Patent Publication Number: US-2023158363-A1

Title: Differential air pressure exercise and therapeutic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/101,806, filed Nov. 23, 2020, which is a continuation of U.S. patent application Ser. No. 16/278,619, filed Feb. 18, 2019, which claims the benefit of and priority to U.S. Provisional Patent Application No. 62/632,310, filed Feb. 19, 2018, all of which are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to the field of exercise and therapeutic devices. 
     BACKGROUND 
     In general, a treadmill includes a moving belt that allows a user to walk or run on the treadmill while the user remains in a substantially stationary position. Treadmills are effective to provide exercise and therapeutic benefits to a user. For rehabilitation, physical therapy, or other purposes, some treadmills include a system that reduces or offloads the weight of the user to lighten the load that the user supports while using the treadmill. Beneficially, this system reduces the force of each repeated impact between the user and the treadmill. Such a system may be beneficial for users who are rehabilitating injuries where repeated impacts with the treadmill running belt may adversely affect their limbs or joints. 
     SUMMARY 
     One implementation of the present disclosure is an exercise and therapeutic device. The exercise and therapeutic device includes a treadmill comprising a running belt coupled to a treadmill frame and an offloading system coupled to the treadmill. The offloading system includes an air chamber surrounding the running belt adapted to be selectively inflated between a deflated condition and an inflated, operating condition, a user seal coupled to the air chamber, adapted to receive a user so that, in an operating condition, at least a portion of a user is received in the user seal and positioned within the air chamber and to seal the air chamber around the user, a pump operable to inflate the air chamber, at least one strap coupled to the treadmill frame and adapted to restrict the expansion of the air chamber in an operating condition and adjust a spacing of the user seal relative to a running surface of the running belt when the air chamber is inflated in the operating condition. 
     Another implementation of the present disclosure is an exercise and therapeutic device. The exercise and therapeutic device includes a treadmill, which includes a running belt coupled to a frame, and an offloading system coupled to the treadmill. The offloading system comprising an air chamber surrounding the running belt, a user seal coupled to the air chamber and configured to allow a user to extend at least partially into the air chamber and to seal the air chamber around the user, a pump operable to inflate the air chamber, a plurality of straps coupled to the frame, and a user seal frame coupled to the plurality of straps and configured to restrict a distance between the user seal and a running surface of the running belt when the air chamber is inflated. Changing a length of the plurality of straps changes the height of the user seal when the air chamber is inflated. 
     Another implementation of the present disclosure is an exercise and therapeutic device. The exercise and therapeutic device includes a treadmill, which includes a running belt coupled to a treadmill frame, and an offloading system coupled to the treadmill. The offloading system includes an air chamber at least partially surrounding the running belt, a user seal coupled to the air chamber and configured to receive at least a portion of a body of a user so that in an operating condition, at least a portion of a user is positioned within the air chamber and to substantially seal the air chamber around a user, a pump operable to selectively inflate the air chamber, a user seal frame configured to substantially surround the user seal. The exercise device also includes a rear actuator column coupled to the treadmill frame. The rear actuator column includes a first shaft configured to couple to the user seal frame and a first actuator controllable to adjust a position of the first shaft relative to a running surface of the running belt. 
     Another implementation of the present disclosure is an exercise device including a treadmill and an offloading system coupled to the treadmill. The treadmill includes a treadmill frame, a running belt coupled to a treadmill frame, and a motor coupled to the running belt. The offloading system includes an air chamber at least partially surrounding the running belt, a user seal coupled to the air chamber and configured to selectively receive at least a portion of a user so that, in an operating condition, at least a portion of a user extends at least partially into the air chamber and to seal the air chamber around a user, and a pump operable to selectively inflate the air chamber. The exercise device includes a controller coupled to the motor and the pump and configured to concurrently control the motor and the pump. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG.  1    is a side perspective view of an exercise and therapeutic device, according to an exemplary embodiment. 
         FIG.  2    is a front perspective view of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  3    is a partial perspective view of the exercise and therapeutic device of  FIG.  1    with the air chamber in a deflated condition, according to an exemplary embodiment. 
         FIG.  4    is another partial perspective view of the exercise and therapeutic device of  FIG.  1    with the air chamber in a deflated condition, according to an exemplary embodiment. 
         FIG.  5    is a depiction of user shorts for use with the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  6    is a side view of a leg for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  7    is a block diagram of a controller of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  8    is a flowchart of a process of operating the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIGS.  9 - 12    are depictions of charts that provide guidance to a user or other person(s), such as a physical therapist, for operating the exercise and therapeutic device of  FIG.  1   , according to exemplary embodiments. 
         FIG.  13    is a side view of a first alternative height adjustment mechanism, shown as a pin lock, for use with the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  14    is a side view of the exercise and therapeutic device of  FIG.  1    including the pin lock of  FIG.  13   , according to an exemplary embodiment. 
         FIG.  15    is a side view of a second alternative embodiment of a height adjustment mechanism of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  16    is a rear view of a third alternative embodiment of a height adjustment mechanism of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  17    is a side view of a fourth alternative embodiment of a height adjustment mechanism, of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  18    is a perspective view of a fifth alternative embodiment of a height adjustment mechanism of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  19    is a top view of the fifth alternative embodiment of a height adjustment mechanism of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  20    is a rear view of a sixth alternative embodiment of a height adjustment mechanism of the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  21    is a side view of the sixth alternative embodiment of the height adjustment mechanism of  FIG.  20   , according to an exemplary embodiment. 
         FIG.  22    is close-up view of the sixth alternative embodiment of the height adjustment mechanism of  FIG.  20   , according to an exemplary embodiment. 
         FIG.  23    is a side view of seventh alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  24    is a side view of an eighth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  25    is a side view of a ninth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  26    is a side view of a tenth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  27    is a side view of a eleventh alternative embodiment a height adjustment mechanism for an exercise and therapeutic device, according to an exemplary embodiment. 
         FIG.  28    is a perspective view of a first alternative embodiment of an exercise and therapeutic device, according to an exemplary embodiment. 
         FIG.  29    is a side view of a twelfth alternative embodiment of a height adjustment mechanism for an exercise and therapeutic device, according to an exemplary embodiment. 
         FIG.  30    is a side view of a thirteenth alternative embodiment of a height adjustment mechanism for an exercise and therapeutic device, according to an exemplary embodiment. 
         FIG.  31    is a side view of a fourteenth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device of  FIG.  1   , according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS.  1 - 4   , an exercise and therapeutic device  100  is shown in an inflated state, according to an exemplary embodiment. The exercise and therapeutic device  100  includes a treadmill and an offloading system which, in general, beneficially supports at least a portion of the user&#39;s body weight while the user walks, jogs, runs, or otherwise uses the treadmill. As a result, the weight reduction or offloading system reduces the stresses and forces experienced by the user during use of the treadmill. The exercise and therapeutic device  100  is therefore well suited for rehabilitation and injury prevention applications. However, the exercise and therapeutic device  100  is also well suited for exercise applications (e.g., cardiovascular exercises, workout programs, training programs, and the like). As shown, the exercise and therapeutic device  100  includes a treadmill  102  having a treadmill frame  103 , a handrail assembly  104  coupled to the frame (e.g., handrail structure, guide rail, etc.), a user console  106  coupled to the treadmill frame  103 , an offloading system  108  including an air chamber  130  coupled to the treadmill  102 , and a controller  110 .  FIGS.  1 - 2    show the exercise and therapeutic device  100  with the air chamber  130  in an inflated condition, while  FIGS.  3 - 4    show the exercise and therapeutic device  100  with the air chamber  130  in a deflated condition. 
     Treadmill  102  includes a running belt  112  coupled to the frame  103  and a treadmill motor  114  (shown in  FIG.  7   ) adapted to drive rotation of the running belt  112 . In the embodiment shown, the running belt  112  is structured as a slatted running belt including a pair of endless or continuous loops with a plurality of slats that couple to each endless loop. The slats are positioned substantially perpendicular to the longitudinal length of the treadmill  102 . The endless loops may engage with front and rear running belt pulleys (not shown). In another embodiment, the running belt  112  is a continuous loop running belt and the running belt  112  is driven or rotated by the treadmill motor  114 . The treadmill motor  114  is controllable by the controller  110  to rotate the running belt  112  at various speeds in a longitudinal direction, simulating movement of the running surface from a front end  116  of the treadmill  102  to a rear end  118  of the treadmill  102 . The treadmill  102  is thereby configured to allow a user to walk, jog, run, etc. on the treadmill  102  towards the front end  116  at various speeds while remaining stationary relative to the exercise and therapeutic device  100  and the surrounding environment. In some embodiments, the treadmill motor is also configured to rotate or allow rotation of the running belt  112  in the reverse direction to allow a user to walk, jog, run, etc. backwards (i.e., towards the rear end  118 ) while remaining stationary relative to the exercise and therapeutic device  100 . In an alternate embodiment, the running belt  112  may be manually powered or driven (i.e., motor-less, where rotation of the running belt  112  is caused solely by the user). 
     The treadmill frame  103  is an assembly of elements such as longitudinally-extending, opposing side members. The treadmill frame  103  is structured to support a front shaft assembly positioned near a front end of the frame, and a rear shaft assembly positioned near the rear end of frame. In some embodiments, a first plurality of bearings are coupled to and extend generally longitudinally along the first (e.g., right) side member of the frame, while a second plurality of bearings are coupled to and extend generally longitudinally along the second (e.g., left-hand) side member of the frame. The pluralities of bearings are substantially opposite each other about the longitudinal axis of the treadmill  102 . The treadmill frame  103  may support, at least partly, many of the components described herein, such as the running belt  112 , handrail assembly  104 , and so on. In some embodiments, the treadmill frame  103  is supported on a base that includes actuators controllable to vary an inclination of the treadmill  102 . 
     The handrail assembly  104  as shown in  FIGS.  1 - 4    includes substantially parallel guiderails  120  that extend from proximate the rear end  118  of the treadmill  102  towards the front end  116 . The handrail assembly  104  is coupled to the treadmill frame  103 . A user may grasp or otherwise engage with the handrail assembly  104  during usage of the device  100  to at least partly support or stabilize himself or herself during use of the treadmill. 
     The user console  106  (e.g., input/output device, display device, etc.) is coupled to the treadmill frame  103  and is positioned proximate the front end  116  of the treadmill  102 , and vertically above the running belt  112 . Particularly, the user console  106  is disposed at a vertical height and orientation suitable for interaction with a user standing, walking, running, and otherwise using the device  100 . The user console  106  is configured to provide information about operation of the exercise and therapeutic device  100  to a user and to receive one or more inputs from a user relating to operation of the exercise and therapeutic device  100 . According to various embodiments, the user console  106  includes one or more of a touch-screen display, a digital display, buttons, knobs, number pads, switches, speakers, and/or other input or output devices. In certain embodiments, the user console  106  includes one or more jacks/ports (e.g., USB, headphone jack, power adapter, etc.) that facilitate the coupling of remote devices (e.g., headphones, phones, tablets, etc.) with the user console  106  and exercise and therapeutic device  100 . The user console  106  is coupled to the controller  110 , such that information may be exchanged with the controller  110 . In the example of  FIG.  2   , the device  100  is shown to also include a second display screen  107 . In such an embodiment, the second interface device  107  can display information and receive user inputs relating to operation of the offloading system  108  while the user console  106  can display information and receive user inputs relating to operation of the treadmill motor  114 . 
     In some embodiments, the treadmill  102  is configured in accordance with the disclosure of U.S. patent application Ser. No. 14/832,708, filed Aug. 21, 2015, the entire disclosure of which is incorporated by reference herein. For example, the running belt of the treadmill  102  may have a curved shape/running surface (i.e., a non-planar running surface). The running belt may be constructed from slats and endless loops and supported, at least partially, by longitudinally extending pluralities of bearings coupled to the treadmill frame in accord with this application. In such embodiments, the motor  114  may be omitted, such that the treadmill  102  is manually powered (i.e., rotation of the running belt is caused solely from manual power). A measurement of the speed of the treadmill  102  may be used as an input to a control strategy, therapy routine, etc. for the offloading  108 . 
