Abstract:
A training method and device for the lower body providing a mode of exercise that manifests as a functional, closed-kinetic-chain training of the gluteus maximus and the hamstrings in a natural sequential firing pattern. The device construction allows an upright stance so that during exercise the lower body mimics a stride action, as in walking. By combining this natural stride action with adjustable resistance elements in the device, a wide range of uses, from strength training to rehabilitation, are achieved. The device generally includes footplates that are movable in forward and backward directions and also can be simultaneously moved upward against resistance. The heel of the foot can simultaneously be raised with respect to the toe of the foot, also against resistance.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of devices and methods for exercising the human body, particularly the gluteus maximus and hamstring muscles. 
     BACKGROUND OF THE INVENTION 
     Physical performance depends heavily on the attributes of muscular development such as flexibility, strength, power, endurance, and neuromuscular control. The ultimate goal of developing these muscular attributes is to improve muscle performance. Training to improve running and jumping performance, rehabilitate injured knees, or prevent injuries to the lower leg involves activity specific training, and development of strength, power, and neuromuscular control. 
     Various types of devices have been created for the exercise and training of various muscle groups. U.S. Pat. No. 5,788,615 to Jones details a device for exercising the quadriceps and hamstrings while lying on the back. U.S. Pat. No. 6,196,950 to Emick shows a weight attachment device so one can stand and exercise the hamstrings. U.S. Pat. No. 3,759,511 to Zinkin et al. describes a device for strengthening the quadriceps while lying face down at approximately 45 degrees. These types of devices are typically for strength training. Using adjustable weights or the like, a particular physical movement is performed to strengthen the muscles. This type of training isolates specific muscles but does not synergistically train those muscles to mimic the functional muscular activity. 
     Other devices such as stationary bicycles (e.g., U.S. Pat. No. 4,509,742 to Cones), climbing machines (e.g., U.S. Pat. No. 4,720,093 to Del Mar), or other stationary exercises devices (e.g., U.S. Pat. No. 5,242,343 to Miller), offer a wider range of motion for the hips and legs. These reciprocating devices provide for more even physical development and a maximum level of aerobic exercise. Some include elements that incorporate the movement of the arms and shoulders during exercise. These devices, however, are all reciprocal in nature and the footpads or plates for each foot are linked together such that pushing down on one pad raises the opposite pad. Although these devices offer a wide range of motion, they do not isolate the lower extremity muscle groups. 
     Treadmill type devices (e.g., U.S. Pat. No. 3,703,284 to Hesen), offer walking and/or running exercise, and are similar to the reciprocating devices above in that they provide for more even physical development in the area of aerobic exercise. 
     There remains a need for a machine that can effectively train and exercise the gluteus maximus and the hamstrings in a natural manner consistent with a walking or running stride. 
     SUMMARY OF THE INVENTION 
     The present invention is an exercise method and device for strengthening and training the muscles of the hip and leg, specifically the gluteus maximus (GM) and the hamstrings (HS), in a natural, functional manner. It mimics the walking or running stride and thus naturally isolates and exercises the hip extensors, or gluteus maximus (GM), and the knee flexors, or hamstrings (HS), in their natural firing sequence. It also trains the quadriceps (QD) in its proper roll as antagonist to the HS. The device includes a footplate that secures a foot of the user at all times and limits the freedom of movement of the foot. The attachment of the foot to the surface of the footplate ensures that the lower extremities are guided through a multi-joint, closed-kinetic-chain, functional movement pattern involving the foot, ankle, knee and hip. This closed-kinetic-chain mode of exercise isolates and sequentially loads the GM and HS, in their natural firing sequences, during the exercise cycle. The device of the present invention is also non-reciprocal, and though usually operated sequentially, each leg is properly exercised independently and in turn without being influenced by the opposite leg. 
     In jumping, the hips and knees are loaded prior to an explosive, sequential action of the muscles. Likewise, during running, hip extension is followed closely by knee flexion in which the hip/knee joint action and accompanying muscular contractions and control occur synergistically. This synergistic muscle contraction and control involving the GM, HS and, QD, is important for proper neuromuscular training. 
