"Aerobic" exercise is generally defined as exercise which develops respiratory and circulatory fitness and exercises the cardiovascular system, by increasing the body's use of oxygen. By contrast, "anaerobic" exercise is a form of exercise aimed at developing muscle strength and tone through concentrated stress and work of particular muscles and muscle systems, rather than concentrating on working the respiratory and

circulatory systems. Anaerobic exercises typically used for muscular development include weightlifting and isometric exercises.

The familiar exercise of jumping over a skipping rope held in either hand and swung around the body is acknowledged to be an effective form of aerobic exercise, well adapted to building respiratory and circulatory fitness. However, this exercise does not significantly stress or work the muscles employed so as to develop the muscles and build their strength, since the muscles are only subject to relatively light loads.

The proposal has been made to increase the weight of a skipping rope in various ways so as to enhance its value as an anaerobic or muscle-conditioning exercise device. The aerobic advantages of skipping rope as an exercise remain, and the muscles are called upon to work harder in swinging the rope. Hence, a weighted rope can provide anaerobic exercise for the muscles of the arms, chest, shoulders and back. One prior art weighted skipping rope has a hollow, flexible rubber tube, filled loosely with sand as a weighting material, and capped at either end by a handle. This device can function similarly to a conventional skipping rope, while the weight of the sand provides the required extra wor for the muscles.

A characteristic property of the prior art rope follows from the pronounced elastomeric property of the rubber tube. This material stretches very readily, and when the rope is swung around the body as a skipping rope, it elongates considerably, being stretched further by the centrifugal effect of the mass of sand. The sand migrates into a compact mass towards the centre of the tube's length, leaving the portion of the tube immediately adjacent the handles hollow or only partially filled with sand. This allows the tube to neck or narrow in these portions, further increasing its springiness.

It has been found that the pronounced elasticity of this rope and the variable moment arm induced by both its ready propensity to stretch and the outward migration of the sand filling make this device awkward, uncomfortable and difficult to use, particularly for users who are less fit, weaker and less agile.

When selecting such a device for use, it is difficult to choose the appropriate length, since the elastomeric tube material stretches considerably in use according to the device's weight and its rate of rotation. Hence, a device that may seem an appropriate length when at rest becomes increasingly cumbersome and difficult to use as rotation increases. With increasing elongation, a substantial component of the rope at its bight must strike the ground and either rebound with a destabilising impulse or be dragged along the ground beneath the user. The impact with the ground is transmitted as a wave or longitudinal impulse along the rope to the handles, which can give the user a serious jolt at high speeds of rotation. This jolt, and the prolonged contact with the ground, lead to discomfort and imbalance for the user.

The pronounced elastic property of this device means that any irregularity of swing is transmitted along the rope as a pulse or wave, making for an uncomfortable, irregular and uncertain swing. It is often difficult for the user to settle into a regular swing pattern. The rope's springiness creates an uncomfortable whipping effect, with the rope's free bight flicking back and forth, even when the device is simply being carried by the user.

The rope's elastic stretching in use further makes it difficult to use at high speeds of rotation, since a substantial lag develops at the extreme point of the bight due to the intertia of the weighted tube.

When this lag is associated with uneven pulses passing along the tube, the shape of the rope can depart substantially from the desirable U- or V-shape. This deformation leads to further discomfort and imbalance, and the rope's bight may even strike the user, particularly when the lagging and whipping effects coincide.

In practice, the lagging effect imposes an unnecessarily low maximum on the rate of rotation that can be comfortably achieved, as the increasing lag and stretch make it practically impossible for the rope to function as required. This significantly reduces the range of the device as an aid to aerobic exercise.

A prior art device of this type is disclosed in U.S. Patent 4,505,474, which describes a jump rope designed to stretch significantly in use, particularly in the portion adjacent the handles. In the embodiments described, each side of the device elongates elastomerically in a range of twenty-five to forty-five percent.

