Isokinetic Control Module and Method for Strength Training with User-Generated Resistance and Graphical Force Display

Abstract

An isokinetic control module and method for incorporation on both new and existing exercise equipment. The control module replaces standard friction and hydraulic resistance components offering constant speed of the moveable elements of the machine rather than a selected resistance or weight. The constant user-generated resistance prevents injury and enhances strength training of the targeted muscle groups by maintaining constant strain on those muscles throughout the exercise. This method and device incorporates both a PCFC valve and a check valve device, removing all resistance the moment the user stops applying force to the machine. This enhances safety and facilitates the rapid return of the lifting element to its home position between repetitions. An optional graphical display is also disclosed.

Claims

1. An apparatus for maintaining a constant speed and user-generated resistance within exercise equipment, the apparatus comprising: a. a closed loop hydraulic system comprised of a piston moveably seated within a cylinder and in fluid communication with a pressure compensating unit; b. wherein the cylinder further comprises at least one port to facilitate fluid flow within the closed loop hydraulic system; c. wherein the pressure compensating unit is comprised of a reverse flow check device and a pressure compensating flow control valve (PCFC valve) comprising a valve adjustment shaft mechanically connected to a speed adjustment mechanism, and wherein said reverse flow check device is integral to or in fluid communication with the PCFC valve; d. wherein the piston is mechanically fastened to a user driven element on a piece of exercise equipment having an exercise stroke and a return stroke and wherein movement of said piston imparts a force that results in an increase or decrease in pressure within the closed loop hydraulic system; e. wherein the PCFC valve responds to an increase or decrease in pressure within the closed loop hydraulic system such that a constant fluid flow rate is maintained within said closed loop hydraulic system during the exercise stroke, subsequently allowing or inhibiting the motion of the user driven element to maintain a constant speed; and f. wherein the reverse flow check device allows unrestricted fluid flow within the closed loop hydraulic system during the return stroke.

2. The apparatus of claim 1, wherein the pressure compensating unit is in fluid communication with an accumulator such that fluid flows into and out of said accumulator as the user driven element moves between the exercise stroke and the return stroke.

3. The apparatus of claim 1, wherein a bottom rod is positioned beneath the piston and extends from the bottom of the cylinder.

4. The apparatus of claim 1, wherein the speed adjustment mechanism is connected to a motor such that the position of the speed adjustment mechanism is electronically controlled through a wireless or direct electrical connection with said motor.

5. The apparatus of claim 1, further comprising a touch screen in electronic communication with the speed adjustment mechanism, wherein a specific or preset speed may be selected from said touch screen to adjust the position of the speed adjustment mechanism.

6. The apparatus of claim 1, further comprising a display screen, a pressure transducer, and a data acquisition device in digital communication with a computer, wherein said pressure transducer transmits data pertaining to a force exerted on the user element over a time period to complete each exercise stroke to the data acquisition device and computer, and wherein said computer calculates statistical information pertaining to the movement of the user driven element over time, and wherein said statistical information is transmitted and displayed on said display screen.

7. The apparatus of claim 1, further comprising a display screen, a pressure transducer, and a data acquisition device in digital communication with a computer, wherein said pressure transducer transmits data pertaining to a force exerted on the user element over a time period to complete each exercise stroke to the data acquisition device and computer, and wherein said computer calculates statistical information pertaining to the movement of the user driven element over time, and wherein said statistical information is transmitted and displayed on said display screen in a graphical form.

8. The apparatus of claim 1, wherein the cylinder comprises a single port and further comprises a breather valve.

9. A method for providing constant speed and user-generated resistance within a piece of exercise equipment, said method comprising: a. selecting a piece of exercise equipment having a user driven element comprised of one or more lifting bars or arms for exercising targeted muscle groups during an exercise stroke wherein each bar or arm returns to a home position during a return stroke; b. providing a flow control mechanism comprised of a closed loop hydraulic system, said closed loop hydraulic system being comprised of a piston moveably seated within a cylinder having at least one port in fluid communication with a pressure compensating unit, wherein the pressure compensating unit is comprised of a reverse flow check device and a pressure compensating flow control valve (PCFC valve), and wherein the PCFC valve is comprised of a valve adjustment shaft mechanically connected to a speed adjustment mechanism, and wherein said reverse flow check device is integral to or in fluid communication with the PCFC valve, and wherein the PCFC valve responds to an increase or decrease in pressure within the closed loop hydraulic system by maintaining a constant speed of the user driven element during the exercise stroke regardless of the force applied to the piston unit, and wherein the reverse flow check device allows unrestricted flow within the closed loop hydraulic system during the return stroke; and c. mechanically fastening the piston to the user driven element.

