US20070298949A1

US20070298949A1 - Lower extremity exercise device

Info

Publication number: US20070298949A1
Application number: US11/473,587
Authority: US
Inventors: Michael M. Soletski
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-06-22
Filing date: 2006-06-22
Publication date: 2007-12-27

Abstract

A portable, compact lower extremity exercise device, suitable for exercising feet and legs of the user while the user is sitting or standing with his/her heels on the floor or ground. The device is adapted and configured to be used where foot space is limited, such as at a desk, a work table, or in an airliner seat. The bottom of the exercise device has first and second sides, and a rocking surface between the sides and proximate the middle of the device. Foot ramps at the top of the device, are spaced from each other and angled downwardly toward the front of the device, thus downwardly toward the user. The working unit can be suspended in a frame, and the frame supported from the floor. The device is used by rocking the device back and forth under the user's feet.

Description

BACKGROUND

This invention relates generally to exercise devices. It is well known that prolonged sitting, such as at a desk or in an airplane results in poor blood circulation in the lower extremities, especially in the lower portion of the leg below the knee and in the foot.
A known remedy for such poor circulation is to periodically exercise the lower extremities. Where the person has the option of periodically getting up and walking about, such walking exercise can alleviate at least some of the poor circulation issues.
However, many people work at jobs which require that they remain at their work stations for prolonged periods of time, negating the option of getting up and walking around to address such circulation issues.
For those who are unable to get up and walk around, it is desirable that they engage into some form of exercise while in the sitting position.
A variety of exercise devices are known which can be put under a desk or table, such as at home or at work, thus to engage the legs and/or feet in order to get the desired exercise. However, such devices known to the inventor of this invention are so large, or so heavy that they are inconvenient to work with, and/or too large to be carried onto an airplane and placed under the seat in front of the user. Thus, there remains a need for an exercise device which solves the above described physical health problems which attend the passive work environment.
A related problem of poor circulation exists among people who have limited mobility for other reasons, such as those who have foot or leg injuries or degradations, those who are too weak to walk, the aged, those recovering from certain medical procedures, and the like. Such people encounter the same problems with getting enough exercise of the legs and feet to ensure proper levels of blood circulation.
It would be desirable to provide a lower extremity exercise device which is simple and convenient to use, and compact in size, so as to be readily used under a desk, under a table, or under an airplane seat.
It would be desirable to have such lower extremity exercise device which is small enough, and light-weight enough to be readily portable.
It would be desirable to have such lower extremity exercise device which is adapted for use by medically challenged people such as the handicapped, or adapted for use by those suffering from temporary infirmity, or adapted for use by those recovering from medical procedures, or adapted for use by the aged, or other medically challenged people.