     Isolating specific muscle groups for training can strengthen these muscles. The present invention, while isolating and strength training the GM and HS, also trains the neuromuscular pathways that control the hip/knee joint complex. With the functional, sequentially firing, closed-kinetic-chain mode of training provided by the present invention, the exerciser is now training in a way that specifically mimics functional muscular action needed to develop increased strength, power, and neurological activity that can improve running speed and jumping skills. Electromyographic (EMG) recordings of subjects exercising with the present invention demonstrate a high degree of GM and HS activity. The machine of the present invention isolates the HS with resistance, after activation of the GM. 
     Training the GM and HS to help prevent injury to the knee is also an aspect of the present invention. The HS and QD are dynamic stabilizers of the knee, but the HS is often disproportionately weaker, especially in females, than the QD. This strength difference can add to the likelihood of knee injuries, especially during active sports such as soccer or basketball. The present invention provides an ideal method of exercise for functional strength training of the GM and HS by combining a closed-kinetic-chain mode of exercise with a natural sequential firing pattern. This is the optimal type of training for joint stability of the lower extremities. 
     Another aspect of the present invention is rehabilitation. When individuals sustain injuries to the anterior cruciate ligament (ACL) or have reconstructive surgery to replace the ACL, HS training is a standard part of the rehabilitation program. The closed-kinetic-chain aspect of the present invention provides for a safe, stabilizing training regime, and with adjustable resistance, can be used early on and throughout the rehabilitation program. 
     The exercise device generally includes a frame for attachment of movable components, the frame remaining stationary during use of the device. One subframe is pivotally attached to the forward end of the frame for the foot and leg intended to be exercised. A footplate is secured to the subframe in a fashion that allows the user&#39;s foot to move forwardly or rearwardly with respect to the subframe, while a resistance element provides resistance to rearward travel. The pivot at the front of the subframe allows the foot to be raised with respect to the frame, against a resistance element, at the same time that it is moved forwardly or rearwardly. The footplate includes toe and heel attachments. The heel attachment allows the heel to be raised with respect to the toe during use of the device, also against a resistance element. A body support assembly, including a handlebar, is attached to the front of the frame for upper body support and stability during use of the device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the exercise device embodying the principles of the present invention. 
         FIG. 2  is a schematic of a typical foot travel path. 
         FIGS. 3A–3E  are detailed representations of a foot travel path and the corresponding hip, leg, and foot positions. 
         FIG. 4  is a perspective view of an alternative embodiment of the exercise device. 
         FIG. 5  is a perspective view of another alternative embodiment of the exercise device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The exercise/training device shown in  FIG. 1  comprises four main assemblies; a frame, e.g., frame body assembly  10 , a body support assembly  20 , two footplate assemblies  30 , and two slide bar assemblies  40 , each of which is pivotally affixed to the forward end of the frame body assembly  10 . The frame body assembly  10  provides the support structure for the device and is a generally rectangular frame with a forward end and a back end wherein the forward end is in front of a user and the back end is to the rear of a user. It generally comprises two longer side members  11 , two shorter end members  12 , and a single long central member  13 . The frame body  10  preferably rests on four lateral supports  14  extending out from and at each corner of the rectangular framework. These lateral supports  14  are of sufficient length to provide lateral stability during exercise and contain elements at each end capable of leveling the device during setup. They also incorporate materials that prevent scarring of a floor surface and skidding of the device. 
     Attached to the forward end of the long axis of the frame body  10  is the body support assembly  20 . The body support assembly  20  provides support and balance for the exerciser during use and is made up of two upright members  22  and a handlebar  24 . The bottom end of the body support assembly  20  is attached to the forward end of the frame body assembly  10  by having one of each of the uprights  22  arise from one of each of the long side members  11 . The plane of the body support assembly  20  is preferably within about 15 degrees of perpendicular to the plane of the frame body assembly  10 . Handlebar  24  is a straight or slightly bent, rigid tube or rod, not unlike a bicycle handlebar, and is attached to the two upright members  22  of the top end of body support assembly  20 . It is in the plane of the body support assembly  20  but is substantially perpendicular to both upright members  22 . The handlebar  24  may be made so as to be adjustable in height to allow for balance and support of a person during training and exercise. 
