Abstract:
An abdominal exercise machine is provided which includes a seat, which is pivotally linked to a base frame. At least one link includes a handle that can be actuated by a user sitting on the seat. The user presses the handle away from the seat by flexing the trunk muscles of the user. This curls the user&#39;s body into a flexed trunk position. As the handle is actuated forward, the linkage arrangement causes the seat to displace upward. This pushes the center of gravity of the user up, thereby doing work and thereby providing resistance to the movement caused by the exercise. The handle may be adjustable in position relative to the link, thereby varying the load used by the user. Foot supports may also be provided either in front of the seat or behind the seat. The foot supports may be mounted to the frame of the seat frame which supports the seat.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to exercise devices. More specifically, the present invention relates to devices that exercise the trunk muscles or the muscles around the abdominal cavity. 
     BACKGROUND OF THE INVENTION 
     Abdominal exercise devices have recently gained popularity with the American public. Consumers are flooded with advertising which promise of a midsection with a six-pack yet allowing you to continue to drink as many six-packs as you desire. Though many are inaccurate, the value of strengthened abdominal muscles is well documented in the scientific literature. These core muscles including the rectus abdominis and the internal and external obliques support proper posture and support lower back health. For those with low bodyfat, the sections of the rectus abdominis show through the skin, revealing that prized “six-pack”. A true abdominal exercise device must enable a contraction of the main abdominal muscle, the rectus abdominis. This muscle is located on the anterior portion of the abdomen. The action of this muscle is to move the chest toward the groin in such a way as to cause the spine to flex forward. If the chest moves toward the knees with the back straight, the primary movers are the hip flexors (including the psoas muscle). In this case the rectus abdominis contracts only to stabilize the spine to prevent it from bending backward. Any resistive movement of the chest, while it moves forward, thereby curing the spine, results in abdominal muscle stimulation. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention is an abdominal exercise device that features a frame with a first axis and a second axis that are non-collinear. The device also includes a seat frame with a seat portion, the seat frame including a third axis and a fourth axis, which are also are non-collinear. A handle link is included with a handle, the link including a first end pivotally mounted to the first axis and a second end pivotally mounted to the third axis. A guide link is provided with a first end pivotally mounted to the second axis and a second end pivotally mounted to the fourth axis. These elements function together such that when the handle is articulated away from the seat, the seat is displaced relative to the frame. 
     The device may also include a foot support that is mounted to the seat frame, and preferably movably mounted to the seat frame. The foot support may be positioned opposite to the handle relative to the seat. The foot support may also be mounted to the frame. If mounted to the frame, the foot support is preferably on a same side as the handle relative to the seat. 
     The handle is preferably adjustably mounted to the handle link. In the preferred embodiment the handle is slideably mounted to the handle link. 
     The guide link is preferably between 1.5 and 2.0 times the length of the handle link. The optimal relationship as determined by the inventor includes the guide link being 1.7 times the length of the handle link. 
     In another aspect, the invention includes a method of performing an abdominal exercise including the steps of providing a device as previously specified. The method includes sitting on said seat with said handle anterior to a user&#39;s torso. The user grasps the handles with the hands of the user and pressing forward on the handle while generating movement form the user&#39;s trunk, thereby flexing the trunk muscles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects of this invention, the various features thereof, as well as the invention itself, may be more fully understood from the following description, when read together with the accompanying drawings, described: 
         FIG. 1  is an isometric view of an abdominal exercise device with a rear foot support, the device produced in accordance with a version of the present invention. 
         FIG. 2   a  is a side view of an abdominal exercise device with a rear foot support shown in a starting position, the device produced in accordance with a version of the present invention. 
         FIG. 2   b  is a side view of an abdominal exercise device with a rear foot support shown in a final position, the device produced in accordance with a version of the present invention. 
         FIG. 3   a  is a side view of an abdominal exercise device with no foot support, the device shown in a starting position and produced in accordance with a version of the present invention. 
         FIG. 3   b  is a side view of an abdominal exercise device with no foot support, the device shown in a final position and produced in accordance with a version of the present invention. 
         FIG. 4  is a side view of an abdominal exercise device with a front foot support and a backrest, the device shown in a starting position and produced in accordance with the preferred embodiment of the present invention. 
         FIG. 5  is an isometric view of an abdominal exercise device with a front foot support and a rear foot support, the device shown in a starting position and produced in accordance with a version of the present invention. 
         FIG. 6  is an exploded, isometric view of an abdominal exercise device with a front foot support and a rear foot support, the device produced in accordance with a version of the present invention. 