SUMMARY OF THE INVENTION

The invention provides a portable, compact lower extremity exercise device suitable for exercising the feet and legs of the user while the user is in a sitting position. The device is adapted and configured, without limitation, to be used by a user sitting in a limited-space environment such as at a desk, a work table, or in an airliner seat. The exercise device has first and second sides. A rocking surface is located on the bottom of the device, between the sides and proximate the middle of the device. First and second foot ramps are disposed at the top of the device, spaced from each other and angled downwardly in a common direction toward the user. Foot-receiving surfaces of the foot ramps extend downwardly toward the front side of the exercise device, thus downwardly toward the user. The device is used by rocking the device back and forth under the user's feet by alternately applying and relieving force to first one foot and then the other.
In general, the invention comprehends a lower extremity exercise device, comprising a top, a bottom, generally opposing front and back sides extending between the top and the bottom; and opposing ends; a length, defined between the opposing ends, a width defined between the front side and the back side, and a thickness defined between the top and the bottom. A middle of the lower extremity exercise device is defined generally mid-way along the length between the opposing ends. The bottom has first and second sides associated with respective ones of the ends of the lower extremity exercise device. The first and second sides of the bottom extend toward each other, and define a rocking surface proximate the middle of the lower extremity exercise device, and about which the lower extremity exercise device can rock when the lower extremity exercise device is placed on a floor. First and second foot ramps are defined at the top of the lower extremity exercise device, spaced from each other. Foot-receiving surfaces of the foot ramps extend from upper ends thereof, at the back side of the lower extremity exercise device, downwardly toward the front side of the lower extremity exercise device, to lower ends of the ramps.
In some embodiments, first and second sides of the bottom extend along generally mirror-image paths toward the rocking surface.
In some embodiments, the ramps extend in generally common directions.
In some embodiments, the exercise device is generally symmetric with respect to the middle of the lower extremity exercise device.
In some embodiments, the distance from an underlying floor to the foot ramps, when both foot ramps are at a common height, e.g. the top of the device is horizontal, is no more than about 7 inches to the lower ends of the foot ramps.
In some embodiments, the lower ends of the foot ramps extend to the front side and are readily accessible to receive a user's feet thereon.
In some embodiments, when the exercise device is placed on the floor, the lower ends of the ramps are located at heights relative to the floor, and the ramps are inclined at corresponding angles relative to the floor, such that a user sitting in a chair adjacent the lower extremity exercise device can place the heels of his feet on the floor and rest balls of his feet on the ramps, with the bottoms of the user's feet generally extending along extensions of the foot-receiving surfaces defined by the ramps.
In some embodiments, the foot ramps define angles β of about 5 degrees to about 15 degrees with respect to a front-to-back definition of the rocking surface.
In some embodiments, the planar surfaces of the first and second sides of the bottom define angles α of about 10 degrees to about 20 degrees with respect to the upper ends of the ramps.
In some embodiments, the length of the exercise device is no more than about 17 inches and each of the width and thickness is no more than about 2.5 inches.
In some embodiments, the exercise device is made of a plastic shell, and has a central light-weight or hollow interior cavity defined inwardly of the plastic shell, whereby the lower extremity exercise device is light in weight and correspondingly readily portable.
In some embodiments, the rocking surface is an arcuate surface, centered at the middle of the exercise device, the arcuate surface having an effective rocking radius of at least about 0.13 inch, and extending to planar surfaces which define at least substantial portions of the first and second sides of the bottom.
In some embodiments, relatively more remote portions of the planar surfaces of the bottom function as stop surfaces which stop instantaneous rocking motion of the lower extremity exercise device when the corresponding more remote portions of the planar surfaces of the bottom come into contact with an underlying floor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a pictorial view of an exemplary lower extremity exercise device of the invention, illustrating the top and front of the device.

FIG. 2 shows a cross-section of the exercise device taken at 2-2 of FIG. 1.

FIG. 3 shows a front elevation view of the device of FIG. 1.

FIG. 4 shows a plan view of the device of FIG. 1.

FIG. 5 shows a bottom view of the device of FIG. 1.

FIG. 6 shows a plan view of the device of FIG. 1, as in FIG. 4, with a user's feet superimposed on the device.

