Ambulatory Traction Assembly

1. Field of the Invention.

The present invention relates to a traction system, and more particularly to a traction system for rehabilitative, diagnostic, therapeutic and training programs.

2. Description of Related Art

When a patient is suffering from one of various spinal injuries and diseases, such as disc compressional syndromes, facet syndromes, compression fractures, arthritides, contusional injuries, scoliosis, strains and sprains, etc., a traction system may be required to alleviate spinal stress and load to facilitate rehabilitation and hasten healing and recovery.

Various traction systems have been proposed which include a harness to suspend and pull particular parts of the patient's body. However, these traction systems generally do not provide sufficient rehabilitative and therapeutic results for a patient particularly suffering from these spinal injuries and diseases. For example, the ambulatory systems described in U.S. Pat. No. 2,812,010 to Abdallah or U.S. Pat. No. 3,780,663 to Pettit include a harness suspended from an overhead sliding track in which the patient may walk upright while suspended by the harness. However, such harness and support assemblies typically have limited adjustability and can interfere with proper breathing.

It is an object of the present invention to provide a traction system particularly designed to provide rehabilitative and therapeutic treatments to patients suffering from spinal injuries and diseases in which healing response as well as rehabilitative and training response are maximized.

It is another object of the present invention to provide a traction system which alleviates compressional/load stress in/to all parts of the human body to facilitate decreasing somatic adaptive responses, such as muscle inflammation and muscle spasms, reducing adhesions such as intraarticular, juxtarticular, myofascial, myotendinous and tenoperiosteal adhesions, increasing connective tissue strength and circulation, and realigning connective tissue fibers in a "normal" manner.

It is still another object of the present invention to provide a traction system which facilitates, maintains and reeducates the body's neurological responses to movement through but not limited to the mechanoreceptive, proprioceptive, and cross-extensor reflex pathways, alpha motor pathways, and through stimulating and facilitating cerebellar and cerebral neurons to enhance normal and or optimal ambulation movement patterns.

It is a further object of the present invention to provide a traction system in combination with a variable ambulation speed system which provides decompressional forces to the lumbosacral spine, lower extremities and related connective tissues at varying speeds from static to ambulation speed.

It is still a further object of the present invention to provide a traction system in combination with a treadmill and a harness assembly for suspending a patient which facilitates the adjustment of suspension or pull of the harness assembly, inclination and speed of the treadmill, and tension (pull) angle (vector) of the harness assembly.

It is yet another object of the present invention to provide a traction system with unique harness and pulley designs which provide uniform symmetrical pull of the harness.

These and other objects and advantages are achieved in an ambulatory traction system which comprises, in accordance with one embodiment of the present invention, a horizontal beam member, an overhead support assembly for linear displacement along the horizontal beam member and a harness assembly suspended from the overhead support assembly to support and suspend the patient's body. The harness assembly is designed to provide a stable support to the upper body of the patient as well as to facilitate breathing of the patient while the patient is suspended by the harness assembly. To maximize healing response of the body as well as rehabilitative and training response, a variable ambulation speed system is provided beneath the harness assembly which allows the patient, while being suspended by the harness assembly, to walk thereon. The overhead support assembly provides a translational linear displacement of the harness assembly in parallel with the horizontal beam member. As a result, the patient's upper body is stabilized in the upright position while walking on the variable ambulation speed system.

FIG. 1 is a schematic side view illustrating an ambulatory traction unit in accordance with a preferred embodiment of the present invention and showing the manner in which a patient is suspended thereby in an upright walking position;

FIG. 2 is a perspective view of the ambulatory traction unit shown in FIG. 1;

FIG. 3 is an enlarged sectional view illustrating a splice joint between two members of the frame structure shown in FIG. 2;

FIG. 4(a) is an enlarged side view illustrating an overhead support assembly and a harness assembly of the ambulatory traction unit of FIG. 1;

FIG. 4(b) is a perspective view of a space bar assembly having a length adjusting mechanism in accordance with a preferred embodiment;

FIG. 4(c) is a partially broken side view of a space bar assembly shown in FIG. 4(b);

FIG. 4(d) is a partially broken plan view of a space bar assembly shown in FIG. 4(b);

FIG. 5(a) is a perspective view of a corset of the harness assembly in accordance with one embodiment of the present invention;

FIG. 5(b) is a front view showing the manner in which a patient is suspended by the corset of the harness assembly of FIG. 5(a) with the corset being partially broken;

FIG. 5(c) is a side view of FIG. 5(b);

FIG. 6 is a partially broken perspective view illustrating an ambulatory traction unit in accordance with another preferred embodiment of the present invention and showing the manner in which a patient is suspended thereby in an upright walking position; and

FIG. 7 is a schematical perspective view of an ambulatory traction unit in accordance with still another embodiment.