     In some embodiments, the treadmill  102  is configured in accordance with the disclosure of or U.S. patent application Ser. No. 15/966,598, filed Apr. 30, 2018, the entire disclosure of which is incorporated by reference herein in its entirety. For example, the treadmill  102  may include an electrical power generator coupled to the running belt  112  and configured to convert rotational motion of the running belt  112  into electrical power. In such embodiments, the electrical power generated by the electrical power generator can be used to power one or more components of the exercise and therapeutic device  100 , such as the pump  142  described below. Accordingly, in such embodiments, the treadmill  102  is configured to provide some or all of the electrical power consumed by the offloading system  108 . This configuration may be beneficial in environments where conservation of energy is desired, such that electrical power for the device  100  is not completely provided by a wall outlet or other external power source. 
     In some embodiments, the treadmill  102  is configured in accordance with the disclosure of U.S. patent application Ser. No. 15/640,180, filed Jun. 30, 2018, the entire disclosure of which is incorporated by reference herein. For example, the treadmill  102  may be configured to provide a non-motorized mode, a motorized mode, a brake mode, and a torque mode as described therein. By providing the non-motorized mode, motorized mode, brake mode, and/or torque mode in combination with weight offloading provided by the offloading system  108  as described below, a wide variety of therapeutic options may be provided, for example as part of a therapy routine described below with reference to  FIGS.  7 - 8   . For example, the controller (described below) is configured to provide a control instruction or signal to the motor to output a braking torque according to the processes described in the aforementioned referenced application. The braking torque is applied to the running belt. As a result, rotational movement of the running belt is restricted. This resistive mode of operation of the treadmill may be beneficial for users of the device  100  for strength training via the resistive mode while at least some of their weight is offloaded, which may reduce stresses from impacts associated with using the treadmill. 
     The offloading system  108  (weight offloading system, harnessing system, suspension system, and the like) is configured to offload a user&#39;s weight (or a portion thereof) while the user is using the exercise and therapeutic device  100 . In this regard, the offloading system  108  at least partially supports a user above the treadmill  102  to offload a portion of the user&#39;s weight (i.e., to bear a portion of the user&#39;s weight), which in turn reduces the impact forces and stresses experienced by the user as the user walks, runs, and otherwise uses the exercise and therapeutic device  100 . While the person is partially supported, suspended, offloaded, etc., it should be understood that the user is still in contact/capable of being contact with the treadmill  102 , particularly, the running belt  112 . The offloading system  108  includes a fluid or air chamber  130  (e.g., air chamber, inflatable enclosure, etc.) that is selectively inflatable/deflatable, a user seal  134  coupled to the chamber  130 , a user seal frame  136  positioned adjacent to the chamber  130 , a pair of front racks  138  (e.g., front ladders) and a pair of rear racks  140  (e.g., rear ladders) positioned adjacent to the chamber  130 , and a pump  142  fluidly coupled to the air chamber  130 . As described in detail below, the air chamber  130  is selectively inflated by the pump  142  to support a user sealed into the user seal  134  at a height determined in part by the position of the user seal frame  136  on the front racks  138  and the rear racks  140 , while the user&#39;s lower body extends into the air chamber  130  to walk, run, etc. on the treadmill  102 . 
     As shown, the air chamber  130  surrounds the running belt  112 . The air chamber  130  may also surround one or more other components of the exercise and therapeutic device  100 . The air chamber  130  is coupled to the treadmill frame  103 . In particular, the air chamber  130  is coupled to the handrail assembly  104  by, in this example, straps  144  and loops  146 . The straps  144  couple the air chamber  130  to the handrail assembly  104  proximate the front end  116 , where the coupling point is vertically below the user console  106 . While the air chamber  130  is deflated, the straps  144  at least partially suspend, lift, or otherwise hold the air chamber  130  up to prevent the air chamber  130  from collapsing upon itself in an adverse manner that could cause damage to the air chamber  130 . Thus, the use of the straps  144  may improve durability of the air chamber  130  through repeated uses of the device  100 . In other embodiments, different coupling mechanisms between the air chamber  130  and the frame  103  may be used (e.g., Velcro, cables/wires, etc.), such that the depicted implementation is not meant to be limiting. In an alternate embodiment, the use of straps or another device to hold, at least partially, the air chamber up above the treadmill base when the air chamber is deflated or substantially deflated is excluded. 
     The air chamber  130  is structured to be flexible and substantially resistant to stretching. In particular, the air chamber  130  includes a substantially air impermeable membrane that prevents air from passing therethrough. As such, upon inflation, the air chamber  130  retains/holds or substantially retains the air that is pumped into the air chamber  130  to create an area of increased air pressure which is used to at least partially offload some weight of the user. The air chamber  130  may be constructed from any one or more of a variety of materials including, but not limited to, vinyl, rubber, plastic, and/or any combination thereof In the example shown, the air chamber  130  includes a plurality of windows that facilitate other non-users (and, the user) to peer into the air chamber  130  while the user is using the device  100 . Beneficially and for therapeutic uses, others (e.g., physicians, physical therapists) may then observe, catalog, diagnose, and otherwise track, e.g., gait or rehabilitation progress of the user. In an alternate embodiment, the windows are removed such that the air chamber  130  is non-see through. 
     The user seal  134  defines an opening  148  in the air chamber  130  and includes a sealing element or sealer  150 . When the air chamber  130  is inflated, the opening  148  may be positioned substantially centrally above the running belt  112  (i.e., above a midpoint of a longitudinal length of a running surface and above a midpoint of the width of the running surface) and is configured to allow a portion of a user&#39;s body, for example a user&#39;s feet, legs, and hips, to pass through the opening  148  into the air chamber  130  while the remainder of the user remains outside the chamber. The opening  148  may be substantially circular as shown, or may be any other shape suitable to receiving a user. The sealer  150  is configured to create a substantially air-tight seal between the user and the air chamber  130  to prevent the flow of air through the opening  148 . More particularly, the sealer  150  couples user shorts  300  (shown in  FIG.  5    and described in detail with reference thereto) to the air chamber  130 , while the user shorts  300  are configured to substantially seal around the user&#39;s body. In the embodiment shown, the sealer  150  is a zipper which mates with a complementary zipper of the user shorts  300  (e.g., zipper  304  shown in  FIG.  5   ). A flap or other covering may be included to cover the zippers to reduce a rate of air leakage through the zippers. In other embodiments, the sealer  150  is a Velcro connection, a button connection, a buckle connection (e.g., a belt and buckle connection), and/or a strap connection (straps on one of the user shorts or user seal are received in hoops or loops in the other of the user shorts or user seal), etc. When the opening  148  receives a user wearing user shorts  300  sealed to the air chamber  130  by sealer  150 , the air chamber  130  is substantially air tight and the user&#39;s waist is preferably aligned with the user seal  134 . 
     The user seal frame  136  (bar, rod, tube, etc.) is coupled to the air chamber  130  and substantially surrounds the user seal  134 . The user seal frame  136  includes a girdle  152  (i.e., a closed perimeter structure; in other embodiments, the perimeter structure need not be closed perimeter and may include one or more openings) coupled to a pair of front arms  154  and a pair of rear arms  156 . In the embodiment shown, the girdle  152  has an irregular hexagonal shape, while other shapes are possible in various embodiments (circular, elliptic, triangular, rectangular, pentagonal, etc.). Front pegs  158  extend laterally outward and away from the front arms  154  and rear pegs  160  extend laterally outward and away from the rear arms  156 . The user seal frame  136  is configured to provide structural support to the air chamber  130  by constraining an amount of inflation expansion of the air chamber. The user seal frame  136  is also configured to enable a vertical height adjustment of the user seal  134  relative to the running surface of running belt. More particularly, as described in detail below, the front pegs  158  and the rear pegs  160  engage the front racks  138  and the rear racks  140 , respectively, to control the relative height of the user seal  134  in relation to the running belt  112  (i.e., a distance between the user seal  134  and the running belt  112 ). Thus, taller users may desire to have the user seal positioned vertically higher from the running surface of the running belt than shorter users. Placing the user seal frame  136  into various positions of the front and rear racks allows control of the height of the user seal to accommodate various user heights. 
     The front racks  138  are positioned proximate (at or near/close) the front end  116  of the device  100  and are coupled to the handrail assembly  104  before the user console  106  (i.e., the user console  106  is disposed closer to a front of the device  100 , while the front racks  138  are disposed relatively closer to a rear end of the device  100  than the user console  106 ). As shown in  FIGS.  1 - 4   , the front racks  138  extend vertically upwards (i.e., away from the running belt  112 ) from the handrail assembly  104 . In the embodiment of  FIGS.  1 - 4   , each front rack  138  includes a series of notches  162  (e.g., openings, etc.) positioned at various vertical heights away from the running surface of the running belt  112 . While each front rack  138  is shown to include nine notches  162 , it should be understood that any suitable spacing and number of notches  162  is possible. In one embodiment, the notches  162  are labelled (e.g., named, numbered) to identify each notch  162  in the series of notches  162 . For example, the lowest notch  162  may be “1” with the remaining notches  162  labelled as integers up through “9” for the highest notch  162 , or vice versa. As another example, each notch  162  may be labelled based on a distance of the notch  162  from some landmark, such as from the lowest notch  162  or from the running surface of the running belt  112 . The notches  162  of the respective pair of front racks  138  are preferably aligned, such that each notch  162  on one of the front racks  138  corresponds to a notch  162  at the same height above the running belt  112  on the other front rack  138 . Corresponding notches  162  may have the same label. 
     The notches  162  are configured to receive the front pegs  158  (e.g., protrusions, members, extensions, etc.). The user seal frame  136  is structured such that the front pegs  158  simultaneously fit in corresponding notches  162  (i.e., in notches  162  at the same height on both front racks  138 ). In some embodiments, the front racks  138  and the user seal frame  136  are configured to prevent the front pegs  158  from being simultaneously received by two notches  162  at different heights relative to a support or ground surface for the device  100  (e.g., a first notch  162  on one front rack  138  and a lower notch  162  on the other front rack  138 ). 
     Each front rack  138  also includes a retaining member or gate  164  (e.g., latches, levers, etc.) which are coupled, particularly rotatably coupled, to the corresponding front racks  138 . The gates  164  are rotatable between an open position to allow the front pegs  158  to be freely inserted into or removed from the notches  162  and a closed position to confine the front pegs  158  in the notches  162 . A locking mechanism may be included to releasably secure the gates  164  in the closed or open positions. 
     The rear racks  140  are positioned along the sides of the treadmill  102  between the front end  116  and the rear end  118 . The rear racks  140  are coupled to the treadmill frame  103  on opposing transverse sides of the running belt  112 , such that the rear racks  140  are disposed on the sides of the user while the user is using the device  100  (proximate each of the user&#39;s arms when the user is facing the console  106 ). The rear racks  140  are substantially parallel to the front racks  138  and each rear rack  140  includes a series of notches  168  positioned at various vertical heights relative to the treadmill  102 . As shown, each rear rack  140  includes nine notches  168 , while any suitable spacing and number of notches  168  is possible. The notches  168  are labelled (e.g., named, numbered) to identify each notch  168  of the series of notches  168 . For example, the lowest notch  168  may be “9” with the remaining notches  168  labelled as integers down through “1” for the highest notch  168 , or vice versa. As another example, each notch  168  may be labelled based on a distance of the notch  168  from some landmark, such as the lowest notch  168 , the running belt  112 , or a support or ground surface for the device  100 . The notches  168  align across the pair of rear racks  140 , such that each notch  168  on one of the rear racks  140  corresponds to a notch  168  on the other rear rack  140  at the same height above the treadmill  102 . Corresponding notches  168  may have the same label. 
     The notches  168  are configured to receive the rear pegs  160  (e.g., protrusions, members, extensions, etc.). The user seal frame  136  is structured to allow the pair of rear pegs  160  to simultaneously be received by two corresponding notches  168  (i.e., one notch  168  on each rear rack  140 ). In some embodiments, the rear rack  140  and the user seal frame  136  are configured to prevent the rear pegs  160  from being simultaneously received by two notches  168  at different heights off the treadmill  102  (e.g., a first notch  168  on one rear rack  140  and a higher notch  168  on the other rear rack  140 ). 