The invention is not limited in its application to the details of construction or the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in other various ways. Also, it is to be understood that the terminology and phraseology employed herein is for purpose of description and illustration and should not be regarded as limiting. Like reference numerals are used to indicate like components.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows a pictorial view of an exemplary lower extremity exercise device 10 of the invention. The exercise device has a top 12, a generally opposing bottom 14, a front 16, a back 18, and opposing ends 20. The front and back generally extend between the top and the bottom. The ends generally define the longitudinal extremities of the exercise device.
The device has a length “L” between ends 20, a width “W” between front 16 and back 18, and a thickness “T” between top 12 and bottom 14.
A middle “M” of the exercise device is defined generally mid-way along the length between ends 20.
Bottom 14 has opposing left and right bottom sides 22, 24 as illustrated in FIGS. 1 and 3. Between bottom sides 22, 24 is rocking radius 26. In the illustrated embodiment, bottom sides 22 and 24, together with rocking radius 26 collectively define the entirety of bottom 14. In other embodiments, bottom 14 can be otherwise configured such that the bottom is not entirely defined by bottom sides 22 and 24 and rocking radius 26.
Top 12, as illustrated, has foot ramps 28 disposed toward ends 20 of the device, and a centrally-located foot spacing platform 30 between the foot ramps. Foot ramps 28 extend, in planar configurations, from upper ends of the ramps at or adjacent back 18, downwardly toward the floor or ground, and reach the lower ends of the ramps at or adjacent front 16. The ramps typically extend in common directions, typically within a common imaginary plane 31. Accordingly, the bottoms of the feet 33 of a user of such exercise device are typically in a common imaginary plane when placed on the foot ramps.
In the illustrated embodiment, bottom sides 22 and 24 extend toward each other along intersecting paths. Bottom sides 22 and 24 are illustrated as being planar from ends 20 to where they merge into rocking radius 26. Where a bottom side is thus planar/flat for a significant portion of the length of the bottom side, the respective bottom side generally functions as a stop surface, stopping the rocking motion of the exercise device when the planar/flat portion of the bottom side comes into typically interfacial contact with the underlying floor or the ground.
Bottom sides 22 and 24 can well have other surface characteristics. The bottom sides can be represented by structural framework rather than solid surfaces. Similarly, the front, the back, and the top can be fabricated as other than solid surfaces. Thus, there can be mentioned structural framing configurations which carry corresponding foot ramps. The critical feature is the foot ramps, associated with corresponding bottom sides in suitable spatial relationships so as to enable the rocking motion exercise contemplated herein, with the user in a sitting position.
FIG. 5 illustrates cross-grooving 32 in the rocking radius portion of the bottom surface thereby to discourage “walking” of the device on a textured floor such as on carpeting.
The exercise device of the invention is illustrated in FIGS. 1 and 2 as having been made of wood. And indeed wood is an acceptable material of choice in some embodiments. However, in order to reduce weight, facilitate manufacture, and control cost, the device can well be made of plastic, e.g. molded plastic. Such device can be solid plastic. However, in the interest of controlling cost, where continuous surfaces are contemplated to enclose the exercise device, the central portion of the device is a hollow cavity, or can comprise a central portion filled with a low-density relatively rigid material such as expanded foam polystyrene or other light-weight, relatively rigid, cost effective material.
Yet further, the device can be made as a connecting series of stringers and braces, as in bridge and/or truss construction, with the foot ramps strategically located as illustrated in the drawings, and properly supported with respect to strength. In such instances, the quantity of material used can be optimized. Similarly, such bridgework or truss structure can be readily molded by plastic molding machines, and assembled as needed.
As illustrated in the drawings, rocking surface 26 is optionally arcuate. While the rocking surface can have other configurations, an arcuate configuration provides the least resistance to the rocking exercise contemplated for the exercise device disclosed herein. In that regard, a relatively larger rocking radius generally facilitates the rocking activity. To that end, the rocking radius typically, though not necessarily, defines an effective radius of at least about 0.13 inch. “Effective radius” of a stated dimension means a surface which enables the exercise device to rock back and forth in an exercise action which simulates, or approximates, the action of a radius of a corresponding dimension. An illustrative, though not limiting, efficient radius is about 2 inches to about 2.25 inches.
The effective radius can have any of a wide range of sizes, so long as the radius is large enough to provide a smooth transition from side to side, and so long as some stop structure is provided in association with bottom 14.
The exercise device of the invention, as illustrated, is symmetrical about middle “M”. While such symmetry is not required, symmetry typically accompanies devices of the invention and facilitates their use.
Devices of the invention can be fabricated in a wide variety of dimensions, so long as the dimensions are compatible with the exercise activity contemplated herein. Thus, any length “L” can be used so long as the feet can be separated, and so long as both feet can be placed on the device at the same time. A typical, though not limiting, length “L” is about 12 inches to about 17 inches. Typical width “W” is about 1 inch to about 3 inches, commonly no more than about 2.5 inches. Similarly, thickness “T” is typically about 1 inch to about 3 inches, commonly no more than about 2.5 inches.
Overall, a handy size device is about 15 inches overall length “L”, and 1.5 inches each in width “W” and thickness “T”.
Typical width for the foot ramps, measured along length “L” of the device, is about 4.75 inches, with a range of e.g. about 3.0 inches to about 5.0 inches.