It is proposed in U.S. 4,505,474 that stretching of this order is essential for the advantages claimed for this prior art product. In particular, the stretching is intended to reduce the jolting effect of a weighted skipping rope and to enhance its efficacy as an exercise means. In fact, the characteristic propensity of this device to stretch longitudinally, and its pronounced elasticity, which readily transmits any irregularities of swing, lead to all the undesirable effects discussed in detail above.

Moreover, it is claimed for this device that its pronounced elastic stretching improves its conditioning effect. Yet it is claimed that the periodical stretching and contracting of the device lessens the jolting effect as it changes vertical direction. In fact, it has been found that the periodic

stretching and contracting of the rope may detract from the exercise potential of the device, the contraction performing part of the work the user would normally be called upon to perform in swinging the weighted rope around. Moreover, in the skipping motion, far from lessening the jolting effect, the propensity to stretch has been found to accentuate it.

It has also been found that existing weighted skipping ropes have inadequate handles, with a propensity to slip and a failure to provide a sure grip, particularly as the hands begin to sweat.

I have determined that a satisfactory weighted skipping rope must have the property of readily adopting and maintaining with stability a suitable arcuate shape even when used by the inexperienced and the less fit, and must perform in a regular, predictable way, with irregularities of swing being dampened, to encourage security and the development of skill in the user. Irregularities of swing are of particular concern with a weighted skipping rope, as contrasted with a conventional skipping rope, due to the greatly increased momentum of the freely swinging rope.

The present invention follows from the specific determination that a particular construction incorporating a tube of semi-rigid material containing weighting matter can produce a weighted skipping rope which is sufficiently flexible to adopt the appropriate arcuate shape in skipping while avoiding the shortcomings of the prior art discussed above. It has been determined that a device according to this construction which is of such flexibility, but with such elasticity as not to elongate noticeably or significantly in use, may also have the precise dampening effect required, without inhibiting the natural circular swinging movement.

According to the present invention there is provided an exercise device adapted for use as a skipping rope, comprising: an elongate cylindrical tube of semi-rigid material; a handle fitted to or over each end of the tube; and weighting matter contained in the tube. The term "semi-rigid material: as used herein is understood to mean a material which has a degree of flexibility sufficient to allow the exercise device to be rotated in an arc and has a degree of rigidity sufficient to resist significant elongation during such rotation.

The semi-rigid material may, for example, be a body whose flexibility is approximately one-third to two-thirds the flexibility of an equivalent body of unmodified latex rubber, although a specific determination of the appropriate semi-rigid property may be made according to particular embodiments. It is preferred that the semi-rigid material is selected from the group comprising plasticised PVC, polyurethane rubber, ethylene vinyl acetate, ethylene propylene diene terpolymer (EPDM), and thermoplastic rubber/elastomer compounds. One example of a semi-rigid material for use in the invention is a compound of PVC which has a Shore A hardness of 50 to 100, preferably 70 to 80, made up, with a tolerance of about 5%, approximately to the following proportions: PVC homopolymer and/or copolymer DIOP or other suitable plasticiser stabiliser lubricant

colours/pigments/carbon black/ 0.01 to 2 parts τio ₂

In a preferred configuration the compound is extruded into a tube with an external diameter of between 20 and 35 mm and constant wall thickness of between 1 and 3 mm.

The weighting matter may comprise a core of flexible material formed to fit snuggly in the tube. The flexible material may be selected from the group comprising latex rubber, ethylene vinyl acetate compound, polyurethane compound and EPDM compound, either foamed or unfoamed. The core may be formed as a combination of foamed and unfoamed laminations or layers of flexible material selected to provide the exercise device with a desired weight and flexibility.

In a preferred configuration the core comprises an inner core of one flexible material and an outer shell of another flexible material, wherein the flexible material of the inner core has a higher density than that of the flexible material of the outer shell.

Alternatively, the weighting matter may comprise a particulate matter compacted in the tube. The particulate matter may be bird seed, sand, or any other suitable material selected to provide the device with a desired weight and flexibility.

