Abstract:
An exercise apparatus comprising a rigid movable booster bar having two flexible elastic elements attached to the booster with an attachment. The attachments are spaced from each other and configured to allow winding the elastic element upon the booster bar by rotating the booster bar. Each flexible elastic element comprises at least two stages of flexible shock cords, with the stages disposed serially along the length of the flexible element, with adjacent stages having a different elastic stiffness.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    (Not applicable) 
       FEDERAL RESEARCH STATEMENT 
       [0002]    (Not applicable) 
       BACKGROUND OF INVENTION 
       [0003]    The use of exercise machines has proliferated in the last decade or so. In general there are two main classifications of such machines—those primarily intended for use in a commercial sports center and those primarily intended for use in the home. Those intended primarily for use in a sports center are quite complex, are structurally heavy and bulky, are usually attached to the floor or the wall, and oftentimes have a complicated arrangement of levers, pulleys, weights, etc. Normally they may also be adjustable for different users having different physical strengths. Those intended primarily for the home are simpler, lighter, much less expensive but still adjustable to some degree. 
         [0004]    One such exercise machine comprises flexible elastic shock cords, usually two, which are stretched by a force exerted by the user. As a cord is stretched more and more, the force required to stretch it increases more and more. One end of the shock cord is attached to a fixed structure and the other end attached to a booster bar adapted to be moved by the user&#39;s arms or legs as the cord is stretched by the user. As a natural consequence of the size of the user the stretched length of the shock cord will be substantially constant for a given user but will be different for a different user. Also as a natural consequence of the physical characteristics of shock cords the force-length curve is an inverse exponential when the force is displayed as the abscissa. Thus the maximum force required for a given user to stretch his arms or his legs to their fullest extent depends on the characteristics of the shock cord and also on the ratio of the stretched length to the unstretched length of the shock cords. Since a different user having a different physical size or strength will require a different ratio of stretched length to unstretched length it becomes necessary to provide some means for shortening or lengthening the unstretched length. This is normally effected by means of clamps; however the clamps oftentimes damage the shock cord and thus make the shock cord essentially unusable after a given number of adjustments. 
         [0005]    In U.S. Pat. No. 5,125,649, to Conrad Fuller (Fuller) (incorporated hereby by reference) is an exercise machine with a booster bar that mitigates the problems of adjustment found in previous systems, where the stretched and unstretched length of the shock cord are adjusted by the user without the use of clamps or tools. In the Fuller system a booster bar is attached to pair of flexible elastic shock cords, which have their other ends attached to fixed structural members. The user exercises his arms or his legs by repeatedly pushing against the booster bar, thus stretching and unstretching the shock cords. The unstretched (and thus the stretched) length of the shock cords is adjusted by rotating the booster bar about its axis, thus winding or unwinding, the shock cords around the booster bar. This, in turn, adjusts the force required to stretch the shock cords to a given dimension. 
         [0006]    However, the Fuller system is still not adequate in providing an exercise machine that can be used by different users of different size and with different strengths. This is due to the force-length properties of braided shock cords, which as mentioned in the Fuller patent can be represented as an inverse exponential curve. Basically as the cord is stretched, the stretching or return force is approximately constant or increases proportionally at a modest rate. But, as the maximum stretching length for the cord is approached, the return force increases much more rapidly, where (at least as perceived by the user) even significant increases in the force will not cause the cord to stretch further. Thus, the perceived effect by the exerciser is a movement that is suddenly or abruptly stopped. In other words, as the cord is stretched, the user at first perceives a constant or modest increase in force as determined by the stiffness of cord until a point is reached where the stretching or return force increases rapidly with no or little increase in the stretching length. At this point the exerciser perceives an abrupt stop and cannot continue extending the cord. 
         [0007]    Basically, a braided shock cord will extend, depending on the particular cord construction, up to 100% or more of its unstretched length, until it reaches a this “abrupt stop” point where under higher and higher forces it will stretch only a small amount. 
         [0008]    As described in the Fuller patent, the length of the shock cords can be adjusted by wrapping them around the booster bar. However, when fully unwound to lengthen stretching cord and allow the user to stretch the cords a greater distance before reaching the abrupt stop, the initial force and the force over the most of the length of the stretching is also reduced, which reduces the exercise effect. To increase the force and the exercise effect, the stretched length of the shock cord can be shortened by wrapping the cord around the booster bar. But if the stretching length is shortened too much this will prevent the user from extending the cord to the length required for the exercise. This is because the user is attempting to stretch the shortened shock cord beyond its design and the “abrupt stop” is encountered before the exercise movement is completed. 
         [0009]    A partial solution is to use shock cords of different elastic, i.e., stiffness, properties. “Stiffness” or “stiff” is a measure of the amount of elastic return force obtained for a given amount of stretching. For a strong person, a machine with stiffer cords is chosen so that the stretching force is high at the beginning during the stretch. Because the cord does not have to be shortened excessively, and the abrupt stop isn&#39;t reached during exercise movements, the person is allowed to stretch to the desired length for the exercise. A weak person could not use such a machine, because, even when the cords are fully unwound to the full length, the stretching force is too high, and he would only be able to successfully accomplish few or none of the exercises. For the weak person, a machine with less stiff or compliant shock cords would be suitable. However, the strong person would not find this machine suitable, because she would be able to extend the cords as far as she can extend her limbs without feeling adequate increase in the stretching force. Winding the cords around the booster bar to increase the force, may result in insufficient stretching length where the abrupt stop will likely be reached during routine exercises. Exercises with long stretches then become difficult or impossible. 
