Patent Publication Number: US-2018036575-A1

Title: Portable exercise equipment

Description:
REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of application Ser. No. 14/639,930, filed on Mar. 5, 2015 titled “PORTABLE EXERCISE EQUIPMENT”, which is a continuation of Ser. No. 14/310,912, filed on Jun. 20, 2014 titled “PORTABLE EXERCISE EQUIPMENT.” The entirety of the foregoing is hereby made part of this specification as if set forth fully herein and incorporated by reference for all purposes, for all that it contains. Moreover, any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are also hereby incorporated by reference under 37 CFR §1.57. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present technology generally relates to exercise portable equipment. 
     Description of the Related Art 
     There exists various types of exercise equipment. Most of the equipment is heavy and must reside in a single place. This equipment often uses metal weights for resistance, which are often tens, or hundreds of pounds in weight. The exercise equipment that supports these weights often weighs hundreds of pounds themselves. Additionally, each piece of exercise equipment may only provide a user with a limited number of exercises that can be performed on that piece of equipment. In some cases, only a single exercise may be performed on a single piece of equipment. 
     Some exercise equipment can be portable. These systems allow the user to engage the exercise equipment at home or while traveling. The portable exercise equipment generally comprises an anchor portion, intermediate straps, and two handles. However, these pieces of equipment are cumbersome and difficult to use. The anchor portion has a limited number of structures to which it can attach. The straps often become tangled. The number and types of exercises that can be performed is limited. 
     SUMMARY 
     The systems, methods and devices described herein have innovative aspects, no single one of which is indispensable or solely responsible for their desirable attributes. Without limiting the scope of the claims, some of the advantageous features will now be summarized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned aspects, as well as other features, aspects, and advantages of the present technology will now be described in connection with various embodiments, with reference to the accompanying drawings. The illustrated embodiments, however, are merely examples and are not intended to be limiting. Like reference numbers and designations in the various drawings indicate like elements. Not all of the elements of the drawings are in to scale relate to other drawings and the comparative size of one element relative to another element in the drawings is not necessarily indicative of the relative sizes of the elements in one or more embodiments. 
         FIG. 1  illustrates a perspective view of an embodiment of the invention. 
         FIG. 2  illustrates a top view of an embodiment of the invention. 
         FIG. 3  illustrates a top view of an embodiment of at least an anchor portion. 
         FIG. 4  illustrates a top view of an embodiment of at least an upper strap. 
         FIG. 5  illustrates a top view of an embodiment of at least a connector. 
         FIG. 6  illustrates a top view of an embodiment of at least an elongate strap. 
         FIG. 7A  illustrates a top view of an embodiment of at least a lower strap and a spring. 
         FIG. 7B  illustrates a top view of an embodiment of at least a lower strap and a spring. 
         FIG. 7C  illustrates a top view of an embodiment of at least a lower strap and a spring. 
         FIG. 8  illustrates a top view of an embodiment of at least a spring. 
         FIG. 9A  illustrates a top view of an embodiment of at least a handle. 
         FIG. 9B  illustrates a top view of an embodiment of at least a handle. 
         FIG. 10  illustrates an embodiment of the invention. 
         FIG. 11  illustrates a first force/displacement chart. 
         FIG. 12  illustrates a second force/displacement chart. 
         FIG. 13  illustrates a third force/displacement chart. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings, which form a part of the present disclosure. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and form part of this disclosure. For example, a system or device may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such a system or device may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. Elements that are described as “connected,” “engaged,” “attached,” or similarly described, shall include being directly and/or indirectly connected, engaged, attached, etc. Alterations and further modifications of the inventive features illustrated herein, and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the art and having possession of this disclosure, are to be considered within the scope of the invention. 
     Descriptions of unnecessary parts or elements may be omitted for clarity and conciseness, and like reference numerals refer to like elements throughout. In the drawings, the size and thickness of layers and regions may be exaggerated for clarity and convenience. 
     Features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. It will be understood these drawings depict only certain embodiments in accordance with the disclosure and, therefore, are not to be considered limiting of its scope; the disclosure will be described with additional specificity and detail through use of the accompanying drawings. An apparatus, system or method according to some of the described embodiments can have several aspects, no single one of which necessarily is solely responsible for the desirable attributes of the apparatus, system or method. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how illustrated features serve to explain certain principles of the present disclosure. 
     As shown in  FIG. 1 , the exercise device  100  may comprise various buckles, connectors, straps, springs, etc. The various buckles, connectors, straps, springs, etc. may be configured to allow the user to connect, disconnect, and/or reconnect various parts of the device depending on the desired use of the device. In some embodiments, a first end of the exercise device  100  comprises an anchor portion  200 . The anchor portion  200  may comprise straps, stitching, buckles, connectors, and/or an obstruction device. The anchor portion  200  is proximate an upper strap  250 . The upper strap  250  is proximate a connector  300 . The connector  300  is proximate at least one elongate strap  400 . The at least one elongate strap  400  is proximate a lower strap  450  and a spring  500 . The lower strap  450  and spring  500  are proximate at least one handle  550 . 
     As shown in  FIG. 2 , the anchor portion  200  of an exercise device  100  may be attached to or engaged with a stable structure; a user may grip or otherwise engage a second end of the device  100 , which may comprise one or more handles  550 . The stable structure may provide a point from which the exercise device  100  can be extended. It may be advantageous for the structure, to which the device  100  is attached, to be capable of preventing or reducing movement of at least part of the exercise device  100 , even when a force is applied to the device  100  in a direction away from the structure. Various exercises may be performed by the user by engaging the device  100  and then performing movements. The orientation of the user relative to the device  100  and the direction of the user&#39;s movements may vary depending on the preferences of the user. 
