motion. The increase in resistance to lateral movement reaches a zenith when cable link point  50  is pulled into alignment with fixed point  16  and fixed roller  49 , at which point further lateral movement is not possible, without breaking the left guide cable  11 , i.e. the left guide cable  111  is substantially pulling directly on the frame  2  via the fixed point  16 . 
         [0040]    Throughout the skating stride the two triangles continuously interact with each other in a complex interplay of forces. As described above, the applied lateral forces working on the small triangle ( 16 ,  49 ,  50 ) change the forces working on the large triangle ( 13 ,  14 ,  16 ). Conversely, changes in forces on the large triangle (caused by the inevitably varying magnitude of rearward force applied to foot support  6 , as the user of the device  1  expends more or less energy), results in changes of applied forces on the small triangle, as well. For example, the greater the force with which left foot support  6  is driven rearward, the greater the tension on pull cable  8 , which results in greater force being required to move cable link point  50  downward, which will in turn increase resistance to lateral motion, thereby augmenting the user&#39;s balance and control during high intensity workouts. These constantly changing mechanical interactions between the rearward and lateral force components add immeasurably to the fidelity of the skating stride. 
         [0041]    Left guide cable  11  is under the least amount of tension at the end of the skating stride, at which time the reciprocating pulley  14  is substantially in alignment with the fixed point  16  and the fixed roller  13 , whereby the tension on the left pull cable  8  no longer has any additive effect on the tension of the guide cable  11 . The reduction of tension in the left guide cable  11 , when the left pull cable  8  is at maximum extension, enables the user&#39;s stride path to follow a natural arc in the transition from the power portion of the skating stride to the return (or recovery) portion of the skating stride, thereby defining the broad rearward curve of one of the two ovoid shaped skating stride containment areas defined by the pull and guide cables  8 ,  9 ,  11  and  12 . 
         [0042]    A practical pull cable system is illustrated in  FIG. 4 , in which the fixed point  16  is provided by a roller  16 ′, and in which the end of the left pull cable  8  is removeably fixed in a cleat  20  positioned on the front leg  2   b  of the frame  2  enabling easy access for adjusting the length of the left pull cable  8  for adjusting the stride length of the user. Moreover, the straight chain  17  is replaced by an endless chain  17 ′, which loops around both the sprocket  18  and a second sprocket  22  mounted adjacent the reciprocating pulley  14 , and is fixed at a point  19 ′. The looped endless chain  17 ′ doubles the length of the chain  17  per stroke moving over the sprocket  18 , thereby enabling a more effective RPM on the flywheel  3 . Preferably, a loop of the endless chain  17 ′ also passes over a sliding sprocket  24 , sliding in the rear leg  2   c  of the frame  2 , and connected to an end of the spring return  21 , which is fixed on the back leg  2   c  of the frame  2 . Passing the chain over the sliding sprocket  24  shortens the required elongation of the return spring  21 , thereby increasing the longevity thereof. 
         [0043]    The ends of the left and right guide cables  11  and  12 , respectively, are fixed at spaced apart positions  31  and  32 , respectively, to the rear of the users stride length on a rear bracket  33 , which is either mounted on the surface  5  or on the permanent surface provided. The rear bracket  33  is provided with slots  34  and  35  enabling the positions  31  and  32  to be adjusted according to the width of the users stride. The left and right guide cables  11  and  12  pass through guides, e.g. front and back guide rollers  37  and  38 , on the left and right foot supports  6  and  7 . The left and right guide cables  11  and  12  keeps the base of the left and right foot supports  6  and  7  oriented towards the front of the device  1 . A set of rollers  26  can be provided at the front of the frame  2  for guiding the left and right pull cables  8  and  9 , and the left and right guide cables  11  and  12 . 