With the exercise device resting on the floor, with both ends at equal heights above the floor, thus with the top of the device level/parallel with the floor, bottom sides 22, 24 define angles α of about 10 degrees to about 20 degrees with respect to the floor. An angle of about 15 degrees is found be about optimal.
With the exercise device 10 in the orientation, relative to the floor, as described immediately above, and as illustrated in FIG. 3, each foot ramp 28 extends, from an upper end 34 at or proximate back 18 of the exercise device, downwardly toward front 16 of the exercise device, at an angle β of about 5 degrees to about 15 degrees with respect to bottom 14 of the device, and accordingly to the underlying floor. Angles of about 7 degrees to about 8 degrees are found to be about optimal when the thickness of the device is about 1.25 inch to about 1.5 inch. Each foot ramp 28 ends at a lower end 36 at or proximate front 16 of the exercise device.
Typically, foot ramps 28 extend in generally common directions, generally aligned with, or in, a common imaginary plane 31. In keeping with the contemplated uses of the invention, when the exercise device is in a generally horizontal position, as illustrated in FIG. 3, e.g. with both foot ramps at the same height “H” above the floor, height “H” of the foot ramps at lower ends 36 is at heights which facilitate use of the exercise device when the user is sitting, with his/her heels on the floor adjacent the ramps. If the height is too low, the device is ineffective to facilitate the desired level of exercise. If the height is too high, the balls of the user's feet do not reach to the lower ends of the ramps while the heels are on the floor. In the alternative, the user can use the toes of his/her feet on ramps 28, which extends the height range to a limited extent.
Another factor which affects the height “H” at the lower ends of ramps 28 is the thickness “T” of exercise device 10 proximate ends 20, and specifically at ramps 28. The thicker the device proximate ends 20 the less the vertical travel distance between the top of the rocking action of the device, illustrated at the right end in dashed outline on FIG. 3, and the bottom of the rocking action, illustrated at the left end in dashed outline on FIG. 3. Specifically, the critical dimension is the vertical difference between the lower end of a ramp and the configuration of bottom side 22 or 24 adjacent that ramp. Namely, the relationship between the lower end of the ramp, and the adjacent bottom side 22 or 24 of bottom 14 of the device, establishes the extremities of the vertical distance between the bottom of the rocking motion and the top of the rocking motion.
At the bottom of the rocking motion, the ball of the foot can approach floor level. At the top of the rocking motion, the ball of the foot can be as high off the floor as the ball can go with the heel still on the floor, and without overstressing the available range of motion of the foot about the user's ankle. In that regard, the upper limit of height “H” of lower end 36 of ramp 28, at the top of the rocking motion, as at the ramp on the right side of the device in FIG. 3, is about 9 inches.
With the upper limit of the rocking motion established at about 9 inches to lower end 36 of the ramp, the range of motion between the upper limit and the lower limit is further established by the position of bottom side 22 or 24 relative to the lower end of the ramp. In the embodiments illustrated, the bottom side of the ramp is about 0.1 inch to about 0.2 inch below the remote end of ramp 28 at lower end 36. With the location of bottom side 22 or 24 thus established relative to a foot ramp 28, the vertical range of the rocking motion can thus be determined.
In the illustrated embodiments, the lower end of the foot ramp is typically between 0.25 inch and 0.5 inch off the floor at the lower limit of the rocking motion. Minor increments downward can be achieved if desired. At the upper limit of the rocking motion, the lower end of the raised foot ramp, as shown in dashed outline on the right side of FIG. 3, is between about 6 inches and about 7 inches off the floor. FIG. 3 illustrates the fact that distance from the floor to the ramps 28 varies from the distal end of the respective ramp to the proximal end of the same ramp. Thus, the recited distances are approximations only, within the limits of the rocking motion of the exercise device.
A comfortable range of motion, as measured at the lower ends of the ramps most distal from middle “M” of the exercise device, is about 0.25 inch off the floor at the lower limit of the range of motion and about 2.5 inches off the floor at the upper limit of the range of motion. Thus, an illustrative range of rocking motion, without limitation, is about 2 inches to about 3 inches, from the bottom the motion of an end 20 to the top of the range of motion of that same end.
While a user's perception varies depending on what specific part of the foot is on the ramps, as the ramps approach the floor, the ball of the user's foot approaches the floor, whereby the user can perceive that his/her foot has reached the floor. Thus, the user may perceive a lower limit of the rocking motion as being a situation where his/her foot is approximately in contact with the floor.
As illustrated in the drawings, a typical such exercise device is symmetrical about the middle “M” of the device, whereby the left and right sides of the device are mirror images of each other.
Angles β are defined with respect to the bottom of the exercise device. When the exercise device is placed on the floor, the same angles β also define the angles between the ramps and the underlying floor. With the exercise device placed on the floor with the ramps at a common height, the angles β of the ramps generally represent angles where the user can comfortably maintain his/her feet on the ramps for an extended period of time, without undue stress and/or discomfort. In that orientation, the user's feet can readily be aligned with the angles β of the ramps, with the user's heels on the floor, such that the bottoms of the user's feet, optionally wearing generally flat-soled shoes, define angles approximating the same angles β of foot ramps 28 with the floor, whereby the user's feet are generally aligned with the surfaces of the foot ramps.
As is discussed briefly following, while the exercise device of the invention interfaces with the user's feet, the exercise activity involved in use of device 10 provides substantial exercise to the legs as well as to the feet.