     As shown in  FIG. 3 , the anchor portion  200  may comprise an obstruction device  205  and an anchor strap  210 . The obstruction device  205  may comprise various shapes and may be several inches wide and high. In some embodiments, the obstruction device  205  is a cylindrical section of foam with a harder plastic core. The core defines a hole through which the anchor strap  210  may be disposed. In other embodiments, the obstruction device  205  may be other three-dimensional shapes, or may more closely resemble a flat plate. In other embodiments, the obstruction device  205  may be a pipe, tube, plate, sphere, or other shape, and may comprise a protective layer on at least part of the surface of the obstruction device. In the embodiments where the obstruction device  205  is shaped like a flat plate, the anchor strap  210  may be threaded through one or more holes in the plate. The obstruction device  205  may comprise foam, plastic, PVC, or other material. In some embodiments, the obstruction device  205  may comprise a PVC pipe that is at least partially covered, and may be wrapped in a nylon strap. The nylon strap may comprise a loop or other connector at one end of the obstruction device  205 , in order to engage other portions of the exercise device  100 . It may be advantageous for the obstruction device  205  to comprise a material that does not leave a mark or residue when rubbed against a surface. In some embodiments, it may also be advantageous for the obstruction device  205  to be generally lightweight, in total weight or in density. The obstruction device  205  may be between 0.5 inches and 5 inches wide; or it may be between 1 inch and 3 inches wide, or it may be approximately 2 inches wide. Dimensions for the height of the obstruction device  205  may be similar to those of the width, however the scope of the invention is not limited by the relative or absolute dimensions of the obstruction device  205 . 
     The anchor strap  210  may be disposed within at least part of the obstruction device  205 , or may otherwise be attached or attachable to the obstruction device  205 . In some embodiments, the anchor strap  210  comprises nylon webbing, which may be approximately 1 inch in width. The anchor strap  210  may be wider or narrower and still provide the same function or benefits. The anchor straps  210  on either side of the obstruction device may be sewn or attached to each other to create a loop  215  onto which the obstruction device  205  may be disposed. The anchor strap  210  may comprise a second loop  220  that may engage or attach to, directly or indirectly, at least a portion of the upper strap  250 . In some embodiments, the upper strap  250  may be disposed in a loop  220  created by the anchor strap  210 , or the upper strap  250  may engage a connector, which in turn engages the anchor strap  210 . 
     As shown in  FIG. 4 , the upper strap  250  may be connected to an upper strap connector  255  and/or an upper strap adjuster  265 . The upper strap connector  255  may be disposed at a first end of the upper strap  250  and may be temporarily or permanently attached to the upper strap  250 . The upper strap  250  may comprise nylon webbing, which may be approximately 1 inch in width. The upper strap  250  may be wider or narrower and still provide the same function or benefits. In some embodiments, the upper strap  250  is sewn to create a loop  260 , onto which the upper strap connector  255  may be disposed. 
     The upper strap  250  may engage an upper strap adjuster  265 , which may comprise a ladder lock buckle. In some embodiments, the upper strap  250  is disposed in one or more openings in the adjuster  265  such that the adjuster  265  may slide or move along at least part of the upper strap  250 . An adjuster grip  270  may be connected to the upper strap adjuster  265  and may allow a user to more easily adjust the location of the adjuster  265  along the upper strap  250 . A second strap  275  may be attached to the adjuster  265  and may be sewn to create a loop  280 . The loop  280  may be configured to engage at least a part of the upper strap connector  255 . When the loop  280  is engaged with the upper strap connector  255 , a larger loop  285 , largely defined by the upper strap  250 , may be created. The size of the larger loop  285  may be adjusted by sliding the adjuster  265  along the upper strap  250 . The adjuster  265  may be moved before or after the larger loop  285  is created. 
     The upper strap connector  255  may comprise a buckle, carabineer, or other connector that may temporarily connect together one or more portions of straps. In some embodiments, the upper strap connector  255  is a carabineer with an opening on the side through which a strap may be passed. In some embodiments, the connector  255  may be a buckle wherein a female portion of the buckle is disposed on the end of the upper strap and a male portion of the buckle is disposed on the second strap, or vice versa. The male portion may engage the female portion of the buckle to create a larger loop  285 . Other methods of directly or indirectly connecting the upper strap  250  to the second strap  275  may be employed and the scope of the invention is not limited by the configuration of such a connection. The adjuster  265  may comprise plastic or metal or other material. Other methods of adjusting the size of the larger loop  285  may be employed. 
     As shown in  FIG. 5 , the upper strap  250  may be attached to a main connector  300 . In some embodiments, an end of the upper strap  250  may be configured to create a loop  305 , which engages a first end  310  of the main connector  300 . The first end  310  may comprise an eyelet  315  through which the end of the upper strap  205  may be disposed. In some embodiments, a portion of the upper strap  250  other than the end may engage the main connector. In some embodiments, the anchor portion  200  may comprise the components adjacent the main connector  300  up to an including the obstruction device  205 . 
     The main connector  300  may also comprise a second end  320 , which may also comprise an eyelet  325 . The eyelet of the second end  325  may be configured to engage an eyelet strap  330 , which may comprise one or more eyelet connectors  335 . In some embodiments, each of the one or more eyelet connectors  335  engages one or more elongate straps  400 . In some embodiments, the eyelet strap  330  engages two eyelet strap connectors  335 , each of which engages an elongate strap  400 . In some embodiments, the one or more elongate straps  400  may engage the second end of the main connector  320  directly or indirectly. The main connector  300  may be configured such that the elongate straps  400  are disposed through eyelet strap connectors  335 , or through the eyelet of the second end  325 . 
     In some embodiments, the main connector  300  comprises a swivel portion  340 , wherein the first end of the main connector  310  is capable of rotating relative to the second end  320 . The first end  310  may be configured to be able to rotate less than 360 degrees relative to the second end  320 , or may be configured to rotate 360 degrees or more relative to the second end  320 . In some embodiments, the first end  310  is configured to not substantially move longitudinally away from the second end  320 , and may be capable of withstanding significant longitudinal tensile force without substantial longitudinal movement. 
     An exercise device  100  that comprises a main connector  300  with a swivel portion  340  may be beneficial to a user of the exercise device  100 . For instance, the user may be able to perform different exercises because the swivel portion  340  prevents the one or more elongate straps  400  from becoming tangled. As a non-limiting example, a user may perform an exercise that twists or rotates the exercise device  100 . When rotating, the first elongate strap  400  may become tangled with the second elongate strap  400  or catch on the second elongate strap  400 . However, by using a swivel portion  340  of the main connector  300 , the first and second elongate straps  400  may rotate relative to the anchor portion  200  and the first and second elongate straps  400  may remain in substantially the same position relative to each other, even during a twisting motion. 