         [0044]    Offset pull cable wheels  25  direct the pull cables  8  and  9  at an acute angle to the guide cables  8  and  9 , respectively, prior to passing through the rollers  26 , which ensures immediate engagement of the flywheel  3  at the start of the rearward stride, when the lateral vector of the stride is greater than the rearward vector. 
         [0045]    In the preferred and illustrated embodiment, lateral force on the left and right guide cables  11  and  12  also impart energy to, i.e. receive resistance from, the flywheel  3  by interacting with the aforementioned pull cable system. Accordingly, as illustrated in  FIG. 4 , the left guide cable  11  passes over a lever arm roller  41  back around a horizontal roller  42  up to an adjustable end point  43 . In the illustrated embodiment, the end of the guide cable  11  is connected to a clamp  44  slidable on a rod  45 , but other adjustment means are also possible to enable the width of the users stride to be adjusted. The lever arm roller  41  is mounted on a pull arm  46 , which is pivotally connected to a lever  47 , on which the fixed roller  13  and a force applying roller  48  are mounted, whereby when the user, via the left foot support  6 , pushes out laterally on the left guide cable  11 , the guide cable  11  pulls on the pull arm  46 , which rotates the lever  47 . Rotating the lever  47  causes the force applying roller  48  to apply a downward force on the left pull cable  8 , which forces the pulley  14  downwardly, thereby rotating the flywheel  3 , as described hereinabove. The mechanical linkage provided by the pull arm  46 , the lever  47 , and the force applying roller  48  multiplies the force on the guide cable  11 , and ensures that any given magnitude of lateral motion of the left foot support  6  results in a greater downward movement of the reciprocating pulley  14  than would occur with the identical magnitude of lateral motion in the simplified embodiment of  FIG. 3   b . Accordingly, just as in actual skating in which both the rearward and lateral components of the user&#39;s skating stride will impart energy to the flywheel  3 , i.e. will contribute to the flywheel&#39;s rotational inertia, thereby enhancing the simulation and exercise aspects of the device  1 . 
         [0046]    The harder the user drives the left and right foot supports  6  an  7  rearward, the greater the tension on the pull cables  8  and  9 , which tends to rotate the lever  47  in a counter-clockwise direction, thereby pulling on the pull arm  46  and increasing the tension on the guide cables  11  and  12 . The increased tension of the guide cables  11  and  12  helps to stabilize the user by preventing the user&#39;s feet from splaying out when accelerating. 
         [0047]    The pull and guide cables  8 ,  9 ,  11  and  12  define the limits of movement of the left and right foot supports  6  and  7 , whereby the magnitude of the rearward distance traveled by either the left or right foot support  6  or  7  is proportional to the distance the reciprocating pulley  14  moves between the upper and lower positions, and the magnitude of the lateral distance traveled by either the left or right foot support  6  or  7  is directly proportional to the distance the cable link point  50 , e.g. force applying roller  48 , moves between the upper and lower positions. Accordingly, the pull and guide cables  8 ,  9 ,  11  and  12  have an adjustable length to provide each user with appropriate limits of movement. 
         [0048]    As illustrated in  FIG. 4   b , as the height of the first (or second smaller) triangle  13 ,  14 ,  16  (or  13 ,  49 ,  50 ) decreases to zero, the force transmitted to the reciprocating pulley  14  decreases at an exponential rate to approximately zero, and the force transmitted to the frame  2  increases at an exponential rate until approximately equal to the total force applied by the user. Accordingly, the resistance to movement of the foot supports  6  and  7  in the rearward or lateral directions (or any combination thereof) increase at an exponential rate. 