An ambulatory traction unit in accordance with a preferred embodiment of the present invention is indicated generally at 10 as illustrated in FIGS. 1-2. The ambulatory traction unit 10 includes a frame structure 12. The frame structure includes a horizontally extending overhead frame assembly 18 which is supported by a pair of front and rear vertical frame assemblies 14 and 16. An overhead support assembly 20 slidably engages the overhead frame assembly 18 for substantially linear horizontal displacement between the front and rear vertical frame assemblies 14 and 16. A harness assembly 22 includes a front strap assembly 24 and a rear strap assembly 26, both attached at respective upper ends thereof to the overhead support assembly 20. Connected to the lower ends of the front and rear strap assemblies 22 and 24 is a harness main body 28 which is releasably attached to the body of the patient. A variable ambulation speed system 30 is positioned below the harness assembly 22 to allow the patient to walk thereon while the patient is receiving treatments. The front strap assembly 24 and the rear strap assembly 26 are downwardly and diagonally angled with respect to each other (as best seen in FIG. 1) so that the front and rear strap assemblies 24 and 26 generally define two sides of an inverted triangle when the patient is supported and suspended by the harness assembly 22 in an upright position. As a result of the triangular configuration defined by the harness strap assemblies 24 and 26, the patient's upper body is substantially stably suspended while walking on the variable ambulation speed system 30.

The frame structure 12 may be made of any one of a variety of suitable materials, such as, aluminum, iron, reinforced glass-fiber, plastic or a combination thereof. In the illustrated embodiment, the front vertical frame assembly 14 of the frame structure 12 includes a pair of vertically extending frame members 32 and a laterally extending upper frame member 34 spanning between the vertical frame members 32 adjacent the top end portions thereof. The rear vertical frame assembly 16 also includes a pair of vertically extending frame members 36 and a laterally extending upper frame member 38 spanning between the vertical frame members 36. The vertical frame members 32 and 36 may be connected with each other at their respective lower end portions by two longitudinally extending lower frame members 40 and two laterally extending lower frame members 42.

The overhead frame assembly 18 of the frame structure 12 preferably includes three longitudinal overhead frame members 44 which extend generally in parallel with each other between the front vertical frame assembly 14 and the rear vertical frame assembly 16. Two of the longitudinal overhead frame members 44 are connected to the front and rear vertical frame assemblies 14 and 16 adjacent the vertical frame members 32 and 36. The remaining one of the longitudinal overhead frame members 44 may be connected to the intermediate portions of the laterally extending upper frame members 34 and 38. It should be appreciated that the number of the longitudinal overhead frame members may be more or less depending on the particular requirements. For example, a single longitudinal overhead frame member may be provided to allow horizontal and linear displacement of the overhead support assembly 20 along that single overhead frame member.

The frame members may be connected to each other in any suitable manner. In one embodiment, the frame members may, at least partially, be joined with each other by spline connections. FIG. 3 shows a typical spline connection 46 which is formed by a male protrusion 48 on one frame member and a female recess 50 on another frame member. After the two members are coupled with each other through the spline connection 46, screws or other suitable fastening devices may be used to fasten the two frame members together. In this embodiment, screw holes 52 are provided in one frame member having the female recess 50 and in the associated male protrusion 48 to receive screws (not shown). To provide greater structural rigidity to the frame structure 12, corner bracing webs 54 or the like may be provided. In addition, base plates 56 may be attached to the bottom of the frame structure 12, preferably at four bottom corners of the frame structure 12, to provide greater stability to the frame structure 12.

FIG. 4(a) shows in detail the overhead support assembly 20 and the harness assembly 22. The overhead support assembly 20 includes a plurality of front sliding elements 58 and a plurality of rear sliding elements 60. As best seen in FIG. 2, the overhead assembly 20 of this embodiment has two front sliding elements 58 and two rear sliding elements 60, both of which are mounted respectively on the two spaced longitudinal overhead frame members 44. Each of the front and rear sliding elements 58 and 60 has a truck and wheel assembly 62 which is guided along a guide track 64 of the overhead frame members 44. It should be appreciated that each of the longitudinal overhead frame members may be formed by a beam member having an appropriate track for horizontally guiding the truck and wheel assembly 62. Alternatively, an independent guide track may be attached to each of the longitudinal overhead frame members which carries the truck and wheel assembly 62. It should be appreciated that sliding elements other than the truck and wheel assemblies such as sliding pads or bearings may be used.