     Also attached to the forward end of the frame body  10  are the two slide bar assemblies  40 , one for each foot. These are preferably identical, but are not linked together and thus each can pivot independently about the common pivot axle  45 . Each slide bar assembly  40  includes a pivot block  41 , the shared pivot axle  45 , two slide bars  42 , end cap  43 , and pivot resistance elements  44 . The pivot axle  45  is attached to the forward end of the frame body assembly  10  within the confines of the two long side members  11  and the two short end members  12  and parallel to the short end members  12 . It is a rod or tube of round cross-section, rigid enough to withstand the forces exerted upon it during the use of the device. Pivot axle  45  is sufficiently back from the short end member  12  so that the pivot blocks  41  can swing about the pivot axle  45  without contacting the short end member  12 . 
     The pivot blocks  41 , along with the pivot axle  45 , comprise the forward end of the slide bar assemblies  40 . Each pivot block  41  rides on, and is free to pivot about, pivot axle  45 . The two slide bars  42  of each assembly are rigidly attached to the respective pivot block  41  and are positioned on the pivot block  41  such that, in the down or rest position, a plane through the slide bars  42  is substantially parallel to the plane of the frame body assembly  10 . The slide bars  42  extend back and terminate in the end caps  43  such that the length of the slide bar assembly  40  is about the same length as the long axis of the frame body assembly  10 . The spacing of the slide bars  42  at the end caps  43  is the same as the spacing at the pivot blocks  41  so that the slide bars  42  are parallel along their length. Thus by pivoting about the pivot axle  45 , the slide bar assembly  40  follows a fixed arcuate path from a position in the plane of the frame body assembly  10  to a position in the plane of the body support assembly  20 . Attached to the end caps  43  and to the frame body assembly  10  are the pivot resistance elements  44 . These may be, for example, elastic bands, springs, hydraulic or pneumatic elements and thus can provide fixed or adjustable resistance to the pivoting of the slide bar assembly from its down or rest position in the plane of the frame body assembly  10 , up toward the plane of the body support assembly  20 . 
     Completing this embodiment of the device are the two identical footplate assemblies  30 , one on each slide bar assembly  40 . The footplate assemblies  30  are comprised of the anchor block  31 , the toe plate  34 , the heel plate  35 , the footplate hinge  36 , the toe strap  37 , the heel strap  38 , the stride resistance element  32 , and the heel plate resistance element  33 . The rectangular anchor block  31 , whose long axis is parallel to the long axis of the slide bar assembly  40 , provides a platform for the elements that are used to secure the foot during use of the device. Anchor block  31  captures and rides on the two slide bars  42  of the slide bar assembly  40  using linear bearings or bushings or the like so that it slides smoothly without sticking or jerking. This capture of the slide bars  42  limits the movement of the anchor block  31  to a simple back and forth motion in the plane of the slide bars  42  independent of the position of the slide bar assembly  40  as it rotates about the pivot axle  45 . The toe plate  34  and heel plate  35 , connected to one another by the footplate hinge  36 , are located on top of the anchor block  31  so the long axis is parallel to the long axis of the anchor block  31 . The toe plate  34  is securely attached to the front end of the anchor block  31  thus securing half of the footplate hinge  36  and allowing the heel plate  35  which is attached to the other half of the footplate hinge  36  to rotate up off the anchor block  31 . When the user&#39;s foot is properly affixed to the toe plate  34  and heel plate  35  with the toe strap  37  and heel strap  38  such that the ball of the foot is over the footplate hinge  36 , the pivot at the hinge allows the foot to bend in a natural manner and still be securely attached to the device. The toe strap  37  and heel strap  38  can be leather, Velcro, elastomeric material or the like. They are made and positioned such that they not only securely fix the foot of an exerciser to the footplate assemble  30 , but secure the foot in the proper position with the ball of the foot over the footplate hinge  36 . The stride resistance element  32  and the heel plate resistance element  33  provide resistance to the respective parts and can be springs, elastic elements, pneumatic or hydraulic elements or the like and thus may be a constant or adjustable resistance. The stride resistance element  32  provides resistance to the sliding of the anchor block  31  from the front to the back of the slide assembly  40 , and the heel plate resistance element  33  provides resistance to the pivot of the heel plate  35  about the footplate hinge  36 . 