10. The method of claim 9, further comprising an accumulator in fluid communication with said pressure compensating unit.

11. The method of claim 9, wherein a bottom rod is positioned beneath the piston and extends from the bottom of the cylinder.

12. The method of claim 9, comprising the additional steps of: a. electronically connecting the speed adjustment mechanism to a motor; and b. controlling the position of the speed adjustment mechanism through a wireless or direct electrical connection to said motor.

13. The method of claim 11, wherein the closed loop hydraulic system further comprises a pressure transducer electronically connected to a data acquisition device and computer and wherein said computer is electronically connected to a display screen, the method further comprising the steps of: a. measuring the force within the closed loop system over the time the force was exerted via the pressure transducer; b. transmitting the force over time data to the data acquisition device and computer; c. calculating statistical data sets based on the measured force over time; and d. displaying the statistical data sets on the display screen as discrete data points.

14. The method of claim 11, wherein the closed loop hydraulic system further comprises a pressure transducer electronically connected to a data acquisition device and computer and wherein said computer is electronically connected to a display screen, the method further comprising the steps of: a. measuring the force within the closed loop system over the time the force was exerted with the pressure transducer; b. transmitting the force over time data to the data acquisition device and computer; c. calculating statistical data sets based on the measured force over time; and d. displaying the statistical outputs on the display screen graphically.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0023] FIG. 1A is a front perspective view of a piece of exercise equipment where the arrows illustrate both the exercise and return stroke directions in a dead lift machine;

[0024] FIG. 1B is a rear respective view of a deadlift machine showing the isokinetic closed loop hydraulic system connected to the lifting arm of the equipment;

[0025] FIG. 2 is a perspective view of the isokinetic flow control module showing the optional accumulator;

[0026] FIG. 3A is a detailed cross sectional view of the isokinetic flow control module having an accumulator where the arrows illustrate fluid flow during an exercise stroke;

[0027] FIG. 3B is a detailed cross sectional view of the isokinetic flow control module having an accumulator where the arrows illustrate fluid flow during a return stroke;

[0028] FIG. 4A is a detailed cross sectional view of the isokinetic flow control module having a bottom rod in lieu of an accumulator where the arrows illustrate fluid flow during an exercise stroke;

[0029] FIG. 4B is a detailed cross sectional view of the isokinetic flow control module having a bottom rod in lieu of an accumulator where the arrows illustrate fluid flow during a return stroke;

[0030] FIG. 5A is a detailed cross sectional view of the isokinetic flow control module during an exercise stroke wherein the cylinder has one port and a breather valve in lieu of two ports and a PCFC-RC valve in place of a reverse flow check valve;

[0031] FIG. 5B is a detailed cross sectional view of the isokinetic flow control module during a return stroke wherein the cylinder has one port and a breather valve in lieu of two ports and a PCFC-RC valve in place of a reverse flow check valve;

[0032] FIG. 6A is a cross-sectional view of the PCFC valve where the arrows illustrate the fluid flow along with the various components within the valve body;

[0033] FIG. 6B is a perspective view of the PCFC valve where the arrows illustrate the fluid flow through the restriction mechanism and into the body of the valve;

[0034] FIG. 7A is a perspective front view of a dead lift machine;

[0035] FIG. 7B is a perspective rear view of the dead lift machine depicted in FIG. 7A having an isokinetic closed loop hydraulic flow control module connected to the user driven element of the machine;

[0036] FIG. 8A is a perspective front view of a bench press;

[0037] FIG. 8B is a perspective rear view of the bench press depicted in FIG. 8A having an isokinetic closed loop hydraulic flow control module connected to the user driven element (lifting bar) of the machine;

[0038] FIG. 9A is a perspective front view of a squat machine;

[0039] FIG. 9B is a perspective rear view of the squat machine depicted in FIG. 9A having an isokinetic closed loop hydraulic flow control module connected to the user driven element (lifting bar) of the machine;