A spacer bar assembly 66 is provided between the front sliding elements 58 and the rear sliding elements 60 to maintain a predetermined separation therebetween. The spacer bar assembly 66 may preferably include a length adjusting mechanism 67 for changing the length of the spacer bar assembly 66 and therefore the separation between the front sliding elements 58 and the rear sliding elements 60. As described below in greater detail, the front and the rear strap assemblies 24 and 26 of the harness assembly 22 are connected to the respective front and rear sliding elements 58 and 60. Accordingly, the separation between the front and the rear strap assemblies 24 and 26 adjacent the front and rear sliding assemblies can be changed by varying the length of the spacer bar assembly 66.

FIGS. 4(b), 4(c) and 4(d) show an embodiment of the length adjusting mechanism 67. As shown in FIG. 4(b), the length adjusting mechanism 67 may be formed from a telescoping tube 78 having an external tube 80 and an internal tube 82. The external tube 80 and the internal tube 82 preferably have diameter of 3/4" and 1/2", respectively. The internal tube 82 is inserted in the external tube 80 so that the internal tube 82 slides through the external tube 80, or vice versa, to change the overall length of the telescoping tube 78. Both tubes 80 and 82 may have any one of appropriate cross-sections, such as, a square cross-section and a circular cross-section. The external tube 80 has a through hole 84 in side walls 86 thereof through which a pin 88 can be inserted. In a preferred embodiment, the through hole 84 is 1/4" in diameter, and the pin 88 is 3/16" in diameter and 1" long. The inner tube 82 is provided with a plurality of holes 90, preferably twelve, in side walls 92 thereof, through which the pin 88 can be inserted. In one embodiment, the holes 90 are 1/4" in diameter and generally evenly spaced from each other. The pin 88 is inserted through the hole 84 in the external tube 80 and one of the holes 90 at an appropriate location to vary the overall length of the telescoping tube 78 and thus the angle between the front to rear strap assemblies 24 and 26. In a preferred embodiment, the pin 88 is a standard steel pin with a stopper. The stopper may comprise a push button internal mechanism 93 provided adjacent one end of the pin 88. The push button internal mechanism 93 typically has a steel ball that is laterally pushed out from the pin 88 by a built-in resilient device in the pin 88 to entrap the pin 88 in place once inserted through the holes 84 and 90. The telescoping tube 78 is mounted between the front and the rear sliding elements 58 and 60. In an embodiment, a steel plate 94 may be welded to one end of each of the external tube 80 and the inner tube 82. Each steel plate 94 is 1/4" thick and has drill holes 96 for bolts so that the external tube 80 may be coupled to the front sliding element 58 and the inner tube 82 may be coupled to the rear sliding element 60, or vice versa.

As shown in FIG. 4(a), each of the front and rear strap assemblies 24 and 26 of the harness assembly 22 includes a cleated pulley assembly 68 for length adjustment, a tension scale 70 for measurement and indication of the tension along the strap assembly and a tension spring 72 for maintaining substantially constant tension along the strap assembly. The cleated pulley assembly 68 has at its upper end a pulley 74 coupled to the associated sliding element and a rope 73 cleated at its lower end which is connected to the upper end of the tension scale 70. The harness assembly 22 has the main harness body 28 which is connected to the front strap assembly 24 and the rear strap assembly 26. In this embodiment, the harness main body 28 is connected to the lower ends of the tension springs 72 of the front and rear strap assemblies 24 and 26. In one aspect of the present invention, the front and rear sliding elements 58 and 60 are separated by the spacer bar assembly 66 to an extent that the upper ends of the front and rear strap assemblies 24 and 26 are separated from each other substantially greater than the longitudinal separation at the lower ends thereof which are connected to the harness main body 28. As a result, the front strap assembly 24 and the rear strap assembly 26 are downwardly and diagonally angled with each other so that the harness main body 28 is suspended between the front and rear strap assemblies 24 and 26 which generally define two sides of an inverted triangle. Furthermore, the two longitudinal overhead frame members 44 carrying the two front sliding elements 58 and the two rear sliding elements 60 may be laterally separated substantially wider than the lateral separation between the lower ends of the two front strap assemblies and the two rear strap assemblies respectively as shown in FIG. 2. As a result, the two front strap assemblies and the two rear strap assemblies are downwardly and diagonally angled with each other so that the harness main body 75 is suspended at the lower ends of the four strap assemblies which generally define four sides of an inverted pyramid configuration.

