It is known that athletes in hot countries often want to cool their muscles down prior to competition. Such a process can improve performance since muscles fatigue to a greater extent when warm. Normally, athletes cool themselves in a cold water tank prior to competition. Typically, it requires 1 hour in such a bath to cool down 1-2°C. Athletes have been known to put ice in the lining and pockets of jackets in order to cool down. However, cooling the body on a relatively rapid timescale is potentially a dangerous activity, due to the risks of frostbite and heart attack. These risks are exacerbated when moisture is present adjacent to the skin. Also, such practices are rather uncomfortable for the wearer of the jacket.

To avoid these problems, and to address the limitations of ice jackets, researchers have attempted to achieve the same effect by utilising a'perfusion suit'. A perfusion suit is a garment incorporating some sort of auxiliary heating and cooling system, normally a liquid heating and cooling tube. A perfusion suit is also referred to as a Liquid Cooling Garment.

Perfusion suits with different liquid heating and cooling systems have been investigated in the prior art under various conditions. The efficiency of auxiliary body cooling under a simulated hot evening was examined using a garment incorporating a water recirculating three-layered vest of cotton fabric. The effects of multi-loop controlled liquid cooling garments during exercise under heat stress (35'C, 40%) was investigated using a triple-loop liquid cooling garment by which the torso, arms and legs could be independently cooled. The result showed that a multi-loop control is more effective than a single-loop control.

According to studies carried out using such perfusion suits, wearers experience restriction of mobility. This is partly due to the length and coiling of the tubing for the water supply system and partly due to the fact that perfusion suits used in previous studies were not designed for comfort when a tubing system is incorporated.

Thus there is a need for the further development of such garments to maximise the athlete's muscle performance and also to allow freedom of movement.

It is also possible that athletes in cool climates might want to warm up prior to competition or training.

It is known to provide garments in which can be stored bladders containing a phase change material. Such a material can maintain a constant temperature when the material is at a transition point between phases (e. g. , the solid and the liquid phase).

Garments for the upper body (vests, jackets) are produced by Microclimate Systems Inc: these garments can house cooling strips, wherein each cooling strip comprises a number of bladders.

The cooling strip can be regarded as a one dimensional array of bladders containing phase change material. Typically, the garment houses four cooling strips. It is a disadvantage that cooling of the body of a wearer will only occur with maximum efficiency at the discrete locations in the garment in which the cooling strips are located.

The present invention overcomes the abovementioned problems and disadvantages, and provides garments for efficiently heating or cooling a body part of a wearer. The garments are convenient and minimise the risk of adverse physical effects such as frostbite and heart attack. The garments can be worn by athletes and sports persons prior to competition, but, also, can be worn by persons not engaged in competitive activity, for example during training, or merely to keep cool in hot conditions or warm in cold conditions.

For the avoidance of doubt, the term"garment"is understood to encompass blankets, and the term"wearer"is understood to refer to animals as well as humans.

According to the invention there is provided a garment for heating or cooling a body part of a wearer, in which the garment is fabricated from a multiple layer material which extends over substantially the entire surface area of a body part of the wearer, and wherein the multiple layer material comprises: an innermost layer formed from a wicking material; a cooling or heating layer comprising a phase changing material which has the ability to maintain its temperature against a temperature gradient over a period of time; and an outermost shell layer formed from a material having a low thermal conductivity.

Muscle cooling at a rate of 2°C in 15 minutes is possible using garments of the present invention. Furthermore, by producing a cooling (or heating) layer which extends over substantially the entire surface area of a desired body part, efficient cooling (or heating) of the body part is possible. Thorough cooling of the surface over the working muscles (especially the leg muscles) provides the greatest thermoregulatory advantage during exercise. Furtherstill, the provision of a wicking layer, which is positioned directly against the skin, enables moisture to be removed form the skin, thereby substantially reducing the chances of frostbite and heart attack. The body part might comprise a leg, an arm, or the torso, or might comprise a more specific region, such as an upper leg or upper arm. Alternatively, (or additionally) the body part might comprise a specific muscle group, such as the quadriceps. The cooling (or heating) layer may extend over substantially the entire surface area of the garment.

The multiple layer material may further comprise a lining layer disposed between the cooling or heating layer and outermost layer.

The innermost layer, cooling or heating layer and optionally, the lining layer may form an insert which is retained in folds formed in the outermost layer. This enables convenient removal of cooling or heating layer for heating or cooling prior to the user wearing the garment.

