ANTIGRAVITY MUSCLE EXERCISER AND METHODS OF USING SAME

TECHNICAL FIELD The invention described herein relates generally to an exercise device which can be used to enhance the stability of the spine, shoulder girdle and upper limb joints, and to promote muscle and bone health in the region. In particular, the invention is directed to the use of the exercise device for specifically activating the antigravity posture muscles which support and protect the spine from injury. BACKGROUND ART

The spine, shoulder girdle and upper limb are necessarily very mobile parts of the body which take part in a huge variety of everyday movements needed for normal activities as well as sports and recreation.

Due to the continual vertical force of gravity on the body, it is also necessary to have strong muscles to protect the skeleton (bones and joints) from injury. To prevent deterioration in bone and muscle health and the development of conditions such as osteoporosis and osteoarthritis, the body requires a strong antigravity muscle system to stabilise and protect the skeleton and counteract the potentially harmful effects of gravity.

It is known that gravity is responsible for the 'heaviness' or 'weight' of the body. In addition gravity is also responsible for the compressive forces on the spine and other joints of the body. These compressive forces increase with increased body weight as well as with various body positions and unstable exercise surfaces. If these high joint compressive forces are not counteracted by antigravity muscle activity, the health of the joints deteriorates due to wear and tear caused by the increased compressive forces. Antigravity muscle strength is gained by using the antigravity muscles in a way that pushes the skeleton in an upwards direction, in order to lift, as well as lower, the body weight.

This upwardly directed antigravity muscle force is also required to counteract the compressive force of gravity on the joints. This type of exercise is often referred to as 'weightbearing' exercise. It is the axial strength and stiffness of the spine that is the most important requirement to counteract the vertical, compressive forces of gravity and therefore is the most critical element for the protection of the spine from injury.

Stability of the spine has been demonstrated to be enhanced under axial loads directed through the vertebral bodies (Patwardhan et ah, 2000). This compressive load needs to be directed through a spine when it is in a 'lordotic' or neutral spine position (see Figure 3).

The stabilising action of the muscles to counteract this compressive axial load on the top of the spine, is activated by postural cues — viz., stretching tall, trying to lengthen the spine, chin tuck (horizontal gaze), moving the shoulder blade down and in, and drawing in the abdominal wall. These postural cues facilitate an 'upwardly directed' muscle force equal and opposite to the opposing axial compressive force of gravity. There is no device available to safely provide this compressive force which is required to activate the antigravity muscles.

It is known that high compressive loads on top of the head can be hazardous to the health of the spine and has been shown to increase degenerative changes in people who carry loads of up 50-60 kg on the head (Echarri and Forriol, 2005). For these reasons, it is critical to control how much load is applied to the head and how it is applied to the head. There is accordingly a need for an exercise device that is suitable for exercising the antigravity muscles. The requirements of such a device are that in use:

1. the axial compressive load applied to the head can be quantified;

2. the axial load is equal and opposite to the upwards antigravity muscle force generated through postural cues; and

3. the axial load is applied through the axis of the spine (through the ear, shoulder, and hip in sagittal plane) when the spine is in a neutral, lordotic posture.

Objects of the invention are to provide an exercise device that meets this need and to provide methods utilizing the device. SUMMARY OF THE INVENTION

In a first embodiment, the invention provides an exercise device comprising: a pair of opposed longitudinal handles which are rigidly separated at their proximal ends by a spacing member, wherein the spacing member has a central portion which is displaced from the handles and the central portion includes an indicator of a force applied by way of the device.

In a second embodiment, the invention provides a method of strengthening and increasing the stability of the spine by providing a self resisted axial head load, the method comprising the steps of: a) holding the device according to the first embodiment by said handles; b) positioning the central portion of the device against the top of the head; c) applying pressure on the device via the hands holding the device while counteracting that pressure with an opposite axial force, wherein said applied pressure generates a force no greater than a maximum force signal given by the indicator included in the device;

d) relaxing the applied pressure while reducing the counteractive force; and e) repeating steps (c) and (d).