     As a second non-limiting example, the swivel portion  340  may allow the a first elongate strap  400  to remain at a constant angle relative to a second elongate strap  400  during exercise motions in which the exercise device  100  is rotated or twisted. For instance, an exercise to be performed with the exercise device  100  may comprise applying a tensile force to the handles  550  in a direction away from the anchor portion  200 . The first and second elongate straps  400  (connected to the first and second handles  550  respectively) may be at a specific orientation to one another. The user may benefit from the elongate straps  400  being at a certain angle, where the angle is defined by the first handle  550 , to the main connector  300 , then to the second handle  550 . An exercise may be performed wherein the user twists or rotates the handles  550  around an axis that is in generally parallel to the tensile force applied to the anchor portion  200 . In such a configuration, without a swivel portion of the main connector  340 , the elongate straps  400  may have a tendency to wrap about one another, effectively shortening their length. If the user keeps his hands at a constant distance apart, the angle from the first handle  550 , to the main connector  300 , to the second handle  550 , will increase in magnitude. However, if a swivel portion of the main connector  340  is present, the elongate straps  400  may be able to freely rotate about the axis, such that the elongate straps  400  do not become twisted, which may allow the angle to remain unchanged. It may be important for different exercises for the angle between the elongate straps  400  to remain constant and to not change throughout the motion of the exercise. 
     In addition, in some embodiments, it may be easier for the user to arrange the exercise device  100  for use if a swivel portion  340  is present. For example, if the user attaches the anchor portion  200  to a suitable structure, the exercise device  100  may be twisted from storage, and may not be in a condition for use without untwisting. However, if the exercise device  100  comprises a main connector  300  comprising a swivel portion  340 , the user may be able to grab the handles  550  and begin use immediately, since any tensile force applied an the exercise device  100  that is twisted, may have the tendency to untwist the anchor portion  200  relative to the elongate straps  400  by rotating at least part of the swivel portion of the main connector  340 . This may save the user time and reduce frustration. 
     As shown in  FIG. 6 , the elongate straps  400  may be connected, directly or indirectly, to a portion of the main connector  300 . In some embodiments, the main connector  300  attaches to two elongate straps  400 . Each elongate strap  400  may comprise two pieces of nylon webbing, which may be approximately 1 inch in width. The elongate straps  400  may be wider or narrower and still provide the same function or benefits. The elongate straps  400  may be several feet in length. For each elongate strap  400 , the two pieces of webbing may be attached to each other at regular intervals. The intervals between the stitching may be between 0.5 inches and 12 inches, between 2 inches and 8 inches, or may be approximately 5 inches. The stitching may also be irregularly spaced, with some intervals being larger than others. 
     In some embodiments, an end of an elongate strap  400  comprises a loop  405 , which is connected to an adjuster  410 . The adjuster  410  may comprise a ladder lock buckle. The adjuster  410  may be configured to slide or move along at least part of the elongate strap  400 , and may comprise an adjuster grip  415  that may make it easier for the user to adjust the position of the adjuster  410  long the strap  400 . Another end of the elongate strap  400  may be connected to a lower strap  450  or to a spring  500 . The distance between the lower strap  450  and the main connector  300  may be changed by altering the position of the adjuster  410  along the elongate strap  400 . As a non-limiting example, if the adjuster  410  is moved closer to the main connector  300 , the distance between the main connector  300  and the lower strap  450  may be increased. If the adjuster  410  is moved closer to the lower strap  450 , the distance between the main connector  300  and the lower strap  450  may be decreased. This may be true for both elongate straps  400  on the exercise device. In some embodiments, moving the adjuster  410  closer to the main connector  300  may decrease the distance between the main connector  300  and the lower strap  450 , and may depend on the specific configuration of the connectors, straps, and adjusters. By sliding the adjusters  410  to different positions along the elongate straps  400 , the user may be able to change the total length of the exercise device  100 , including the distance between the anchor portion  200  and the handles  550 . This may be advantageous in that different exercises may benefit from the exercise device  100  being different lengths. An embodiment that uses adjusters  410  that slide along the elongate straps  400  to adjust its length may be advantageous because they may allow the user to quickly change the length of the exercise device  100  between different exercises and may prevent the user from having to take excessive time between exercises to make adjustments to the equipment. 
     As shown in  FIG. 7A , an end of the elongate strap  400  may be connected to a lower strap  450  and/or a spring  500 . The elongate strap  400  may attach to a connector  420 , which may be attached to one end of a spring  500 . The second end of the lower strap  450 , and the second end of the spring  500 , may both connect to a handle strap  555 . The lower strap  450  may attach to a connector  560 , which may be attached to the handle strap  555 . The spring  500  may be attached to a connector  560 , which may be attached to the handle strap  555 . 
     The lower strap  450  may comprise nylon webbing, which may be approximately 1 inch in width. The lower strap  450  may be wider or narrower and still provide the same function and benefits. In some embodiments, the lower strap  450  is attached directly to the elongate strap  400  via stitching. Or, the lower strap  450  may attach to a connector  420 , which may attach to the elongate strap  400 . The elongate strap  400  may comprise a loop  425 , through which a connector  420  may be disposed. The connector  420  may be attached to a first end of a spring  500 . The spring  500  may be a tubular or cylindrical spring band, or may have another shape such as a flat band, commonly used for exercising. Springs designed for exercise may be used, or springs designed for other purposes may be utilized. In some embodiments, the first end of the spring  500  may comprise a webbing loop  505  that engages the connector  420  to secure the end of the spring  500  to the connector  420  and to the end of the elongate strap  400 . 
     In some embodiments, the handle strap  555  comprises at least one loop  565 , and may comprise two, three, or more loops  565 . Each loop  565  may be configured to receive a connector  560 . A connector  560  attached to the handle strap  555  may be configured to be attached to the lower strap  450 , to the spring  500 , to both the lower strap  450  and the spring  500 , or to another component of the exercise device  100 . 
     As depicted in  FIG. 7A , the lower strap  450  may be shorter than the spring  500 . As depicted in  FIG. 7B , the lower strap  450  may be generally the same length as the spring  500 . As depicted in  FIG. 7C , the lower strap  450  may be longer than the spring  500 . 