         [0010]    In summary, the Fuller machine has the ability to change the stretching length of the shock cord, which enables a person to vary the stretching force and to do a variety of exercises, from short stretches to long stretches. But, the advantage is not fully met if the stiffness of the shock cords does not well match with a user&#39;s size and strength. This is a particular problem as the user becomes stronger over time, requiring the user to obtain a new machine or rebuild the old one. 
       SUMMARY OF INVENTION 
       [0011]    An aspect of the present invention is an exercise apparatus comprising a rigid booster bar with two flexible elastic elements attached to the booster with an attachment. The attachments are spaced from each other and configured to allow winding the elastic element upon the booster bar by rotating the booster bar. Each flexible elastic element comprises at least two stages of flexible shock cords, with the stages disposed serially along the length of the flexible element, with adjacent stages having a different elastic stiffness. 
         [0012]    The present invention is an apparatus that improves upon the Fuller machine by extending the range of user size and strength that can be matched to a particular apparatus. Any one apparatus is optimal for a wider range of user size and strength. The apparatus of the present invention can be used like the Fuller machine, by stretching and unstretching flexible elastic elements by means of a booster bar, and the user can change the stretching length of the elastic elements by wrapping same upon the booster bar. However, the present apparatus has replaced the shock cords in Fuller machine with improved flexible elastic elements that have a more optimum force-length curve. In addition, the apparatus of the present invention, because of its unique construction, can be used in different ways. 
         [0013]    The improved elastic elements can be wound and unwound upon the booster bar to adjust force, but with a small or minimal amount of winding required to obtain a higher stretching force. This leaves a larger stretching length and lessens the probability that the abrupt stop will be reached during an exercise movement. The cord can be stretched to high stretching forces without encountering an abrupt stop, even in exercises requiring high force and a long stretch. 
         [0014]    Not only is the abrupt stop essentially eliminated, but the force-length profile is improved. During a stretch, higher forces are obtained at a slower rate. In addition, the stretching force encountered in an exercise movement is over a wider range, allowing a user to start the stretch at a lower force and stretch up to and sustain a higher force, a force that cannot be sustained if the high force comes on quickly or abruptly. This allows a user to sustain higher forces and gain more strength building benefit than in previous devices. In previous devices, one could not gradually obtain a high stretching force when starting a low stretching force, because the abrupt stop would be reached before the high force was obtained. 
         [0015]    In addition, for any given apparatus a stronger user will be able to derive more exercise and obtain and sustain higher forces, and a weaker user has lower forces available that allows accomplishment of more exercises. Both weaker and stronger users benefit from the better force-length profile. Thus, it is possible by practice of the invention that a single apparatus can be provided that better meets the needs of a person as he grows stronger, and be more easily adjusted for wider variety of people, including children, adults, athletes, sedentary persons, and persons with physical disabilities. 
         [0016]    The apparatus of the present invention achieves the above advantages in part by having a rigid booster bar with a flexible elastic element constructed with multiple stages of braided elastic stretch cords attached to each end. By “staged”, is meant that the length of each stretch cord is subdivided into at least two regions or stages. Each stage is constructed with one or more braided shock cords, such that each adjacent region has a different stiffness from its neighboring or adjacent stages. Thus the stages are attached in series end to end such that the stiffness of the elastic element changes from stage to stage. This contrasts with the Fuller machine where the elastic cords are designed with essentially the same stiffness for their entire length. 
         [0017]    Because the flexible elastic element is staged, with high stretch force a high elongation can be obtained without encountering an abrupt stop. This is in part to the fact that the large stretching forces can be obtained with a minimum of wrapping around the bar, allowing more of the length of the elastic element to be stretched. 
         [0018]    In addition, as the flexible element is stretched, the lengthening or elongation is not distributed evenly along it length. During a stretch all of the stages will begin to elongate, but the less stiff stages will initially stretch more than the stiffer stages. As the less stiff stages approach their maximum elongation, more elongation will then occur in stiffer stages. Thus, elongation is serially transferred from the less stiff stages to the stiffer stages, with the stiffest stages being the last to sustain significant elongation. The stiffest stage is designed to sustain the maximum design force of the equipment without reaching its maximum elongation required for exercise. Thus, at any elongation during exercise, there are always one or more stages that have not reached maximum elongation, thus eliminating an abrupt stop. 
         [0019]    Furthermore, at the beginning of the stretch the force is mostly determined by the least stiff or most compliant stage, but the elastic element can be stretched to a high final force as determined by the stiffest stage. By the staged system a rather even force profile can be provided that extends from a low stretching force of stiffness to a stiffness, and this profile can be predetermined by the selection of different stiffnesses of multiple stages. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0020]      FIG. 1  is a perspective drawing of an exemplary exercise apparatus. 
           [0021]      FIG. 2A  to  FIG. 2N  are schematic drawings illustrating various configuration of an exercise apparatus. 
           [0022]      FIG. 3  is a drawing of part of an elastic element of an exercise apparatus. 
           [0023]      FIG. 4  is another drawing of part of an elastic element of an exercise apparatus. 
           [0024]      FIG. 5  is a perspective drawing of an exercise apparatus in use. 
       