In a third embodiment, the invention provides a method of maintaining upper trunk postural alignment and spinal stability during lower limb exercise, the method comprising the steps of: a) holding the device according to the first embodiment by said handles; b) positioning the central portion of the device against the top of the head; and c) holding the upper trunk in postural alignment while exercising the lower limbs. In a fourth embodiment, the invention provides a method of graduated unstable weight- bearing exercise for the spine, shoulder girdle and arms, the method comprising the steps of: a) holding the device according to the first embodiment by said handles; b) positioning the device against a surface; c) bending and extending the arms to move the body towards or away from the surface; and d) maintaining a neutral spine position and postural cues during said exercise.

With reference to the first embodiment defined above, the handles can have hand-grips associated therewith to aid the gripping of the handles. Furthermore, the distal end of each handle advantageously comprises a knob which serves to space the hand-grip portions of the handle away from a surface when the device is used in the method of the fourth embodiment. A knob can comprise a mere flattening of the end of a handle. Alternatively, the knob can be a separate member that is fitted to an end. Such fitment can be by any suitable means.

The indicator included in the central portion of the device according to the first embodiment can be a deformable member or spring. Such a member can be connected to a user selectable audible or visual alarm and can be mechanical or electronic in its operation. In this manner a therapeutic regime can be prescribed and monitored. Loading can be prescribed by the therapist and a user selectable indication or alarm provided which is activated on reaching the required axial load. Electronic measurement and recording of the axial force applied can also be implemented. Such electronic means advantageously interface to a personal computer, personal digital assistant (PDA), or ambulatory electronic display device (iPod) for storage of recordings and display of performance.

Those of ordinary skill in the art will be familiar with the mechanical and electronic devices that can act as a suitable indicator.

The central portion of the device can be padded to afford greater comfort when the device is applied to the head of a user. The indicator can be incorporated into the padding.

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The exercise device can be manufactured from any suitable material including metals and plastics. Typically however, the device is manufactured from aluminium or steel. Devices according to the invention will be described in greater detail below.

As indicated above, the second embodiment provides a method of strengthening and increasing the stability of the spine by providing a self resisted axial head load, to give simulated axial compression of the spine. The method is generally employed with at least the torso of the user upright. In this mode of use, the downward pressure applied by the arms holding the device acts as a resistance to the upwardly directed muscle activity created by postural cues. It is important to ensure that the axial load is applied through axis of the spine (through the ear, shoulder, and hip in sagittal plane) when the spine is in a neutral, lordotic posture. An added advantage of this 'isometric' exercise is that the downward pressure or force on the device is provided by a simultaneous action of bringing the shoulder blades downwards and inwards. This action of the shoulder girdle is, in turn, also reinforcing the postural cues involved in the 'stretch tall' action. In addition, this method of increasing the stability of the spine by self resisted isometric exercise can be applied in a variety of body positions, not just in upright (vertical) positions which are demonstrated below. For example, the same antigravity muscle action (i.e., antigravity exercise) can be initiated when in a horizontal (supine) position. In this case the exercise is performance of 'simulated' weightbearing. In step (b) of the second and third embodiment methods, the central portion of the device is applied to back part of the crown of the head, just above the ears. This positioning is aided by the device having appropriately shaped padding associated with the central portion. It is important in step (c) of the second embodiment method to ensure that the axial load is applied through the axis of the spine (see below). In certain methods, the exercise device can be used in conjunction with the posture indicator described in International Application No. PCT/AU2007/000685 (WO 2007/134380), the entire content of which is incorporated herein by cross-reference. This aspect of the invention will be exemplified below.

With reference to the method according to the fourth embodiment, the surface is typically a vertical surface or a horizontal surface such as a wall or a floor, respectively. However, the surface can be at any angle between vertical and horizontal.

Use of the device in the methods of the invention will be explained in greater detail below.

In order that the invention may be more readily understood and put into practice, one or more preferred embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figures Ia and Ib are elevation and plan views, respectively, of an exercise device according to the invention.

Figures 2a and 2b are perspective views of a central portion of the device shown in Figures Ia and Ib to illustrate the nature and function of a force indicator.

Figures 3a to 3c are, respectively, an elevation view, a plan view from above, and a plan view from below, of an alternative exercise device according to the invention while Figure 3d is a cross section at A-A of Figure 3a.

Figure 4 is a schematic cross-sectional view of an individual to illustrate correct postural alignment.