Using the embodiments illustrated in the drawings, an exercise device of the invention is used as follows. The user places the exercise device on the floor in front of e.g. a chair, within easy reach of the user's feet when the user is sitting in the chair. The exercise device is oriented with the front of the device facing the chair. In that orientation, the lower ends of the ramps are closer to the chair than are the upper ends of the ramps.
The user sits in the chair and places the heels of his/her feet between the chair and the device, with the balls or toes of his feet over the ramps. The user then places the balls or toes of both feet on the ramps while maintaining his/her heels on the floor. Assuming the user's feet apply equal weight on both ramps, the equal weight maintains the ramps at approximately equal heights. The user then places a relatively greater weight on one ramp while placing a relatively lesser weight on the other ramp.
As a result of the weight imbalance, the ramp which receives the greater weight moves downwardly while the ramp which receives the lesser weight moves upwardly, thus starting the rocking motion which typically characterizes use of exercise devices of the invention. For example, the left ramp moves down while the right ramp moves up, as illustrated in dashed outline in FIG. 3.
The relative weight imbalance can be achieved by adding a greater level of downward force to the ramp which is to move downwardly such as by applying more weight, or by releasing some of the downward force on that ramp such as by applying a lifting force to that foot e.g. by applying a rotationally-upward force about the ankle, thus lifting upwardly on the ball of the foot. In the alternative, the relative weight imbalance can be achieved by simply lifting the ball of the foot under which the ramp is to rise. Yet further, the weight imbalance can be achieved by a combination of applying weight/force to the ramp which is to move downwardly while releasing weight from the ramp which is to rise.
The left ramp reaches the bottom of its path of travel when the left bottom side 22 of bottom 14 reaches the floor, as suggested in dashed outline in FIG. 3. The user then reverses the weight/force imbalance by applying relatively more force/weight on the right foot ramp and relatively less force/weight on the left foot ramp, which results in a reverse direction motion, namely the rising of the left foot ramp and the downward motion of the right foot ramp. When the right bottom side 24 of bottom 14 reaches the floor, the user again reverses the weight imbalance, which again moves the left side of the exercise device downwardly while the right side moves upwardly. This process is repeated as desired, resulting in a rocking motion of the exercise device, and corresponding movements in the feet of the user, with cooperative contraction and expansion of the muscles in the user's legs.
When the user uses the device of the invention in a sitting position, and as desired, the user can raise his/her heels off the floor, placing relatively more weight on the balls or toes of the feet, thus on ramps 28. In this position, the user then uses his/her leg muscles to raise and lower the legs, and thus the corresponding ramps, to effect the above-described rocking motion, but as an exercise primarily for building leg muscle as well as for lower extremity blood circulation.
While exercise devices 10 of the invention have been described in the context of use by a person sitting in a chair, devices 10 can as well be used by a person who is standing in one location for a substantial period of time. For example, a person standing at a work bench can place the balls of his/her feet on the device and rock the device back and forth at will in that one location thus to exercise the legs and feet.
The invention as described above, and illustrated in the drawings, is a stand-alone one-piece device. In an alternative embodiment (not shown), the exercise device includes a supporting frame. The exercise device shown is supported from the frame by a rod or other supporting pivot structure which passes through the middle of the device at an appropriate height, and thence extends to supporting structures on the frame, which thus suspends the working portion of the exercise device from the frame and vicariously from the floor. The frame rests on the floor and suspends the exercise device at a low height above the floor.
In such case, the amount of energy needed to activate and rock the exercise device can be controlled and/or adjusted by mounting extension springs or compression springs proximate the ends of the device, and which springs extend e.g. from the top of the device to the frame. Similarly, compression springs can be mounted to bottom 12 of the device, and extend downwardly to the frame. Finally, a combination of extension springs and compression springs can be mounted proximate the ends of the device so as to cooperate with each other, e.g. work against each other, in defining the amount of force required to rock the device back and forth, somewhat as described above. In a given such structure, the springs can be arranged so as to work against each other, and optionally so as to present the exercise device with the foot ramps at a common height when the device is not under use load.
As desired, lesser-force springs can be replaced with greater-force springs, or greater-force springs can be replaced with lesser-force springs, in order to achieve the desired levels of energy consumption, circulation stimulation, and muscle development, as the device is being used.
In the suspended embodiments, the function of rocking radius 26 is taken over by the suspension system, whereby the exercise device is supported by the pivot pin at middle “M”, and the device is not supported by contact between the bottom of the exercise device and the floor. In such embodiment, rocking radius 26 is obviated, and is omitted.
Those skilled in the art will see that certain modifications can be made to the apparatus and methods herein disclosed with respect to the illustrated embodiments, without departing from the spirit of the instant invention. And while the invention has been described above with respect to the illustrated embodiments, it will be understood that the invention is adapted to numerous rearrangements, modifications, and alterations, and all such arrangements, modifications, and alterations are intended to be within the scope of the appended claims.
To the extent the following claims use means plus function language, it is not meant to include there, or in the instant specification, anything not structurally equivalent to what is shown in the embodiments disclosed in the specification.