    
    
     DESCRIPTION 
       [0025]    Reference is now made to  FIG. 1 , and  FIGS. 2A to 2N . The apparatus  11  comprises a booster bar  13  with two elastic element  15  attached to the booster bar  13  by an attachment  17 . Each elastic element comprises two or more stages  19 , with at least two adjacent stages having a different stiffness. 
         [0026]    The stages are constructed of braided elastic cords  23 , also known as “shock cords”, or “bungee cords”. These cords have an inner core of an elastomer, such as latex, covered with a braided sheath. Shock cords are widely available in various diameters and stiffness. Any diameter can be used. Diameters between ¼ and ½ inches have been found suitable. 
         [0027]    A stage may comprise one shock cord or multiple shock cords attached together in parallel. Multiple shock cords in a stage may be of the same stiffness and diameter or different stiffness and diameter. In addition, the thickness and diameter of shock cords in the different stages may be the same or different. 
         [0028]    A requirement of the present invention is that the elastic element comprise at least two adjacent stages that have a different stiffness. The varying stiffness of the stages can be provided by changing the number of shock cords in the stages. Thus, for example, a first stage may comprise one shock cord, a second stage or two shock cords, and third stage or three shock cords. The stage may be in any order. It is preferred that the stage with fewer shock cords be adjacent to the booster bar to ease the wrapping of the elastic element around the bar easier. However, putting stiffer stages adjacent the booster bar is also contemplated. In the table below is shown various illustrative combinations, showing the number of shock cord strands in each stage, with the first being at the near end  18  nearest to the booster bar. Also in the Table, there are references to Figures illustrating that particular combination. 
         [0029]    The stiffness can also changed by changing the stiffness of the cords used in the stages. Thus, for example, a two-stage flexible element can be constructed with ¼ in. cord in stage 1, and ½ inch cord in stage two. Referring to  FIG. 2G  and  FIG. 2H  are shown flexible elements, each with a thicker or stiffer cord (e.g. ½ in) continuing through all stages, with a less stiff or thinner cords (e.g. ¼ in) in stages 2 and 3.  FIG. 2G  shows one thinner and one thicker in stage 2, while  FIG. 2H  shows two thinner and a thicker cord in stage two. In stage three are respectively two thinner and one thicker in  FIG. 2G , and one thinner and two thicker in  FIG. 2H . 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 
               