     
    
    
     For the most part, and as will be apparent when referring to the figures, when an item is used unchanged in more than one figure, it is identified by the same alphanumeric reference indicator in all figures. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is an abdominal exercise device  10 . In  FIG. 1 , this device  10  is shown in one form. The key elements include a seat portion  12  to receive the posterior of a user. A variety of forms of the seat portion  12  can be used, but it is preferable that seat portion  12  enable the user&#39;s upper legs to drop below the seat, as does a bicycle seat. This seat  12  has a similar shape in that it provides a wide rear base  14  and a narrower front section  16 . This combination provides comfortable support. A seat back  18  may also be used and may be provided adjacent to the seat portion  12 . The seat back  18  allows for support from posterior forces applied to the device  10  by the user. The seat back  18  may be desired but need not always be used in all forms of the present invention. 
     The seat portion  12  is mounted to a seat frame  20 . The seat frame  20  not only supports the seat  12  and seat back  18 , when provided, but also provides an axial support to the base frame  22 . The base frame  22  provides a base of support for the seat  12  and a user positioned thereon. The seat frame  20  is pivotally mounted to the base frame  22  by way of a “4-bar link”. A 4-bar link is many times referred to as a “parallel link”. A 4-bar link includes two movable and two stationary links. In many cases the stationary links are part of the frames on either ends of the movable links. By altering the link lengths and positions, the two moving links may not always be parallel, as is implied by the name “parallel link”. This is the case in the present invention. Though a parallel arrangement could be functional, the optimal arrangement is for the links to be of different lengths to provide a seat  12  movement that tilts slightly back (posteriorly) as the seat  12  is elevated relative to the base frame  22 . 
     The upper moving link of the device  10  is the handle link  24 . The handle link  24  includes a first end  26  and a second end  28 . The first end  26  is adapted to be pivotally mounted to the frame  22  at a first axis  30 . The specifics of providing axial movement is not critical in that ball bearings or bushings can be used to provide a sufficient bearing surface. A detailed explanation of the preferred embodiment, including these details, will be outlined later in this disclosure. Near the second end  28  of the handle link  24  is another pivotal mounting, the third axis  32  located on the seat frame  20 . 
     The handle link  24  also includes a handle  34 . The handle  34  need only be a suitable engagement for the hands of the user and allow for force to be applied thereto in order to articulate the handle link  24  relative to the frame  22 . Here the handle  34  is shown to be adjustable in length. That is desirable in that the user applies force to the handle  34  to create a torque one the handle link  24  about the first axis. Increasing the length of the bar  36  of the handle  34  from the first axis  30 , decreases the necessary force applied to the bar  36  of the handle  34  in order to overcome the torque of the weight of the user on the seat  12 . The adjustable mounting, or in this case slideable mounting, of the handle to the handle link  24 , provides a typical example of this resistance adjustable feature. This adjustment here is provided by a female portion  38  that receives a male portion  40 . The bar  36  is mounted to one end of the male portion  40 . A lock  42  is used to releaseably secure the male portion  40  to the female portion  38 . 
     The base frame  22  also includes a second axis  44 , which is non-collinear with the first axis  30 . The second axis  44  provides the pivotal mounting of a guide link  46  with the frame  22 . The guide link  46  is the second movable link of the 4-bar link system. The first end  48  of the guide link  46  is pivotally mounted to the frame at the second axis  44 . The second end  50  of the guide link  46  is pivotally mounted to the seat frame  20  at a fourth axis  52 . The two axes of the seat frame  20 , the second axis  32  and the fourth axis  52  are non-collinear, as is shown here. 
     A final element of the device  10  as is illustrated in this view is a rear foot support  54 . The foot support can take a variety of forms and some variations will be illustrated in this disclosure. Here the rear foot support  54  is used which is movably mounted to the seat frame  20 . As with the handle  34 , a lock  56  releaseably secures a male portion inside a female portion, thereby enabling variable placement of a foot bar  58  relative to the seat  12 . The foot bar  58  can also be rigidly mounted to the seat frame  20  and therefore not adjustable. 
     The function of the device  10  is more clearly illustrated in  FIGS. 2   a  and  2   b.  Here the seat frame does not include a back pad, but does have a seat portion  12  to support a user  60 . The unit in a starting position is shown in  FIG. 2   a.  The user sits with his feet  62  against the foot bar  58  and his glutes on the seat portion  12 . The user&#39;s hands  64  are placed on the bar  36  of the handle  34 . The user  60  presses against the bar  36  of the handle  34  and supports himself as needed by pushing against the foot bar  58 . As the handle  34  is moved forward (anteriorly) the handle link  24  is rotated forward about the first axis  30 . This elevates the seat  12  with the user  60 , thereby doing work. This raised or final position is illustrated in  FIG. 2   b.    