     As shown in  FIG. 8 , the lower strap  450  may be detached from the handle strap  555 . In some embodiments, the lower strap  450  is detachable from the handle strap  555  and may be attached to another portion of the exercise device  100 . The end of the lower strap  450  may remain attached to the connector  560 , and then once the connector  560  is detached from the handle strap  555 , the connector  560  may be attached to a portion of the elongate strap  400 . The connector  560  may be configured to attach to the space between the two pieces of webbing of the elongate strap  400 . The stitching connecting the two pieces of webbing may be configured to keep the connector  560  from detaching or from sliding excessively along the elongate strap  400 . In some embodiments, once the lower strap  450  has been detached from the handle strap  555 , only the spring  500  is left connecting the elongate strap  400  to the handle strap  555 . Thus, the distance between the elongate strap  400  and the handle  550  may be variable depending on the amount of force applied to the handle  550 . In some embodiments (not shown) more than one spring  500  may connect the elongate strap  400  to the handle  550 . Each spring  500  may have the same or different spring constant. 
     As shown in  FIG. 9A , the handle strap  555  may comprise one or more loops  565  that can accommodate one or more connectors  560 . The handle strap  555  may also attach to a grip portion  570 . In some embodiments, the grip portion  570  comprises a generally rigid core and a softer outside. The core may allow the grip portion  570  to be configured in a specific shape and may allow the grip portion  570  to remain in that shape. The softer outside may be advantageous as it may allow the user to more securely engage the grip  570 . The shape of the grip portion  570  may be variable and different configurations may be more advantageous for different exercises. For instance, the configuration of the grip portion  570  depicted in  FIG. 9B  may be easier for some users to grab onto or otherwise engage. 
     In some embodiments, the handles may be configured to engage one or more parts of the user&#39;s body. For instance, as a non-limiting example, the handle may be sized to accommodate a user&#39;s hand, foot, ankle, elbow, wrist, knee, or other part of the user&#39;s body. The handle may be configured to allow the user to easily insert his foot and/or ankle into the handle portion. This may be advantageous because the user may be able to perform more exercises. This may also be an improvement over conventional portable exercise devices because often these exercise devices do not have handles that are sized to accommodate different parts of the user&#39;s body. In some embodiments, the handle may be configured to accommodate two or more parts of a user&#39;s body at the same time. 
     In some embodiments, to use the exercise device  100 , the user first anchors a portion of the exercise device to a stable structure. The stable structure may include the top of a door frame, the side of a door frame, the bottom of a door, a horizontal pole, a vertical pole, or some other stationary object (e.g., door handle, bed post, etc.). The device may be anchored in a door frame by first starting with the door open. The user may place the obstruction device  205  on the far side of the door with the anchor strap  210  disposed between the door and the door frame. The door may then be closed. When tension is applied to the exercise device  100 , the anchor strap  210  pulls on the obstruction device  205 . Because the obstruction device  205  is on the far side of the door and cannot easily fit through the space between the door and the door frame, the exercise device  100  does not move easily and is substantially prevented from moving away from the door. The same procedure may be used when the exercise device  100  is to be anchored to the top of the door frame, to the side of the door frame, or at the bottom of the door between the door and the floor. 
     In some embodiments, the exercise device  100  may be anchored to a stable object other than a door and/or door frame. For instance, the exercise device  100  may be anchored to a pole, bar, tree, or some other stable object around which a strap may be placed. For these objects, there may not be a convenient place into which the obstruction device  205  may be placed. Instead, the upper strap  250  may be wrapped around the stable object. For instance, in order to anchor the exercise device  100  to a horizontal bar, a tree branch, or similar stable structure, the upper strap  250  and upper strap connector  255  may be disconnected from the second strap  275 . The upper strap  250  may then be wrapped around the stable object and then reconnected to the second strap  275 , wherein the upper strap  250  and second strap  275  create a loop  285  and the stable object is disposed within the loop  285 . The upper strap adjuster  265  may then be positioned along the upper strap  250  to shorten the size of the loop  285  such that the upper strap  250  fits snuggly against the stable structure. 
     Conventional exercise devices may contain a mechanism to attach to a stable structure such as a horizontal bar, and may contain the equivalent of an upper strap  250 . However, the attachment mechanism that is used to create the loop  285 , into which the stable structure is disposed, is often very different. In conventional devices, the upper strap has a finite number of discrete attachment points, creating a limited number of sizes of loops that can be created. In order to attach such a device to a horizontal bar, the user must use the next largest loop, which will undoubtedly have unnecessary and unwanted slack. However, in some embodiments, the exercise device  100  has an unlimited number of sizes of loops  285  that can be created due to the fact that the upper strap adjuster  265  can continuously slide along the length of the upper strap  250 . Additionally, as described above, the upper strap  250  can be positioned around the stable object and then reconnected, and then the size of the loop  285  is adjusted. Being able to adjust the size of the loop  285  after the stable object has been disposed within the loop  285  is advantageous because it allows the user to create a more stable connection between the upper strap  250  and the stable object. 
     When the exercise device is attached to a horizontal bar, the differences between the exercise device and conventional exercise devices may not be as apparent. However, when attaching the exercise device to a vertical pole (e.g., a bed post, tree trunk, etc.), the differences may become more important. Since the straps from a conventional exercise device cannot be snugged up against the pole, the device may have a tendency to fall down when tension is not applied to the device. Contrastingly, when the upper strap  250  of the exercise device  100  is snugged up against the vertical pole, being adjusted after the loop  285  has been created, the ability of the exercise device  100  to maintain its position on the vertical pole improves, even when tension is not applied. This is true not just for vertical poles, but also for other objects as well. For instance, a user may desire to attach the exercise device  100  to a door knob. Conventional exercise devices will have a tough time adequately securing a strap to a door knob, since the conventional exercise device has a limited number of loop sizes, and the loop cannot be decreased once the loop is created. Conversely, the upper strap  250  of the exercise device  100  may wrapped around a door knob, the upper strap connector  255  can then attach to the second strap  275  creating a loop  285 , and then the upper strap adjuster  265  can be positioned along the upper strap  250  to decrease the size of the loop  285  in order to securely fit the upper strap  250  to the door knob. 