[0040] FIG. 10A is a perspective front view of an abdominal machine;

[0041] FIG. 10B is a perspective rear view of an abdominal machine depicted in FIG. 10A having an isokinetic closed loop hydraulic flow control module connected to the user driven element (leg bar) on the machine;

[0042] FIG. 11A illustrates the flow of data from the pressure transducer to the display; and

[0043] FIG. 11B illustrates a sample user display

REFERENCE NUMERALS

[0044] 5 Isokinetic Flow Control Module/Mechanism [0045] 10 User Driven Element/Lifting Arm [0046] 15 Closed Loop Hydraulic System [0047] 20 Hydraulic Cylinder [0048] 25 Hydraulic Piston Unit [0049] 30 PCFC Unit [0050] 35 Fluid [0051] 40 Hydraulic Tubing [0052] 45 Upper Port of Hydraulic Cylinder [0053] 50 Lower Port of Hydraulic Cylinder [0054] 55 Piston [0055] 60 Top Rod of Piston [0056] 65 Manifold [0057] 70 Reverse Flow Check Valve [0058] 72 PCFC valve Inlet/PCFC-RC Valve Inlet [0059] 75 PCFC valve/PCFC-RC Valve [0060] 80 Tee/PCFC valve outlet [0061] 85 Accumulator [0062] 90 Accumulator Piston [0063] 95 Pressurized Inert Gas [0064] 100 Charge Port [0065] 105 Bottom Rod of Piston [0066] 110 Valve Adjustment Shaft [0067] 120 Restriction Mechanism [0068] 125 Compensator Spool [0069] 128 Breather Valve [0070] 130 Speed Adjustment Mechanism [0071] 135 Touch Screen [0072] 140 Pressure Transducer [0073] 145 Data Connection (from Pressure Transducer to DAQ) [0074] 150 Data Acquisition Device or System (DAQ)

DETAILED DESCRIPTION OF THE INVENTION

[0075] In this patent application, the moveable portion of an exercise machine defining the ROM of a particular movement shall be referred to as a “user driven element,” “arm,” or “lifting arm.” It should be noted that more than one user driven element or lifting arm may exist on any given piece of exercise equipment. Pipe, conduit, and tubing capable of withstanding the pressures within the closed loop hydraulic system contemplated herein shall be referred to as “hydraulic tubing.” While inventor contemplates the use of oil in the closed loop hydraulic system, the term “fluid,” as used in this application, shall mean any incompressible liquid.

[0076] Exercise equipment generally has an “exercise stroke” wherein the user driven element 10 is moved in one direction to tax a targeted group of muscles. The equipment also has a “return stroke” wherein the user driven element 10 moves in the opposite direction and either allows the user's muscles to recover or, alternatively, exercises a different group of muscles. It should be recognized that the direction of flow in a given application will depend on how the module is connected to the user driven element.

[0077] One object of the present invention is to create a family of exercise machines by mounting an isokinetic flow control mechanism 5 (hereinafter “mechanism”) to the user driven element(s) 10 of the respective equipment. The substantially constant flow of fluid within this mechanism 5 translates to instantaneously adaptive user-generated resistance throughout the specific ROM linked to the user driven element 10. The mechanism 5 prohibits the exerciser from moving the user driven element 10 faster than the selected speed during the exercise stroke, regardless of the force applied.

[0078] Another object of the invention is to offer a device and method that provides resistance to the user only when that user is applying force to the machine in which it is connected (“user-generated resistance”). The moment that user relaxes, the machine returns to its home position, gently but rapidly preparing for the next repetition. The immediate release of resistance enhances safety particularly when the user is feeling exhausted by the exercise.

[0079] While inventor anticipates the creation of multiple species of exercise equipment incorporating this mechanism 5, it should be recognized that one may also upgrade friction based or standard hydraulic resistance units in existing machines with the mechanism 5 described herein. Replacement of these standard resistance methods will result in a safer and more efficient means of exercising the selected muscle group(s) by offering a constant speed and subsequent instantaneous and adaptive user-generated resistance rather than a mechanism that can be overcome with additional force.