       FIG. 2  is a schematic describing a typical foot travel path during use of the present invention. It is only typical because the foot travel path is not fixed by the device but is determined by the exerciser. Within the limits of the device, and without requiring any adjustments, the sliding and pivotal elements of the present invention allow a wide variety of foot travel paths based on the exerciser&#39;s stride length, the type of training pursued, or input from a physician, physical therapist or trainer. 
       FIGS. 3A–3E  sequentially illustrate a typical foot travel path and corresponding hip, leg, and foot positions of the present invention.  FIG. 3A  shows the foot and leg at a rest position prior to exercise with the foot properly positioned on the footplate assembly  30 , with the ball of the foot directly over the footplate hinge  36 . As shown next by  FIG. 3B , as the foot and leg extend rearwardly, the GM must overcome the stride resistance element  32  as it extends the hip. Also the heel of the foot and the attached heel plate  35  are just starting to rise and engage the heel plate resistance element  33 . Between the different positions shown by  FIGS. 3B and 3C , the hamstring is engaged and takes over from the GM further overcoming the stride resistance element  32  and the heel plate resistance element  33  as the knee flexes and the foot bends. At the position shown in  FIG. 3D , the HS is under the greatest load as now all three resistance elements  32 ,  33  and  44  are fully engaged. Finally,  FIG. 3E  shows the foot and leg striding forward toward the rest position and starting to unload the HS. 
     While typically both legs are exercised during a training session with alternating strides of sliding rearward and stepping forward, it is simple and possible to exercise only one leg by securing only the foot to be exercised to the footplate. It is also simple and possible for a user to exercise each leg differently. Resistance elements can be adjusted based on the strength of each leg. Differences in flexibility, leg to leg, are automatically accounted for by the sliding and pivotal elements. 
     It is also apparent that a device may be manufactured for the exercise of only a single leg if it is felt necessary to exercise each leg independently. Such a device would have, for example, only a single slide bar assembly including only a single footplate assembly. 
     While the device described above in  FIG. 1  represents a preferred embodiment of the present invention, other devices can be imagined that, though mechanically distinct, would still preserve the training method outlined; namely, the sequentially firing, closed-kinetic-chain mode of training the GM and HS. Although mechanically distinct, these alternative embodiments may share various features, for example, the frame body assembly  10 , the body support assembly  20 , or (more particularly), the footplate assembly  30 . 
     One such alternative embodiment, as shown by  FIG. 4  described herein, comprises four main assemblies; a frame body assembly  10 , a body support assembly  20 , two footplate assemblies  30 , and two continuous belt assemblies  50 . In this device of  FIG. 4  the slide bar assembly  40  of  FIG. 1  is replaced by the continuous belt assembly  50  of  FIG. 4 . This substitution does not affect the training method but simply provides a different support and attachment point for the footplate assembly  30 . 
     The frame body assembly  10  and the body support assembly  20  may be the same for the devices shown in  FIGS. 1 and 4 . 