     The rear rack  140  and the front rack  138  are positioned such that a pair of notches  168  of the rear rack  140  receive the pair of rear pegs  160  while the notches  162  of the front rack simultaneously receive the front pegs  158 . When the pair of rear pegs  160  is received by a pair of notches  168  and the front pegs  158  are received by a pair of notches  162 , the user seal frame  136  is fixed at a particular height (i.e., a vertical displacement) in relation to the treadmill  102 . When the air chamber  130  is inflated as described below, the fixed height of the user seal frame  136  confines the expansion air chamber  130  near the user seal  134  to establish the approximate height of the user seal  134 . Thus, the front pegs  158  and the rear pegs  160  are moveable to different notches  162  and notches  168  to adjust the height of the user seal  134  relative to the running surface, for example to set the user seal  134  at roughly the height of the user&#39;s waist. The rear rack  140 , the front rack  138 , and the user seal frame  136  are thereby configured to adjust the distance between the user seal  134  and the running belt  112  to accommodate the various heights of various users. 
     When describing the various relative heights with respect to the running belt  112 , it should be understood that this is meant to mean the height from a point that is vertically substantially perpendicular from the running surface of the running belt  112  and the designated component (i.e., a straight vertical line distance between the designated component and the corresponding point on the running belt). However, other landmarks may also be used to define various relative heights, such as from a support or ground surface to the designated component. Further, other points on the running belt  112  may also be used in place of the vertically perpendicular point. For example, a longitudinal center of the running belt  112  may also be used as the reference point. All such variations are intended to fall within the scope of the present disclosure. 
     The pump  142  is configured to selectively pump, force, direct, or move air or other fluid into the air chamber  130 . The pump  142  is operable to inflate the air chamber  130  and to control the air pressure in the air chamber  130  above atmospheric pressure. At a typical operating pressure above atmospheric pressure, the air chamber  130  has a substantially consistent volume, as the air chamber  130  is resistant to stretching. Thus, as more air is added to the air chamber  130  after full inflation, the air pressure in the air chamber  130  increases beyond atmospheric pressure. Some amount of air leakage out of the air chamber  130  may be likely in these conditions, which necessitates the periodic operation of the pump  142  to replace the leaked air and maintain a certain air pressure within the chamber  130 . 
     More particularly, the pump  142  is configured to controllably vary the air pressure in the air chamber  130 . In this regard, the pump  142  includes a motor operable at a variable power to push air at a higher or lower rate into the air chamber  130 . Because some amount of air may leak out of the air chamber  130 , the motor may operate at a roughly consistent power to maintain the air pressure at a particular pressure (i.e., to push in air at a rate equivalent to the leakage). To increase the air pressure, the power of the pump motor is increased to cause the pump  142  to provide air to the air chamber  130  at a higher rate, i.e., faster than air can leak out of the air chamber  130  as the amount of air in the air chamber  130  increases, the air pressure in the air chamber  130  similarly increases. To decrease the air pressure, the power of the pump motor is decreased or terminated such that air leakage out of the air chamber  130  exceeds the rate of air pumped into the air chamber  130  by the pump  142 . In some embodiments, the pump  142  is configured to reverse directions to actively pump air out of the air chamber  130  to proactively decrease pressure. In some embodiments, a vent is opened through the air chamber  130  (e.g., vent hole) to facilitate a decrease in pressure. 
     In some embodiments, the pump  142  includes a pressure sensor disposed within the air chamber  130  that measures the air pressure inside the air chamber  130 . In some embodiments, a strain gauge, pressure-sensing bladder, load cell, and/or other sensor configured to measure a pressure, strain, or force on the air chamber  130  is included. For example, a strain gauge may be positioned on the air chamber  130  and measure a degree of curvature of the air chamber  130  that may correlate to pressure. As another example, the pressure sensing bladder may be positioned within the air chamber and measure pressure based on deformation of the bladder. As another example, a load cell may be positioned outside of the air chamber  130  and between the air chamber  130  and a solid surface (e.g., an element of the treadmill frame  103 ) such that the load cell can measure an outward force exerted by the air chamber  130 . In other embodiments, the air pressure inside the air chamber  130  is determined based on the amount of power required by the pump  142  to push a certain volume of air into the air chamber  130  (i.e., as the pressure increases, adding a certain amount of air gets harder). Using the measurements from one or more such sensors, a feedback control system may be used to control the air pressure in the air chamber  130 . 
     When a user is sealed into the user seal  134  and the pump  142  controls the air pressure in the air chamber  130  to exceed atmospheric pressure, the air pressure in the air chamber  130  pushes outward on the air chamber  130  to inflate the chamber. Part of the outward force on the air chamber  130  is transferred to the user via the physical contact between the user and user shorts  300 , which are coupled to the air chamber  130 , with the net force on the user direct up and away from the running belt  112 . Additionally, the air pressure may exert a force directly on the user (the part of the user disposed in the air chamber  130 ) that pushes the user up and away from the running belt  112 . A portion of the user&#39;s weight is thereby offloaded by the offloading system  108 . At higher air pressures in the air chamber  130 , more of the user&#39;s weight is offset by the offloading system  108  (i.e., increasing air pressure increases the amount of upward force exerted on the user). Thus, the portion of the user&#39;s weight offloaded by the offloading system  108  is controllable by varying the air pressure in the air chamber  130 . 
     Referring now to  FIG.  5   , user shorts  300  for use with the exercise and therapeutic device  100  are shown, according to an exemplary embodiment. Shorts  300  are available in a variety of sizes, for example extra-small, small, medium, large, extra-large, and extra-extra-large. Shorts  300  are configured to create a substantially airtight seal between shorts  300  and the user&#39;s skin. Shorts  300 , in cooperation with the user&#39;s body, thereby facilitate the creation of a substantially air-tight air chamber  130 . 
     Shorts  300  include waistband  302  configured to engage with sealer  150  (e.g., zipper, Velcro, buckles, buttons, etc.) of the user seal  134  to seal the shorts  300  to the air chamber  130  to substantially close the opening  148 . In the example shown, the waistband  302  includes a zipper  304  that facilitates connection of the shorts  300  to the sealer  150  in a proper position. Other connection mechanisms [e.g., buckles, buttons, Velcro (i.e., hook-and-loop fastener)] may be included in various embodiments. The shorts  300  are also shown to includes various straps configured to facilitate creation of a substantially airtight seal around the user and/or provide various other support to the user. Thigh straps  306  are positioned at a lower end of each leg of the shorts  300  and can be tightened around a user&#39;s thighs to reduce a rate of air leakage between the shorts  300  and the user. Waist strap  308  is positioned at waist region of the shorts  300  adjacent the waistband  302  and can be tightened to secure the shorts  300  to a user to resist displacement of the user relative to the shorts  300  during an exercise or therapy. Diagonal straps  310  extend from a hip region of the shorts  300  to an inner thigh region of the shorts  300  and may provide structural support. Outside straps  312  extend along opposing sides of shorts  300 . The diagonal straps  310  and the outside straps  312  can distribute forces across the shorts  300  to facilitate comfortable offset of a user&#39;s weight by the offloading system  108 . The various straps  306 - 312  can be adjusted to facilitate customization of the shorts  300  to match the physical dimensions of each of a variety of users. 
     Referring now to  FIG.  6   , a leg  400  for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. In the example depicted, the device  100  includes a plurality of legs  400  (in this example, four) that are coupled to the treadmill frame  103  and structured to support the treadmill frame  103  and, in turn, device  100  above a support surface for the device  100 . The legs are adjustable in height relative to the support surface in order to increase or decrease an incline of the device  100 . As shown, the leg  400  includes a threaded shaft  402 , a foot  404  extending from a bottom end  406  of the leg  400 , and a gasket assembly  408  positioned along the threaded shaft  402 . The threaded shaft  402  extends through an aperture or hole in the air chamber  130 , such that the foot  404  is positioned outside the air chamber  130  while the top end  410  of the threaded shaft  402  is positioned within the air chamber  130 . 
     The foot  404  may be rotated in order to adjust a distance from the foot  404  relative to the treadmill frame  103  to, in turn, adjust a height (incline, decline, parallel or substantially parallel) of the frame  103  relative to the support surface. As mentioned above, the exercise and therapeutic device  100  includes multiple legs  400 , such that threaded shafts  402  facilitate the adjustment of the offsets to help level the treadmill  102  and prevent the exercise and therapeutic device  100  from wobbling, feeling unsteady, etc. In some embodiments, the leg  400  includes a spacer  411  that provides structural support to the threaded shaft  402 . 
     The gasket assembly  408  substantially seals the hole in the air chamber  130  that the threaded shaft  402  extends through to reduce the likelihood of air escaping or leaking from the air chamber  130  through the hole. The gasket assembly  408  includes a pair of gasket washers  412 , a pair of washers  414 , and a pair of hex nuts  416 . The gasket washers  412  are positioned on either side of the air chamber  130  (i.e., external or outside of the air chamber and internal or inside of the air chamber such that the washers  412  sandwich a portion of the air chamber adjacent the hole), the washers  414  are positioned on either side of the pair of gasket washers  412 , and the hex nuts  416  are positioned on either side of the pair of washers  414 . Each washer  414  abuts a gasket washer  412  and a hex nut  416 . The gasket washers  412  have an external radius greater than the radius of the hole through the air chamber  130  that receives the threaded shaft  402 . To seal the hole through the air chamber  130  that receives the threaded shaft  402 , the hex nuts  416  are tightened towards each other, squeezing the pair of washers  414  together, which in turn squeezes the pair of gasket washers  412  together against the air chamber  130 . The gasket washers  412  are thereby sealed against the air chamber  130 , preventing or substantially preventing airflow out of the air chamber  130  through the gasket assembly  408 . 
     Applicant has determined that during inflation and while the air chamber  130  is inflated, there exists the possibility that the air chamber  130  lifts or otherwise reduces stability of the device  100 . In these situations, the air chamber is inflated to such a degree that the bottom of the chamber bears against the surface supporting the treadmill (e.g., the floor of a room) and begins to offload the treadmill itself. By piercing the legs through the air chamber  130  in a manner that still ensures the integrity of the air chamber  130  (i.e., preventing or substantially preventing leaks), the effect of the air chamber  130  causing the device  100  to “walk” or be unstable is substantially reduced/alleviated. As a result, the leg  400  structure described herein improves the usability of the device  100 . 
     The controller  110  is configured to control, manage, and otherwise operate various components of the exercise and therapeutic device  100  including the pump  142 , the treadmill motor  114 , and the user console  106 . In the case primarily described herein with the treadmill being a motorized treadmill (as compared to a manually-powered treadmill), the controller  110  controls the pump  142  and the treadmill motor  114  in response to input from the user via the user console  106  and data provided by the pump  142  and/or the treadmill motor  114 . The configuration and functionality of the controller  110  is described in detail below with reference to  FIG.  7   . 
     Referring now to  FIG.  7   , a block diagram of the controller  110  is shown, according to an exemplary embodiment. More particularly,  FIG.  7    shows the controller  110  is coupled to the user console  106 , the pump  142 , and the treadmill motor  114 . It should be understood that the controller  110  may also be coupled to one or more sensors disposed or included with the device  100  (e.g., heart rate sensors, running belt speed sensors, pressure sensor for the air chamber, etc.). 
     The user console  106  provides information to a user of the exercise and therapeutic device  100  and receives information from the user and the controller  110 . The user console  106  includes both output elements (e.g., screens, speakers, displays) and input elements (e.g., touchscreen, buttons, knobs, keyboards). One or more permanent markings on the user console  106  may be included to help to communicate the meaning of digital output elements to the user (e.g., permanent field labels like “speed”, “level”, “time”, “distance” positioned next to digital displays of numbers). The user console  106  is communicably coupled to the controller  110  to receive data from the controller  110 , for example a graphical user interface generated by the controller  110 , and to send data to the controller  110  as input by a user, for example a user&#39;s short size, a user&#39;s waist size, a frame height setting, a pressure scale level selection, and a treadmill speed. 