Claims

1. A lower extremity exercise device, comprising:

a top;

a bottom;

generally opposing front and back sides extending between the top and the bottom; and

opposing ends;

a length, defined between the opposing ends,

a width, defined between the front side and the back side,

a thickness, defined between the top and the bottom,

a middle of said lower extremity exercise device being defined generally mid-way along the length between the opposing ends,

the bottom having first and second sides thereof associated with respective ones of the ends of said lower extremity exercise device,

the first and second sides of the bottom extending toward each other, and defining a rocking surface proximate the middle of said lower extremity exercise device,

and about which said lower extremity exercise device can rock when said lower extremity exercise device is placed on a floor,

first and second foot ramps being defined at the top of said lower extremity exercise device, spaced from each other, foot-receiving surfaces of said foot ramps extending from upper ends thereof, at the back side of said lower extremity exercise device, downwardly toward the front side of said lower extremity exercise device, to lower ends of said ramps.

2. A lower extremity exercise device as in claim 1 wherein first and second sides of the bottom extend along generally mirror-image paths toward the rocking surface.

3. A lower extremity exercise device as in claim 1 wherein said ramps extend in generally common directions.

4. A lower extremity exercise device as in claim 1 wherein said lower extremity exercise device is generally symmetric with respect to the middle of said lower extremity exercise device.

5. A lower extremity exercise device as in claim 1 wherein a distance from an underlying floor to said foot ramps, when both said foot ramps are at a common height, is no more than about 7 inches to the lower ends of said foot ramps.

6. A lower extremity exercise device as in claim 1 wherein lower ends of said foot ramps extend to the front side and wherein the lower ends of said foot ramps are readily accessible to receive a user's feet thereon.

7. A lower extremity exercise device as in claim 1 wherein, when said exercise device is placed on a floor, the lower ends of said ramps are positioned at heights relative to such floor, and said ramps are inclined at corresponding angles relative to such floor, such that a user sitting in a chair adjacent said lower extremity exercise device can place heels of his feet on such floor and rest balls of his feet on said ramps, with bottoms of such user's feet generally extending along extensions of the foot-receiving surfaces defined by said ramps.

