Abstract:
A device used for ankle-based inversion therapy and which does not require hardware is described in this document. It allows the user to be suspended in an inverted posture from their ankles while being supported by an auxiliary mounting bar. The design of this device is presented in this document as an alternative to traditional hook-based gravity boots.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Inversion therapy is a method for achieving a decompression of the musculoskeletal system. Spinal traction occurs when the head is at a lower plane of elevation than the feet, thereby reversing the normal gravitational loading that occurs while standing or sitting. 
         [0002]    The degree of traction is measured by the angular displacement of the head from the horizontal plane that exists while lying flat in a prone position. The range of traction is therefore zero to ninety degrees, with maximum traction occurring while suspended orthogonal to the level surface below. 
         [0003]    Gravity boots are an established method for enabling an inverted posture through ankle-based suspension. Traditional gravity boot designs use hooks which connect to an elevated horizontal bar. This requires attaching a pair of gravity boots to the ankles, and then raising the feet to the elevation of the bar in order to enter the inverted posture. 
       SUMMARY OF THE INVENTION 
       [0004]    The purpose of the device described is to provide a means for suspension by the ankles in a fully inverted position and thereby achieve maximum traction. Pull-up bars, of the type used in gymnastics and fitness activities that are designed to support the static loads generated by human body weight, are the intended support structures for this device to be used in conjunction with. 
         [0005]    The device described can be constructed from synthetic polymer webbing that has a rated tensile strength which determines the safe working load that can be supported. It is sewn together, according to the described design, using synthetic polymer thread that is also rated in terms of the load-bearing capacity of each stitch (pounds/stitch). This combination of materials provides a means to predict the maximum load bearing capacity of this device when assembled, and thereby incorporate large safety factors. 
         [0006]    Advantages to using the device described for ankle-based inversion therapy are:
       1. The device adds no weight to the ankles. When the feet are raised up toward the mounting bar, no extra load must be carried, which translates to less effort required.   2. The device described, when mounted to a horizontal support bar, has handles that are significantly lower in elevation than the bar itself. This makes it unnecessary to reach all the way to the bar when exiting the inverted position, because the device has extended handles that are closer to the hands   3. The load tension of applied body-weight causes the device to close around the ankles, due to its self-tightening nature. It is therefore not possible to fall or slip out of the device while in the inverted position.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  depicts the device described, with numbers referring to the individual components outlined in the claims section. 
           [0011]      FIG. 2  depicts two devices attached to a horizontal mounting bar and secured around both ankles while in use. 
           [0012]      FIG. 3  depicts a pair of devices, showing the directional difference between the left and right version. 
           [0013]      FIG. 4  depicts an as-built test model assembled from webbing and thread. 
           [0014]      FIG. 5  depicts an as-built test model with a toe-hold loop of adjustable position relative to the main device body and a handle composed of separate finger loops. 
           [0015]      FIG. 6  depicts an as-built test model based on the design shown in  FIG. 1 . 
           [0016]      FIG. 7 a    shows the handle augmented with surrounding material to provide more grip surface. 
           [0017]      FIG. 7 b    shows the handle composed of individual finger loops. 
           [0018]      FIG. 8  depicts the self-encircling part of the primary loop in isolation, with the black region representing a protective covering attached on the inside to prevent abrasion. The sheath could be made of durable and flexible plastic-polymer, and would eliminate friction contact between layers of webbing when the device is opened and closed. The sheath concept shown is a tubular single piece of material, and the webbing would be inserted through it prior to assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Directions for Use: 
         [0020]    Entry:
       1. Verify that the left and right versions of the device are oriented correctly (the left should form a lowercase “D” letter shape, and the right should form a lowercase “B” letter shape, as shown in the figures).   2. Attach a pair of devices to the horizontal support bar, by placing the mounting loop over the bar and then threading the body of the device through the loop as shown in the figures.   3. Slide the main loop into its fully open position, by moving the self-encircling portion of the main loop upward. This provides the maximum open surface area for the foot to be inserted through.   4. Verify that the handle and its extension are within the interior region of the sliding portion of the main loop, as shown in the figures.   5. Grasp the handle of the left-foot device with the left hand, and grasp the right-foot device handle with the right hand, and verify that all connections are secure by lifting feet off the ground and applying body-weight load to the pair of devices.   6. Raise feet upward to the bar while holding device handles, and lean back simultaneously to minimize the amount of upper-body effort used.   7. Position the device around each ankle by inserting the left and right foot through the opening provided by the main loop of each device while using the big toe of the opposite foot in conjunction with the toe-hold loop to further control the device.   8. While still holding the handles, tighten each device around the ankles by pulling both feet downward.   9. Release the handles and move backward into a fully inverted posture.       
 
         [0030]    Exit:
       1. Raise the torso upward until the handles are within reach.   2. Grasp the left handle with the left hand, and the right handle with the right hand. Apply load to each handle by pulling downward as if the weight of the upper body were being supported by the handles and their extensions.   3. Shifting the static load application point, as described in the previous step, allows the main loop of the device to be relaxed and expanded. While briefly supporting the majority of body weight with the handles, use the big toe of the opposite foot in conjunction with the toe-hold loop to pull the main loop off of each ankle and allow the feet to exit.   4. Using a controlled movement, while still holding the handles securely, lower the feet to the ground. Do not release the handles until footing is secure.       
 
         [0035]    Optional but Recommended Steps Prior to Use:
       1. Cover the mounting bar with tape or protective cloth, to prevent the abrasion of webbing or stitching by exposed rough metallic surfaces.   2. Wear a pair of tube socks with the toe box cut open to provide a protective padding barrier between skin and device webbing.       
 
         [0038]    Instructions for Assembly: 
         [0039]    The size of the device can be scaled depending on foot-size and ankle circumference. The relative dimensions of the major components, as shown in the figures and described in the claims, are critical. The handle loop must be large enough to accommodate the hand, the main loop must be large enough when fully expanded to accommodate the through-passage of the foot, and the handle extension must be of sufficient length for the extension to remain inside of the self-encircling sliding region of the main loop when it is fully contracted around the ankles. The mounting loop must also be large enough to encircle the supporting bar structure and allow the whole device to pass through. 
         [0040]    An ideal construction material is polyester webbing, with 2″ width used for the main loop and body of the device, and 1″ width used for all other components. The width-reducing attachment interface between the main loop and the handle extension maximizes the surface area of the seams connecting these two components. 
         [0041]    Webbing used for assembly is heat sealed at exposed ends to prevent fraying. Heat-treated ends are hard and brittle and must be folded over once and sewn in place to prevent contact abrasion. 
         [0042]    Sheaths to prevent webbing abrasion can be installed on sections of the device that are exposed to friction. These sections can include the self-encircling, sliding region of the main loop, the mounting loop, and the handle itself. The sheath can be made from durable fabric by sewing a tubular structure that surrounds the section of webbing being protected. The webbing would be inserted through the pre-fabricated tubular coverings prior to sewing. Single-piece molded polymer units could be used, if the plastic material were sufficiently durable and flexible. 
         [0043]    The device can be constructed according to the drawings and descriptions using a sewing machine. The as-built test models of the device depicted in  FIGS. 4-6  use reinforced box-tack stitching patterns at all major connection points.