FIG. 5 shows one embodiment of the harness assembly indicated generally at 100. The harness assembly 100 includes a corset-like main body 102 which is designed to provide under-rib cage lift when the patient is suspended by the harness assembly 100. The corset main body 102 may be provided with a high friction lining 103 on its inside surface and is shaped to generally encircle the abdomen, sides and back of the patient. The corset main body 102 may be made of any one of a variety of materials, such as for example, canvas, leather, plastic material or a combination thereof. The corset main body 102 has an open front section 104, side sections 106, and a rear section 108. The open front section 104 is provided with a generally U-shaped cut 109 to substantially avoid contact with the frontal chest portion of the patient. It is found that the U-shaped cut 109 substantially facilitates breathing of the patient when the patient, relatively tightly wrapped within the corset main body 102, is suspended by the harness assembly 100. The open front section 104 includes a fastening device 110 which is provided below the U-shaped cut 109. Preferably, the fastening device 110 is formed by VELCRO straps 112 for repeated opening and closing of the corset main body 102 and for ready adjustment of the peripheral size of the corset body 102 to accommodate patients of varying body sizes. The VELCRO straps 112 are positioned to extend over the lower abdomen of the patient so that an upward lifting force is applied at the lower abdomen when the patient is suspended by the harness assembly 100. The side sections 106 are both tapered so that a lower portion 114 of each of the side sections 106 relatively tightly fits to the side and below the rib-cage of the patient. As shown in FIG. 5(b), on the other hand, an upper portion 116 of each of the side sections 106 relatively loosely fits to the side and over the rib-cage of the patient to provide sufficient support to the patient's upper body particularly in the lateral direction and yet to facilitate breathing of the patient. As a result of the tapered side sections 106, the harness assembly 100 will provide under-rib cage lift while allowing the patient to relatively easily breath when the patient is suspended by the harness assembly 100. The rear section 108 of the corset main body 102 is designed to generally fit to the lower back of the patient to provide support to the patient.

The harness assembly 100 further includes a pair of front strap assemblies 118 and a pair of rear strap assemblies 120 connected to the corset main body 102. Each of the strap assemblies 118 and 120 may be formed by a plurality of band straps 122 having upper ends 124 and lower ends 126. The upper ends 124 of the band straps 122 are bound together and looped through a triangular metal connector 128 which may be connected to the lower end of a tension spring 129 in a similar manner described with reference to FIG. 4. The lower ends 126 of the band straps 122 are generally vertically funneled out and connected to each of the side sections 106. The length of each of the band straps 122 and locations of the lower ends 126 to be connected to the side section 106 should be determined so that the tension acting along the band straps 122 is substantially evenly distributed to each of the band straps 122. The corset main body 102 may be provided with a rear tension band strap assembly 130 which is connected to the rear section 108 thereof. As shown in FIG. 5(a) and FIG. 5(c), the rear tension band strap assembly 130 is coupled to the overhead support assembly 20 and has lower ends being substantially laterally distributed and connected to the rear section of the corset main body 102. The pair of front strap assemblies 118, the pair of rear strap assemblies 120 and the rear tension band strap assembly 130 are generally symmetrically placed posteriorly and anteriorly to evenly distribute the lifting force vectors. In one embodiment, the pair of front strap assemblies 118 and the pair of rear strap assemblies 120 are downwardly and diagonally angled with respect to each other so that the corset main body 102 is suspended at the lower ends of the four strap assemblies which generally define four sides of an inverted pyramid configuration. Further, the rear tension band strap assembly 130 may be coupled to an additional truck and wheel assembly which is provided along the central longitudinal overhead frame member 44. It should be appreciated that more tension band strap assemblies may be used to further distribute the lifting force vectors.

In further embodiments, a front tension strap band assembly (not shown) may be connected to the front portion of the corset main body 102. In this case, the rear tension strap band assembly 130 and the front tension strap band assembly may be adjusted in their respective length to vary the amount of anterior or posterior pull to change the amount of lift anteriorly or posteriorly during inclination or declination of the treadmill, respectively.