     Once the exercise device  100  has been secured to a stable object, the user may perform a variety of exercises. In some embodiments, the user may grasp the handles  550  with his hands and exert a force on the handle  550  in the direction opposite of the stable object. The user may push the handles  550  away from the stable object, pull the handles  550  away from the stable object, he may rotate at least part of his body to exert a force on the handles  550  in the direction away from the stable object, or he may perform a different motion that exerts a force on the exercise device  100  away from the stable object. The user may exert a force on a single handle  550  using a single hand, he may exert a force on a single handle  550  using both hands, he may exert a force on both handles  550  using a single hand, or he may exert a force on both handles  550  using both hands. Other combinations may be possible. In some embodiments, the user may engage a different part of his body with the handles  550  in order to exert a force on the handles  550  in a direction away from the stable object. For instance, as non-limiting examples, the user may engage one or more handles  550  with the user&#39;s elbows, ankles, heels, tops of feet, bottoms of feet, shins, backs of knees, or some other body part. Different exercises may benefit from different body parts being used to engage one or more handles  550 . 
     In some embodiments, to use the exercise device  100 , the user may use a part of his body to exert a tensile force on the exercise device  100  in a direction away from the stable object. For instance, as a non-limiting example, the user may use the exercise device  100  to perform an exercise similar to a lat row. To perform this exercise, the user may begin with the exercise device  100  anchored to a stable object, such as the top or side of a door frame, so that the height of the anchor portion  200  above the ground is similar to the height of the user&#39;s chest above the ground. The user then grips the handles  550 , one hand per handle  550 , faces the door frame, and places his hands close to his chest. The user may then step back until the exercise device  100  is generally taught and fully extended. The user then begins the exercise movement by extending his arms and simultaneously leaning back so that the exercise device  100  remains fully extended. Then, the user may pull his hands back towards his chest, resulting in his body moving forward towards the door frame. This exercise may work out the muscles in the user&#39;s upper back. 
     In some embodiments, the user may be able to perform an exercise similar to a chest press. To perform this exercise, the user begins with the exercise device  100  in the same position, but instead begins with his back towards the door frame and his arms stretched out in front of himself. Then, to begin the exercise, the user leans forward and allows his hands to come close to his chest. Then, the user pushes his hands away from his chest, resulting in his body being pushed back into an upright position. This exercise may work out the muscles in the user&#39;s chest. 
     Either of these two example exercises may be performed by either conventional devices or with an exercise device  100  wherein the elongate strap  400  is connected to the handle  550  by the lower strap  450 . However, the exercise could be improved if the lower strap  450  is detached from the handle  550  and attached to a point on the elongate strap  400  (see  FIG. 8 ), with only the spring  500  connecting the elongate strap  400  to the handle  550 . In such a configuration, the user may be able to perform the exercise without having to rely on his own body weight for resistance, and would not have to tilt his whole body in the process. Instead, the user can begin the lat row exercise facing the door frame with his arms extended and the exercise device  100  in a fully extended position. The user then pulls his hands towards his chest. Because the spring  500  connects the elongate strap  400  to the handle  550 , and the lower strap  450  does not connect the elongate strap  400  to the handle  550 , the handle  550  may move away from the door frame when a tensile force is applied to the exercise device  100 . Since a spring  500  is providing the resistance to the user&#39;s pulling motion, the more force that is applied, the further the handles  550  can be moved away from the door frame. In this exercise, the user&#39;s body may remain in an upright position and may facilitate a better posture for the exercise motion. 
     Similar advantages may be found performing the chest press exercise using a spring  500  as resistance. For instance, the user may begin with his back to the door frame, exercise device  100  fully extended, and hands near his chest. The user may then extend his arms forward away from the door frame, exerting a tensile force on the exercise device  100 , and using the spring  500  as resistance to his movement. Once the user extends his arms fully, or as far as he desires, the user can then bring his hands back to his chest. Similar to the lat row exercise, the user can perform this exercise without having to tilt and move his upper body and does not need to rely on his own body weight for resistance. This configuration is advantageous in that the user can focus more on specific muscles and can achieve a better posture for the exercise movement. Using an exercise device that comprises springs instead of solely the user&#39;s body weight for resistance, may also allow the user to perform exercises in a more comfortable or ergonomic position. For instance, when using an exercise device that comprises straps but no springs, the user&#39;s feet are generally placed parallel together in the user&#39;s body must tilt forwards or backwards. This may require the user to keep his core tight prevent his hips from dropping to avoid any injuries to his lower back. However, when using an exercise device that comprises springs, the user may be able to place one foot ahead of the other foot, resulting in a more stable stance. In this stance, the user&#39;s hips may no longer drop and may not put pressure on the user&#39;s lower back. 
     Although two exercises were described that could be performed with conventional exercise devices, and performed better using one or more embodiments of the current exercise device  100 , there are other exercises that are not possible with conventional exercise devices because the range and direction of movement does not rely on the user&#39;s body weight. For instance, as a non-limiting example, the user may anchor the exercise device  100  to the bottom of a door. The user may perform an exercise similar to a shoulder row. Here, the user begins with his hands near his waist and the exercise device  100  fully extended. Note that the length of the exercise device  100  may need to be adjusted, and may be accomplished by moving the adjuster  410  along the elongate strap  400 . For this exercise, the user may prefer to have the lower strap  450  be disconnected from the handle portion  550  so that only the spring  500  connects the elongate strap  400  to the lower strap  450 . To begin the exercise, the user pulls up on the handles  550 , exerting a tensile force on the exercise device  100 , until his hand are near his shoulders or chin. Because the spring  500  provides resistance to the user&#39;s movement, the handles  550  will generally be more difficult to pull up on as the user&#39;s hands get closer to his shoulders or chin. The user may then lower his hands back down towards his waist, decreasing the tensile force on the exercise device  100 . Since this exercise is performed with the user pulling up on the handles  550 , it is not possible to perform a similar exercise on a conventional exercise device that relies only on the user&#39;s body weight for resistance. Thus, one or more embodiments of the exercise device  100  that use springs  500  for resistance may be advantageous because it allows the user to perform more exercises using the same equipment. 