         [0049]    The adjustable limits to movement are more accurately described as adjustments to the size, geometry, and juxtaposition of the substantially ovoid shaped areas in which the user&#39;s right and left foot movements are confined. The length of the left and right ovoid areas can be adjusted by adjusting the length of the left and right pull cables  8  and  9 . The width of the left and right ovoid areas can be adjusted by adjusting the length of the left and right guide cables  11  and  12 . The adjustment of the left and right guide cables  11  and  12  will also affect the amount of central overlap of the two ovoid areas. The degree of angular displacement between the central longitudinal lines of the two ovoid areas can be adjusted by changing the positions of the end positions  31  and  32  of the left and right guide cables  11  and  12 , which also affects the amount of overlap between the two ovoid areas. The adjustments to the containment areas of the left and right stride path geometries are completely independent of each other. 
         [0050]    With reference to  FIG. 5a , the left and right foot supports  6  and  7 , each comprise an upper foot receiving structure  51  rotatably mounted on a lower base  52  by bearing  53 . The rotation of the upper foot receiving structure about a generally vertical axis enables the user&#39;s feet and ankles to turn relative to the forward direction, as in a real skating stride, while keeping the lower base  52  pointing generally frontward. A ball and socket joint or some other form of universal joint may be used to provide rotation of the upper foot receiving structure  51  relative to the lower base  52 ; however, most of the aforementioned universal joints typically result in an unstable arrangement. In the preferred, illustrated embodiment, the bearing  53  is mounted at an acute tilt angle between first and second cylindrical sections  56  and  57 , respectively, having mating surfaces formed at the tilt angle. 
         [0051]    The preferred embodiment provides a solid, safe and wobble-free platform for feet, while enabling an ergonomically correct tilting and turning of the foot throughout the skating stride. Accordingly, when the left and right foot supports  6  and  7  are in the forward position with the upper foot receiving structure  51  in line with the lower base  52 , the mating surfaces are aligned whereby the first and second cylindrical sections  56  and  57  form a perfect cylinder. However, as the upper foot receiving structure  51  is rotated about an axis at an acute angle from vertical, i.e. perpendicular to the tilt angle, the front of the upper foot receiving structure  51  tilts downward, while the back of the upper foot receiving structure  51  tilts upward, providing the user with a more realistic skating motion. As the upper foot receiving structure  51  rotates about the axis of bearing  53 , the front of the upper foot receiving structure  51  tilts downwardly and to a side of a top center axis CA, while the back of the upper foot receiving structure  51  tilts upwardly and to the opposite side of the top center axis CA, exactly following the natural tilting and turning of the foot that occurs during actual skating. Accordingly, the user has a feeling of digging in and pushing forward with the upper foot receiving structure  51 , while the lower base  52  remains parallel with the surface  5 . 
         [0052]    To ensure natural movement of the feet during striding, the first and second cylindrical sections  56  and  57  of the left foot support  6  have mating surfaces, which are at an acute angle, e.g. 10° to 25°, from the horizontal, and rotated clockwise (for the right foot) or counterclockwise (for the left foot). Accordingly the lowest point LP of the mating surfaces of the first and second cylindrical section  56  and  57  of the right foot support  7  is approximately 60° clockwise from the top center axis extending from front to back (see  FIG. 5   c ), while the highest point HP is diametrically opposed thereto. The lowest point LP of the mating surfaces of the first and second cylindrical sections  56  and  57  of the left foot support  6  is approximately 60° counter clockwise from the top center axis extending from front to back (see  FIG. 5   b ), while the highest point HP is diametrically opposed thereto. 
         [0053]    The front and back guide rollers  37  and  38  are mounted on the lower base  52  utilizing a mounting bracket  58  and screw fasteners  59 . Castor wheels  61 , or some other suitable low friction gliding apparatus, are mounted on the lower base  52 . The upper foot receiving structure  51  can be any suitable structure; however, the illustrated embodiment includes a foot strap  62  and a heel receiving bracket  63 , made adjustable by a threaded rod  64  extending through a slot in the heel receiving bracket  63  into the upper foot receiving structure  51 . Since the castor wheels  61  always remain on the smooth surface, the skating simulation exercising device  1  provides a non-impact workout. 