     As discussed above, the pump  142  operates at various pump operating capacities (e.g., pump motor powers, pump airflow rates) to selectively pump air from the external environment into the air chamber  130 . The pump  142  is configured to vary the pump operating capacity as instructed by the controller  110  (e.g., via an operating parameter of the motor that drives the pump, such as power, voltage, pump frequency, etc.). In one embodiment, the pump is also configured to provide a pressure measurement or estimate or determination to the controller  110 , for example as measured by a pressure sensor disposed within the air chamber  130  or strain gauge positioned on the air chamber  130 . The pressure measurement may also be generated in some other way, for example by comparing the operating power of the pump with a rate of airflow provided to the air chamber  130 . Accordingly, the pump  142  is communicably coupled to the controller  110  to receive a pump operating capacity command from the controller  110  and provide a pressure measurement to the controller  110 . 
     The treadmill motor  114  is controllable by the controller  110  to drive the running belt  112  at various speeds. The treadmill motor  114  may be an electrical motor that engages the running belt  112  (e.g., via a shaft) to cause the running belt  112  to move a proportional distance for each revolution of the treadmill motor  114 . The controller  110  compares this proportional distance and the electrical motor revolutions to store a calibration of how the rate of revolutions of the treadmill motor  114  corresponds to the speed of the running belt  112 , which information may be provided to the user via the user console  106 . In such embodiments, the controller  110  controls the rate of revolution of the treadmill motor  114  to provide these various desired simulated running/walking speeds to the user, for example in response to a user request to run at a certain speed input via the user console  106 . 
     The controller  110  is structured to control the pump  142  and the treadmill motor  114  to facilitate the functions of the exercise and therapeutic device  100  described herein. In the example shown, the controller  110  includes processing circuit  500 , user interface circuit  502 , pump control circuit  504 , and therapy routine circuit  510 . 
     The processing circuit  500  is structured to execute the computing and processing steps of the controller  110 . The processing circuit  500  includes memory  506  and processor  508 . The processor  508  may be implemented as one or more general-purpose processors, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital signal processor (DSP), a group of processing components, or other suitable electronic processing components. Processor  508  is configured to execute computer code or instructions stored in memory  506  or received from other computer readable media (e.g. CDROM, network storage, a remote server, etc.). Memory  506  (e.g., NVRAM, RAM, ROM, Flash Memory, hard disk storage, etc.) may store data and/or computer code for facilitating at least some of the various processes described herein. Memory  506  may include one or more devices (e.g. memory units, memory devices, storage device, etc.) for storing data and/or computer code and/or facilitating at least some of the various processes described in the present disclosure. In this regard, the memory  506  may include tangible, non-transient computer-readable medium. Memory  506  may be communicably connected to processor  508  via processing circuit  500  and may include computer code for executing (e.g., by processor  508 ) one or more processes described herein. When processor  508  executes instructions stored in memory  506 , processor  508  generally configures controller  110  to complete such activities. 
     The user interface circuit  502  is structured to generate user interface elements for display by the user console  106 , and receives input from a user or other person via the user console  106 . In some embodiments, the user interface circuit  502  generates a graphical user interface that is displayed via user console  106 . In some embodiments, the user interface circuit  502  generates a digital display signal that controls digital display elements (e.g., LED lights) that can be turned either on or off selectively to create characters (e.g., symbols, images, etc.) on the user console  106 . In general, the user interface circuit  502  generates an output in any format compatible with the hardware included with user console  106 . As described in detail with reference to  FIG.  8   , the user interface provided on the user console  106  as controlled by the user interface circuit  502  can prompt and accept user input of a user&#39;s short size, a user&#39;s waist size, a frame height setting, and a pressure scale level, and a treadmill speed. 
     The pump control circuit  504  is structured to control the pump  142  in response to inputs from the pump  142  and the user console  106 . The pump control circuit  504  generates a pump operating capacity control signal to transmit to the pump  142  to cause the pump to operate at an operating capacity (e.g., power, frequency, etc.) determined by the pump control circuit  504  in response to inputs from the pump  142  and the user console  106 . As described in detail with reference to  FIG.  8   , the pump control circuit  504  uses any number of a variety of inputs including a user&#39;s short size, a user&#39;s waist size, and a frame height setting to associate user-selectable scale levels with air pressures for the air chamber  130  and generates a control signal for the pump  142  to control the pump  142  to bring the air chamber  130  to the air pressure associated with a user-selected scale level. In some embodiments, the pump control circuit  504  and/or memory  506  stores pressure-to-scale-level associations for various possible combinations of short size, waist size, and frame height setting to facilitate a look-up process. Accordingly, a pressure setpoint can be determined based on the user-selected scale level. In other cases, a default pressure value is used as the pressure setpoint (e.g., to enable a quick-start mode of the device  100 ). The pump control circuit  504  receives a pressure measurement from the pump  142  and/or a sensor (e.g., pressure sensor, strain gauge, etc.) and uses the pressure measurement in a control loop (e.g., feedback controller, proportional-integral, proportional-integral-derivative control) to control the pump  142  to maintain the air pressure within a band (e.g., acceptable range) around a pressure setpoint. The pump  142  is thereby controlled to provide and maintain a pressure in the air chamber  130  in accordance with a user-selected scale level. 
     In some embodiments, the pump control circuit  504  is configured to provide dynamic pressure adjustment that adjusts control of the pump  142  to account for changes in pressure attributable to user activity. For example, depending on whether a user is running, walking, jogging, skipping, etc. on the running surface, the user exerts various forces on the air chamber  130  (e.g., via user shorts  300 ) that may cause dynamic changes in the pressure in the air chamber  130 . For example, a running user may oscillate vertically relative to the device  100 , thereby causing repeating fluctuations of pressure in the air chamber  130 , while a user walking on the running surface may exert less forces and have less effect on the pressure in the air chamber  130 . The pump control circuit  504  may be configured to account for such differences, for example by receiving measurements of pressure fluctuations over time (e.g., from a pressure sensor disposed in the air chamber  130 , from a strain gauge positioned on the air chamber  130 , etc.) and using the pressure fluctuations to update the pressure setpoint (i.e., increase or decrease the pressure setpoint) to account for the user&#39;s influence on measured pressure. As another example, the pump control circuit  504  may be configured to filter out user-attributable pressure fluctuations (e.g., remove a repeating wave having a frequency corresponding to a running cadence of a user) from pressure measurements before such measurements are used for feedback control of the pump, thereby reducing noise in the measurement signal used for feedback control of the pump  142 . 
     The therapy routine circuit  510  is configured to facilitate coordination between the pump  142  and the treadmill motor  114  to provide therapy routines and/or other interactive behavior between the pump  142  and the treadmill motor  114 . As used herein, a “therapy routine” refers to a series of pressure setpoints and treadmill motor controls that guides a user through a therapy (e.g., rehabilitation program) or workout (e.g., exercise). The therapy routine circuit  510  is configured to provide a scale level or pressure setpoint to the pump control circuit  504  to cause the pump control circuit  504  to operate the pump  142  in accordance with the scale level or pressure setpoint. The therapy routine circuit  510  is also configured to control the treadmill motor  114  to vary the speed of the running belt  112 , start and stop the running belt  112 , change the direction of movement of the running belt  112 , provide resistance to user-driven motion of the running belt  112 , etc. The therapy routine circuit  510  is thereby configured to control both the amount user weight offloaded by the offloading system  108  and the movement of the running belt  112  (e.g., the speed at which a user is running, jogging, walking, etc. on the treadmill  102 ). This can include the resistive mode of operation of the treadmill as described above. 
     In some cases, the therapy routine circuit  510  may control the pressure level or setpoint to vary as a function of speed of the running belt  112  (e.g., a monotonically-increasing function), for example such that a larger portion of a user&#39;s weight is offloaded by the offloading system  108  at higher speeds of the running belt. In some embodiments, the therapy routine circuit  510  is communicable with a heart rate monitor, muscle oxygenation sensor, cadence sensor, fitness tracker, or other sensor or measurement of user activity or biological behavior. In such embodiments, the therapy routine circuit  510  may be configured to determine a pressure level and/or speed based on measurements of user activity (e.g., heart rate, muscle oxygenation, cadence, ground contact time, etc.), for example to maintain a user at approximately a preferred heart rate level or zone or to drive the user&#39;s heart rate to various zones in sequential intervals. 
     The therapy routine circuit  510  may store and execute various therapy routine programs that include control of both the pump  142  and the treadmill motor  114 , to dynamically vary the user weight offloaded by the offloading system  108  and the movement of the running belt  112  over a predesigned workout or therapy routine. For example, the therapy routine circuit  510  may be configured to provide intervals of various speeds of the running belt  112  in addition to intervals of various pressure settings (i.e., various weight offloads) for the offloading system  108  and/or gradually increase or decrease the speed and/or pressure. The therapy routine circuit  510  may be configured to receive customized therapy routine programs for particular users, for example from physical therapists, doctors, coaches, etc. for the users. The therapy routine circuit  510  may thereby facilitate unsupervised therapy using the device  100 . 
     As shown, the user interface circuit  502 , the pump control circuit  504 , and the therapy routine circuit  510  are a part of the controller  110 . In other embodiments, the user interface circuit  502 , therapy routine circuit  510 , and/or the pump control circuit  504  may be separate, discrete components relative to each other and the controller  110 . In this regard and in this configuration, at least one of the user interface circuit  502 , therapy routine circuit  510 , and the pump control circuit  504  may be positioned in different locations within or adjacent to the exercise and therapeutic device  100 . 
     It should be understood that the structures of the user interface circuit  502  and the pump control circuit  504  are highly configurable. In one configuration, one or both of user interface circuit  502  and the pump control circuit  504  are discrete processing components [e.g., each includes one or more of various processing components (e.g., processing and memory components, whereby the processor and memory may have the same or similar configuration as described above with respect to the memory  506  and processor  508 )], and may be structured as described above, such as one or more e.g., a microcontroller(s), integrated circuit(s), system(s) on a chip, etc. In another embodiment, one or more both of the user interface circuit  502  and the pump control circuit  504  may be structured as machine-readable media (e.g., non-transient computer readable medium that stores instructions that are executable by a processor or processors to perform at least some of the processes herein) that may be stored in the memory  506  and executable by the processor. This latter configuration may be appealing because of the “all-in-one” characteristic. In the example shown, each of the pump control circuit  504  and the user interface circuit  502  is structured as machine-readable media. However, and in the spirit of the disclosure herein, this exemplary configuration is not meant to be limiting (i.e., one or both of these components may be separate and discrete processing components). 
     Referring now to  FIG.  8   , a flowchart of a process  800  of operating the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. The process  800  may be at least partly implemented by the controller. At step  802 , the device  100  boots up (e.g., turns on, enters an active mode, awakens from standby), for example in response to a user request made via user console  106  (e.g., the push of a button, flip of a switch). At the time of boot up, user shorts  300 , worn by a user, are secured into the user seal  134 , the front pegs  158  of the user seal frame  136  are received by the desired pair of notches  162 , the rear pegs  160  are received by the desired pair of notches  168 , and the air chamber  130  is deflated. That is, the exercise and therapeutic device  100  is in the state shown in  FIG.  4   , with the addition of a user sealed into the user seal  134 . Additionally, in the example of  FIG.  7   , at step  802  the user console  106  provides the user with an option to enter a quick start mode or an advanced options mode. 
     At step  804 , the advanced options mode is selected. Upon selection, advanced options are provided to the user on the user console  106 . The user interface circuit  502  of the controller  110  generates user interface elements and transmits those user interface elements to the user console  106  to communicate the advanced options to the user by displaying the advanced options on the user console  106 . The advanced options and the advanced options mode are described below with reference to steps  806 - 824 . The following steps  806 - 824  describe one possible mode of advanced options provided by the exercise and therapeutic device  100 . 