     In some embodiments, another exercise that cannot be performed using a conventional device is an exercise similar to a standing hip abductor exercise. Here, the user begins by anchoring the device  100  at or near the bottom of a door, or other stable structure at approximately the same height. For instance, a bed post or desk leg may suffice. The user may then engage his foot with the handle  550  and move his ankle away from the stable structure until the there is no slack in the exercise device  100 . The user may the stand and face in a direction, such that the ankle in the handle  550  is furthest from the stable structure and the ankle not in the handle  550  is closest to the stable structure. The user may lift the ankle in the handle  550  a few inches off of the floor and gently move it away from the stable structure, and then return the ankle to the starting position. This exercise motion moves the handle  550  of the exercise device  100  in a generally horizontal direction and the resistance to the movement is not dependent on the user&#39;s own weight. Instead, the resistance to the movement is provided by stretching the spring  100 . Thus, this exercise is not possible with a conventional exercise device that only relies on the user&#39;s own weight for resistance to movement. The configuration of an embodiment of the exercise device  100  that uses springs  550  for resistance may be advantageous because it allows the user to perform more exercises using the same equipment. 
     In some embodiments, a spring  500  connects the elongate strap  400  to the handle strap  555 . The springs  500  may comprise a spring constant, wherein the spring constant is in the form of force/displacement. Common units for spring constants may be N/m or lbf/ft. 
     In some embodiments, more than one spring  500  connects the elongate strap  400  to the handle strap  555 . When two springs are in a parallel configuration, their spring constants are additive. Two springs in parallel, with the same spring constants and the same lengths, will have approximately twice the resistance of a single spring in the same setting. In some embodiments, the exercise device  100  has a connector at the end of the elongate strap  420  and a connector  560  at the end of the handle strap  555 . More than one spring  500  may be attached to the exercise device  100  at the same time. The springs  500  may be of different lengths and of different spring constants. 
     For embodiments of an exercise device  100  that comprises two springs  500  (of the same spring constant and length) disposed between an elongate strap  400  and a handle strap  555 , the exercise device  100  may provide approximately twice the resistance as would embodiments where only a single spring  500  was disposed between an elongate strap  400  and a handle strap  555 . It may be advantageous for the user to have the ability to easily increase the resistance of the exercise device  100  by simply adding or taking away springs  500 . In some embodiments, two springs  500  may be attached, wherein the springs  500  have the same length, but different spring constants. The resulting spring constant of the two springs  500  together may be greater than either spring independently, and the magnitude of the resulting spring constant will depend, at least, on the values of the spring constants of the springs  500  attached to the exercise device  100 . 
     As a non-limiting example, the graph in  FIG. 11  shows a force-displacement curve for one or more springs, of the same length, in parallel where the resulting spring constant is 40 N/m. The one or more springs may comprise a single spring with a spring constant of 40 N/m, or two individual springs in parallel where each spring has a spring constant of 20 N/m, or some other combination of one or more springs of the same length where the resulting spring constant is 40 N/m. In this system, as shown below, when 10 N of force is applied to the one or more springs, the springs displace 0.25 m. When 14N of force is applied to the one or more springs, the springs displace 0.35 m. When 20 N of force is applied to the one or more springs, the springs displace 0.5 m. 
     In some embodiments, the exercise device  100  may comprise two springs  500 , wherein the two springs  500  have different lengths, but the same spring constant. The second spring  500  may have a length that is 0.25 m greater than the first spring  500 . The springs  500  may be disposed between an elongate strap  400  and a handle strap  555 . In this configuration, the first spring  500  may be shorter than the second spring  500 . Since the springs  500  have different lengths, there may be a point at which only the first spring  500  is providing resistance. A user may apply enough force to the first spring  500 , such that its stretched length is approximately equal to the length of the unstretched second spring  500 . If any more force is applied, the second spring  500  may begin to provide resistance. In this case, the spring constant of the two springs  500  may be different depending on whether the second spring  500  is providing resistance. The spring constant of the first spring  500  alone (before the second spring  500  provides resistance) may be less than the spring constant of the two springs  500  in parallel (after the second spring  500  provides resistance). In this sense, the spring constant of the two-spring system changes depending on how much force is applied and how much the first spring  500  is displaced. 
     The graph in  FIG. 12  shows a force-displacement curve for two springs in parallel where the first spring has a spring constant of 40 N/m and the second spring has a spring constant of 40 N/m, and the second spring is 0.25 m longer than the first spring. Similar to the graph in  FIG. 11 , when 10 N is applied to the two springs, the first spring displaces 0.25 m. This is also the point at which the second spring begins to provide resistance. If any more force is applied, the second spring will begin to provide resistance and the spring constant for the two springs from this displacement and farther, will be larger than the spring constant of the first spring individually. If the second spring has a spring constant of 40 N/m, then the resulting spring constant of the two springs in parallel, for displacements greater than 0.25 m, will be 80 N/m, or twice that of either spring individually. Therefore, when 10 N of force is applied to the two springs, the first spring displaces 0.25 m and the second spring does not displace (because its length is 0.25 m greater than the first spring). This result is similar to  FIG. 11 . When 14N of force is applied to two springs, the first spring displaces 0.3 m, and the second spring stretches from 0.25 m to 0.3 m. In this scenario, the first spring applies 12N of force resistance and the second spring applies 2N of force resistance. When 20 N of force is applied to the two springs, the first spring displaces 0.375 m, and the second spring displaces 0.125 m. In this scenario, the first spring applies 15N of force and the second spring applies 5N of force. 
     In some embodiments, the exercise device  100  may comprise two springs  500 , wherein the two springs  500  have different lengths, but the same spring constant, and also comprise a lower strap  450  disposed between an elongate strap  400  and a handle strap  555 . The lower strap  450  may attach to the elongate strap  400  at the same or similar place as do the two springs  500 , and may attach to the handle strap  555  at the same or similar place as do the two springs  500 . The lower strap  450  may have a length greater than either the first or second springs  500 , and may have a length that is 0.3 m greater than the first spring  500 , and 0.05 m greater than the second spring  500 . In this configuration, when the user applies any force up to 14N, the two springs  500  will stretch up to 0.3 m, and may generally act as if the lower strap  450  is not attached. Since the lower strap  450  is 0.3 m longer than the first spring  500 , the first spring  500  must displace 0.3 m before the lower strap  450  becomes engaged. However, once more than 14N of force is applied to the first spring  500 , the second spring  500 , and the lower strap  450 , the lower strap  450  will not elongate further. 