[0080] FIGS. 1A and 1B depict a dead lift machine wherein the person exercising lifts a bar or arm. This bar or arm comprises the user-driven element 10. Referring now to FIG. 2, the isokinetic flow control mechanism 5 is comprised of a substantially air-free closed loop hydraulic system 15 having a hydraulic cylinder 20 (hereinafter “cylinder”), a hydraulic piston unit 25, a PCFC unit 30, fluid 35, hydraulic tubing 40, an optional pressure transducer 140, and an optional accumulator 85 as described below. The mechanism 5 is primed such that a negligible amount of air remains in the system making it “substantially air free.” Any air remaining in the system is undetectable through standard measurement techniques.

[0081] In one embodiment, illustrated in FIGS. 2, 3A, and 3B, the cylinder 20 has an upper port 45 and a lower port 50 to allow for the forward and reverse flow of fluid 35 within the closed loop hydraulic system 15. The piston 55 within the hydraulic piston unit 25 fits snugly and moves within the cylinder 20 while the top rod 60 of the hydraulic piston unit 25 is mechanically fastened to the user driven element 10 of the exercise machine.

[0082] The heavy arrows in FIG. 3A illustrate the fluid flow 35 within the mechanism 5 during an exercise stroke. In a deadlift machine for instance, the athlete pulls on the user driven element 10, applying an upward force to the top rod 60 of the hydraulic piston unit 25. Movement of the piston 55 within the cylinder 20 pushes fluid 35 above that piston 55, out the upper port 45, and into the PCFC unit 30. The reverse flow check valve 70 may either be in fluid communication with the PCFC valve inlet 72 or it may be integral to the PCFC valve. Said reverse flow check valve 70 has a spring-backed piston or similar mechanism that remains closed when fluid enters near the PCFC valve inlet 72. This ensures that fluid 35 is directed to the PCFC unit 30.

[0083] In the embodiment shown in FIGS. 2, 3A and 3B, the PCFC unit 30 is comprised of a manifold 65, a reverse flow check valve 70, a PCFC valve inlet 72, and a PCFC valve 75. Because the system is full of fluid 35 and substantially air-free, force on the user driven element 10 propels fluid 35 above the piston 55 up and out of the upper port 45 of the cylinder 20 and into the PCFC valve inlet 72 of the PCFC unit 30. A reverse flow check valve 70 in fluid communication with both the PCFC valve inlet 72 and manifold 65 directs fluid 35 into the PCFC valve 75. The PCFC valve 75 permits only a predetermined quantity of fluid 35 to flow through it at any given instant in time regardless of how hard the user pulls on the user driven element 10. A more detailed description of the path of flow within the PCFC unit 30 is provided below. Fluid 35 exits the PCFC valve 75 and enters the manifold 65 where it exits the PCFC unit 30 and returns through the hydraulic tubing 40 into to the lower port 50 of the cylinder 20.

[0084] The heavy arrows in FIG. 3B illustrate the fluid flow 35 in a return stroke of the exercise equipment in this same embodiment. At the end of the exercise stroke, the user returns the user driven element 10 to its home position readying the machine for the next repetition. In a dead lift machine for example, weight of the user driven element 10 exerts a downward force on the top rod 60 of the hydraulic piston unit 25 when released. This force pushes that piston 25 into the cylinder 20, reducing the volume of fluid 35 beneath the piston 55 within that cylinder 20. It should be noted that movement of the user driven element 10 will be determined by the orientation of that component and the return stroke may not necessarily be in a downward movement depending on the type of exercise machine being used; such movement may be horizontal, vertical, arcuate, linear, or pendular in nature.

[0085] During the return stroke of this embodiment, the movement of the hydraulic piston unit 25 within the cylinder 20, drives fluid 35 below the piston 55 out of the lower port 50. Fluid 35 subsequently flows in a reverse path to that described in the exercise stroke. Pressure within the system drives fluid 35 within the manifold 65 into the reverse flow check valve 70. This reverse flow check valve 70 uses a spring-backed piston that opens when fluid 35 enters the bottom of said valve 70; this allows fluid 35 to flow into the upper port 45 of cylinder 20 above the piston 55. By bypassing the PCFC valve 75, the user driven element 10 can be quickly returned to its home position.