Referring back to FIG. 2, the variable ambulation speed system 30 may be any one of the various commercially available motorized treadmills, such as the PRICOP, E system or IMAGE 935 system. The variable ambulation speed system 30 is capable of driving an endless belt 132 at varying speeds, for example from zero to twelve miles per hour, and changing the height of the front end of the belt 132, for example from minus ten (-10) to plus fifteen (+15) degrees. If the treadmill does not have capability of a declination, a block of suitable size, for example 4", can be placed at the rear end of the treadmill. The variable ambulation speed system 30 may be provided with a hand rail 134 to allow the patient to balance on the belt 132. The system 30 may also be provided with a step-off platform 136 to allow the patient to step off the belt 132 during the operation of the variable ambulation speed system 30. Both the handrail 134 and step-off platform 136 can be mounted on either side or bilaterally depending on space restrictions.

In operation, the length of the spacer bar assembly 66 should be appropriately adjusted by the length adjusting mechanism 67 to determine the angle of suspension between the front strap assembly 24 and the rear strap assembly 26. Also, the degree of suspension is measured by the tension scale 70 and adjusted if necessary by the cleated pulley assembly 68 or the traction unit 280 either previously to make it consistent with the design protocol or during the diagnostic or therapeutic operation to make it commensurate to the patient's response. It is found that the combination of the above described frame structure, harness assembly and speed system facilitate varying the angle of suspension, the amount of tension, and the degree of treadmill inclination or declination, which factors in turn affect the amount and specific type of decompression within the skeletal structural region and throughout the lower extremities being diagnosed or treated. It is also found that the use of the variable ambulation speed system 30 in combination with the harness assembly 22 will facilitate achieving uniform-symmetrical pull for maintaining and reeducating the body's neurological responses to movement and maximize healing response as well as rehabilitative and training responses.

An ambulatory traction unit in accordance with another preferred embodiment of the present invention is indicated generally at 210 as illustrated in FIG. 6. The ambulatory traction unit 210 includes a frame structure 212. The frame structure 212 includes a horizontally extending overhead frame assembly 218 which is supported by a pair of front and rear vertical frame assemblies 214 and 216. Two overhead support assemblies 220 slidably engages the overhead frame assembly 218 for substantially linear horizontal displacement between the front and rear vertical frame assemblies 214 and 216. A harness assembly 222 includes two front straps 224 and two rear straps 226, both attached at respective upper ends thereof to the overhead support assembly 220. The lower ends of the front and rear straps 222 and 224 are connected to a harness main body 228 which is releasably attached to the body of the patient.

A variable ambulation speed system 230 is positioned below the harness assembly 222 to allow the patient to walk thereon while the patient is receiving treatments. The front straps 224 and the rear straps 226 are downwardly and diagonally angled with respect to each other so that the harness main body 228 is suspended at the lower ends of the four straps which generally define four sides of an inverted pyramid configuration.

The frame structure 212 may be made of any one of a variety of suitable materials, such as, aluminum, iron, reinforced glass-fiber, plastic or a combination thereof. In the illustrated embodiment, the front vertical frame assembly 214 of the frame structure 212 includes a pair of vertically extending frame members 232 and a laterally extending upper frame member 234 spanning between the vertical frame members 232 adjacent the top end portions thereof. The rear vertical frame assembly 216 also includes a pair of vertically extending frame members 236 and a laterally extending upper frame member 238 spanning between the vertical frame members 236. The vertical frame members 232 and 236 may be connected with each other at their respective lower end portions by two longitudinally extending lower frame members 240 and two laterally extending lower frame members 242.

The overhead frame assembly 218 of the frame structure 212 preferably includes five longitudinal overhead frame members 244 which extend generally in parallel with each other between the front vertical frame assembly 214 and the rear vertical frame assembly 216. Two of the longitudinal overhead frame members 244 are connected to the front and rear vertical frame assemblies 214 and 216 adjacent the vertical frame members 232 and 236. The middle three of the five longitudinal overhead frame members 244 may be connected to the intermediate portions of the laterally extending upper frame members 234 and 238.

Each of the overhead support assemblies 220 includes two front sliding elements 258 and two rear sliding elements 260, both of which are mounted respectively on the two spaced longitudinal overhead frame members 244. Each of the front and rear sliding elements 258 and 260 has a truck and wheel assembly similar to the one described above with reference to FIG. 4.