Figures 5 to 11 are illustrations of methods according to the second to fourth embodiments, in which embodiments an exercise device of the invention is utilized.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In Figures Ia and Ib there is shown exercise device 1 comprising handles 2 and 3, and spacing member 4. Handles 2 and 3 can be seen to be angled away from a plane normal to a central plane of the device. The angle is about 5° but can be between 0 and 10°. Spacing member 4 has a central portion 5 which can be seen to be displaced from handles 2 and 3. It can be further appreciated from Figure Ib that the central portion is bifurcated thereby broadening the portion in a plane normal to the central plane of the device. A pad 6 is located on the underside of the central portion and is mounted to a plate 7 which spans the central portion by a spring (see Figures 2a and 2b). The pad and spring comprise a force indicator. The indicator can alternatively be located elsewhere in the bifurcated portion or within the pad. Nylon or plastic knobs — see items 8 and 9 — are fitted to the ends of handles 2 and 3 which also have hand grips 10 and 11 fitted thereto. The hand grips typically consist of a natural or synthetic elastomer.

Device 1 has an overall length of about 920 mm and the handles are about 450 mm apart. Central portion 5 has a length of about 100 mm and a width of about 170 mm. The device can be hinged at a convenient site in central portion 5 for ease of storage.

The components of the force indicator referred to above are shown in greater detail in Figures 2a and 2b. The bifurcated central portion 5 of the device of Figures Ia and Ib is shown in Figures 2a and 2b. The mounting of pad 6 to plate 7 via a spring 12. It can be

further appreciated from Figures 2a and 2b that pad 6 is curved to allow more comfortable contact with the head of a user (see below).

Figures 2a and 2b also show how pad 6 and spring 12 function as a force indicator. When there is no head pressure on pad 6, spring 12 will be decompressed and hence a user will be aware that the head is not being forced against central portion 5 of the device (see Figure 2a). However, as the user moves his or head towards the central portion (as generally shown by the arrow in Figure 2b), spring 12 will compress so that the force against the device can be sensed.

An alternative form of the exercise device of the invention is shown in Figures 3a to 3d. With reference to Figures 3a to 3c, there is shown exerciser 13 comprising handles 14 and 15 extending from spacing member 16 which is curved. Rubber hand grips 17 and 18 are fixed to each of the handles and the ends of the members have knobs screwed thereinto — see items 19 and 20.

It can be appreciated from Figures 3b to 3d that a central portion 21 of spacing member 16 is broadened. This broadened area has padding fitted to its upper and lower surfaces^see items 22 and 23 respectively — the upper padding being smaller than the lower padding.

It can be further appreciated from Figure 3 a that broadened area 21 is laterally curved. This affords greater comfort when the lower surface of the area is applied to the head of a user (see below). The handles 14 and 15, and spacing member 16, of device 13 are unitary with this unitary article typically being manufactured from steel tubing. The unitary article can also be manufactured as an aluminium moulding. In the latter instance, broadened area 21 can have an opening through there into which a unitary article comprising padding 22 and 23 is fitted. As with device 1 of Figures Ia and Ib, the device includes a force indicator which is incorporated into padding 22 and 23.

Device 13 as illustrated in the drawings has a length of 850 mm while curved member 16 separates handles 14 and 15 by about 350 mm. The overall height of the device (see Figure 3a) is 125 mm. Knobs 19 and 20 have diameters of 85 mm.

Methods of using the exercise device according to the invention are depicted in Figures 5 to 11. However, before describing these methods in detail, reference will first be made to Figure 4 where correct postural alignment is depicted.

In Figure 4, there is shown an individual 24 in a standing position and adopting a neutral spine position as generally indicated at 25. A line of gravity 26 passes through the ear

lobe 27, shoulder joint 28, and hip joint 29. An axial head load as generally indicated by arrow 30 will consequently act on the line of gravity.

The same configuration can prevail even when the legs of individual 24 are bent. Use of the device in accordance with the second embodiment method is depicted in Figures 5a and 5b. In Figure 5a, user 31 can be seen gripping device 1 by each of the handles with spacing member 4 over and against the head 32 of the user. Arrow 33 indicates the downward axial force. The user exerts an upward force 34 to counteract the pressure applied via the arms of the user, the latter being indicated by arrows 35.