     At step  806 , the user console  106  prompts the user to enter the user&#39;s short size and accepts input of the user&#39;s short size from the user. The user&#39;s short size is the size of the user shorts  300  configured to seal the user into the user seal  134  (e.g., XS, S, M, L, XL, XXL). In an embodiment where the user console  106  includes a touchscreen, for example, at step  806  the user interface circuit  502  generates a graphical user interface that includes user-selectable short size options and transmits the graphical user interface to the user console  106 . The user console  106  receives a user selection of a short size option and transmits the user&#39;s short size selection to the controller  110 . 
     At step  808 , the user console  106  prompts the user to enter the user&#39;s waist size and accepts input of the user&#39;s waist size from the user. The user&#39;s waist size is the circumference of the user&#39;s waist (i.e., a distance measured around the user at the user&#39;s waist). In some embodiments, the user&#39;s waist size correlates to a user&#39;s short size, with greater precision. For example, users with a short size of large (“L”) may have waist sizes ranging between 32 inches and 36 inches, while the waist size may be entered into the user console  106  with specificity to the inch or fraction of an inch (e.g., 34.5 inches) or other unit of distance (e.g., centimeters). In an embodiment where the user console  106  includes a touchscreen, for example, at step  806  the user interface circuit  502  generates a graphical user interface that includes user-selectable waist size options (e.g., a number pad to enter a waist size, a scrollable list of waist sizes) and transmits the graphical user interface to the user console  106 . In some embodiments, the user console  106  includes arrow buttons that allow the user to scroll through a list of selectable waist sizes presented on a digital display, and a select button to select a waist size from the list. The user console  106  receives a user selection of the user&#39;s waist size and transmits the user&#39;s waist size to the controller  110 . 
     At step  810 , the user console  106  (via the interface circuit) prompts the user to enter the frame height setting and accepts input of the frame height setting from the user. The frame height setting is the determined by the notches  162  that receives the front pegs  158  and/or the notches  168  that receives the rear pegs  160 , and more particularly by the labels associated with the notches  162  and/or the notches  168 . For example, in some cases, if the front pegs  158  are in notches  162  labelled “7”, the frame height setting is “7.” As another example, in some cases, if the rear pegs  160  are in notches  168  labelled “2”, the frame height setting is “2.” The user may be instructed (e.g., by a user interface on the user console  106 ) about whether to enter a rear frame height or a front frame height. In some embodiments, the front racks  138 , the rear racks  140 , and the user seal frame  136  are configured such that the rear pegs  160  and the front pegs  158  are restricted to fit into notches  168  and notches  162  with the same label, in which case that label is the frame height setting. 
     In an embodiment where the user console  106  includes a touchscreen, at step  806  the user interface circuit  502  generates a graphical user interface that includes user-selectable frame height setting options (e.g., a button corresponding to each possible frame height setting) and transmits the graphical user interface to the user console  106 . The user console  106  receives a user selection of the frame height setting and transmits the frame height setting to the controller  110 . In some embodiments, the front racks  138 , the rear racks  140 , and the user seal frame  136  include sensing elements configured to automatically detect the frame height setting and transmit the frame height setting to the controller  110 . 
     At step  812 , the pump control circuit  504  associates scale levels, for example denoted by an integer scale (e.g., 1-20), with air pressure setpoints (i.e., particular pressure values in mmHg, atm, Pascal, or other units of pressure) based on the various inputs such as the user&#39;s short size, the user&#39;s waist size, and/or the user&#39;s height setting. Notably, the user&#39;s weight is not used to control the amount of pressure in the air chamber and, in turn, the amount of weight offloaded from the user. This is advantageous in that less steps are used to begin operation of the device. Further, complicated control routines that may be prone to errors are avoided. In operation, the pump control circuit  504  assigns a different pressure (e.g., 2 atm, 3 atm) to each scale level (e.g., 5, 10) depending on the inputs of the short size, the user&#39;s waist size, and/or the user&#39;s height setting. Accordingly, the mapping of pressure setpoints to scale levels may be different for different short sizes, waist sizes, height settings, and combinations thereof. In other words, different pressure-to-scale maps are used/implemented based on the designations of one or more of: shorts size, waist size, height setting on the front and/or rear racks, and waist size. So, in operation, a scale input of 2 for a first pressure-to-scale map may result in a pressure value of X in the air chamber and a scale input of 2 for a second pressure-to-scale map may result in an pressure value of X+Y in the air chamber (where X and Y are non-zero). Thus, size differences in different users are accounted for in the pressure scale based on the inputs of one or more of the aforementioned inputs into the controller. The scale levels are selectable by a user to vary the air pressure in the air chamber  130 , and thus change amount of the user&#39;s weight that is offloaded by the offloading system  108 . Scale level association may allow the exercise and therapeutic device  100  to avoid offering air pressures a user that are too low (e.g., do not offload a noticeable amount of the user&#39;s weight by the offloading system) or too high (e.g., more than enough for all of the user&#39;s weight to be offloaded by the offloading system  108 ) for a particular user, and can center the scale on or provide more precise control around a predicted preferred pressure setpoint. 
     In some embodiments, the pump control circuit  504  generates the pressures for each scale level based on a pressure calculation algorithm (e.g., a mathematical relationship between the pressure scale levels and one or more of short size, waist size, or frame height setting). In other embodiments, the pump control circuit  504  stores pressure-to-scale-level mappings for all possible combinations of short size, waist size, and/or frame height setting. That is, based on the input of short size, waist size, and/or frame height setting for a current user, the pump control circuit  504  can identify the pressure-to-scale-level mapping associated with the one or more of short size, waist size, and frame height setting for the current user. The pump control circuit  504  can thereby select a suitable set of pressure setpoints at step  812 . 
     At step  814 , in one scenario, the user console  106 , via one or more commands from the interface circuit, prompts and accepts a user selection of a scale level. The scale level may be selectable on the user console  106  by using arrow buttons to scroll up and down through the scale levels. When the user selects a scale level, the selection is transmitted to the controller  110 . 
     At step  816 , the pump control circuit  504  controls the pump  142  to establish and maintain the air pressure in the air chamber  130  at the pressure associated with the user or attendant-selected scale level. For example, the controller  110  may generate a pump operating capacity command and transmit the command to the pump  142  to cause the pump  142  to operate a particular capacity. When a pressure sensor of the pump  142  detects that the pressure has reached the pressure associated with the user-selected scale level, the controller  110  adjusts the pump operating capacity command to instruct the pump  142  to lower the pump operating capacity (i.e., to pump less air into the air chamber  130 ). A control loop may be established to maintain the air pressure measured for the air chamber  130  within a threshold range of the pressure associated with the user-selected scale level. 
     At step  818 , the treadmill motor  114  is operated as commanded by a user or an attendant. For example, the user may indicate via the user console  106  that the user wants to walk at three miles per hour. That indication is transmitted to the controller  110 , which in turn controls the treadmill motor  114  to cause the running belt  112  to rotate at three miles per hour, for example based on a calibration stored by the controller  110 . The treadmill  102  is thereby controllable through a range of walking/running speeds. The treadmill  102  may also be controllable at step  818  to provide a resistance or torque in accordance with a command received from the user via the user console  106 . 
     In some cases, the process  800  returns to step  814  when the user selects a new scale level. At step  818 , the pressure in the air chamber  130  is modified to match the pressure corresponding to the newly-selected scale level by generating pump control signals at the controller  110  as discussed above. The treadmill motor  114  may automatically stop while the pressure is altered, or may continue to run the running belt  112  at a user-selected speed while the pressure is adjusted to match the newly selected scale level. 
     In another scenario, following step  812 , the user console  106 , via one or more commands from the user interface circuit  502  and information from the therapy routine circuit  510 , prompts and accepts a user selection of a therapy routine at step  822 . For example, a list of therapy routines stored by the therapy routine circuit  510  may be displayed on the user console  106 . The user may select a therapy routine from the list. 
     At step  824 , the therapy or exercise routine selected by the user provided by automatically controlling the pressure in the air chamber  130  and the behavior of the treadmill motor  114  in accordance with the selected therapy routine. The therapy routine circuit  510  can change the scale level over time and cause the pressure in the air chamber  130  to be controlled in accordance with such changes in the scale level. Because the advanced settings have been received in steps  806 - 812 , the scale levels applied by the therapy routine circuit  510  to execute the selected therapy routine may correspond to the height, waist size, and/or short size of the particular user. The therapy routine circuit  510  also controls the behavior of the treadmill motor  114  to provide various speeds of the running belt  112  and/or other behaviors over the duration of the selected therapy routine. 
     Returning to step  802 , in some scenarios a quick start mode is selected at step  826 . If the quick start mode is selected, a default set of pressure scale levels is used. The default set of pressure scale levels associates scale levels (e.g., levels 1-20) with pressure setpoints (pressure values), such that each scale level corresponds to a particular pressure setpoint. In some embodiments, the default scale levels are suitable for an average or median user (e.g., corresponding to the most common selections of short size, weight size, and/or frame height as described for steps  808 - 810 ). In some embodiments, the default scale levels are configured to provide a large range of pressure setpoints such that a suitable pressure level may be found for any user. 
     At step  828 , the user console  106 , via one or more commands from the user interface circuit  502 , prompts and accepts a user selection of a scale level. The scale level may be selectable on the user console  106  by using arrow buttons to scroll up and down through the scale levels. When the user selects a scale level, the selection is transmitted to the controller  110 . 
     At step  830 , the pump control circuit  504  controls the pump  142  to establish and maintain the air pressure in the air chamber  130  at the pressure associated with the user-selected scale level, for example as described above for step  816 . At step  832 , the treadmill motor  114  is controlled as commanded by a user. For example, the user may input a speed to the user console  106 , and, in response, the controller  110  controls the treadmill motor  114  to drive the running belt  112  at the user-selected speed. Steps  828  and  830  may be repeated indefinitely in accordance with user inputs to the user console  106 . 
     Following step  818 ,  832 , or  824 , at step  820 , the workout ends. A button or other user-selectable feature is included on the user console  106  to allow the user to indicate that the user wants to end the workout. In response, the controller  110  slows the treadmill motor  114  to a stop and commands the pump  142  to allow the air chamber  130  to deflate. In some embodiments, the pump  142  is controlled to proactively pump air out of the air chamber  130  to deflate the air chamber  130 . The exercise and therapeutic device  100  then turns off or enters a power saver or standby mode. 
     Step  820  may also include emergency stops that end the workout. For example, the workout may automatically be ended if pressure is lost in the air chamber  130  (e.g., due to a puncture, tear, unsealing, etc. of the air chamber  130 ). In such a case, the controller  110  may determine that the air pressure in the air chamber  130  as measured or otherwise determined by the air pressure sensor of the pump  142  is not responding as expected to the pump control signal, and, in response, control the treadmill motor  114  to stop the running belt  112  and turn off the pump  142  (e.g., to facilitate deflation of the air chamber  130 ). In some embodiments, the console  106  includes an emergency stop button which can be selected to initiate concurrent deflation of the air chamber  130  and stopping of the movement of the running belt  112 . Other events may also trigger an emergency stop, for example an electrical or mechanical failure in the pump  142  or the treadmill  102  or a detectable unsafe action of a user. 
     Referring now to  FIGS.  9 - 12   , a series of charts or diagrams  900 - 906  that provide guidance to a user (or other person, such as a physician) for selecting a scale level of pressure in the air chamber  130  are shown, according to exemplary embodiments. In various embodiments, one or more of the charts  900 - 906  are presented to a user and/or a supervisor (e.g., therapist, doctor, nurse, personal trainer, coach) in one or more of a variety of formats. In one embodiment, the one or more charts  900 - 906  may be presented as a graphical user interface on a screen of the user console  106 . In another embodiment, at least one of the one or more charts  900 - 906  may be accessible in an app-based or browser-accessible graphical user interface using a smartphone, tablet, personal computer, etc. In still another embodiment, at least one of the one or more charts may be printed in a physical form, for example on a sticker affixed to the exercise and therapeutic device  100  or in a booklet, pamphlet, handout, etc. 
