Abstract:
The present invention concerns a stretching apparatus that is useful to apply controlled, gradual muscular stretching, and is particularly useful for controlled stretching of the hamstring muscle.

Description:
This application claims the benefit of U.S. Provisional Application Ser. No. 60/644,210, filed Jan. 14, 2005. 
    
    
     TECHNICAL FIELD 
     This application relates to an apparatus for stretching a person&#39;s muscles, such as the hamstring muscles. 
     BACKGROUND 
     The terms “hamstring,” “hamstrings” or “hamstring muscle” are generally used to refer to the three large muscles constituting the back of the upper leg. The hamstrings serve to flex the knee joint and extend the hip. Everyday activities as well as most athletic activities involve the repetitive contraction of the hamstring muscle. The hamstring muscle tightens as a result, and requires effective stretching to retain its full range of motion. In the absence of such stretching, the tight hamstrings will have a deleterious effect on the person&#39;s skeletal alignment, typically resulting in lower back and knee pain, as well as problems with posture. 
     Stretching any muscle is best done at a slow rate. Attempting to quickly stretch the muscle will rouse the muscle&#39;s inherent tendency to contract when pulled, thereby resisting the sought-after lengthening of the muscle. 
     SUMMARY OF THE INVENTION 
     The present invention concerns a stretching apparatus that is useful for controlled, gradual muscular stretching, and is particularly useful for controlled stretching of the hamstring muscle. In one embodiment, the stretching occurs while the stretched leg extends generally vertically upwardly adjacent to a stationary vertical surface. The stretched leg is supported for controlled, slow, forced rotation about the hip, away from that surface, thereby to stretch the hamstring muscle. 
     Preferably, the user of the apparatus is situated so that, apart from the stretched leg, the remainder of the person&#39;s muscle groups are relaxed, thereby allowing a focused effort for stretching the hamstring muscle. 
     Other advantages and features of the present invention will become clear upon study of the following portion of this specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating in a side view one embodiment of a stretching apparatus made in accordance with the present invention. 
         FIG. 2  is an enlarged view of an expandable part of the apparatus. 
         FIG. 3  is a diagram illustrating in side view a portion of an alternative embodiment of the present invention. 
         FIGS. 4A and 4B  are side views showing another embodiment of the present invention. 
         FIG. 5A  is a bottom view of the apparatus. 
         FIG. 5B  is an enlarged detail view taken from  FIG. 5A . 
         FIG. 6  is a perspective view showing a portion of another alternative embodiment. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     An apparatus made in accordance with the present invention is amenable for use in yoga exercises or physical therapy, with or without additional components for supporting or isolating the muscles to be stretched.  FIG. 1  illustrates one preferred embodiment of a stretching apparatus that is employed by a user  20  for controlled, gradual stretching of the hamstring muscle. The apparatus may be operated while the user  20  is reclined, on his back, with one “rested” leg  22  extending horizontally on a flat surface  28 . The other “stretched” leg  24  is rotated at the hip and extends vertically upwardly, with the knee held straight. The back of the stretched leg  24  is adjacent to the surface of a stationary, rigid member  26 . 
     In one embodiment, the member  26  may be an existing doorjamb, which is the vertical component of a door frame. In such an embodiment, the components of the stretching apparatus include an expandable member  30  that will hereafter be referred to as an expander  30 . The expander  30  is located adjacent to the vertical member  26  between that member and the back of the user&#39;s stretched leg  24 . The expander  30  may abut or be removably attached to the stationary surface of the vertical member. 
     The expander  30  is cushioned and/or contoured to comfortably receive the stretched leg, preferably in the vicinity of the user&#39;s Achilles tendon. In this regard, the expander  30  may have a boot-like configuration as shown in  FIG. 2  and discussed more below. 
     The expander  30  is controlled for providing incremental or gradual expansion from a contracted position to an expanded position for correspondingly gradual stretching of the user&#39;s hamstring muscle. As one aspect of this invention, the user may maintain the reclined position while remotely controlling the expander  30 . 
     In the contracted position of the expander  30 , the user&#39;s stretched leg  24  is generally vertical, thus making an angle “A” of about 90 degrees with the horizontal surface  28 . The contracted position of the expander  30  appears in  FIG. 1  as cross-hatching of the back portion of the expander  30  that is between the leg  24  and the vertical member  26 . Movement of the expander  30  toward the expanded position (shown in dashed lines in  FIG. 1 ) increases the angle between the stretched leg  24  and the surface  28  by angle “B” from vertical. The act of gradually moving the user&#39;s leg  24  through the angle “B” effectively stretches the hamstring muscle of that leg. 