8. A lower extremity exercise device as in claim 1 wherein said foot ramps define angles β of about 5 degrees to about 15 degrees with respect to a front-to-back definition of the rocking surface.

9. A lower extremity exercise device as in claim 1 wherein the length is no more than about 17 inches and each of the width and thickness is no more than about 2.5 inches.

10. A lower extremity exercise device as in claim 1 wherein said lower extremity exercise device is made of a plastic shell, and has a central light-weight or hollow interior cavity defined inwardly of said plastic shell, whereby said lower extremity exercise device is light in weight and correspondingly readily portable.

11. A lower extremity exercise device as in claim 1 wherein the rocking surface is an arcuate surface, centered at the middle of said lower extremity exercise device, the arcuate surface having an effective rocking radius of at least about 0.13 inch, and extending to planar surfaces which define at least substantial portions of the first and second sides of the bottom.

12. A lower extremity exercise device as in claim 11 wherein relatively more remote portions of the planar surfaces of the bottom function as stop surfaces which stop instantaneous rocking motion of said lower extremity exercise device when the corresponding more remote portions of the planar surfaces of the bottom come into contact with an underlying floor.

13. A lower extremity exercise device as in claim 11 wherein the planar surfaces of the first and second sides of the bottom define angles α of about 10 degrees to about 20 degrees with respect to the upper ends of said ramps.

14. A lower extremity exercise device, comprising:

a top;

a bottom;

opposing ends;

a length, defined between the opposing ends,

a width, defined between the front side and the back side,

a thickness, defined between the top and the bottom,

the first and second sides of the bottom generally defining straight-line wedges with respect to the top, and meeting each other proximate the middle of said lower extremity exercise device, and defining an arcuate rocking surface proximate the middle of said lower extremity exercise device, about which rocking surface said lower extremity exercise device can rock when said lower extremity exercise device is placed on a floor,

first and second foot ramps being defined at the top of said lower extremity exercise device, foot-receiving surfaces of said foot ramps extending from upper ends thereof at the back side of said lower extremity exercise device, downwardly toward the front side of said lower extremity exercise device.

15. A lower extremity exercise device as in claim 14 wherein the first and second sides of the bottom define angles α of about 10 degrees to about 20 degrees with respect to the upper ends of said ramps.

16. A lower extremity exercise device as in claim 14 wherein the straight line wedges of the sides of the bottom define stop surfaces, and wherein a such stop surface stops the rocking motion of said lower extremity exercise device when the respective stop surface comes into contact with an underlying support surface.

17. A lower extremity exercise device, comprising:

a top;

a bottom;

opposing ends;

a length, defined between the opposing ends,

a width, defined between the front side and the back side,

a thickness, defined between the top and the bottom,

the first and second sides of the bottom extending along generally mirror-image paths toward each other, and defining an arcuate rocking surface proximate the middle of said lower extremity exercise device, and about which said lower extremity exercise device can rock when said lower extremity exercise device is placed on a floor, the arcuate surface having an effective rocking radius of at least about 0.13 inch,

first and second foot ramps being defined at the top of said lower extremity exercise device, spaced from each other, foot-receiving surfaces of said foot ramps extending from upper ends thereof, at the back side of said lower extremity exercise device, downwardly in generally common directions toward the front side of said lower extremity exercise device, to lower ends of said ramps,

said lower extremity exercise device being generally symmetric with respect to the middle thereof, and wherein a distance from an underlying floor to said foot ramps, when both said foot ramps are at a common height, is no more than about 7 inches to the lower ends of said foot ramps.

18. A lower extremity exercise device as in claim 17 wherein the first and second sides of the bottom define generally straight-line wedges with respect to the top.

19. A lower extremity exercise device as in claim 18 wherein the length is no more than about 17 inches and each of the width and thickness is no more than about 2.5 inches.

20. A lower extremity exercise device as in claim 17 wherein the first and second sides of the bottom define angles α of about 10 degrees to about 20 degrees with respect to the upper ends of said ramps and wherein the straight line wedges of the sides of the bottom define stop surfaces, and wherein a such stop surface stops the rocking motion of said lower extremity exercise device when the respective stop surface comes into contact with an underlying support surface.