         [0054]    In an alternate embodiment, illustrated in  FIG. 5d , the upper foot receiving structure  51  is replaced with a more ergonomic upper foot receiving structure  151 , including a foot roller  152  mounted between ends of torsional spring arms  153   a  and  153   b  extending from platform  154 . The spring arms  153   a  and  153   b  bias the foot roller  152  into contact with the user&#39;s foot providing easy initial engagement, while enabling the foot to automatically disengage from the upper foot receiving structure  151 , if a loss of balance should occur. 
         [0055]    Adjustment of the heel receiving bracket  63  enables the foot of the user to be positioned such that the axis of rotation of the user&#39;s foot is in alignment with the axis of rotation of the upper foot receiving structure  151 . 
         [0056]    As illustrated in  FIGS. 6 and 7 , the torso-supporting arm  4  extends outwardly from the frame  2  into contact with the user&#39;s chest area, thereby supporting the user and enabling the user&#39;s upper body to freely move in concert with their lower body as the user&#39;s weight transfers from one leg to the other during the skating stride, furthering the accurate replication of body movement experienced during actual skating. The torso-supporting arm  4  includes left and right braces  71  and  72  pivotally mounted to the frame  2  about a horizontal axis defined by holes  73  extending horizontally through left and right rear brackets  74  at the ends of the left and right braces  71  and  72 , enabling the torso-supporting arm  4  to be rotated down into alignment with the front leg of the frame  2  when not in use or if the user prefers not to use it. The rear brackets  74  are pivotally connected to the left and right braces  71  and  72  about a generally vertical axis defined by pins  76 , enabling the torso-supporting arm  4  to rotate from side to side about the generally vertical axis, thereby following the user&#39;s side to side movement during use. Adjustable handle grips  77  are reciprocatable in slots in the left and right braces  71  and  72 , respectively, and secured thereto with threaded fasteners  78 . 
         [0057]    An adjustable chest engaging padding guide  79  is pivotally mounted on the ends of the left and right braces  71  and  72  about horizontal axes via front brackets  81 , which are pivotally mounted on the ends of the left and right braces  71  and  72  about a vertical axis defined by pins  82 . The front and rear brackets  74  and  81 , respectively, enable the left and right braces  71  and  72 , respectively, to remain parallel, while the frame  2  and the padding guide  79  remain generally parallel to the user&#39;s shoulder, while the user moves side to side during use. Left and right chest pads  83  and  84  are also pivotally connected about a vertical axis to the padding guide  79 , providing additional adjustment for engaging the upper body of the user. 
         [0058]    To provide the torso-supporting arm  4  with a resistance to rotation about the vertical axis to ensure a gradual increase in resistance before reaching a hard stop, a center block  90  is mounted between the left and right braces  71  and  72 , with front and rear springs  91  and  92  extending from either end thereof into contact with front and rear sliding blocks  93  and  94 . The center block  90  is fixed to a first one of the left and right braces  71  and  72  and slide freely in a groove in second one, while the front and rear sliding blocks  93  and  94  are fixed to the second one of the left and right braces  71  and  72  and slide freely in a groove in the first one. Accordingly, as the user moves to one side the front spring  91  contracts, while the rear spring  92  expands, and as the user move to the other side the front spring  91  expands, while the rear spring  92  contracts. The gradual increase in resistance before reaching the stopping point ensures that the user maintain their balance during a stride, and that the user does not reach an abrupt stop at either end of the range of motion of the torso-supporting arm  4 . The torso-supporting arm  4  provides an inherent element of safety. Not only do the blocks  90 ,  93  and  94 , in combination with springs  91  and  92 , ensure that the user&#39;s side to side movement is kept within a safe range, but should either spring  91  and  92  fail, the blocks  90 ,  93  and  94  will act as safety stops to arrest the user&#39;s sideways movement before loss of balance occurs. Adjusting knobs  96  can be used to adjust the preload on the front and rear springs  93  and  94 .