               
                   
               
               
                   
                 No. of Shock Parallel Cords in 
                   
               
               
                 No. of 
                 Respective Stages (Bold Nos. 
                 Figure 
               
               
                 Stages 
                 represent stiffer cords) 
                 where illustrated. 
               
               
                   
               
             
             
               
                 3 
                 1-3-4 
                 FIG. 1 
               
               
                 5 
                 1-2-4-6-7 
                 Not Shown- 
               
               
                 4 
                 2-1-2-3 
                 Not Shown 
               
               
                 2 
                 1-3 
                 FIG. 2A 
               
               
                 2 
                 1-2 
                 FIG. 2B 
               
               
                 3 
                 1-2-3 
                 FIG. 2C 
               
               
                 3 
                 1-3-5 
                 FIG. 2D 
               
               
                 3 
                 1-2-3 
                 FIG. 2E 
               
               
                 3 
                 2-3-4 
                 FIG. 2F 
               
               
                 3 
                 1-(1,  1 )-(2,  1 ) 
                 FIG. 2G 
               
               
                 3 
                 1-(2,  1 )-(1,  2 ) 
                 FIG. 2H 
               
               
                 4 
                 1-2-4-6 
                 FIG. 2I 
               
               
                 3 
                 3-1-5 
                 FIG. 2J 
               
               
                 3 
                 2-1-3 
                 FIG. 2K 
               
               
                 3 
                 1-3-1 
                 FIG. 2L 
               
               
                 5 
                 1-3-5-3-1 
                 Not Shown 
               
               
                 3 
                 2-2-3 
                 FIG. 2M 
               
               
                 3 
                 1- 1 -1 
                 FIG. 2N 
               
               
                   
               
             
          
         
       
     