     In the embodiments shown in  FIGS.  9 - 12   , the charts are displayed on a graphical user interface of the user console  106 , as generated by the user interface circuit  502 .  FIG.  9    shows user console  106  displaying chart  900 , according to an exemplary embodiment. Chart  900  shows an array of scale levels and their correspondence to two variables, namely a user weight and an assistance percentage, for a pressure scale corresponding to default settings (e.g., without the advanced settings of process  800 ). The user weight is how much the user weighs, shown in pounds in this example. The assistance percentage is the approximate percentage of a user&#39;s weight that is offloaded by the offloading system  108 . Thus, chart  900  indicates a scale level that will allow a user of a particular weight to offset a particular percentage of the user&#39;s weight. For example, if the user weighs two hundred pounds and wants to offload half of his or her weight, the chart indicates that the user should select a scale level of eight. In an embodiment where the chart  900  is presented on a touchscreen of the user console  106 , the user can touch an “8” on the chart  700  to instruct the controller  110  to control the pump  142  to change the air pressure in the air chamber  130  to the pressure associated with scale level eight. 
       FIG.  10    shows user console  106  displaying chart  902 , according to an exemplary embodiment. Chart  900  shows an array of scale levels and their correspondence with user weight and assistance percentage, for a pressure scale associated with a user height of 5′6″, a waist size of 32″, and a frame height setting of 4, as indicated in header  910 . In some embodiments, chart  902  also indicates that it corresponds to a particular user short size (e.g., medium). Thus, chart  902  may be tuned to a specific user in response to the user inputs of steps  806 - 810 . As for chart  900 , chart  902  indicates the scale level that will allow a user of a particular weight to offset a particular percentage of his or her weight. 
       FIG.  11    shows user console  106  displaying chart  904 , according to an exemplary embodiment. Chart  904  shows an array of scale values and their correspondence to two variables, namely frame height setting and assistance percentage. As indicated in box  912 , the values on chart  904  are tuned to be accurate for a user that weighs one hundred and seventy-five pounds. For example, the chart communicates that a user who weighs one hundred and seventy-five pounds and has a frame height setting of 8 can offload seventy percent of his or her weight by selecting a scale level of 12. Such correlations can be pre-determined by laboratory testing or calculations, such that weight is not used in online control of the device  100 . 
       FIG.  12    shows user console  106  displaying chart  906 , according to an exemplary embodiment. Chart  906  indicates maximum recommended assistance scale levels for users based on the user height and user weight. The maximum recommended assistance scale level may correspond to a scale level that offsets all or a predefined percentage of a user&#39;s weight (e.g., 100% assistance percentage). For the largest users (e.g., tallest and heaviest), the maximum recommended assistance level may correspond to the maximum amount of assistance that the offloading system  108  can provide due to limitations on pump power, membrane (air chamber  130 ) strength, etc. 
     Charts  900 - 906  thereby help a user or attendant (e.g., therapist, doctor, coach) to control the exercise and therapeutic device  100  to carry out a training or rehabilitation program designed around assistance percentages or weight offsets without the need for the user&#39;s weight to be input into or measured by the exercise and therapeutic device  100 . Control of the exercise and therapeutic device  100  is achieved without use of user weight as an input, measurement, or calculated value. The device  100  reduces the stresses and forces created by the impact of the user on the treadmill  102  with each stride in a controllable manner tailored to particular users. Exercise and therapeutic device  100  is therefore well suited for rehabilitation and injury prevention. 
     Referring now to  FIGS.  13 - 31   , various alternative embodiments of the exercise and therapeutic device  100  and components and/or systems therefor are shown. As described in detail below, the various alternative embodiments provide various options for altering, customizing, selecting, etc. the height of the user seal  134  relative to the running surface (i.e., various height adjustment mechanisms). As described in detail below,  FIGS.  13 - 27  and  31    show various structures for adjusting the position of the user seal frame  136  relative to the running surface, while  FIGS.  28 - 30    show embodiments in which a user seal frame  136  is omitted and a top strap  2800  is used to restrict a height of the user seal  134 . The dimensions and geometric configuration of the user seal frame  136  may vary to accommodate the various embodiments of  FIGS.  13 - 27  and  31   . Additionally, where a side view is shown in  FIG.  13 - 31   , it should be understood that a symmetric and/or substantially symmetric arrangement of elements of the device  100  is contemplated by such an embodiment. Furthermore, it should be understood various combinations, rearrangements, etc. of the embodiments of the exercise and therapeutic device  100  and components and/or systems therefor are contemplated by the present disclosure, including symmetric and asymmetric arrangements. 
     Referring now to  FIG.  13   , a pin lock  1300  for use with a height adjustment mechanism for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. The pin lock  1300  is shown mounted on a vertical column  1302 . The vertical column  1302  may correspond to a front rack  138  and/or a rear rack  140 . The position of the pin lock  1300  on the vertical column  1302  is adjustable along the vertical column  1302 , such that the pin lock  1300  can be selectively positioned at multiple discrete positions along the vertical column  1302 . 
     The pin lock  1300  is shown to include a collar  1304  (body, ring, slider, cuff, etc.) that surrounds or partially surrounds the vertical column  1302  and is configured to slide along the vertical column  1302 , a pin  1306  extending into the collar  1304 , a rotating head  1308  coupled to the collar  1304 , and a tray  1310  (carrier, receptacle, cart, etc.) extending from the rotating head  1308 . In the embodiment shown, the tray  1310  is configured to receive a front peg  158  or a rear peg  160  of the user seal frame  136  to secure the user seal frame  136  to the pin lock  1300 . The rotating head  1308  is configured to allow the tray  1310  to rotate slightly (e.g., around an axis of rotation defined by the vertical column  1302 ) to reduce the difficult of placing the front peg  158  or rear peg  160  in the tray  1310 . In other embodiments, the user seal frame is permanently coupled to the rotating head  1308 . 
     The pin  1306  is moveable between a locked position and an unlocked position. In the locked position, the pin  1306  extends through the collar  1304  and into the vertical column  1302 . The vertical column  1302  defines a plurality of holes spaced vertically apart from each other. The holes are configured to receive the pin  1306 , which thereby controls (sets, establishes, restricts) the vertical distance between the pin lock  1300 /user seal frame  136  and the running surface. By extending into a hole of the vertical column  1302 , the pin  1306  thereby prevents movement of the collar  1304  relative to the vertical column  1302  in the locked position. In the unlocked position, the pin  1306  is removed from engagement with the vertical support, such that the collar  1304  can move freely relative to the vertical column  1302 . Accordingly, in the unlocked position, the relative height or position of the pin lock  1300  along the vertical column  1302  can be adjusted. The pin lock  1300  may include a spring that forces the pin  1306  towards the locked position while allowing a user to apply force to the pin  1306  to overcome the force of the spring and draw the pin  1306  to the unlocked position. The pin lock  1300  thereby facilitates adjustment of the height of the user seal frame  136  relative to the running belt  112 . 
     Referring now to  FIG.  14   , a side view of a portion of a height adjustment mechanism for the exercise and therapeutic device  100  that includes the pin lock  1300  is shown. In the example shown in  FIG.  14   , the vertical column  1302  is coupled to the handrail assembly  104  and positioned proximate a front end of the treadmill  102  (e.g., proximate the user console  106 ). The pin lock  1300  is positioned on the vertical column  1302  and coupled to the user seal frame  136 . Accordingly, the position of the user seal frame  136  relative to the handrail assembly  104  is adjustable by moving the pin lock  1300  to various positions along the vertical column  1302 . The pin lock  1300  and vertical column  1302  thereby facilitate adjustment of a height of the user seal frame  136  relative to the running belt  112 . Although  FIG.  14    shows the pin lock  1300  used to adjust a position of a front end of the user seal frame  136  (e.g., of front arms  154 ), it should be understood that a pin lock  1300  and vertical column  1302  can also or alternatively be used to adjust a height of the rear end of the user seal frame  136  (e.g., of rear arms  156 ). 
     Referring now to  FIG.  15   , a second alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. As shown in  FIG.  15   , a track  1500  is coupled along an underside of the handrail assembly  104 . The track  1500  is configured to receive front pegs  158  of the user seal frame  136 , which extend downward from the user seal frame  136  as shown in  FIG.  15   . The front pegs  158  can slide along the track  1500  to adjust a position of the user seal frame  136  relative to the handrail assembly  104 . The front pegs  158  may include or be rollers (wheels) permanently coupled to the track  1500  or detachably coupled to the track  1500  to enable easy movement of the pegs  158  along the track  1500 . Movement of the pegs  158  along the track  1500  facilitates easy on-boarding of a user into the user seal  134  and user seal frame  136 . 
     The track  1500  is configured to allow the user seal frame  136  to be moved between a position that allows a user to enter the user seal  134  and a position suitable for restricting a height of the user seal  134  to a proper height relative to the running surface of the running belt for the particular user when the air chamber  130  is inflated. The track  1500  follows an arcuate path between a rear of the device  100  and a front of the device  100 . Movement of the pegs  158  along the track  1500  controls a height of the pegs  158  and the user seal frame  136  relative to the running surface. When the pegs  158  are positioned at a point in the track  1500  closest to the rear of the device  100 , the pegs  158  and seal frame  136  are vertically closest to the running surface. The pegs  158  and seal frame  136  are at the maximum vertical height from the running surface when the pegs  158  are positioned at a point in the track  1500  closest to the front of the device  100 . The track  1500  may be positioned below and aligned with the handrail assembly  104  (e.g., coupled to an underside of the handrail assembly  104 ) such that the track  1500  is positioned to beneficially avoid interference with running or other user behavior on the running surface. 
       FIG.  15    also shows a rear peg  160  supported in a notch  168 . In the example of  FIG.  15   , the notch  168  is included with a pin lock  1504  coupled to a vertical support  1502 . The pin lock  1504  may be adjustable along the vertical support  1502  as described above for the pin lock  1300  of  FIGS.  13 - 14    to facilitate a height adjustment of the user seal frame  136 . The rear peg  160  can be removed from the notch  168  to allow the user seal frame  136  to be moved to a position that allows a user to enter the user seal  134 , and positioned in the notch  168  as shown in  FIG.  15    to secure the user seal frame  136  in a position suitable for restricting a height of the user seal  134  to a proper height for the particular user when the air chamber  130  is inflated. 
     Referring now to  FIG.  16   , a front view of a third alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment.  FIG.  16    shows mounts  1600  coupled to the handrail assembly  104 . Mounts  1600  are shown to include brackets  1602  coupled to vertical poles  1604 . The position of the brackets  1602  along the handrail assembly  104  is adjustable. In some embodiments, the brackets  1602  each include a clamp that can be loosened to allow movement of the bracket and retightened to restrict or substantially prevent movement of the bracket  1602 . In some embodiments, the brackets  1602  include a pin lock (e.g., similar to the pin lock  1300 ) are configured to slid along the handrail assembly  104  unless locked in position by the pin lock. The vertical poles  1604  can be coupled to the user seal frame  136 , for example using the pin lock  1300  of  FIG.  13   . The adjustability of the positon of the brackets  1602  along the handrail assembly  104  allows adjustment of the position of the user seal frame  136  along a longitudinal direction (i.e., back-to-front along the treadmill  102 ) while the adjustability of vertical position along the vertical poles  1604  allows vertical adjustment of the position of the user seal frame  136  relative to the running surface. 
     Referring now to  FIG.  17   , a fourth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown. In  FIG.  17   , a rotatable rear rack  1700  is included. The rotatable rear rack  1700  is rotatable between an upright position and a horizontal position about an axis that is transverse to a longitudinal axis of the running surface. The rotatable rear rack  1700  includes a hinge coupled to the treadmill  102  (e.g., to the treadmill frame  103 ). The hinge may include a latch or locking mechanism configured to releaseably secure the rotatable rear rack  1700  in the upright position or horizontal position. In some embodiments, the hinge is motorized and configured to provide automated rotation between the upright position and the horizontal position. 
     In the upright position, the rotatable rear rack  1700  is spaced furthest from and oriented perpendicular to the running surface and is configured to hold the user seal frame  136  over the running surface as shown in  FIG.  1   . In some embodiments, the user seal frame  136  is coupled to the rotatable rear rack  1700  such that the user seal frame remains attached to the rotatable rear rack  1700  during normal startup and operation of the exercise and therapeutic device  100 . In other embodiments, the rotatable rear rack  1700  may include a notch  168  as for the rear rack  140  of  FIGS.  1 - 4   . 