A spacer bar assembly 266 is provided between the front sliding elements 258 and the rear sliding elements 260 to maintain a predetermined separation therebetween. The spacer bar assembly 266 may preferably include a length adjusting mechanism 267 for changing the length of the spacer bar assembly 266 and therefore the separation between the front sliding elements 258 and the rear sliding elements 260.

In accordance with embodiments of the present invention, each of the space bar assembly 266 has a front pulley assembly 270 and a rear pulley assembly 272. Alternatively, the front pulley assembly 270 and the rear pulley assembly 272 may be connected to the overhead support assemblies 220. In one embodiment, the front pulley assembly 270 and the rear pulley assembly 272 may be connected to the two front sliding elements 258 and two rear sliding elements 260, respectively.

In the illustrated embodiment, the front straps 224 are carried by the associated front pulley assemblies 270 and the rear straps 226 are carried by the associated rear pulley assemblies 272. Four ends of the front and rear straps 224 and 226 are tied together at a cleat 273 in a manner that the length of each of the front straps and rear straps may be adjusted at the cleat 273. The cleat 273 is connected to a first tension spring 274 which in turn connects to a strap or a rope 275. The rope 275 is guided through a first guide pulley assembly 276 and a second guide pulley assembly 278 provided adjacent the upper frame member 234 and is connected to a traction unit 280. The traction unit 280 is used to control, measure and indicate the tension through the front and rear straps 224 and 226, and may be any one of appropriate off-the-shelf traction units, such as for example, an electromechanical traction unit with a built-in pneumatic tensiometer "TX-7" manufactured by CHATTANOOGA Corporation (Product No. 74121 Rev. B03/91). The rope 275 may include a second tension spring 282, preferably between the second guide pulley assembly 278 and the traction unit 280. The first tension spring 274 and the second tension spring 282 are adapted to maintain substantially constant tension along the strap assemblies.

The main harness body 228 (which is similar to the one described above with reference to FIG. 5) is connected to lower ends of the front straps 224 and the rear straps 226. In one aspect of the present invention, the front and rear sliding elements 258 and 260 are separated by the spacer bar assembly 266 to an extent that the upper ends of the front and rear straps 224 and 226 are separated from each other substantially greater than the longitudinal separation at the lower ends thereof which are connected to the harness main body 228. As a result, the front straps 224 and the rear straps 226 are downwardly and diagonally angled with each other so that the harness main body 228 is suspended between the front and rear straps 224 and 226 which generally define four sides of an inverted pyramid configuration. It has been found that the harness assembly 222 described above further stabilizes the patient suspended thereby who is walking or running on the variable ambulation speed system 230. It has also been found that the harness assembly 222 decreases the inward compressional forces on the rib cage and diaphragm of the patient. As a result, the harness assembly 222 in combination with the harness main body 228 allow the patient to breath more easily and comfortably.

FIG. 7 shows another embodiment of a variable ambulation speed system 300. The variable ambulation speed system 300 has substantially the same structure and structural elements shown and described above with reference to FIG. 6. In place of the traction unit 280 described above, however, the variable ambulation speed system 300 has a tension scale 302 for measurement and indication of the tension along the strap assembly. The end of the rope 275 is tied to a hook 304.

In operation, the length of the spacer bar assembly 266 should be appropriately adjusted by the length adjusting mechanism 267 to determine the angle of suspension between the front straps 224 and the rear straps 226. Also, the degree of suspension is measured by the tension unit 280 or the scale 302 and adjusted if necessary.

In accordance with embodiments of the present invention, the harness assembly 222 may be used, depending upon the patients' or users' particular requirements, in combination with exercise apparatuses other than the variable ambulation speed system 230, such as for example, a stationary bicycle apparatus, a cross-country skiing apparatus, a vertical climbing apparatus, a portable stairs.

While the invention has been described with respect to the illustrated embodiments in accordance therewith, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. For example, the two upper ends of the pair of front strap assemblies 24 and the two upper ends of the pair of rear strap assemblies 26 as shown in FIGS. 1 and 2 may be suspended from a single front sliding element and a single rear sliding element, respectively. Moreover, the two overhead support assemblies 220 as shown in FIG. 6 may be coupled to each other so that the two overhead support assemblies 220 move together along the overhead support frames 244. Also, each of the front and rear sliding elements 258 and 260 may be fixed or locked to the overhead support frames 244 so that the overhead support assemblies 220 do not move from a predetermined position. Other embodiments are also possible, their specific designs depending upon the particular application. As such, the scope of the invention should not be limited by the particular embodiments herein described but should be defined only by the appended claims and equivalents thereof.