[0086] One should note that the top rod of the piston 60 displaces fluid; the position of the top rod within the cylinder consequently displaces fluid at a different rate above the piston than it displaces below it. While there is a negligible amount of air in the system, all fluid traps some quantity of air by its nature. As the piston extends and retracts, the minute quantity of air within the system compresses or expands respectively. This may lead to an undesired suction within the system, undermining the function of the machine.

[0087] In a return stroke for example, the volume of fluid beneath the piston 55 will increase at a faster rate than the volume of fluid 35 decreases above that piston 55. This disparity in the rate of volumetric changes throughout the stroke creates suction. An optional tee 80 and accumulator 85 may be added to the closed loop hydraulic system 15 to compensate for this disparity as shown in FIGS. 3A and 3B. This tee 80 allows any excess fluid 35 within the hydraulic tubing 40 to flow into the accumulator 85.

[0088] The accumulator 85 is comprised of an accumulator piston 90 supported by an inert pressurized gas 95 such as nitrogen. This inert pressurized gas 95 exerts a constant force on the accumulator piston 90 that inversely increases as the volume beneath the accumulator piston 90 decreases. An optional charge port 100 may be mounted beneath the accumulator 85 to allow for periodic recharging of the inert pressurized gas 95 as needed.

[0089] A given quantity of fluid 35 is stored above the accumulator piston 90 at any instant in time. As the volume of fluid 35 below the piston 55 increases, the accumulator piston 90 moves upward, pushing the stored fluid 35 through the tee 80 and down toward the lower port 50 of the hydraulic cylinder 20. See FIG. 3A. As the volume of fluid 35 below the cylinder 20 decreases, the accumulator piston 90 shifts downward, taking on more fluid 35 above said piston 90 for the next exercise cycle. See FIG. 3B.

[0090] While FIGS. 3A and 3B illustrate one embodiment using a standard cylinder and piston with an accumulator 85 to address the volume disparity above and below the piston 55, FIGS. 4A and 4B illustrate an alternate embodiment employing a cylinder 20 having a bottom rod 105 to offset these differences volumetrically. The heavy arrows in FIG. 4A illustrate the fluid flow 35 during the exercise stroke of a given piece of exercise equipment. As with the first embodiment, the athlete moves the user driven element 10, applying force to the top rod 60 of the hydraulic piston unit 25. Movement of the hydraulic piston unit 25 within the cylinder 20 pushes the fluid 35 above the piston 55, up and out of the upper port 45 and into the inlet 72 of the PCFC unit 30. The reverse flow check valve 70 directs fluid 35 into the PCFC valve 75 in the same manner as in the first embodiment, the valve 75 allowing only a regulated quantity of fluid 35 to flow through it at any given instant in time regardless of the force applied to the user driven element 10. Fluid 35 leaves the PCFC valve 75 as in the previous embodiment shown in FIG. 3A, entering the manifold 65 where it exits the PCFC unit 30 and returns through the hydraulic tubing 40 into the lower port 50 of the cylinder 20. As in the previous embodiment, the fluid flow rate and subsequent instantaneous user-generated resistance within the isokinetic flow control module 5 is determined by the position of the valve adjustment shaft 110 within the PCFC unit 30 as described more fully below.

[0091] The difference between the first embodiment and the invention illustrated in FIG. 4A lies in the double rod cylinder 20. Referring again to FIG. 4A, the piston has a bottom rod 105 positioned beneath the piston 55. The length of the bottom rod 105 is substantially equal to the length of the cylinder, extending from the base of the cylinder 20 during the exercise stroke (see FIG. 4A) and being substantially encased within the cylinder 20 during the return stroke (see FIG. 4B). The introduction and withdrawal of the bottom rod 105 creates an equal volume of fluid 35 on either side of the piston 55 during the exercise and return strokes. The volume of this bottom rod 105 obviates the need for the accumulator 85 used in the first embodiment.

[0092] Referring again to FIG. 4B where the heavy arrows illustrate fluid flow during the return stroke, force on the user driven element 10 drives the top rod 60 into the cylinder 20. Fluid 35 beneath the piston 55 is forced through the lower port 50 of the cylinder 20 and into the hydraulic tubing 40 where it enters the PCFC unit 30. Fluid 35 flows into the manifold 65 and through the reverse flow check valve 70. This check valve 70 allows the fluid 35 to flow back into the space above the piston 55 within cylinder 20. As noted in the embodiment above, the reverse flow check valve 70 uses a spring-backed piston or similar mechanism that opens when pressurized fluid 35 enters the bottom of that valve 70.

