Variable resistance exercising apparatus and method

Exercising apparatus and method whereby the resistance encountered by the body part or parts being exercised is varied by moving the body part or parts along a discretely curved incline, whereby the resistance varies automatically and instantaneously commensurate with the sine of the angle of the incline.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to exercising apparatus and method. More 
particularly, this invention relates to exercising apparatus and method 
whereby the resistance encountered by the exerciser varies automatically 
and instantaneously. 
2. Description of the Prior Art 
The advantages of incorporating variable resistance into exercising 
apparatus have been well established. These advantages include providing a 
resistance that corresponds closely to the strength curve of the body part 
or parts being exercised. Also, the chances of injury to the exerciser are 
minimized when it is considered that the variable resistance can 
accommodate the particular weakness of the body part as is the case, for 
example, at the beginning of the exercise. Finally, the variable 
resistance enables the exerciser to encounter a higher level of exercise 
intensity, if desired. 
The variable resistance concept is recognized in U.S. Pat. No. 3,858,873 
issued on Jan. 7, 1975 to Arthur A. Jones. However, the present invention 
affords the exerciser the aforenoted variable resistance features in a 
simplier and thereby more effective way than has been accomplished by this 
and other prior art. 
SUMMARY OF THE INVENTION 
This invention contemplates variable resistance exercising apparatus and 
method whereby a discretely curved incline is provided and the exercise is 
accomplished by exerting a force to move the exerciser's body part or 
parts being exercised up the incline so that the resistance encountered 
corresponds closely to the strength curve of the body part or parts being 
exercised, and which resistance varies automatically and instantaneously 
with the sine of the angle of the incline. 
One object of this invention is to provide variable resistance exercising 
apparatus and method. 
Another object of this invention is to provide the variable resistance by 
moving the exerciser's body part or parts being exercised up a discretely 
curved incline, wherein the resistance encountered by the body part or 
parts varies instantaneously and automatically with the sine of the angle 
of the incline. 
Another object of this invention is to provide variable resistance 
exercising apparatus and method which varies the resistance commensurate 
with the strength curve of the body part or parts being exercised to 
lessen the chances of injury to the exerciser and to provide the level of 
exercise intensity that is desired. 
The foregoing and other objects and advantages of the invention will appear 
more fully hereinafter from a consideration of the detailed description 
that follows taken together with the accompanying drawings wherein a 
single embodiment of the invention is illustrated. It is to be expressly 
understood, however, that the drawings are for illustration purposes only 
and are not to be construed as defining the limits of the invention, 
reference being had to the appended claims for that purpose.

DESCRIPTION OF THE INVENTION 
With reference first to FIG. 1, it is a well known principle that an 
inclined plane may be used to reduce the force required to raise a weight 
W, as compared to the force required to vertically raise the weight. Thus, 
to move weight W up an inclined plane 1 at an angle .theta. with the 
horizontal, a force F is required which varies directly with the sine of 
angle .theta. as follows: 
EQU F=W sine .theta. 
If angle .theta. is 30.degree., the force F required to move weight W a 
unit distance up inclined plane 1 equals 0.500 W, since the sine of 
30.degree. is 0.500. Likewise, if angle .theta. is 45.degree. force F 
required to move weight W a unit distance up inclined plan 1 equals 0.707 
W and if angle .theta. is 60.degree. force F equals 0.866 W. 
It will be seen that the steeper the angle of the incline the greater the 
force required to move the weight a unit distance up the incline. That is 
to say, the steeper the angle of the incline, the greater the resistance 
that the weight offers to movement. Thus, when angle .theta. is at 
45.degree. force F required to move weight W up incline 1 is the quotient 
of the sine of 45.degree. divided by the sine of 30.degree. (0.707/0.500), 
or 1.414 times the force required for a 30.degree. incline. Likewise, when 
angle .theta. is 60.degree., the force required is the quotient of the 
sine of 60.degree. divided by the sine of 45.degree. (0.866/0.707) or 
1.255 times the force required for a 60.degree. incline. This relationship 
is used to provide a variable resistance exercising device as will be next 
described with reference to FIGS. 2, 3, 4 and 5. 