     The graph in  FIG. 13  shows a force-displacement curve for two springs and a static strap in parallel, where the first spring has a spring constant of 40 N/m and the second spring has a spring constant of 40 N/m, the second spring is 0.25 m longer than the first spring, and the static strap is 0.3 m longer than the first spring and 0.05 m longer than the second spring. Similar to the graphs in  FIGS. 11 and 12 , when 10 N is applied to the two springs and strap, the first spring displaces 0.25 m. And similar to the graph in  FIG. 12 , when 14N of force is applied to the two springs and strap, the first spring displaces 0.3 m and the second spring stretches from 0.25 m to 0.3 m. However, when more than 14N is applied to the two springs and strap, the first spring will only displace 0.3 m and the second spring will only stretch from 0.25 m to 0.3 m. Any additional force applied, may be resisted by the lower strap  450 . For instance, if 20 N of force is applied, the first spring  500  will displace 0.3 m and apply 12N of force resistance, the second spring  500  will displace from 0.25 m to 0.3 m and apply 2N of force resistance, and the static strap will not stretch or elongate and will apply 6N of force resistance. Any force applied greater than 20 N may be resisted by an equal and opposite resistance force from the lower strap  450 . 
     The above examples involving at least one spring  500  and in some instances one or more springs  500  and/or a lower strap  450  are for illustrative purposes only and do not limit the scope of the invention. This includes the configurations and embodiments described, as well as the graphical depictions in  FIGS. 11-13 . More or fewer springs or straps, in parallel or series may be added to the exercise device or comprise the exercise device depending on the configuration and/or the result desired. 
     It may be advantageous for an exercise device  100  to comprise one or more springs and/or straps, in parallel or series. Some exercises that are available to an exercise device  100  may work well with a static strap. However, the exercise may work equally well with at least one spring  500  attached to the exercise device  100 . The exercise may target different muscles or parts of the user&#39;s body depending on whether a spring or strap is used. In some embodiments, a user may benefit from a configuration of an exercise device  100  where the spring constant is not the same throughout the entire range of the exercise motion. For instance, a user may benefit from the beginning movement of the exercise motion to be relatively easy with little elastic resistance exerted by the spring. However, the user may also benefit from more resistance further in to the exercise motion. This may be accomplished by using a configuration similar to that described above where the exercise device  100  comprises two springs  500  in parallel with the first spring  500  shorter than the second spring  500 . In this configuration, the exercise device  100  may provide more resistance during the second part of the exercise motion than the first part of the exercise motion. 
     In some embodiments, a user may benefit from an exercise device  100  that comprises two springs  500  in parallel, with the first spring  500  shorter than the second, and a lower strap  450  that is longer than the second spring  500 . In this configuration, the first part of the exercise motion may be easier than the second part of the exercise motion, and the second part of the exercise motion may be easier than a third part of the exercise motion where the lower strap  450  provides resistance force. In some embodiments, the lower strap  450  may be substituted with a third spring  500  to provide a different user experience that may be beneficial in some exercise movements. 
     In some embodiments, an exercise device  100  may comprise two springs  500 , one attached to each elongate strap  400 , and two handles  550 , one attached to each spring  500 . The exercise device  100  may be configured such that the springs  500  comprise a connector  420  at a first end of each spring, and may be detachable from the elongate straps  400 . At least part of the anchor portion  200  may be configured such that the anchor strap  210  may be detachable from the upper strap  250 . The connectors of each spring  420  may then be connected to at least a portion of the anchor portion  200 , such as the anchor strap  210 , wherein the anchor strap  210  may not be connected to the upper strap  250 . The result may be a smaller, more compact exercise device  100  that may be capable of providing at least some of the benefits of a different embodiment of an exercise device  100 . For instance, as shown in  FIG. 10 , a user may connect the springs  500  at least directly to the anchor strap  210  using connectors. The user may secure the obstruction device  205  to a suitable structure. The user may be able to perform various upper-body exercises such as the lat row or chest press, or lower-body exercises such as a standing hip abductor exercise. The user may also be able to perform exercises even if the obstruction device  205  is not connected to a suitable structure. For instance, the exercise device  100  may be configured such that the springs  500  are connected to the anchor strap  210  or to each other, and the user may be able to exercise his shoulders by moving his hands away from each other. The springs  500  may be configured such that as the user moves his hands away from each other, the springs  500  provide tensile resistance against the user&#39;s movement. In some embodiments, a first handle  550  may be connected to a first end of a single spring  500 , with a second handle  550  connected to a second end of the spring  500 . This configuration may also provide the user with available exercises. In some embodiments (not shown), the two handles may be connected to two springs respectively, and the two springs may be connected to each other using a connector such as a carabiner. Other configurations using one or more handles, one or more springs, the anchor, and one or more straps may be possible. The various configurations may be at least partially influenced by the user&#39;s preference. 
     An exercise device  100  that can be separated in to components and reattached into different configurations may be advantageous to a user. For instance, a user may desire to use an exercise device  100  while traveling. It may be advantageous for the exercise device  100  to be configured to allow the user to take parts of the exercise device  100  while traveling and be able to perform different exercises. The user may desire to take all parts of the exercise device  100  in order to be able to perform all of the available exercises; or the user may desire to take only some components of an exercise device  100  and perform the exercises that may be performed with only those components. Since the user may have different options as to configurations, the user may appreciate the ability to customize the exercise device  100  depending on his or her needs for a particular trip or situation. Other configurations may be possible for an exercise device  100  and the scope of the invention is not limited to the configurations explicitly described herein. 