         [0030]    There must be at least two stages having different stiffness in an elastic element. The more stages, the more even will be force-length profile, but the number of stages is limited by practical construction limitations. More stages may be recommended where there is a large difference between the number of cords between the most compliant and the stiffest stage. The length of the stages can be any suitable length. The stages may of the same length or one stage may be lengthened or shortened relative to the others. 
         [0031]    Where there are three or more stages, stages may have the same or different stiffness as long as there are at least two stages that are adjacent and have different stiffness. Combined length of the stages, or the total length of an elastic element is consistent with the nature of the exercises to be performed, the size of the user and the construction of the opposing element. For an exercise device as in  FIG. 1 , a flexible elements of length around 4 feet are suitable. 
         [0032]    The stages are attached to each other end to end in series by a suitable attachment system  21 . Methods for attaching cords to one another at the ends of the stages can be any suitable method, and include any combination of: tying with knots, thermally fusing, gluing, molding together without or with separate elements, sewing, using crimped or other metal fasteners, wrapping or fixing material around the cords (e.g., wire ties, tape, string, shrink-wrap, wire). One or more shock cords can be continuous through adjacent stages. For example, a single cord may extend through all of the stages, or through two or more stages. (See  FIGS. 2G and 2H ). 
         [0033]      FIG. 3  is a detail of a attachment  21  of stages of a flexible element and shows how shows cords  23  can be assembled into stages using knots  31  and polymeric wire ties  29 . The figure also shows attachment  27  of the last stage or the distal end of the elastic element attached to an opposing member  25 . In  FIG. 3  the illustrated stage has three cords joined to a stage of one cord. One cord is continuous though both stages. The opposing member is a flexible web strap and is attached using knots  31  and tape wrapping . 33   
         [0034]      FIG. 4  is another detail of a flexible element showing a stage of four cords  23  glued and bound with wrapping tape  33  at the joinder with an adjacent stage of one cord. Also note in  FIG. 4  is a loop. The loop  35  can function as an opposing member, by, for example, attachment to a foot, or fixed object. The loop can also function as part of the attachment to an apposing member of any suitable configuration. 
         [0035]    The attachment to the booster bar may be the same as in the Fuller machine. The attachment is preferably placed so that the elastic elements can be wound upon a region of the booster bar between the attachments, with handgrips outside of the attachments at the ends of bar, as illustrated in  FIG. 1 , and  FIG. 5 . It is preferred that the least stiff stage in the elastic element be at its near end  18 , i.e., the end that is near to or attached to the booster bar. This is to ease the winding of the flexible element around the bar. However, any of the stiffer stages can be the first stage or the stage at the near end  18  that is attached to the booster bar, as long as such does not materially affect the function of the exercise apparatus. (See  FIGS. 2J and 2K ) In  FIG. 5  are shown elastic elements  15  wrapped around the booster bar  13 . 
         [0036]    The near ends  18  of the elastic elements  15  are attached to the booster bar  13 , by a fixed attachment  17  to permit winding, so that the stretched length of the elastic element can be adjusted by rotating the booster bar and thus winding cords of the stages around the booster bar to any degree desired. The attachment may also optionally include a length of nonstretching flexible cord between the cord and the booster bar. 
         [0037]    Optionally, handgrips  37  ( FIG. 1 ) are applied to the bar in an appropriate region for grasping the bar, such at the ends of the bar, or in a medial hand grip region. This is to assist the user in grasping and holding the bar, to ease holding and winding of the bar, and hinder rotation of the bar within the grasp while the elastic elements are stretched. The grips may be any suitable materials, such as sections of hoses of suitable diameter, shrink wrap polymers, rubber applied by stretching or dipping, wrapped plastic or cloth tape, and the like. However, it is also contemplated that only a bare booster bar be used in apparatuses where adequate gripping force can be applied by the bare hands or with gloves. 
         [0038]    The booster bar may be any suitable bar-like structure of suitable strength and dimension that functions as described. The bar may be solid or tubular, and may be of metal (aluminum, steel, aluminum, etc.) wood, polymeric materials (fiber reinforced polymers, engineering plastics, etc.) or any other suitable material. The bar may a single unit, assembled from separate parts, or may be constructed to allow disassembly into smaller parts for transport. This may be by means of telescoping tubes or the like. The cross-section is circular, or non-circular (oval, polygonal, polygonal with rounded edges, ridged, knurled, etc.), but sufficiently round to allow winding of the elastic members around the booster bar. 