In a preferred configuration, the particulate matter compacted within the tube is divided by one or more intermediate plugs to enhance the compaction and to inhibit unequal concentrations of the particulate matter. Compaction of the particulate matter has the effect of stabilising the shape and hence swing of the semi-rigid tube when in use as a skipping rope, and dampening any irregularities of swing. This construction also reduces stretching of the rope in use to a negligible or null amount.

The handles may be fitted to each end of the tube so as to allow the tube and the weighting matter contained therein to rotate freely with respect to the handles. It is preferred that the exercise device further comprises a swivel assembly between each handle and the respective end of the tube to allow such free rotation of the tube and the weighting matter contained therein with respect to the handles.

Alternatively, the handles may be fitted over each end of the tube so that the tube and the weighting material contained therein are fixed with respect to the handles. It is preferred that the exercise device further comprises a reinforcing tube located in each handle and partially in the tube to increase the rigidity of the exercise device in the region of the handles and to assist in fixing the handles to the tube.

It is preferred that the handles are provided with ribbing to facilitate grip and reduce slippage due to sweat and with flanges for the cupped thumb and forefinger to rest against.

In order that the present invention may be more fully understood, preferred embodiments of the invention are described with reference to the attached drawings in which: Figure 1 shows a general plan view of an exercise device in accordance with one embodiment of the invention;

Figure 2 is a partly exploded side view along the line A to A in Figure 1; Figures 3(a) and 3(b) are partly sectional views of alternate swivel assemblies to connect the handles to the tube to that shown in Figures 1 and 2.

Figure 4 shows a general plan view of an exercise device in accordance with a second embodiment of the invention;

Figure 5 is a cross-section along the line A to A in Figure ; and

Figures 6(a) to 6(f) are partially sectional views of alternate arrangements to connect the handles to the tube to that shown in Figures 4 and 5.

Figures 1 and 2 illustrate one embodiment of an exercise device 10, with a cylindrical tube 11 made of the PVC compound described above, and with handles 12 made of thermoplastic material. The exercise device 10 further comprises a swivel assembly 25 connected between each handle 12 and the tube 11 to allow the tube to rotate freely with respect to the handles 12. The tube 11 is filled with weighting matter 13 to provide a weighted filling which still allows reasonable flexure of the exercise device 10.

The weighting matter may comprise a core of flexible material such as latex rubber, polyurethane compound and EPDM compound, either foamed or unfoamed. Alternatively, the weighting matter may comprise particulate material compacted in the tube such as bird seed and sand.

When the weighting matter is selected to comprise particulate material it is preferred that the exercise device further comprises a plurality of plugs (not shown) spaced along the length of the tube 11 to divide the compacted particulate material into sections, thereby to enhance compaction and to inhibit unequal concentrations of particulate material.

The cross-sectional view of Figure 2 shows that each swivel assembly 25 comprises a male part 26 which is glued or otherwise connected to the handle 12 and is formed with a projection 27 having an internal thread 28. The swivel assembly 25 further comprises, a female part 29 having a central hole 31 which receives the projection 27, and a bolt 32 and washer 33 which hold the female part 29 in position against the male part 26. The tube

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ll is stapled or otherwise connected to the female part 29. It can readily be appreciated that with such an arrangement the female part 29, and therefore the tube 11, is free to rotate around the projection 27 of the male part 26. The configuration at the other end of the tube 11 is identical to that illustrated in Figure 2. Figures 3(a) and 3(b) illustrate alternate arrangements of the swivel assembly 25 shown in Figure 2 to allow the tube 11 to rotate freely with respect to the handles 12.

The arrangement shown in Figure 3(a) comprises a spring lock-in swivel assembly 30 of the type manufactured by Kress and Katner GmbH and marketed under the trade mark GARDENA. The swivel assembly 30 comprises a male part 34 which is adhered to the handle 12 and a female part 35 which has a plurality of teeth 36 to grip the tube 11 and are held in place by an outer sleeve 37 thereby to secure the female part 35 to the tube 11. The female part 35 has a jaw 38 arranged to lock into place against the male part 34 by means of a spring loaded sleeve 41, thereby to lock the female part 35 to the male part 34.