Figure 5b is a back view. User 31 can again be seen gripping device 1 by each of the handles 2 and 3 with spacing member 4 over and against the head 32 of the user. Arrow 33 again indicates the downward axial force. The user exerts an upward force 34 to counteract the pressure 35 applied via the arms of the user. This pressure simultaneously uses muscle action 36 which involves stabilization of the shoulder blades 37.

The third embodiment method is depicted in Figure 6. It comprises maintaining upper trunk postural alignment by gripping device 1 by each handle 2 and 3 using arm force 35, with the pad 6 of spacing member 4 in line with the neutral spine alignment (see 25 of Figure 4). This isometric exercise is held while exercising the lower limbs.

Use of the device in accordance with the fourth embodiment method is depicted in Figure 7. In this use, device 1 is gripped by each of the handles and applied to a wall 38 by way of spacing member 4. The arms 39 and 40 of user 41 are bent so that the body is moved in the direction indicated by arrow 42. Extending the arms reverses this movement while repetition of the extending-bending cycle exercises antigravity muscles. The stretch tall cue 43 is maintained during the exercise. This manner of use is essentially the same as doing push-ups but with the body upright. Application of device 1 to a surface such as floor 44 as shown in Figure 8 affords greater effort by virtue of the 'rolling' capability of the device. This rolling capability can be enhanced by fitting a hemispherical member (not shown in the drawing) to the surface of central portion 5 closest floor 44 when the device is in use (that is, the surface of central portion 5 that is opposite the surface that is placed against the head in the methods of use illustrated in Figures 5 and 6). The hemispherical member can be fitted to the device by any suitable means such as straps or clips, allowing the member to be removed when the device is to be used in other methods according to the invention.

The rolling capability described in the previous paragraph can be eliminated by laying the device flat so that is it applied to the surface by its knobbed ends, 7 and 8, and the spacing member 4 (see Figure 9).

Figure 10 depicts use of a device of the invention when the user is in a supine position, such as on a floor 45. As in Figure 5a, user 46 can be seen gripping device 1 by its handles (not visible in the drawing) with spacing member 4 against the head 47 of the user. For comfort, a pillow 48 is positioned under head 47. Arrow 49 indicates the force opposite to the force — indicated by arrow 50 — exerted by the user. A footrest 51 is provided to assist in exerting the latter force. As noted above, use of a device of the invention in accordance with the Figure 10 method affords 'simulated' weightbearing exercise.

As also noted above, devices in accordance with the invention can be used in conjunction with the WO 2007/134380 posture indicator. The combined use of a device and posture indicator is illustrated in Figures 11a and l ib. Briefly, the posture indicator comprises an adjustable belt formed from a flexible but inextensible material. The belt has fixed to its inside surface a solid and impervious spine contact member comprising a plurality of ridges. This member is fixed at a portion of the belt which spans the lumbar region of a wearer when the belt is in situ. In use, the spine contact member is positioned within the lumbar curve of the wearer and the ridges are in contact with the lumbar spine and adjacent lumbar regions. This provides tactile feedback regarding posture to the wearer without providing passive support.

With reference to Figure 11 , there is shown user 52 holding device 1 in the same manner as illustrated in Figures 5a and 5b. However, user 52 is also wearing a posture indicator 53. The spinal contact member 54 of indicator 53 allows user 52 to sense incorrect posture and hence correct his or her posture in continuing with the exercise. This allows the user to gain the maximum benefit from the use of device 1.

Figure 1 Ib is a side view of user 52 of Figure 11a. It can be appreciated from the former figure that use of posture indicator 53 allows further sensing of posture via belt 55 of the device. This sensing, at the abdomen (item 56), gives information when the user has lost the antigravity postural muscle activity — as generally indicated by the arrows, one of which is item 57 — and the abdomen begins to 'bulge outwards'.

The foregoing embodiments are illustrative only of the principles of the invention, and various modifications and changes will readily occur to those skilled in the art. The invention is capable of being practiced and carried out in various ways and in other

embodiments. It is also to be understood that the terminology employed herein is for the purpose of description and should not be regarded as limiting.

The term 'comprise' and variants of the term such as 'comprises' or 'comprising' are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.

References

Echarri, JJ. and Forriol, F. (2005) Influence of the type of load on the cervical spine: A study on Congolese bearers. Spine 5(3):291-6.

Patwardhan et al. (2000) Load Carrying Capacity of the human cervical spine in compression is increased under a follower load. Spine 25 (12): 1548-54.