         [0039]    The structure and placement of the opposing member and of booster bar are such to work the elastic elements while performing an exercise movement. The opposing member for an exercise can be placed, for example, under one or both feet ( FIG. 5 ), behind the back, under a knee of a bent leg, or under the buttocks. In addition, where an opposing member is a second apparatus of the invention, or a second booster bar ( FIG. 2N ), or other suitable structure, two people may exercise in tandem with one holding and moving the booster bar  13 , and the other holding and moving the opposing member  25 . 
         [0040]    An opposing member may be any suitable structure, including those illustrated herein, and the structures disclosed in Fuller, U.S. Pat. No. 5,125,649. As an example, the opposing member  25  may also be a flexible sling ( FIG. 1 ). A flexible sling comprises a flexible non-elastic or elastic strap or web of sufficient width and length to be comfortable for the exercise contemplated for the apparatus of the invention. The distal end  26  of the elastic element  15  or opposing member  27  may also be attached to a fixed object, such furniture, a wall or closed door, which functions as or a part of an opposing member. 
         [0041]    Any configuration of booster bar, elastic elements, opposing member, and respective attachments are contemplated as long as the booster bar and opposing member are held in a moving or fixed positions to oppose each other in a stretching exercise movement. For example, the booster bar can be held in the hands, with an opposing member sling under a foot or feet ( FIG. 5 ). For example, booster can be placed over a shoulder, head, across the shoulders, with a hand or hands holding bar to provide a nonmoving attachment for stretching movement by a leg with its foot in the sling. In any exercise, the user can wrap or unwrap the elastic element around the bar, as required, to adjust the stretching length and adjust the force. The opposing member can also be a nonflexible platform with the elastic elements attached at its ends, similar in form to a swing seat ( FIG. 5 ), or have a construction similar to a booster bar ( FIG. 2L ). 
         [0042]    The shock cords are preferably seized, fused, taped, or the like, at each end to prevent unraveling. The near ends of the elastic elements are also preferably attached to the booster bar by a system that guards against sharp edges or pressure points bearing against the elastic elements which could cause chafing, which provides positive configurations for preventing the shock cords from pulling away from the booster bar regardless of the force exerted by a user, for preventing relative circumferential movement between the booster bar and the point of attachment of the shock cords to the booster bar, and allowing a user to at least partially wind the shock cords around the booster bar by rotating the booster bar about its long axis. 
         [0043]    An exemplary configuration comprises a booster bar which is hollow, at least near its ends, with a hole near each end passing through the wall. The near ends of the shock cords are threaded through respective holes and out through the open ends of the booster bar; providing a first knot at the near end of each shock cord. Each shock cord is pulled back such that the first knot is positioned inside the booster bar adjacent the hole; and a second knot is tied in each shock cord at a position adjacent the booster bar. As a variation, each shock cord, after having its first knot pulled back inside the booster bar, is looped around the booster bar, and passed under itself, thus providing the second knot. 
         [0044]    An alternate method comprises utilizing a booster bar which bar has a hole, near each end, passing completely through the bar; threading the near ends of the shock cords through respective holes; providing a first knot at the near end of each shock cord adjacent the hole, and tying a second knot in each shock cord at a position adjacent the booster bar. The same variation as noted above may also be used in this configuration. 
         [0045]    The distal ends  26  are attached to the opposing element by any suitable method, and can comprise knots, loops, metal or polymeric ties, rings or ties, sewing, wrapped tape, and the like. 
         [0046]    It is also contemplated for each elastic element to join two, or more, elastic elements into a single elastic element. Such a multiple flexible element would comprise multiple elements at each end of the booster bar attached in a parallel arrangement. 
         [0047]    While this invention has been described with reference to certain specific embodiments and examples, it will be recognized by those skilled in the art that many variations are possible without departing from the scope and spirit of this invention, and that the invention, as described by the claims, is intended to cover all changes and modifications of the invention which do not depart from the spirit of the invention