     As noted, the expansion of the expander  30  is controlled by the user in a manner that permits the user to maintain an otherwise relaxed, reclined position. To this end, a remote control  32  is positionable near the hand  34  of the user. The expansion of the expander  30  may be provided by a pneumatic system, and the control  32  may comprise a hand pump or other valving that communicates with the expander  30  via line  36  for directing pressurized air into the expander  30  to expand it. The control  32  may also include a release valve for slowly returning the expander to the contracted state upon completion of the desired stretching time. A conventional sphygmomanometer bulb will suffice as the pump and release valve. 
     It is also contemplated that the control can be electronically automated with a simple controller for activating an air pump and associated valves for inflating and deflating the expander  30  in accord with built-in or user-defined programming. 
       FIG. 2  illustrates in greater detail a preferred embodiment of the expander  30 . In this embodiment, the expander  30  has a boot-like configuration that includes a base  42 , a back  44 , and two opposing sidewalls  46 ,  48 . The expander  30  may be formed of, for example, sewn synthetic material, such as nylon, that forms the outer casing for internal cushioning and an expandable air bladder  50 . The base  42  of the expander  30  extends across the sole of the user&#39;s foot  25 . The back  44  of the expander  30  extends from the rearward end of the base and along the back of the user&#39;s leg  24  generally adjacent to the Achilles tendon. 
     The sidewalls  46 ,  48  are attached to or integrally formed with the base  42  and back  44  and extend therefrom in a generally parallel relationship across the sides of the user&#39;s foot  25 , ankle, and lower leg. Between the sidewalls  46 ,  48  at the forward edge of the expander  30  (that is, the leftmost side in  FIG. 2 ) there is an open space to permit the user to insert the foot  25  into the expander. Preferably, the sidewalls  46 ,  48  carry one or more straps  52  with associated hook and loop fastening to secure the sidewalls together with the foot inserted into the expander  30 . 
     The base  42  and sidewalls  46 ,  48  may be filled with cushioning (shown cross-hatched in  FIG. 2 ), such as foam, to provide a snug, comfortable fit when the expander is worn. The back  44  houses the expandable air bladder  50  to which the pneumatic line  36  is coupled. As described above, the apparatus is controlled by the user to direct pressurized air through the line  36  for controlled expansion of the bladder  50  and consequent stretching of the hamstring muscle. 
     In a preferred embodiment, the bladder  50  and back  44  are configured so that the portion of the back  44  that is placed in contact with the vertical member  26  remains relatively flat or planar, and the expansion of the bladder  50  is thus primarily directed toward the user&#39;s leg  24 . Moreover, the bladder  50  is shaped so that in expanding away from the stationary surface the bladder enlarges by a progressively greater amount in the direction toward its outermost (upper) part (note the broken line  30  in  FIG. 1 ), so that the portion of the leg that contacts the back  44  of the expander  30  is supported in a generally straight line. 
       FIG. 3  shows an alternative embodiment of the invention whereby the vertical member  126  is integrated with the apparatus. In one approach, the vertical member  126  is in a stationary vertical position and carries the expander  30  ( FIGS. 1 and 2 ). Branching from the vertical member is a brace  38  that is configured to provide contact with the knee of user&#39;s rested leg  22 , so that leg  22  does not bend upwardly (as it otherwise tends to do) while the other leg  24  is being stretched. 
     As another approach to the integrated vertical member embodiment ( FIG. 3 ), the vertical member  126  is constructed to rotate about a pivot point  40  to provide the user-controlled increase in angle “B” mentioned above. Any suitable pneumatic, hydraulic or mechanical system would be employed for moving the member  126 . This type of movable member could be used without, or in combination with, an expander  30 . 
       FIGS. 4A and 4B  illustrate another preferred embodiment of the present invention. These figures show a side view of this embodiment, which includes a rigid, thin back plate  144 . The back plate  144  comprises two layers: a rigid plastic layer  146 , such as acrylonitrile butadiene styrene (ABS) to which is bonded an outer layer  148 , such as polyester felt. The outer layer  148  bears against a stationary surface  150 , such as the surface of a doorjamb, and permits slight vertical sliding movement of the apparatus along the doorjamb without marring that surface. 
     It is noteworthy here that the back plate  144  may be constructed in a variety of other configurations. For example, the back plate could be mounted to a vertical pole or other structure in a fitness club and adjustable in height to enable use of the apparatus by users of various heights (that is, leg lengths). It will be appreciated that the presently described embodiment, featuring abutting contact with a doorjamb, for example, provides a readily portable and compact apparatus that may be used in various locations around the user&#39;s house, hotel room, etc. 
     A generally U-shaped linkage  152  (see especially,  FIG. 5A ) is pivotally mounted to the back plate  144 . That linkage includes a pair of arms  154 , one arm extending from each of the opposing ends of a connector part  156  of the linkage that extends across the inner surface  158  of the back plate  144 . The connector part  156  is secured by spaced-apart sleeves  157  that are fastened to the back plate  144  to make a hinge-like, pivoting connection of the linkage  152  so that the arms  154  are able to swing about the long axis of the connector part  156  toward and away from the back plate  144 . 