     In the horizontal position, the rotatable rear rack  1700  is rotated away from the user console  106  to an orientation approximately parallel with the running surface of the running belt  112 . Accordingly, when the rotatable rear rack  1700  moves from the upright position to the horizontal position, the rotatable rear rack  1700  carries the user seal frame  136  to a position that allows a user to enter or exit the user seal  134 . Rotation of the rotatable rear rack  1700  thereby facilitates easy entry to and exit from the user seal  134  in addition to user-friendly repositioning of the user seal frame  136  from a position that facilitate entry/exit to a position suitable for inflation of the air chamber  130  and operation of the exercise and therapeutic device  100 . 
     Referring now to  FIGS.  18 - 19   , a fifth alternative embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. As shown in  FIG.  18 - 19   , the user seal frame  136  includes a head  1800  (e.g. front portion, extension, front member, protrusion, knob, arms) extending from a front end of the user seal frame  136 . In the embodiment shown, the head  1800  is T-shaped; in other embodiments, a different shape may be used. A crossbar  1802  is coupled to the handrail assembly  104  proximate the user console  106  and the crossbar  1802  includes a receptacle  1804  that is shaped to receive the head  1800 , such that the head  1800  can be inserted into the receptacle  1804  (i.e., into the crossbar  1802 ) to be supported by the crossbar  1802 . As shown in  FIGS.  18 - 19   , a pair of sliders  1806  are positioned on the crossbar  1802  on opposing sides of the receptacle  1804 . The sliders  1806  are configured to slide along the crossbar  1802  to selectively cover (e.g., partially cover) and uncover the receptacle  1804 . When the sliders  1806  are not covering the receptacle  1804 , the head  1800  can be inserted into the receptacle  1804 . When the head  1800  is positioned in the receptacle  1804  and the sliders  1806  are positioned to cover the receptacle  1804 , the sliders  1806  prevent removal of the head  1800  from the receptacle  1804 . 
     In the embodiment of  FIGS.  18 - 19   , the head  1800  can rotate within the receptacle  1804  such that the user seal frame  136  can rotate about an axis defined by the crossbar  1802 . The position and orientation of the user seal frame  136  relative to the running belt  112  can therefore be adjusted by adjusting the height of the rear arms  156  of the user seal frame  136  to rotate about the crossbar  1802 . In various embodiments, the rear arms  156  of the user seal frame  136  can be supported on one or more of the various support structures described herein, for example rear racks  140  of  FIGS.  18 - 19   , rotatable rear rack  1700  of  FIG.  17   , pin lock  1504  of  FIG.  15   , or various other structures described below. In the example shown in  FIG.  19   , the rear arms  156  include locking collars  1900 . The locking collars  1900  slide along the rear arms  156  and selectively cover/uncover receptacles in the rear arms  156  configured to receive support members from a rear support structure of the exercise and therapeutic device  100 . The locking collars  1900  may operate in a similar manner as the sliders  1806  to secure the rear arms  156  to a rear support structure. 
     Referring now to  FIGS.  20 - 22   , a sixth embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown, according to an exemplary embodiment. In the embodiment of  FIGS.  20 - 22   , the exercise and therapeutic device  100  includes a pair of rear columns  2000  (supports, posts, frames, poles, etc.). The rear columns  2000  extend vertically (i.e., perpendicular to the running belt  112 ) and are positioned on opposing sides of the running belt  112 . A pair of pin locks  2001  is positioned on the rear columns  2000 , such that one pin lock  2001  is positioned on each rear column  2000  in the example shown. 
     Each pin lock  2001  includes a collar  2006 , a pin  2002  extending through the collar  2006 , and a hook  2004 . The collar  2006  is configured to surround or partially surround the corresponding rear column  2000 . The pin  2002  is configured to extend through the collar  2006  and into the rear column  2000  to secure the collar  2006  in position relative to the rear column  2000 . The pin  2002  is also configured to be removed from the rear column  2000  to allow the collar  2006  to be repositioned along the rear column  2000 . 
     The hook  2004  extends from the collar  2006  and is configured to receive and support a rear peg  160  of the user seal frame  136 . In the example shown in  FIGS.  20 - 22   , the hook  2004  is oriented at an approximately right angle to the pin  2002 . In other embodiments, the hook  2004  may be positioned on the collar  2006  at other orientations relative to the pin  2002  (e.g., 180 degrees from the pin). The height of the hook  2004  relative to the running belt  112  can be adjusted by repositioning the pin lock  2001  along the rear column  2000 , thereby adjusting a height of the user seal frame  136  supported by the hook  2004 . 
     Furthermore, the hook  2004  and the pin  2002  may be positioned on various sides of the rear columns  2000 . For example,  FIG.  20    shows the pins  2002  positioned on medial sides of the columns  2000 , with the hooks  2004  positioned on an anterior side of the columns  2000 , while  FIG.  21    shows the pins  2002  positioned on lateral sides of the columns  2000  with the hooks  2004  positioned on posterior sides of the columns  2000 . It should be understood that various such arrangements are possible. 
     Referring now to  FIG.  23   , a seventh embodiment of a height adjustment mechanism for use with the exercise and therapeutic device  100  including support column  2300  with a pin lock  2301  is shown, according to an exemplary embodiment. The support column  2300  includes a row of holes  2310  and a slot  2308  that extend along the support column  2300 . The pin lock  2301  includes a collar  2302  and a pin  2304 . The pin  2304  extends through the collar  2302  and can be selectively inserted and removed from the various holes  2310  of the support column  2300 . When the pin  2304  is inserted into a hole  2310 , the pin  2304  prevents the collar  2302  from moving relative to the support structure. When the pin  2304  is not inserted into a hole  2310 , the collar  2302  can be moved along the support column  2300 . 
     The collar  2302  may include a member that extends into the slot  2308 . The slot  2308  may thereby guide the collar  2302  to move along the support column  2300 . In some embodiments, the slot  2308  includes a ratcheting structure that facilitates the user in lifting the collar  2302  along the support column  2300 . For example, the slot  2308  may be configured to allow a user to freely move the collar  2302  upwards along the support column  2300  but prevent the collar  2302  from moving downwards along the support column  2300 . In such a case, the support column  2300  and/or the pin lock  2301  may include a release button or lever that is engageable by a user to allow the collar  2302  to move downwards along the support column  2300 . 
     The collar  2302  includes a slot  2306  that extends beyond the support column  2300 . The slot  2306  is configured to receive a front peg  158  or a rear peg  160  of the user seal frame  136 , depending on placement of the support column  2300  on the exercise and therapeutic device  100 . The support column  2300  with the pin lock  2301  thereby facilitate placement of the user seal frame  136  at a user-selectable height. 
     Referring now to  FIG.  24   , an eighth exemplary embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown. In the embodiment of  FIG.  24   , the exercise and therapeutic device  100  includes a front mount for the user seal frame  136  which is not adjustable in position but allows rotation of the user seal frame  136 , for example as shown in  FIGS.  18 - 19   . 
     As shown in  FIG.  24   , the exercise and therapeutic device  100  includes a curved rear rack  2400 . The curved rear rack  2400  is configured to receive a rear peg  160  of the user seal frame  136  at each of multiple receptacles  2402 . The multiple receptacles  2402  are arranged in a curve having a radius approximately equal to a length of the user seal frame  136 . The multiple receptacles  2402  are spaced from a front mount for the user seal frame  136  such that the user seal frame  136  can be rotated to extend from the front mount to any of the receptacles  2402 . The position and orientation of the user seal frame  136  relative to the running belt  112  can therefore be adjusted by selecting one of the multiple receptacles  2402  to receive and support the rear peg  160  of the user seal frame  136 . Although a single curved rear rack  2400  is visible in the side view of  FIG.  24   , it should be understood that in preferred embodiments a second curved rear rack  2400  is also included, with the pair of curved rear racks  2400  positioned on opposing sides of the running belt  112 . 
     Referring now to  FIG.  25   , an ninth exemplary embodiment a height adjustment mechanism for the exercise and therapeutic device  100  is shown. In the embodiment of  FIG.  25   , the exercise and therapeutic device  100  includes a front mount for the user seal frame  136  which is not adjustable in position but allows rotation of the user seal frame  136 , for example as shown in  FIGS.  18 - 19   . 
     As shown in  FIG.  25   , the exercise and therapeutic device  100  includes a two-degree-of-freedom mounting system  2500 . The two-degree-of-freedom mounting system  2500  is configured to receive a rear peg  160  of the user seal frame  136  at a mounting point  2502 . The position of the mounting point  2502  is adjustable in two dimensions on the two-degree-of-freedom mounting system  2500 , shown as a vertical dimension (orthogonal to the running belt  112 ) and a horizontal direction (parallel to the running belt  112 ). The two-degree-of-freedom mounting system  2500  may include a combination of one or more tracks, slots, trays, etc. configured to facilitate adjustment of the position of the mounting point  2502 . The two-degree-of-freedom mounting system  2500  allows the position and orientation of the user seal frame  136  to be selected by a user by allowing selection of the position of the mounting point  2502 . Although a two-degree-of-freedom mounting system  2500 , it should be understood that in preferred embodiments a second two-degree-of-freedom mounting system  2500  is also included, with the pair of two-degree-of-freedom mounting systems  2500  positioned on opposing sides of the running belt  112 . 
     Referring now to  FIG.  26   , a tenth exemplary embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown. As shown in  FIG.  26    a slot  2600  is formed in the handrail assembly  104  proximate the user console  106 . The slot  2600  is oriented parallel to the running belt  112 . The slot  2600  is configured to receive a front peg  158 . Although a single slot  2600  is visible from the side view of  FIG.  26   , in preferred embodiments a second slot  2600  is also included with the pair of slots  2600  positioned symmetrically on opposing sides of the user console  106 . The slot  2600  is configured to receive and support a front peg  158  of the user seal frame  136 . The slot  2600  allows the front peg  158  to slid along the slot  2600  to allow horizontal movement of the user seal frame  136 . The slot  2600  also allows the front peg  158  to rotate within the slot  2600 , thereby allowing the user seal frame  136  to rotate about an axis defined by the front peg  158 . The slot  2600  can be used with various rear support structures (e.g., curved rear rack  2400  of  FIG.  24   , two-degree-of-freedom mounting system  2500  of  FIG.  25   , rear racks  140  of  FIGS.  1 - 4   , etc.) to secure the user seal frame  136  is a selected position and orientation. 
     Referring now to  FIG.  27   , an eleventh exemplary embodiment of a height adjustment mechanism for the exercise and therapeutic device  100  is shown. As shown in  FIG.  27   , the exercise and therapeutic device  100  includes multiple straps  2700 . The straps  2700  are coupled to the user seal frame  136  and extend from the user seal frame  136  to the treadmill frame  103 . The straps  2700  are coupled to the treadmill frame  103  by fasteners  2702 . When the air chamber  130  is inflated, the straps provide tension that limits or restricts movement of the user seal frame  136  away from the treadmill frame  103 . The straps  2700  are substantially inelastic, such that the length of the straps  2700  remains substantially constant when tension is applied to the straps  2700 . The length of the straps  2700  therefore determines the maximum height of the user seal frame  136  (i.e., a maximum displacement of the user seal frame  136  from the running belt  112 ), which in turn determines the height of the user seal  134  at full inflation of the air chamber  130 . Accordingly, the straps  2700  as shown in  FIG.  27    can be used in place of the front rack  138  and rear rack  140  of  FIGS.  1 - 4    and/or other similar support structures of  FIGS.  13 - 26   . In the embodiment shown, four straps  2700  are included. In other embodiments, a different number of straps may be used. The straps  2700  can include coated ends or edges to reduce friction, rubbing, wear, etc. on the air chamber  130  (e.g., silicone coating, polytetrafluoroethylene coating (e.g., Teflon®), rubberized edges, etc.). 