The arrangement shown in Figure 3(b) comprises a ball 45 connected to the tube 11 and a cavity 47 connected to the handle 12 which receives the ball 45, thereby to allow free rotation of the handle 12 with respect to the tube 11.

Figures 4 and 5 illustrate a second embodiment of an exercise device 10, with a cylindrical tube 11 made of the PVC compound described above, and with handles 12 made of thermoplastic material. The tube 11 houses a core 13 of flexible material to provide a weighted filling which still allows reasonable flexure of the device 10.

The cross-sectional view of Figure 5 shows that the core 13 comprises an inner core 113 and an outer shell 114. The flexible material of the inner core 113 is selected to be more dense than the flexible material of the outer shell 114 so that the mass of the core is concentrated towards the central axis of the exercise device 10. The configuration at the other end of the tube 11 is identical to that illustrated in Figure 3. Each handle 12 is made of a thermoplastic material, with a cylindrical cavity adapted to tightly fit over the tube 11 reinforced by the core 13 of flexible material. Each handle 12 has a flange 21 and ribbing 22. The flange 21 provides a support from the cupped thumb and forefinger, while the ribbing 22 provides a non-slip grip for the cupping fingers and palm so as to provide a secure grip unaffected by sweat. Figures 6(a) to 6(f) illustrate alternate arrangements to connect the handles 12 to the tube 11 to that shown in Figures 4 and 5. In each of the arrangements the exercise device is provided with a reinforcing tube 61 which is located in the cylindrical cavity of each handle 12 and partially in the tube 11. The purpose of the reinforcing tube 61 is to increase the rigidity of the exercise device in the region of the handles 12 and to assist in locating the handles 12 securely to the tube 11.

In the arrangements shown in Figures 6(b) and 6(c) the exercise device is also provided with a corrugated flexible reinforcing tube 63 to prevent buckling of tube 11 in use. It is preferred that the corrugate flexible reinforcing tube 63 is formed from ethylene vinyl acetate compound.

In the embodiments shown in the figures the length of the tubes 11 is selected according to the particular requirements of the user so as to swing around the user as a skipping rope while maintaining minimum contact with the ground.

In the embodiments shown in the figures the external diameter of the tubes 11 is 25 mm and the wall thickness is 2 mm; or the external diameter may be 22 mm and the wall thickness 1.5 mm. The overall length is approximately 2.5 m. The tubes 11 are formed from the PVC compound specified in detail above, and is formed by extrusion. The tubes 11 have a pleasing glossy finish and may be formed in a variety of colours to assist in colour coding various lengths and weights of exercise device. This is in contrast to the matt monochrome finish of the prior art devices using latex.

The exercise devices 10 shown in the figures are used by gripping a handle 12 in each hand, and swinging the device around the body in the familiar, circular skipping motion. It has been found that the properties of the selected semi-rigid tube material allow for a stable arcuate shape for the exercise device when in use. Although flexible enough to form a suitable arcuate shape as shown in Figures 1 and 4 to be coiled for storage, the exercise devices are sufficiently semi-rigid to maintain the preferred shape and an acceptable integrity of swing path in use in spite of the natural irregularity and fluctuations imparted to the device. With the exception of the arrangement shown in Figure 6(d) the exercise devices described herein will not seriously whip or jolt in use and do not elongate significantly during use. In fact, in all normal use conditions the exercise devices remain the same effective length, thus avoiding the disadvantages due to stretching noted in the prior art devices. The described exercise devices thus provide a more stable, predictable swing and

do not jolt or unsettle the user. It is easier to maintain control of the exercise devices, even at low speeds, when the centrifugal effect on the weighted tubes 11 is relatively small. In contrast, the prior art devices tend to collapse inwardly at low speeds of rotation, a relatively high centrifugal effect being required to maintain the integrity of the shape.

In an alternative configuration, the tubes may be filled with a suitable liquid of sufficiently high viscosity to have the required shape-maintenance and impulse-dampening qualities.

It is to be understood that each of the variations described and many other modifications and variations may be made within the scope of the present invention which extends to every novel feature and combination of features herein disclosed.