     The handle  34  is positioned far enough in front of the user  60  to minimize the movement of the arms of the user  60  to move the handle  34  forward. This necessitates the anterior flexion of the trunk to enable the bar  36  to be “pushed” forward. In addition, since any seat back that may be used is minimal in height, any force applied by the user to push forward with the arms must be countered by contraction of the anterior trunk muscles of the user  60 . These include the abdominal muscles. Therefore even if the arm, shoulder and chest muscles provided all the movement, the abdominal muscles would still need to perform an isometric contraction to prevent the upper body from bending backward. 
     Another version of the device is shown in  FIGS. 3   a  and  3   b.  In this version the foot support has been removed. As such, the user  60  is seated with his feet  62  in a forward position. In this way, the user  60  can extend his legs to assist the abdominal flexion work to raise the seat  12  from the starting position in  FIG. 3   a  to the final position in  FIG. 3   b.  The general movement of the device  10  is the same as is previously disclosed. 
     Another variation is shown in  FIG. 4 . This shows a side view of an abdominal device with a seat back  18  mounted to the seat frame  20 . The foot support has been modified in that it includes a front foot bar  66 , which is positioned in front of the user  60  on the handle  34  side of the seat  12 . This bar  66  provides a support that allows the user to position his feet  62  under the bar  66 . When the user  60  pushes the handle  34  forward, the reaction force can be balanced by pulling back on the foot bar  66  with the user&#39;s feet  62 . The foot bar  66  can be movably mounted to the base frame  22  and therefore can be adjusted into a desired position as depicted by the arrow  68 . This adjustment is similar to the adjustment of the handle  34  as shown by the arrow  70  and as was previously noted. Another alternative is to fixably mount the foot bar  66  to the base frame  22  and in so doing remove the adjustment feature of the foot bar  66 . 
     The device can also include both the rear foot bar  58  and a front foot bar  66  as shown in  FIG. 5 . As previously noted, the front foot bar  66  and/or the rear foot bar  58  can be rigidly or movably mounted to their respective frames. The rear bar  58  is mounted to the seat frame  20  and the front foot bar  66  is mounted to the base frame  22 . In this figure the front foot bar  66  is movably mounted to the base frame  22  and the rear foot bar  58  is rigidly mounted to the seat frame  20 . Here the seat back  18  has been removed to illustrate the version without the seat back  18 . 
     An exploded view of the device  10  is shown in  FIG. 6 . This is the same form of the device as was shown assembled in  FIG. 5 . Here it can be more easily seen that the seat portion  12  is mounted to the seat frame  20 . The base frame  22  is shown in two parts, the vertical component  72  and the base component  74 . These are fastened together with the fasteners  76 . The vertical component  72  includes the two supports for the first axis  30  and the second axis  44 . These supports are shown here to be round tubing ( 78  &amp;  80  respectively) that is welded to the vertical component  72  of the base frame  22 . Bushings  82  are pressed inside the first axis tube  78  and the second axis tube  80  and the upper rod  84  rides on the bushings  82 . The upper rod  84  is mounted to the first end  26  of the handle link  24  by way of the roll pins  86 . The second end  28  of the handle link  24  is mounted to the third axis tube  88 . In a similar manner, bushings  90  are pressed therein with the back rod  92  being received by the bushings  90  in the third axis tube  88 . The rod  92  is secured to the second end  28  of the handle link  24  with the rear pins  94 . 
     Another form of linkage pivot is shown with the guide link  46 . In this form, the front rod  96  and the rear rod  98  are mounted to a side bar  100 . The front bar  96  is received by the second axis tube  80 , supported by bushings  102  and secured by a second side bar  104  on the other side of the tube  80 . Likewise, at the rear, a fourth axis tube  106  is mounted to the seat frame  20  and receives bushings  108  and the rear rod  98 . Fasteners  110  mount to the front rod  96  and rear rod  98  to hold the second side bar  104  in an assembled state with the side bar  100 . Either form of linkages and pivots, using ball bearings or bushings can each be used for either movable link. 
     What is disclosed herein is the preferred embodiment as seen by the inventor. It is understood that an infinite number of variations including use of various designs and mountings could be used in place of what is disclosed and are therefore inherently considered part of the present invention.