     In some embodiments of  FIG.  27   , the length of the straps  2700  is adjustable to adjust the height of the user seal frame  136  and the user seal  134  to accommodate users of various heights. In the embodiment shown, each fastener  2702  includes a winch (e.g., a motorized spool) that is controllable (e.g., by the controller  110 ) to automatically alter a length of the straps  2700  disposed between the fasteners  2702 . For example, the fasteners  2702  may be controlled in response to a user input to the user console  106  indicating a height of the user or indicating a command to raise or lower the user seal  134 . Thus, the fasteners  2702  are rotatable to rotate the straps in a tightening or loosening manner. In other embodiments, the fasteners  2702  include a quick-release strap length adjuster or buckle configured to allow a user to manually adjust the length of the straps  2700  disposed between the fasteners  2702  and the user seal frame  136 . In other embodiments, the straps include hook-and-loop material (e.g., VELCRO™) that allows each strap to be adjustably and selectively fastened to itself, and the fasteners  2702  include a loop through which the straps extend. In such embodiments, the coupling of each strap to itself by the hook-and-loop material can be adjusted to adjust a length of the strap disposed between the fastener  2702  and the user seal frame  136 . It should be understood that various automatic and manual length-adjustment mechanisms are contemplated by the present disclosure. Additionally, markings, scales, numberings, etc. can be included on the straps and/or on the air chamber  130  to facilitate a user in ascertaining a current length of the straps between the fastener  2702  and the user seal frame  136  (i.e., a height setting for the user seal  134 ). 
     Referring now to  FIG.  28   , a first alternative embodiment of the exercise and therapeutic device  100  is shown. As shown in  FIG.  28   , the exercise and therapeutic device  100  includes multiple side straps  2802  coupled to the treadmill frame  103  by fasteners  2804 . The multiple side straps  2800  are also coupled to a top strap  2800 . The top strap  2800  is formed as a loop that extends around the user seal  134 . The top strap  2800  is coupled to each side strap  2800 , respectively, by a buckle  2806 . Alternatively, hook and loop fastening material (e.g., VELCRO™) may be used to limit the movement of one strap relative to another. In the embodiment shown, four side straps  2800  are included.  FIG.  28    also shows a support strap  2810  coupled to a side strap  2800  and the handrail assembly  104 . The support strap  2810  is configured to provide lateral stability to the air chamber  130 . 
     When the air chamber  130  is inflated, the side straps  2802  are fully extended and provide tension that restricts movement of the top strap  2800  away from the treadmill frame  103 . The side straps  2802  are substantially inelastic, such that the length of the side straps  2802  remains substantially constant when tension is applied to the straps  2802 . The length of the straps  2700  therefore determines the maximum height of the top strap  2800  (i.e., a maximum displacement of the top strap  2800  from the running belt  112 ). The top strap  2800  is also substantially inelastic, such that the top strap  2800  restricts expansion of the air chamber  130  when coupled to the side straps  2800 . Thus, the length of side straps  2802  (i.e., the position of the top strap  2800 ) determines the height of the user seal  134  at full inflation of the air chamber  130 . In some embodiments, the length of the side straps  2802  can be adjusted as described above for the straps  2700  and fasteners  2702  of  FIG.  27    to adjust the height of the top strap  2800  and the user seal  134  to accommodate users of various heights. 
     In other embodiments, a longitudinal strap extends from the fastener  2804  located proximate the front end  116  of the treadmill  102  and along the user seal  134  (e.g., a long a top of the air chamber  134 ) to the fastener  2804  located proximate the rear end  118  of the treadmill  102 . In such embodiments the longitudinal strap extends along both a side and a top of the air chamber  130 . The longitudinal strap may be positioned in one or more sleeves or loops of the air chamber  130  (i.e., positioned on the outside of the air chamber  130 ) which restrict lateral and/or vertical movement of the longitudinal strap relative to the air chamber  130 . When the air chamber  130  is inflated, the longitudinal strap is configured to restrict expansion of the air chamber  130 . In some embodiments, lateral straps may be included in a similar configuration as described here for longitudinal straps. 
     Changes in the length of the longitudinal strap between the two fasteners  2804  can change the height of the user seal  134  when the air chamber  130  is inflated. The longitudinal strap may be adjustable at one or both fasteners  2804 . For example, in some embodiments, the longitudinal strap may be fixedly coupled (i.e., non-adjustable) at the fastener  2804  located proximate the front end  116  of the treadmill  102 , and may extend through a loop of the fastener  2804  located proximate the rear end  118  of the treadmill  102 . In such embodiments, the longitudinal strap includes hook-and-loop material that allows the longitudinal strap to be coupled to itself (e.g., with hooks positioned along the longitudinal strap substantially on one side of the fastener  2804  and loops positioned along the longitudinal strap substantially on the opposing side of the fastener  2804 ) such that the amount of the longitudinal strap positioned on either side of the fastener  2804  can be selectively secured. In such embodiments, the height of the user seal  134  when the air chamber  130  is inflated can be selected by altering the amount of the longitudinal strap positioned on either side of the fastener  2804 . 
     In some embodiments, a scale (gradation, numbering, etc.) is positioned along the longitudinal strap. The hook-and-loop material allows an end of the longitudinal strap to be coupled to the longitudinal strap along the scale, such that a given position of the end of the longitudinal strap corresponds to a value of the scale. Such scale values may correspond to height settings for the offloading system  108  (e.g., as described above with reference to notches  168 ), which may be used by a user in selecting the position of the longitudinal strap and or for inputting height setting information into the user console  106 . Such scale values may also correspond to a user height (e.g., 6′, 5′3″, etc.). In operation, therefore, an attendant may Velcro (when the straps are coupled via Velcro) the strap onto itself at an indicator associated with the height of the user. This enables a quick start methodology for the user to being using the unit without tailoring the user seal frame (as in the earlier embodiments) to the user&#39;s particular height. In certain embodiments, this height designation (or scale if heights are not used) may be used an input to control the inflation in the air chamber. Similar charts as described herein above may be implemented with the unit and relate to the scale on the Velcro straps. As also described above, coatings may be applied to the straps to prevent them from rubbing adversely against the air chamber in order to maintain the integrity of the air chamber. 
     Referring now to  FIG.  29   , a twelfth exemplary embodiment of the exercise and therapeutic device  100  is shown. As shown in  FIG.  29   , the exercise and therapeutic device  100  includes a top strap  2800  and side straps  2802  that restrict an inflation height of the air chamber  130  based on a length of the side straps  2802  as described above with reference to  FIG.  30   . In the example of  FIG.  29   , the side straps  2802  have a fixed length such that the inflation height of the air chamber  130  is not adjustable. 
     As shown in  FIG.  29   , the user seal  134  includes multiple seal levels. The multiple seal levels include a first seal level  2900 , a second seal level  2902 , a third seal level  2904 , and a fourth seal level  2906  arranged in series at progressively further distances from the running belt  112 . In the example of  FIG.  29   , each seal level  2900 - 2906  includes a zipper that allows a zipper  350  of user seal shorts  300  to be coupled to the user seal  134  at a selected seal level (i.e., at one of the first seal level  2900 , second seal level  2902 , third seal level  2904 , or a fourth seal level  2906 ). The user shorts  300  can thereby be coupled to and sealed to the user seal  134  at various heights relative to the running belt  112 , facilitating adjustment to accommodate users of various leg lengths. 
     Referring now to  FIG.  30   , a thirteenth exemplary embodiment of the exercise and therapeutic device  100  is shown. As shown in  FIG.  29   , the exercise and therapeutic device  100  includes a top strap  2800  and side straps  2802  that restrict an inflation height of the air chamber  130  based on a length of the side straps  2802  as described above with reference to  FIG.  30   . In the example of  FIG.  29   , the side straps  2802  have a fixed length such that the inflation height of the air chamber  130  is not adjustable. 
     As shown in  FIG.  30   , the user seal includes multiple seal levels. The multiple seal levels include a first seal level  3000 , a second seal level  3002 , and a third seal level  3004 , arranged in series at progressively further distances from the running belt  112 . In the example of  FIG.  30   , each seal level  3000 - 3004  includes a buckle  3006  that allows the user shorts  300  to be coupled to the user seal  134  at a selected seal level (i.e., at one of the first seal level  3000 , second seal level  3002 , or third seal level  3004 ). The user shorts  300  can thereby be coupled to and sealed to the user seal  134  at various heights relative to the running belt  112 , facilitating adjustment to accommodate users of various leg lengths. 
     Referring now to  FIG.  31   , a fourteenth exemplary embodiment of the exercise and therapeutic device  100  is shown. In  FIG.  31   , the device  100  includes a rear actuator column  3100  and a front actuator column  3102 . The rear actuator column  3100  is positioned proximate a rear of the device  100  and is configured to support a rear peg  160  of the user seal frame  136 . The rear actuator column  3100  includes a base  3104 , a shaft  3106  extending upwards from the base  3104 , and a receptacle  3108  (tray, notch, clamp) positioned at or near a top end of the shaft  3106 . The receptacle  3108  is configured to receive and hold the rear peg  160 . The shaft  3106  is configured to be controllably extended from the base  3104  and retracted into the base  3104  under the control of an actuator housed within the base  3104 , thereby adjusting the position of the receptacle  3108  (and a rear peg  160  held by the receptacle  3108 ). 
     In the embodiment shown, the actuator is electronically controlled, for example by the controller  110 . The actuator may include a linear actuator, a jack (e.g., a hydraulic jack, a pneumatic jack), or other mechanism configured to extend and retract the shaft  3106  from the base  3104  in order to move the receptacle  3108  to a desired position, and to secure the shaft  3106  in a given position during use of the device  100 . The actuator can be controlled by user input to the user console  106  and/or to one or more buttons, knobs, etc. that can be positioned on the base  3104 . In some cases, the actuator is controlled in response indicating a height of the user. In other embodiments, the position of the shaft  3106  can be manually adjusted by a user, for example by manipulating a hand crank (e.g., wheel) positioned on the base  3104  and mechanically linked to the shaft  3106 . The rear actuator column  3100  is thereby configured to provide for height adjustment of the user seal frame  136  relative to the running surface. 
     The front actuator column  3102  includes a base  3110 , a shaft  3112  extending upwards from the base  3110 , and a receptacle  3114  (tray, notch, clamp) positioned at or near a top end of the shaft  3112 . The front actuator column  3102  is shown as coupled to and supported by the handrail assembly  104 . In other embodiments, the front actuator column  3102  is coupled to and extends upwards from the treadmill frame  103 . The receptacle  3114  is configured to receive and hold a front peg  158 . The shaft  3112  is configured to be controllably extended from the base  3110  and retracted into the base  3110  under the control of an actuator housed within the base  3104 , thereby adjusting the position of the height of the receptacle  3114  (and of the front peg  160  held by the receptacle  3108 ). 
     The actuator of the base  3110  of the front actuator column  3102  may be the same as or similar to the actuator of the rear actuator column  3102 . In some embodiments, the actuators of the front actuator column  3102  and the rear actuator column  3102  are independently controllable, such that the height of the rear receptacle  3108  can be set independent of the height of the front receptacle  3114  and vice versa. In other embodiments, control of the actuators is coupled to maintain a geometric (spatial) relationship between the front receptacle  3114  and the rear receptacle  3108 . For example, the spatial relationship between the front receptacle  3114  and the rear receptacle  3108  may be controlled to match a fixed (rigid) spatial relationship between the front pegs  158  and rear pegs  160  of the user seal frame  136  thereby ensuring that user seal frame  136  fits between and can be received by both the front actuator column  3102  and the rear actuator column  3102  even though the front pegs  158  and the rear pegs  160  cannot move relative to one another. Such automation may facilitate the user&#39;s ability to correctly position the user seal frame  136 . 
     As utilized herein, the terms “approximately,” “about,” “substantially,” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and are considered to be within the scope of the disclosure. 
     It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples). 
     For the purpose of this disclosure, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary or moveable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or may be removable or releasable in nature. 
     It should be noted that the orientation of various elements may differ according to other exemplary embodiments and that such variations are intended to be encompassed by the present disclosure. 
     It is important to note that the constructions and arrangements of the exercise and therapeutic device  100  as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present disclosure.