     Like the slide bar assemblies  40 , the continuous belt assemblies  50  are not linked together and thus can rotate independently about the common pivot axle  45 . Continuous belt assemblies  50  include the continuous belt bed  51 , the continuous belt  52 , the front roller  53 , and the back roller  56 , and have a forward end and a back end. The pivot axle  45  is attached in the same manner as described in the device of  FIG. 1  so that the continuous belt assembly can swing about the pivot axle  45  without contacting the short end member  12 . The continuous belt bed  51  also has a forward end and a back end and is a relatively thin rectangular plate. Although thin, the continuous belt bed  51  is strong enough to support the forces exerted upon it during use. The upper surface is also of sufficiently low friction, either by surface treatment, small rollers, or the like, to allow the continuous belt  52  to slide across the surface unencumbered. The forward end of the continuous belt bed  51  is attached to the frame body assembly  10  by the pivot axle  45 . Like the slide bar assemblies  40 , continuous belt bed  51  rotates about the pivotal axle  45  following a fixed arcuate path from a position in the plane of the frame body assembly  10  to a position in the plane of the body support assembly  20 . The continuous belt  52  is a belt, not unlike an endless treadmill belt, that encircles the continuous belt bed  51  along its long axis. At the forward end and back end of the continuous belt bed  51  are the front roller  53  and the back roller  56 . The rollers are as wide or wider than the continuous belt  52 , and are in the plane of the continuous belt bed  51  perpendicular to the long axis such that the continuous belt can move along the continuous belt bed  51  easily. Attached to the continuous belt bed  52  and the frame body assembly  10  are the pivot resistance elements  44 . These are equivalents of the resistance elements described in the device of  FIG. 1  and may be elastic bands, springs, hydraulic or pneumatic elements, etc. They provide fixed or adjustable resistance to the pivot of the continuous belt assembly  50  from its down or rest position in the plane of the frame body assembly  10  up toward the plane of the body support assembly  20 . Attached to the continuous belt  52  on the under side of the continuous belt bed  51  and to the continuous belt bed  51  are the stride resistance elements  32 . These may be the same type of elements described in the device of  FIG. 1  and provide resistance to the movement of the belt as it moves across the continuous belt bed  51  from the forward end to the back end. 
     Completing the embodiment shown by  FIG. 4  are the two identical footplate assemblies  30 , one on each continuous belt assembly  50 . They are the same as the footplate assemblies  30  of  FIG. 1  except for the anchor plates  31 . In the device of  FIG. 1 , the anchor plate  31  allows the footplate assembly  30  to ride back and forth on the slide bars  42 , while in the device of  FIG. 4  the anchor plate  31  is attached to the continuous belt  52  and thus the footplate assembly  30  rides back and forth with the continuous belt  52 . Otherwise they operate in the same manner and provide the same function of securing the foot to the devices in the proper position of the ball of the foot over the footplate hinge  36 . 
     Another such exercise/training device, as shown in  FIG. 5 , comprises five main assemblies; a frame body assembly  10 , a body support assembly  20 , two footplate assemblies  30 , crankshaft assembly  60 , and two foot link assemblies  70 . Though mechanically different, the device of  FIG. 5  still provides the sequential firing, closed-kinetic-chain training method for the GM and HS described above for the devices of  FIGS. 1 and 4 . 
     The frame body assembly  10  and the body support assembly  20  may be the same for the embodiments of  FIGS. 1 and 5 . 
     Attached to the back end of the frame body is the crankshaft assembly  60 . It comprises the support tower  61 , the axle  62 , the two connecting rods  63 , and the two crankpins  65 . The support tower  61  is attached to and projects up perpendicular to the long central member  13  of the frame body assembly  10  and houses the axle  62  and is tall enough for the connecting rod  63  to rotate about the axle  62  and not hit the floor or any part of the frame body. The axle  62  is mounted in the support tower  61  significantly parallel to the short end member  11  and the plane of the frame body assembly  10 . It is also sufficiently strong that it can support the forces exerted upon it during use. The two connecting rods  63  are attached perpendicular to the axle  62  with bearings or bushings so that they rotate freely. The crankpins  65  are connected to the connecting rods with threads or bolts or the like, and are parallel to the axle  62  and thus perpendicular to the connecting rod  63 . By providing a number of connection points, the crankpins  65  can be placed at varying distances from the axle  62 . They extend out toward the side members  11  of the frame body. The result is that, when observed from a single side, the assembly looks not unlike the cranking portion of a hand-operated winch or windlass. The two connecting rods  63  and accompanying crankpins  65  are preferably not linked together and so are independent of one another in their pivot about the common axle  62  and are of sufficient strength to withstand the forces exerted upon them during use. 