With reference to FIGS. 2 and 3, there is shown, for purposes of 
illustrating the invention, exercising apparatus that provides a variable 
resistance when performing what is commonly known as a deep-knee-bend 
exercise. By way of introduction, the deep-knee-bend exercise is performed 
by the exerciser with his feet braced, exercising his thigh and hip 
muscles and to thereby perform a compound exercise. At the start of the 
deep-knee-bend exercise the legs are bent and the knees are drawn close to 
the chest of the exerciser (such as in a fetal position), and as the 
exercise progresses the knees are displaced away from the chest until the 
exercise is completed, whereupon the legs are in an extended position. 
FIGS. 2 and 3 show exercising apparatus for performing the deep-knee-bend 
exercise as heretofore described, and which apparatus includes a pair of 
side frames 2 and 4 which are identical and substantially parallel and in 
spaced relation to each other. Side frames 2 and 4 are supported in said 
spaced relation by a transversely extending foot rest member 6 and a 
transversely extending upper cross-bar member 7. 
The invention is best illustrated by describing the side frames, and for 
this purpose specific reference is now made to FIG. 3 which shows the 
elements of side frame 2 in substantial detail. Corresponding elements of 
side frame 4 as shown in FIG. 2 have corresponding numerical designations, 
but carrying the subscript "A". 
Thus, side frame 2 includes a short vertical member 8 and a substantially 
longer vertical member 10, and which vertical members 8 and 10 are 
separated by a horizontal member 12. Foot rest member 6 extends angularly 
upward from horizontal member 12 and has secured near the bottom thereof a 
discretely curved rail 14 which extends upward to cross-bar member 7 to 
form an inclined plane with an instantaneously varying angle of incline. 
A supporting member 15 extends angularly and downward from vertical member 
10 to horizontal member 12 and is secured to said members 10 and 12, while 
another supporting member 16 extends horizontally from vertical member 8 
to angularly extending supporting member 15, and is likewise secured to 
said members 8 and 15. 
It is to be noted that this is but one structural arrangement for side 
frames 2 and 4, with other structural arrangements being within the scope 
and accomplishing the purposes of the invention. Further, the frame 
members, which may be metallic tubular or pipe like members, may be 
secured to each other as by welding or the like. The important feature of 
the invention, as will become evident, is discretely curved rail 14 of 
side frame 2 and corresponding rail 14A of side frame 4, and which feature 
will be hereinafter described. 
A carriage 18 is supported on tracks 19 and 19A, respectively, on curved 
rails 14 and 14A by front rollers 20 and rear rollers 22 so as to be 
movable along the rails. In this connection it is noted that front rollers 
20 are carried by front legs 24 extending downward from the front of the 
carriage to the rails and rear rollers 22 are carried by substantially 
shorter rear legs 26 extending downward from the rear of the carriage so 
that the rear of the carriage is near the rails. 
Carriage 18 carries a padding or the like 28 for supporting the back of the 
exerciser. The padding may be of upholstered foam rubber or other such 
similar material as is common in exercising apparatus of the type being 
described. Extending outwardly from and substantially normal to carriage 
18 are arm rests 30 and 30A for supporting the arms of the exerciser. Arm 
rests 30 and 30A may likewise carry foam rubber pads 32 or the like such 
as described with reference to pad 28 carried by carriage 18, while foot 
rest 6 may carry a foam rubber foot stop 33 at the end thereof. 
Extending substantially normal to and outwardly from the top of carriage 16 
are shoulder restraints 34 and 34A. The shoulder restraints may carry 
foam-rubber pads 36 such as described with reference to carriage pad 28, 
arm-rest pads 32 and foot stop 33. The aforenoted pads provide convenient 
supporting and/or restraining means for the respective members of the 
exerciser's body and serve the further purpose of preventing injury to the 
exerciser while the exercise is being performed as might otherwise be the 
case. 
Arm rests 32 and 32A and should restraints 34 and 34A may be adjustable 
relative to carriage 18 to accommodate various body proportions of the 
exerciser as will now be understood by those skilled in the art. 
The purpose of the exercise being described is to exercise the thigh and 
hip muscles of the exerciser. This is accomplished by the exerciser 
pushing against foot rest 6, whereby carriage 16 is displaced upwardly 
along discretely curved rails 14 and 14A. As is well known in the 
exercising field, the muscle or muscle group being exercised has a 
particular strength curve that is substantially the same irrespective of 
the body proportions or the strength of the exerciser. However, the amount 
of weight that an exerciser can or should move does vary with his body 
proportions and strength and with his other physical characteristics, and 
for this purpose a weight 38, which may be of the simple bar-bell type, is 
secured to the under side 39 of carriage 18, and which weight may be 
varied depending upon the aforenoted physical characteristics of the 
exerciser, his strength and the degree of exercise intensity desired. 