[0093] FIGS. 5A and 5B depict yet another embodiment wherein the cylinder is comprised of a single port 45 and a breather valve 128 or similar component (hereinafter “breather valve”). This breather valve 128 allows air to enter and exit the space beneath the piston 55 to allow for movement of said piston 55 within the cylinder 20. Without a breather valve 128, the piston 55 would be vapor locked and unable to move. It should be noted that FIGS. 5A and 5B also illustrate the use of a PCFC-RC valve 75 in lieu of a distinct PCFC valve 75 and reverse flow check valve 70 within the PCFC unit 30.

[0094] Referring now to FIG. 5A, force on the user driven element 10 and connected piston 55 during the exercise stroke propels fluid 35 above the piston 55 up and out of the single port 45 of the cylinder 20 and into the PCFC valve inlet 72 of the PCFC unit 30. A check spool or sleeve within the PCFC-RC valve 75 remains closed allowing only a predetermined quantity of fluid 35 to flow through the PCFC-RC valve 75 at any given instant in time regardless of how hard the user pulls on the user driven element 10. This spool or sleeve has a corresponding spring that allows fluid 35 to move within the spool/sleeve. Fluid movement during the exercise stroke allows the spring to expand, pushing the spool or sleeve in position such that the fluid 35 is directed into the restriction mechanism 120 to regulate fluid speed as described more particularly below. Inventor has disclosed the use of a check spool or sleeve and corresponding spring but it should be understood that any similar directional flow device may be used within the PCFC-RC valve 75. Fluid 35 then exits the PCFC valve 75 and enters the manifold 65 where it then exits the PCFC unit 30 and enters the optional accumulator 85.

[0095] Referring now to FIG. 5B, force on the user driven element 10 and connected piston 55 during the return stroke pulls or draws fluid from the optional accumulator 85 into the PCFC unit 30 and manifold 65 and into the PCFC-RC valve 75. The reverse flow of fluid within the PCFC-RC valve 75 during this stroke compresses the spring thereby allowing fluid 35 to flow freely past the restriction mechanism 120 and through the PCFC-RC valve 75 with virtually no resistance. This, in turn, allows the piston 55 to return to the base of the cylinder 20 more quickly in preparation for the next exercise cycle. While not depicted in FIGS. 5A and 5B, it should be understood that a separate reverse flow check valve 70 may also be added to a PCFC-RC valve 75, as intimated in FIGS. 3A-4B, to further increase the rate of return of the piston 55.

[0096] In each embodiment, the user selects a desired flow rate corresponding to the desired difficulty level of the exercise prior to starting their workout. The bold arrows in FIGS. 6A and 6B illustrate fluid flow through the PCFC valve 75 during each exercise stroke. Once fluid 35 enters the PCFC valve 75, it passes through a restriction mechanism 120 such as the v-notch shown in FIGS. 6A and 6B. This restriction mechanism acts as an adjustable orifice. The fluid flow rate is governed by the position of the valve adjustment shaft 110 illustrated in FIGS. 6A and 6B. As the valve adjustment shaft 110 advances, the restriction mechanism 120 opens, increasing the flow rate of the fluid 35 and allowing the user to exercise at a reduced speed and less intense workout. When the adjustment shaft 110 is retracted, the restriction mechanism 120 closes and constricts the fluid flow, offering the user a slower flow rate and more strenuous workout. The position of the valve adjustment shaft 110 can be modified by moving a speed adjustment mechanism 130 illustrated in FIGS. 6A and 6B. This speed adjustment mechanism 130 can be manually adjusted or it may be altered using a selector mechanism such as a rack and pinion control cable or by selecting specific or preset speeds on a touch screen 135. This touch screen 135 may be electronically configured to rotate a motor controller coupled to the speed adjustment mechanism 130 or directly to the valve adjustment shaft 110.

[0097] Once the flow rate has been selected and the athlete applies force to the user driven element 10 during the exercise stroke, fluid 35 flows in at the inlet 72 of the PCFC valve 75. Referring to FIGS. 6A and 6B, flow through the restriction mechanism 120 creates a fixed pressure drop which governs the rate of flow up into the valve body. As flow at the inlet 72 increases, a compensator spool 125 shifts to cover a portion of the restriction mechanism 120. This shift is what maintains the fixed pressure drop and consistent flow rate within the PCFC valve 75. Conversely, as the flow at the inlet 72 decreases, the compensator spool 125 shifts again to expose more cross-sectional area on the restriction mechanism 120. The dynamic shifting of the compensator spool 125 works in combination with the remaining elements of the flow control module 5 to create the isokinetic nature of the present invention.

[0098] In embodiments where a PCFC-RC valve is used, the valve further includes a check spool and sleeve and corresponding spring that opens only in one direction of fluid flow to bypass the restriction mechanism 120. The opening of the check spool or sleeve allows unrestricted fluid flow within the system as a constant flow is not required in this stroke. See FIG. 5B. In embodiments using a standard PCFC valve 75 in combination with a reverse flow check valve 70 such as that shown in FIGS. 3B-4B, fluid bypasses the PCFC valve 75 altogether. The reverse flow check valve 70 opens and similarly allows free flow of fluid 35 within the closed loop system. See FIGS. 3B and 4B.

[0099] The pressure within the PCFC valve inlet 72 may be read by an optional pressure transducer 140 in fluid communication with said inlet 72. The pressure transducer 140 may alternatively be positioned prior to the manifold 65 near the PCFC valve exit or within the cylinder 20. See FIGS. 3A, 3B, 4A, and 4B. The pressure transducer 140 sends a signal with the pressure reading either through a wireless or direct electrical connection 145 to a DAQ 150 as illustrated in FIG. 11A. This data can be stored and manipulated by a computer and sent to a display such as a touch screen 135 or smart device, if desired. Each exercise stroke may be plotted as an individual graphical display of force over time. As the pressure falls below a preset “low value” the computer interprets this as the beginning of a new exercise stroke and the subsequent data may be plotted as a different color such that each repetition is visually illustrated in a different hue. This allows the athlete to view their performance more easily with each repetition as shown in FIG. 11B. Control valve speed (which is directly related to the level of difficulty of the workout), maximum force applied, average force applied, caloric expenditure, and other pertinent metrics related to user force exerted over time may also be displayed on the user interface 135.

[0100] As previously noted, the present invention 5 may be incorporated or retrofitted into a variety of exercise machines. FIGS. 1A, 1B, 7A and 7B show the front and reverse of a standard dead lift machine wherein the flow control mechanism 5 is connected to a point (yoke) along the user driven element 10, allowing the hydraulic piston unit 25 to extend and retract with each respective exercise and return stroke.

[0101] FIGS. 8A and 8B illustrate the front and rear of a bench press machine, respectively. Referring now to FIG. 8B, the top rod 60 of hydraulic piston unit 25 is similarly affixed to user driven element 10 (lifting bar or arm) allowing said piston 20 to extend and retract during the exercise and return strokes.

[0102] FIGS. 9A and 9B illustrate the front and rear of a squat machine. Again, the top rod 60 of the hydraulic piston unit 25 is affixed to the user driven element 10 which in this case is comprised of a large arm connected to two hand grips. As the exerciser lowers and raises his body, the hydraulic piston unit 25 extends and retracts within the hydraulic cylinder 20.

[0103] The top rod 60 of the hydraulic piston unit 25 is similarly affixed to the user driven element 10 of the abdominal machine shown in FIGS. 10A and 10B. During the exercise stroke, the athlete rotates the hand grips downward, pushing the top rod 60 into the cylinder 20, thereby pulling fluid 35 from the lower port 50 of the hydraulic cylinder 20 and into the PCFC unit 30.

[0104] The above mentioned examples have been included to illustrate the adaptable nature of the isokinetic flow control module 5. The present invention may be used within a variety of exercise equipment; subsequently, the position of said module 5 will depend on the location of the user driven element 10 on any given piece of equipment. Similarly, the direction flow within the closed loop hydraulic system will also depend on the placement and connection of individual components within that system.

[0105] While the above description contains many specifics, these should be considered exemplifications of one or more embodiments rather than limitations on the scope of the invention. As previously discussed, many variations are possible and the scope of the invention should not be restricted by the examples illustrated herein.