     The length of the elongate straps  400  may be variable such that the length can be increased or decreased. The elongate straps  400  may be configured to allow changes to the length using an elongate strap adjuster  410 , which may comprise a ladder lock buckle. In some embodiments, a strap adjuster  410  is disposed on or near an elongate strap  400 . The elongate strap  400  may comprise two ends with the first end connected or connectable to a lower strap  450 , a spring  500 , or a handle  550 . The elongate strap  400  may extend from the first end, through the strap adjuster  410 , through an eyelet strap connector  335 , eyelet of the main connector  325 , or some other portion of the main connector  300 , then back down to the adjuster  410 , wherein a second end of the elongate strap  400  may be attached or connected to the adjuster  410 . The elongate strap  400  and strap adjuster  410  may be configured such that the adjuster  410  may slide or move along at least part of the elongate strap  400 . An adjuster grip  415  may be connected to the elongate strap adjuster  410  and may allow a user to more easily change the location of the adjuster  410  along the elongate strap  400 . 
     An exercise device  100  that comprises an elongate strap  400  comprising an adjuster  410  that may slide or move along at least part of the elongate strap  400  to alter the distance between the main connector  300  and the spring  500  or handle  550 , may be advantageous. Different exercises may benefit from the elongate straps  400  being longer or shorter, and a user may appreciate the ability to quickly and easily change the length of the elongate strap  400  depending on the exercise he prefers to do. In addition, it may be beneficial for the strap adjuster  410  to be disposed between the main connector  300  and the handle  550  and generally away from the handle  550 . When performing exercises, a user may find it uncomfortable for an adjuster  410  to be right next to his hands and/or wrists. Different exercises may require the elongate strap  400  to be near or touching the users hands, wrists, or arms, and an adjuster  410  that is too close to the user&#39;s hands may provide discomfort. Therefore, it may be advantageous for the exercise device  100  to comprise an elongate strap adjuster  410  that is not adjacent the handles  550 . 
     As used in this disclosure, the terms and labels should generally be given their plain and ordinary meaning. For instance, the term “strap” should generally be interpreted to include, without limitation, a strip of pliant material that may be long and narrow. It may comprise various materials including, without limitation, nylon. The term “spring” should generally be interpreted to include, without limitation, an elastic device that at least partially regains its original shape after being compressed or extended. It may include, without limitation, elastic devices made of metal, plastic, rubber, nylon, or other materials that comprise or define a spring constant over at least part of the device&#39;s displacement. The term “handle” should generally be interpreted as including, without limitation, a part that is configured to be held or operated by one&#39;s hand, but may also include a part that may be operated by other parts of one&#39;s body. The term “connector” should generally be interpreted to include, without limitation, a device providing a connection between at least two parts. The term “anchor” should generally be interpreted to include, without limitation, a source of securing or stability and/or a point of support. 
     In some embodiments, a method using the exercise device may include: securing an anchor portion to a generally stable object; gripping one or more handles with one or more body parts; and applying a tensile force to the exercise device in a direction generally opposite from the anchor portion. 
     In some embodiments, a method of using the exercise device may include any of the following steps: securing an anchor portion to a generally stable object; adjusting the upper strap to a desired length; adjusting the length of an elongate strap by moving or sliding a buckle along the elongate strap either towards or away from the handles; connecting a lower strap to the handle portion; disconnecting a lower strap from a handle portion; connecting a lower strap to the elongate strap; connecting a first spring to the handle portion; disconnecting a first spring from the handle portion; and connecting or disconnecting a second spring to or from the handle portion. In some embodiments, the step of securing an anchor portion to a generally stable object may include wrapping an upper strap around a stable object and adjusting the length of the upper strap. 
     In some embodiments, a method of using the exercise device may include: connecting a first handle portion to a first end of a first spring; connecting a second handle portion to a first end of a second spring; and connecting the second end of the first spring to the second end of the second spring, either directly or indirectly. The method may further comprise any of the following steps: connecting the second end of the first spring to an anchor portion; connecting the second end of the second spring to an anchor portion; securing the anchor portion to a generally stable object. An exercise device in configured in these embodiments may be of substantially the same, or similar, length as commercial exercise bands available. Thus, the exercise device may be versatile in that it can be adapted to multiple configurations that may mimic or be close substitutes for individual pieces of exercise equipment that must usually be purchased separately and cannot be easily integrated into other exercise equipment systems. A method to use the exercise device in any of these embodiments may comprise placing a portion of the springs on the floor, wherein the portion of the springs placed on the floor may include the approximate middle of the springs and/or the approximate location where the first and second springs engage; gripping the handles of the exercise device; moving at least one of the handles in either an upward and/or outward movement; and returning the at least one handle to a rest position, wherein the rest position may be a location where the spring is substantially unstretched, or less extended as compared to other portions of the exercise motion. 
     Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. Additionally, a person having ordinary skill in the art will readily appreciate, the terms “upper” and “lower” are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of the device as implemented. 
     Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable sub combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub combination or variation of a sub combination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. 
     In describing the present technology, the following terminology may have been used: The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to an item includes reference to one or more items. The term “ones” refers to one, two, or more, and generally applies to the selection of some or all of a quantity. The term “plurality” refers to two or more of an item. The term “about” means quantities, dimensions, sizes, formulations, parameters, shapes and other characteristics need not be exact, but may be approximated and/or larger or smaller, as desired, reflecting acceptable tolerances, conversion factors, rounding off, measurement error and the like and other factors known to those of skill in the art. The term “substantially” means that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. Numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also interpreted to include all of the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of “about 1 to 5” should be interpreted to include not only the explicitly recited values of about 1 to about 5, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3 and 4 and sub-ranges such as 1-3, 2-4 and 3-5, etc. This same principle applies to ranges reciting only one numerical value (e.g., “greater than about 1”) and should apply regardless of the breadth of the range or the characteristics being described. A plurality of items may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. Furthermore, where the terms “and” and “or” are used in conjunction with a list of items, they are to be interpreted broadly, in that any one or more of the listed items may be used alone or in combination with other listed items. The term “alternatively” refers to selection of one of two or more alternatives, and is not intended to limit the selection to only those listed alternatives or to only one of the listed alternatives at a time, unless the context clearly indicates otherwise. 
     It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. For instance, various components may be repositioned as desired. It is therefore intended that such changes and modifications be included within the scope of the invention. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present invention. Accordingly, the scope of the present invention is intended to be defined only by the claims that follow.