     The free end of each arm  154  of the linkage is pivotally attached as at  159  to opposite sides of a boot member  160 . The linkage arms  154  are rigid, preferably metal, and serve to stabilize the position of the boot member  160  relative to the back plate  144 . The linkage  152  also controls or guides the movement of the boot member as it moves away from and toward the plate. 
     The boot member  160  may be a molded plastic member, or cut from a flat sheet of plastic (such as polyethylene) and bent and joined to define a base  162  and sidewalls  164 ,  166  into which fits the foot  125  of a user. 
     One of the sidewalls  164 ,  166  carries a strap  168  with associated hook and loop fastening. The free end of the strap is threaded through an aperture in the other sidewall so that the strap may be folded back on itself to secure the sidewalls together and hold the user&#39;s foot within the boot member  160 . 
     The boot member  160  may be formed solely of somewhat rigid plastic or, preferably, lined with foam cushioning to enhance the comfort of the boot member. 
     An expandable bladder  170  is connected to the boot member  160  and to the inner surface  158  of the back plate  144 . The bladder  170  is formed or two air-impermeable plastic sheets that are heat-welded together at their peripheral edges. Preferably, the heat-welded edge of the bladder is made wide enough to define a flange  173  ( FIG. 5B ) to which are riveted the male portions  172  of conventional snap fasteners. The male portions  172  on the bladder flange engage corresponding female portions  174  of snap fasteners that are carried on the both the back  176  of the boot member  160  and on the inner surface  158  of the back plate. In this embodiment, two spaced-apart snap fasteners are thus provided for attaching part of the bladder flange  173  to the boot member, and two fasteners are so used to attach another part of the bladder flange to the back plate  144 . It will be appreciated that there may be a variety of alternative ways to attach the bladder between the boot member and back plate. For example, the bladder flange may be stapled or bonded to those respective components. 
     A pneumatic line  178  couples to the bladder for conducting air to and from the bladder as discussed above in connection with the earlier-described embodiment. 
     It is noteworthy that the bladder  170  is somewhat trapezoidal in shape (See  FIG. 4B ) when fully inflated. In this regard, the bladder  170  is connected along a length of the back  176  of boot member, generally adjacent to the user&#39;s Achilles tendon, and configured to expand between the boot member  160  and the stationary surface  150  by a varying amount along the length of the boot member in the direction toward the heel  180  of the user. This configuration of the bladder, in conjunction with the pivotal connection with the linkage  152 , causes rotation of the boot member as the boot member moves away from the stationary surface so that the stretched leg can be held straight as it rotates about the hip. 
       FIG. 6  is an isometric view showing a portion of another alternative embodiment that employs a linkage  182  that is essentially a modification of the linkage  152  described above. The bladder and other components have been omitted for illustration purposes. The modified linkage provides the same stability and guidance as mentioned above, but also provides a relatively greater travel distance for the boot member  184  away from the back plate  186 , thereby to provide a greater amount of muscular stretching. 
     The linkage of  FIG. 6  includes two pivotally attached parts: a plate-mounted part  188 , and a boot-mounted part  190 . The plate-mounted part  188  is generally U-shaped and includes a pair of arms  192 , one arm extending from each of the opposing ends of a connector part  194  of the linkage that extends across the inner surface  258  of the back plate  186 . The connector part  194  is secured to the surface  258  by spaced-apart sleeves  196  that are fastened to the back plate  186  to make a hinge-like, pivoting connection of the plate-mounted linkage part  188  so that the arms  192  are free to swing about the long axis of the connector part  194  toward and away from the back plate  186 . 
     The free end of each arm  192  is pivotally joined to the U-shaped, boot-mounted part  190  of the linkage at the location  204  where the connector part  200  of that linkage joins the arms  202 . The free ends of those boot-mounted linkage arms  202  are each pivotally attached as at  206  to opposite sides of the boot member  184 . As mentioned, this two-bar linkage  188 , although able to collapse so that the boot member  184  can move adjacent to the back plate  186 , also permits a relatively large travel distance for the boot member away from the back plate. 
     While the present invention has been described in terms of preferred embodiments, it will be appreciated by one of ordinary skill in the art that modifications may be made without departing from the teachings and spirit of the foregoing. For example, the expander may be sized to extend nearly the entire length of the user&#39;s leg, between the ankle and upper thigh to enhance the comfort or support of the apparatus during its use. 
     Moreover, it is contemplated that the stationary surface against which the back plate is placed may be horizontal rather than vertical. Also, the air bladder could be replaced with a foam- and/or compression-spring-filled interior that is compressed before use and controlled so that the natural resilience of the foam and/or spring expands the bladder and displaces the boot member from the back plate. A fluid-driven, lightweight telescoping member might also be used alone or with a bladder to expand the distance between the boot member and the back plate.