     The foot link assemblies  70  are made up of the foot link  71 , the foot link journal  72 , and two foot link rollers  73 . The foot links are generally elongated, thin, narrow (relative to their length) members with a forward end and a back end. They are sufficiently strong and stiff to withstand the weight and force of a person using the device without flexing significantly. The back end of the foot link  71  is connected to the crankpin  65  of the crankshaft assembly  60  via the foot link journal  72 . Thus, as the connecting rod  63  rotates about the axle  62 , the trailing foot link  71 , through the foot link journal  72 , turns freely about the crankpin  65 . Though able to freely turn, the foot link  71  is also captured such that it cannot slide off the crankpin  65  during use. The forward end of the foot link  71  rides on the foot link roller  73 . The foot link rollers  73  are mounted to the short end member  12  at the forward end of the frame body assembly  10 . They are made such that the forward end of the foot link  71  rolls easily on the rollers but is prevented from going off either side of the roller during use. The resulting motion of the foot link  71  is an oscillation back and forth at the forward end on the foot link roller  73  as the back end of the foot link  71  revolves about the axle  62 . The stride resistance elements  32  are attached to the foot link  71  and to the frame body assembly  10  and provide resistance to the movement of the foot link  71  as it travels back in its oscillation on the foot link roller  73 . The pivot resistance element  44  is also attached to the foot link  71  and the frame body assembly  10  and provides resistance to the pivot of the foot link  71  up off the plane of the frame body assembly  10  as it rotates about the axle  62 . 
     Completing the embodiment shown by  FIG. 5  are the two identical footplate assemblies  30 , one on each foot link  71 . They may be the same as the footplate assemblies  30  of  FIG. 1  and provide the same function of securing the foot to the devices in the proper position of the ball of the foot over the footplate hinge  36 . 
     The device of  FIG. 5  may also be adjusted for individual needs of the exerciser. Stride length can be adjusted by attaching the back end of the foot link  71 , to the connecting rod  63 , via the foot link journal  72  and crankpin  65 , closer to or farther away from the axle  62 . Knee flexion can be adjusted by moving the footplate assembly  30  closer to or farther away from the forward end of the foot link  71   FIG. 2 , describing the foot travel path, and  FIGS. 3A–3E , illustrating the hip, leg, and foot positions during use of the devices, pertain to the devices described in  FIGS. 1 ,  4  and  5 . 
     Shown simply as springs in the above drawings, the resistance elements of the three device designs described above may also be hydraulic, pneumatic, electro-mechanical devices or the like and could be adjustable both for force and speed. It is also apparent that an adjustable resistance element (as well as other aspects of the device) could be computer controlled. With computer control, the proper resistance elements, transducers, sensors, feedback loops, information capture and storage and the like, the use of the present devices could be broadened to include not only training but also strength, power, and endurance testing. 
     Although the devices described above are different in design, all share two essential concepts, the method of training and the footplate. The various embodiments mimic the walking or running stride and thus train the legs in a natural functional manner. The footplate anchors the foot to the device but allows it to flax naturally. This combination of the training method and the unique footplate, particularly including the heel plate resistance elements, trains the entire neuromuscular activity of the hip/knee joint complex. The resulting closed-kinetic-chain training isolates and selectively trains the GM and the HS, in their proper sequence, in a safe stabilizing training regime. 
     While the principles of the invention have been made clear in the illustrative embodiments set forth herein, it will be obvious to those skilled in the art to make various modifications to the structure, arrangement, proportion, elements, materials and components used in the practice of the invention. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein.