WO2010028435A1

WO2010028435A1 - Isometric exercise device

Info

Publication number: WO2010028435A1
Application number: PCT/AU2009/001184
Authority: WO
Inventors: Bruce James Munns; David O'driscoll
Original assignee: Isopectric Pty Ltd
Priority date: 2008-09-10
Filing date: 2009-09-10
Publication date: 2010-03-18

Abstract

An isometric exercise device (10) comprises an elongate bow-shaped flex structure (12) made of resilient material. The flex structure (12) comprises a central elongate base portion (14) having a first pair of elongate bow members (16a, 16b) provided at one end and a second pair of elongate bow members (18a, 18b) provided at the other end. The exercise device (10) further comprises a flexible elongate tension member (20) which is coupled to the respective ends of the first and second pairs of elongate bow members (16 and 18) respectively so that tension applied to the tension member (20) results in a flexing of the flex structure (12). A resistance adjusting means (30) is provided in connection with the flex structure (12) for adjusting a resistance to flexing of the flex structure (12) and comprises a relatively rigid pair of elongate strut members (32a, 32b). The strut members (32) are made of stiffer material than the bow members (16, 18) and therefore require more force to bend or flex. The stiffness of the bow members in each pair (16, 18) can be adjusted by sliding a respective coupling member (34) towards or away from the central base portion (14). This has the effect of progressively coupling or decoupling the bow members to the respective strut member (32).

Description

"ISOMETRIC EXERCISE DEVICE"

Field of the Invention

The present invention relates to an isometric exercise device and relates particularly, though not exclusively, to such an exercise device that can be used for performing both an upper body and lower body exercise programme.

Background to the Invention

Many people, convinced of the benefits of regular physical exercise, have joined a local gym in order to commence an exercise regime that typically includes some weight training and aerobic exercises. Unfortunately many do not maintain their initial enthusiasm and soon become irregular in their attendance or cease visiting the gym altogether. There are a number of reasons for this, but one of the most common is the lack of time available to most people for regular physical exercise. Other people choose to purchase exercise equipment they can use in the comfort of their own home. Less expensive versions of most gym equipment can be purchased for home use, as well a range of smaller personal exercise devices. However like gym membership, much of this home exercise equipment soon falls into disuse and ends up cluttering up the lounge room, bedroom or study floor. Once again, the most common problem is the lack of time available to most people for regular physical exercise.

For the time-starved person, an isometric exercise programme may be a particularly attractive alternative. Isometrics is a system of physical exercise in which the muscles are caused to act against each other or against a fixed object. The muscle develops tension and hence is exercised, whilst being prevented from contracting. This technique has been found to build muscles just as effectively as weight training, but in less time. The present invention was developed with a view to providing an isometric exercise device that is portable and easy to use.

References to prior art documents in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

According to one aspect of the present invention there is provided an isometric exercise device comprising: an elongate bow-shaped flex structure made of resilient material; a flexible elongate tension member coupled to the respective ends of the flex structure so that tension applied to the tension member results in a flexing of the flex structure; and, resistance adjusting means provided in connection with the flex structure and/or the tension member for adjusting a resistance to flexing of the flex structure wherein, in use, when the flex structure is held stationary and the tension member is gripped by the user a load applied thereto results in exercise of a desired muscle group or groups.

Preferably the bow-shaped flex structure comprises a central elongate base portion having a first pair of elongate bow members provided at one end and a second pair of elongate bow members provided at the other end. Preferably the respective bow members in each pair are substantially parallel to each other. Typically when the flex structure is viewed in plan a first bow member of the first pair is collinear with a first bow member of the second pair, and a second bow member of the first pair is collinear with a second bow member of the second pair. Preferably the base portion and first and second pairs of bow members of the flex structure are all manufactured as a single integral unit. Typically the flex structure is manufactured by injection moulding. Advantageously the flexible elongate tension member has a handle provided thereon to facilitate better gripping of the tension member. Preferably the handle is one of a pair of handles. Typically the handles are slidably attached to the tension member wherein the position of the handles on the tension member can be adjusted to suit the user.

In one embodiment the resistance adjusting means comprises a relatively rigid strut member provided in connection with the base portion of the flex structure and an adjustable mechanical coupling means for coupling at least the first pair of the elongate bow members to the strut member. Preferably the adjustable mechanical coupling means is a coupling member that is slidably received on the strut member and that rigidly couples the first and second bow members of the first pair to the strut member.

Typically the strut member is an elongate strut member extending from one end of the base portion substantially parallel to and between the first and second bow members. Preferably the strut member has a plurality of indentations provided at spaced intervals along its length wherein the coupling member engages with the indentations to hold it in a desired position on the strut member.

Preferably the strut member is one of a pair of strut members provided on respective ends of the base portion of the bow-shaped flex member, and the coupling member is one of a pair of coupling members respectively slidably received on the respective strut members.

The flexible elongate tension member preferably further comprises a flexible elongate member such as a cable which is coupled to the respective ends of the first and second pairs of elongate bow members respectively. The flexible elongate member or cable is preferably connected to the respective ends of the first and second bow members by means of a pair of respective V-shaped coupling members, each V-shaped coupling member having a pair of arms and a sharp end to form the V-shape. The sharp end of each V- shaped coupling member is preferably fixed to a respective end of the cable. The two arms of each V-shaped coupling member are preferably provided with respective lugs that are slidably received in slots provided in the ends of the respective bow members. The arrangement of the lugs in the slots can then act as a regulator for regulating the increase in resistance of the flex structure as it flexes.

According to a second aspect of the present invention there is provided an isometric exercise device comprising: an elongate bow-shaped structure made of substantially rigid material; a flexible elongate tension member coupled to the respective ends of the bow-shaped structure; and resistance adjusting means provided in connection with the bow-shaped structure and/or the tension member for adjusting a resistance to force applied to the tension member wherein, in use, when the bow-shaped structure is held stationary and the tension member is gripped by the user a load applied thereto results in exercise of a desired muscle group or groups.

Preferably the bow-shaped structure comprises a central elongate base portion having a first pair of elongate bow members provided at one end and a second pair of elongate bow members provided at the other end. Preferably the respective bow members in each pair are substantially parallel to each other. Typically when the bow-shaped structure is viewed in plan a first bow member of the first pair is collinear with a first bow member of the second pair, and a second bow member of the first pair is collinear with a second bow member of the second pair. Preferably the base portion and first and second pairs of bow members of the bow-shaped structure are all manufactured as a single integral unit. Typically the bow-shaped structure is manufactured by injection moulding.

Advantageously the flexible elongate tension member has a handle provided thereon to facilitate better gripping of the tension member. Preferably the handle is one of a pair of handles. Typically the handles are slidably attached to the tension member wherein the position of the handles on the tension member can be adjusted to suit the user.

Preferably the resistance adjusting means comprises an adjustable gas spring mechanically coupled to the tension member for adjusting the resistance to force applied to the tension member.

Preferably the resistance adjusting means further comprises a regulator mechanically coupled to the tension member for regulating the force transmitted from the tension member to the gas spring. Advantageously the regulator is a spiral regulator wherein the tension member is wound in a spiral so that as load is applied to the tension member it is progressively released from the centre to the outside of the spiral.

Preferably the resistance adjusting means further comprises a transmission means for transmitting force from the spiral regulator to the gas spring. In one embodiment the transmission means comprises a variable pneumatic gearbox in fluid communication with the gas spring wherein the magnitude of a force transmitted to the gas spring can be adjusted.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word "preferably" or variations such as "preferred", will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. Similarly the word "typically" will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. Brief Description of the Drawings

The nature of the invention will be better understood from the following detailed description of several specific embodiments of the isometric exercise device, given by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a top perspective view of a first embodiment of the isometric exercise device according to the invention shown in a rest or non-flexed condition; Figure 2 shows the isometric exercise device of Figure 1 in a flexed condition;

Figures 3 (a), (b), (c), (d), and (e) show the isometric exercise device of Figure 1 in top plan view, side elevation, bottom plan view, bottom perspective view, and end view respectively; Figure 4 is a top perspective view of a second embodiment of the isometric exercise device according to the invention shown in a rest or non-flexed condition;

Figure 5 is a bottom perspective view of the isometric exercise device of Figure 4; and, Figures 6 (a), (b), (c), (d), and (e) show the isometric exercise device of Figure 4 in top plan view, side elevation, bottom plan view, top perspective view, and end view respectively.

Detailed Description of Preferred Embodiments A preferred embodiment of isometric exercise device 10 in accordance with the invention, as illustrated in Figures 1 to 3, comprises an elongate bow- shaped flex structure 12 made of resilient material. The flex structure 12 comprises a central elongate base portion 14 having a first pair of elongate bow members 16a, 16b provided at one end and a second pair of elongate bow members 18a, 18b provided at the other end. As can be seen most clearly in Figures 3 (a) and (c), the respective bow members 16a, 16b and 18a, 18b in each pair are substantially parallel to each other. When the flex structure 12 is viewed in plan a first bow member 16a of the first pair is collinear with a first bow member 18a of the second pair, and a second bow member 16b of the first pair is collinear with a second bow member 18b of the second pair.

Preferably the base portion 14 and first and second pairs of bow members 16 and 18 of the flex structure 12 are all manufactured as a single integral unit. In the illustrated embodiment the flex structure 12 is manufactured from a suitably strong and resilient material such as injection moulded plastics material or a composite fibreglass. The flex structure 12 is preferably manufactured in a bow-shaped or arcuate form so that when it is an unloaded or rest condition, as shown in Figures 1 and 3, it is already bow- shaped. The full length of the bow-shaped flex structure 12 is typically between about 1.0m to 1.5m in its rest condition. More typically it is about 1.3m to 1.4m in length. Preferably the angle of curvature of the bow-shaped flex structure 12 is sufficiently large that the torso of a user can be comfortably received within the confines of the device 10.

The exercise device 10 further comprises a flexible elongate tension member 20 coupled to the respective ends of the flex structure 12 so that tension applied to the tension member 20 results in a flexing of the flex structure 12. In this embodiment the flexible elongate tension member comprises a cable 20 which is coupled to the respective ends of the first and second pairs of elongate bow members 16 and 18 respectively. Other forms of flexible elongate member may be employed instead of a cable such as, for example, a strap or belt. The cable 20 is connected to the respective ends of the bow members 16a, 16b and 18a, 18b by means of respective V- shaped coupling members 22. The sharp end of each V-shaped coupling member 22 is fixed to a respective end of the cable 20. The two arms of each V-shaped coupling member 22 are provided with respective lugs 24 that are slidably received in slots 26 provided in the ends of the respective bow members 16a, 16b and 18a, 18b (see Figure 1).

Advantageously the arrangement of the lugs 24 in the slots 26 can act as a regulator for regulating the increase in resistance of the flex structure 12 as it flexes. When the cable 20 is put under load it loads the lugs 24 which in turn loads the flex structure 12. As the load to the flex structure 12 increases, its resistance to flexing also increases. However as the load to each lug 24 increases it gradually moves outwards along its respective slot 26. As the lug moves outwards it increases the leverage on the bow members 16, 18 to counteract (regulate) the increasing resistance of the flex structure 12.

Advantageously the cable 20 has a handle 28 provided thereon to facilitate better grip on the cable 20 by a user. Preferably the handle 28 is one of a pair of handles 28a and 28b. The handles 28a and 28b are slidably attached to the cable 20 so that the position of the handles on the cable can be adjusted to suit the user. So, for example, when tensioning cable 20 as shown in Figure 2, the handles 28 may be brought together.

The exercise device 10 further comprises resistance adjusting means 30 provided in connection with the flex structure 12 and/or the tension member 20 for adjusting a resistance to flexing of the flex structure 12. In this embodiment the resistance adjusting means 30 comprises a relatively rigid strut member 32a provided in connection with the base portion 14 of the flex structure 12. The strut member 32a is of elongate shape extending from one end of the base portion 14 substantially parallel to and between the first and second bow members 16a and 16b. Preferably the strut member 32a is one of a pair of strut members 32a, 32b provided on respective ends of the base portion 14.

The strut members 32a, 32b are made of stiffer material than the bow members 16, 18 and therefore require more force to bend or flex. Preferably the strut members are formed integral to the base portion 14 so as to form one continuous strut member 32 that protrudes from each end of the base portion 14. The strut member 32 may be manufactured, for example, from carbon fibre-reinforced plastics material, or metal composite.

The resistance adjusting means 30 further comprises an adjustable mechanical coupling means for coupling at least the first pair of elongate bow members 16 to the strut member 32a. The adjustable mechanical coupling means of this embodiment is a coupling member 34a that is slidably received on the strut member 32a and that rigidly couples the first and second bow members 16a, 16b of the first pair to the strut member 32a. Preferably the coupling member 34a is one of a pair of coupling members 34a, 34b respectively slidably received on the respective strut members 32a, 32b. Preferably each strut member 32 has a plurality of indentations 36 provided at spaced intervals along its length wherein respective the coupling member 34 engages with the indentations 36 to hold it in a desired position on the strut member.

The stiffness of the bow members in each pair 16, 18 can be adjusted by sliding the respective coupling member 34 towards or away from the central base portion 14. This has the effect of progressively coupling or decoupling the bow members to the respective strut member 32. So₁ for example, if the coupling members 34a and 34b are both moved outwards to a position close to the outer extremities of the respective strut members 32a and 32b, then the flex member 12 will be given maximum stiffness by virtue of the relatively rigid strut members 32 being coupled to their full extent to the bow members 16, 18. Most of the flexing of the flex member 12 will occur in those parts of the bow members 16, 18 are that not coupled to the strut member 32. Since these parts are quite short they are more difficult to flex and offer greater resistance to flexing.

On the other hand if the coupling members 34a and 34b are both moved inwards on the respective strut members 32a and 32b to a position close to the base portion 14, then the flex member 12 will be given minimum stiffness by virtue of the relatively rigid strut members 32 being decoupled to their full extent from the bow members 16, 18. Flexing of the flex member 12 can occur over virtually the full length of the bow members 16, 18 since they are not coupled to the strut member 32.

Significantly, the arrangement of the resistance adjusting means 30 is such that the resistance to flexing of the flex structure 12 is regulated. This means that once the desired resistance to flexing has been set, the resistance remains constant no matter how far the flex structure 12 is flexed. This is important when performing isometric exercises as it avoids overstressing particular muscle groups as well as providing a regulated exercise regimen.

The exercise device 10 can be used in a variety of ways to exercise various muscle groups and/or body parts. For example, when the flex structure 12 is held stationary by placing one or both feet on the base portion 14 and the cable 20 is gripped by the user holding the handles 28 a load can be applied thereto by pulling on the cable 20 which results in exercise of a number of upper body muscle groups. Alternatively, the device can be placed around the torso of a user with the base portion 14 resting against the user's back. The user then grips the handles 28 on the cable 20 and pushes outwards away from the chest to exercise a different muscle group. Figures 4 to 6 illustrate a second embodiment of the isometric exercise device 40 which is similar in some respects to the first embodiment 10, and therefore those parts that are similar will be not be described again in detail. As in the first embodiment, the device 40 comprises an elongate bow- shaped structure 42, however in this embodiment the bow-shaped structure 42 is made of substantially rigid material. The bow-shaped structure 42 comprises a central elongate base portion 44 having a first pair of elongate bow members 46a, 46b provided at one end and a second pair of elongate bow members 48a, 48b provided at the other end.

The exercise device 40 further comprises a flexible elongate tension member 50 coupled to the respective ends of the bow-shaped structure 42.

Unlike the previous embodiment, tension applied to the tension member 50 does not result in a flexing of the bow-shaped structure 42. In this embodiment the flexible elongate tension member comprises a cable 50 which is coupled to the respective ends of the first and second pairs of elongate bow members 46 and 48 respectively. The cable 50 is slidably received in a groove 52 provided in respective spindles 54 connected to the respective ends of the bow members 46a, 46b and 48a, 48b. The cable 50 rides over the spindles 54 and extends round to the base portion 44 of the flex member 42. Advantageously the cable 50 has handles 58 provided thereon to facilitate a better grip on the cable 50 by a user for applying a load or force to the cable 50.

The exercise device 40 further comprises resistance adjusting means 60 provided in connection with the bow-shaped structure 42 for adjusting a resistance to force applied to the cable 50. In this embodiment the resistance adjusting means 60 comprises an adjustable gas spring 66 operatively coupled to the cable 50 for adjusting the resistance to force applied to the cable 50. Gas spring 66 of this embodiment comprises a housing within which a piston (not visible) compresses a gas in response to movement of the piston. The compressibility of the gas generates a spring force. The greater the force applied to the gas spring 66 the greater the resistance.

Preferably the resistance adjusting means 60 further comprises a regulator 62 operatively coupled to the gas spring 66 for regulating the resistance to force transmitted from the gas spring 66 to the cable 50. In this embodiment the regulator is a spiral regulator 62 in which the cable 50 is wound in a spiral 64 so that as a load is applied to the cable it is progressively released from the centre to the outside of the spiral.

When the handles 58 or cable 50 are placed under load, the cable 50 is gradually released (unwinds) from the spiral regulator 62. As the cable 50 is released from the spiral regulator, the spiral 64 progressively moves the position of the cable's release from the centre of the spiral 64 to the outside of the spiral 64. In this way the increasing resistance experienced from the gas spring 66 as the cable is loaded can be regulated.

Preferably the resistance adjusting means 60 further comprises a transmission means for transmitting force from the spiral regulator 62 to the gas spring 66. In this embodiment the transmission means comprises a variable pneumatic gearbox 70 in fluid communication with the gas spring

66 wherein the magnitude of a force transmitted to the gas spring 66 can be adjusted. The pneumatic gearbox 70 is in fluid communication with the gas spring 66 via a small pipe 72 through which hydraulic fluid is pumped from the gearbox 70 in response to a force transmitted from the spiral regulator

62.

The spiral regulator 62 is mechanically coupled to a pulley 68 that pulls on a separate cable 74 coupled to the pneumatic gearbox 70 (see Figures 5 and 6(c)). When the cable 74 is loaded by the rotation of the spiral regulator 62, a force is applied to the gearbox 70 which is then transmitted to the gas spring 66 via the hydraulic fluid in pipe 72. Gearbox 70 is anchored to the base portion 44 so that a tensioning of the cable 74 via the pulley 68 applies a force to the gearbox 70. Preferably the pneumatic gearbox 70 has a plurality of pneumatic cylinders which can be selectively engaged to provide variable loading, progressively increasing, for example, from 2kg to 32kg. A digital electronic user interface, for example an LCD touch screen (not shown), may be provided to enable a user to 'dial-up' a desired load.

In this embodiment both the gas spring 66 and the variable pneumatic gearbox 70 are slidably mounted on the cable 50, which passes through a respective channel provided in the housing of the gas spring and gearbox. However it will be understood that both the gas spring 66 and the variable pneumatic gearbox 70 could also be housed within the confines of the base portion 44.

Once again, it is significant the arrangement of the resistance adjusting means 60 is such that the resistance to force applied to the cable 50 is regulated. This means that once the desired resistance to force has been set, the resistance remains constant no matter how much force is applied to the cable 50. This is important when performing certain isometric exercises as it avoids overstressing particular muscle groups as well as providing a regulated exercise regimen.

Now that preferred embodiments of the isometric exercise device have been described in detail, it will be apparent that the embodiments provide a number of advantages over the prior art, including the following:

(i) They facilitate the implementation of an isometric exercise regime, which provides a reduced workout time and improved results compared to conventional exercise machines which depend on repetition.

(ii) They are simple to use and can be readily adjusted to facilitate a wide variety of isometric or isotonic exercises.

(iii) They are relatively lightweight since they do not rely on heavy metal springs or tensioning devices.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, an electronic device for measuring the force generated may be provided, built into the base portion, with a visual display to enable the user to gradually increase the force applied during the exercise programme and to measure their progress with increased strength. Therefore', it will be appreciated that the scope of the invention is not limited to the specific embodiments described.

Claims

1. An isometric exercise device comprising: an elongate bow-shaped flex structure made of resilient material; a flexible elongate tension member coupled to the respective ends of the flex structure so that tension applied to the tension member results in a flexing of the flex structure; and, resistance adjusting means provided in connection with the flex structure and/or the tension member for adjusting a resistance to flexing of the flex structure wherein, in use, when the flex structure is held stationary and the tension member is gripped by the user a load applied thereto results in exercise of a desired muscle group or groups.

2. An isometric exercise device as defined in claim 1 , wherein the bow- shaped flex structure comprises a central elongate base portion having a first pair of elongate bow members provided at one end and a second pair of elongate bow members provided at the other end.

3. An isometric exercise device as defined in claim 2, wherein the respective bow members in each pair are substantially parallel to each other.

4. An isometric exercise device as defined in claim 3, wherein when the flex structure is viewed in plan a first bow member of the first pair is collinear with a first bow member of the second pair, and a second bow member of the first pair is collinear with a second bow member of the second pair.

5. An isometric exercise device as defined in any one of claims 1 to 3, wherein the base portion and first and second pairs of bow members of the flex structure are all manufactured as a single integral unit.

6. An isometric exercise device as defined in any one of the preceding claims, wherein the flex structure is manufactured by injection moulding.

7. An isometric exercise device as defined in any one of the preceding claims, wherein the flexible elongate tension member has a handle provided thereon to facilitate better gripping of the tension member.

8. An isometric exercise device as defined in claim 7, wherein the handle is one of a pair of handles.

9. An isometric exercise device as defined in claim 8, wherein the handles are slidably attached to the tension member wherein the position of the handles on the tension member can be adjusted to suit the user.

10. An isometric exercise device as defined in any one of claims 2 to 5, wherein the resistance adjusting means comprises a relatively rigid strut member provided in connection with the base portion of the flex structure and an adjustable mechanical coupling means for coupling at least the first pair of the elongate bow members to the strut member.

11. An isometric exercise device as defined in claim 10, wherein the adjustable mechanical coupling means is a coupling member that is slidably received on the strut member and that rigidly couples the first and second bow members of the first pair to the strut member.

12. An isometric exercise device as defined in claim 11, wherein the strut member is an elongate strut member extending from one end of the base portion substantially parallel to and between the first and second bow members.

13. An isometric exercise device as defined in claim 12, wherein the strut member has a plurality of indentations provided at spaced intervals along its length wherein the coupling member engages with the indentations to hold it in a desired position on the strut member.

14. An isometric exercise device as defined in any one of claims 11 to 13, wherein the strut member is one of a pair of strut members provided on respective ends of the base portion of the bow-shaped flex member, and the coupling member is one of a pair of coupling members respectively slidably received on the respective strut members.

15. An isometric exercise device as defined in any one of the preceding claims, wherein the flexible elongate tension member further comprises a flexible elongate member such as a cable which is coupled to the respective ends of the first and second pairs of elongate bow members respectively.

16. An isometric exercise device as defined in claim 15, wherein the flexible elongate member or cable is connected to the respective ends of the first and second bow members by means of a pair of respective V- shaped coupling members, each V-shaped coupling member having a pair of arms and a sharp end to form the V-shape.

17. An isometric exercise device as defined in claim 16, wherein the sharp end of each V-shaped coupling member is fixed to a respective end of the cable.

18. An isometric exercise device as defined in claim 17, wherein the two arms of each V-shaped coupling member are provided with respective lugs that are slidably received in slots provided in the ends of the respective bow members.

19. An isometric exercise device as defined in claim 18, wherein the arrangement of the lugs in the slots can act as a regulator for regulating the increase in resistance of the flex structure as it flexes.

20. An isometric exercise device comprising: an elongate bow-shaped structure made of substantially rigid material; a flexible elongate tension member coupled to the respective ends of the bow-shaped structure; and resistance adjusting means provided in connection with the bow-shaped structure and/or the tension member for adjusting a resistance to force applied to the tension member wherein, in use, when the bow-shaped structure is held stationary and the tension member is gripped by the user a load applied thereto results in exercise of a desired muscle group or groups.

21. An isometric exercise device as defined in claim 20, wherein the bow- shaped structure comprises a central elongate base portion having a first pair of elongate bow members provided at one end and a second pair of elongate bow members provided at the other end.

22. An isometric exercise device as defined in claim 21 , wherein the respective bow members in each pair are substantially parallel to each other.

23. An isometric exercise device as defined in claim 22, wherein when the bow-shaped structure is viewed in plan a first bow member of the first pair is collinear with a first bow member of the second pair, and a second bow member of the first pair is collinear with a second bow member of the second pair.

24. An isometric exercise device as defined in claim 3, wherein the base portion and first and second pairs of bow members of the bow-shaped structure are all manufactured as a single integral unit.

25. An isometric exercise device as defined in any one of claims 20 to 24, wherein the bow-shaped structure is manufactured by injection moulding.

26. An isometric exercise device as defined in any one of claims 20 to 25, wherein the flexible elongate tension member has a handle provided thereon to facilitate better gripping of the tension member.

27. An isometric exercise device as defined in claim 26, wherein the handle is one of a pair of handles.

28. An isometric exercise device as defined in claim 27, wherein the handles are slidably attached to the tension member wherein the position of the handles on the tension member can be adjusted to suit the user.

29. An isometric exercise device as defined in any one of claims 20 to 28, wherein the resistance adjusting means comprises an adjustable gas spring mechanically coupled to the tension member for adjusting the resistance to force applied to the tension member.

30. An isometric exercise device as defined in claim 29, wherein the resistance adjusting means further comprises a regulator mechanically coupled to the tension member for regulating the force transmitted from the tension member to the gas spring.

31. An isometric exercise device as defined in claim 30, wherein the regulator is a spiral regulator wherein the tension member is wound in a spiral so that as load is applied to the tension member it is progressively released from the centre to the outside of the spiral.

32. An isometric exercise device as defined in claim 31 , wherein the resistance adjusting means further comprises a transmission means for transmitting force from the spiral regulator to the gas spring.

33. An isometric exercise device as defined in claim 32, wherein the transmission means comprises a variable pneumatic gearbox in fluid communication with the gas spring wherein the magnitude of a force transmitted to the gas spring can be adjusted.

34. An isometric exercise device substantially as herein described with reference to and as illustrated in any one or more of the accompanying drawings.