The variable-resistance feature of the exercising apparatus and method of 
the invention is best illustrated with reference to FIGS. 4 and 5. 
With reference to FIG. 4, carriage 18 is arranged to move along rails 14 
and 14A upon the exerciser exerting a force against foot rest 6 as 
heretofore described with reference to FIGS. 1 and 2. The arrangement is 
such that, for purposes of illustration, at the start of the 
deep-knee-bend exercise being described, the front of carriage 18 is 
disposed along rails 14 and 14A approximately nine inches from foot rest 6 
as shown in FIG. 4. At this starting point, designated as S in the Figure, 
the angle between the carriage and the horizontal is approximately 
28.degree.. As the carriage is displaced by the exerciser further from the 
foot rest along curved rails 14 and 14A, the angle the carriage makes with 
the horizontal varies as shown in the chart of FIG. 5. Thus, when the 
carriage front is displaced six inches from starting point S, the angle is 
approximately 30.degree. and when the carriage displacement is twelve 
inches the angle is approximately 33.degree.. The carriage angle 
automatically and instantaneously varies in accordance with the curve of 
rails 14 and 14A, which is based on the strength of the muscle group or 
groups being exercised, until the carriage front reaches the end of its 
displacement at a point F shown in FIG. 4, and which point F the carriage 
angle is approximately 44.degree.. 
As will be seen from FIG. 5, and with reference to FIG. 1 and the 
description thereof, when the carriage angle is 30.degree., the 
incremental increase in resistance from starting point S is equal to the 
sine of 30.degree. divided by the sine of 28.degree., or 1.066 times the 
starting resistance. Likewise, when the carriage angle is 33.degree. the 
resistance is 1.058 times the resistance at a carriage angle of 
30.degree., and so on as shown in the chart, until the carriage angle 
reaches its final angle of approximately 44.degree.. 
It will thus be seen that the resistance varies automatically and 
instantaneously as the carriage angle varies to provide a variable 
resistance in accordance with the strength curve of the particular muscle 
group being exercised. 
In illustrating the method of the invention reference is again made to FIG. 
3. The exerciser lies with his back flat on pad 28 of carriage 18 and 
braces his feet on foot rest 6 against stop 33 thereon. As heretofore 
noted, at the start of the exercise the exerciser's knees are drawn close 
to his chest. The exerciser positions his head between padded shoulder 
restraints 34 and 34A and positions his arms on padded arm rests 30 and 
30A. 
The exerciser, grasping padded arm rests 30 and 30A, pushes against foot 
rest 6 and by so doing displaces carriage 18 and its associated weight 38 
upward along discretely curved rails 14 and 14A until the carriage reaches 
finishing point F (FIG. 4), at which times the exerciser's legs are 
substantially extended. The exerciser may then allow carriage 18 to slide 
down rails 14 and 14A to starting point S (FIG. 4), and at which time the 
deep-knee-bend exercise as heretofore described may be repeated. Weight 38 
carried on underside 39 of carriage 18 may be increased or decreased to 
accommodate the desired intensity of the exercise and the increased 
strength of the exerciser as will now be understood by those skilled in 
the art. 
There has thus been described variable-resistance exercising apparatus and 
method whereby the resistance encountered by the exerciser varies closely 
with the strength curve of the muscle or muscle group being exercised. The 
exercise is performed by displacing a weight up a discretely curved 
incline, whereby the resistance varies automatically and instantaneously 
commensurate with the sine of the varying angle of incline. The exercising 
apparatus and method described have the advantage of reducing the chances 
of injury, especially at the beginning of the exercise, which is generally 
when the exerciser has the least strength due to minimum leverage, and 
provides a variable level of exercise intensity as may be desired. 
Although but a single embodiment of the invention has been illustrated and 
described in detail, it is to be expressly understood, that the invention 
is not limited thereto. Various changes may also be made in the design and 
arrangement of the parts of the apparatus and the steps of the method 
described without departing from the spirit and scope of the invention as 
the same will now be understood by those skilled in the art. For example, 
although the invention has been desribed with reference to apparatus and 
method for performing the deep-knee-bend exercise, apparatus and method 
for performing other exercises are within the scope of the invention as 
well.