The innermost and lining layers may comprise releasable engagement means, so that the cooling or heating layer can be positioned between said innermost and lining layers and retained thereby. This permits easy removal of the cooling or heating layer itself for prior heating or cooling, and also permits convenient assembly of the innermost, cooling or heating and lining layers into a composite layer which can be inserted as a single item into the shell layer. The releasable engagement means comprise press studs.

The phase changing material may comprise sodium polyacrylate.

Conveniently, the cooling or heating layer comprises a flexible substrate having disposed thereon a two dimensional array of pockets containing phase changing material.

The innermost layer may comprise Cool Max (RTM), Dry Fit (RTM) or like high wicking capacity material.

The outermost layer may comprise Therma-Foil (RTM) or like shell material.

The lining layer may comprise Toille fabric.

The garment may be a trouser garment, such as a pair oftracksuit"bottoms" or a pair of chaps.

The garment may be a blanket, which may be a horse blanket.

Garments in accordance with the invention will now be described with reference to the accompanying drawings, in which:- Figure 1 shows a trouser garment according to the invention; Figure 2 is a cross sectional view of a multiple layer material; Figure 3 shows a cooling or heating layer; Figure 4 is a perspective view of a multiple layer material; Figure 5 shows a) a front view of chaps according to the invention, b) a front view of one half of the chaps, and c) a back view of one half of the chaps; Figure 6 is a view of a multiple layer material for use with the chaps of Figure 5; Figure 7 shows a blanket according to the invention; and Figure 8 shows a horse blanket according to the invention.

Figure 1 shows a trouser garment 10 for heating or cooling the lower body of a wearer. The garment 10 is fabricated from a multiple layer material which extends over substantially the entire surface area of the garment.

Figure 2 shows a cross sectional view of the multiple layer material (shown generally at 20). The multiple layer material comprises: an inmost layer 22 formed from a wicking material; a cooling or heating layer 24 comprising a phase changing material which has the ability to maintain its temperature against a temperature gradient over a period of time; a lining layer 26; and an outermost shell layer 28 formed from a material having a low thermal conductivity.

The innermost layer 22 comprises a material having good wicking properties, such as Cool Max (RTM), Dry Fit (RTM) or like high wicking capacity material. Efficient removal of moisture from the skin reduces the likelihood of conditions such a frostbite and heart attack, as well as improving comfort for the wearer.

The lining layer 26 can comprise any suitable lining material, such as Toille fabric.

The outermost layer 28 is a shell layer having a low thermal conductivity but having good flexibility. A suitable material is Therma-Foil (RTM), produced by Therma-Float Limited of P O Box 8, Beech Lane House, Wilmslow, Cheshire, SK9 SGS, UK.

Figure 3 depicts a preferred configuration for the cooling of heating layer 24, comprising a flexible substrate 30 having a two dimensional array of pockets 32 containing phase changing materials. It is understood that the term"two dimensional array"is not intended to refer solely to a matrix of pockets formed from orthogonal rows and columns. Rather it is intended to embrace any arrangement in which a number of pockets extend in some way along two different axes (as opposed to the strip of bladders described above in respect of certain prior art arrangements). This arrangement enables the phase changing material to be positioned over substantially the entire surface area of the garment (thereby providing excellent cooling and heating) whilst still permitting good flexibility. In turn, this allows the garment to warm comfortably and allows the garment to be used during exercise. Examples of suitable phase changing materials are manufactured by Dynetherm of 5821 Rangeline Road, Suite 102, Theodore, AL, USA (also see www. dynetherm. com). A suitable, but non-limiting, Dynetherm product is known as WrapOns (RTM). It should be noted that phase changing materials are also known as"super absorbent materials".

The cooling or heating properties of the garment are provided by the phase changing material. If cooling is required, the phase changing material must be chilled previously, for example by placing it in a freezer. If heating is required, the phase changing material must be heated previously, for example by warming it up in a microwave oven.

Conveniently, the cooling or heating layer is removable from the garment so as to facilitate this prior cooling or heating of the phase changing material. Figure 4 depicts one way in which this convenient removal of the cooling or heating layer is achieved. The innermost layer 40, cooling or heating layer 42 and lining layer 44 form an insert which is retained in folds 46,48 formed in the outermost shell layer 50. The insert is thus easily removed from the outermost layer 50. The edges of the outermost layer 50 can be provided with a zip fastener 52 so that the edges can be conjoined, thereby providing a tubular portion which can serve as, for example, a trouser leg or sleeve. The extremities of the folds can be secured by stitching 54.

The innermost 40 and lining 44 layers comprise press studs 54 which enable these layers 40,44 to be releasably engaged. When engaged, the cooling or heating layer 42 is retained within the innermost 40 and lining 44 layers. When it is necessary to cool or heat the phase changing material, it is convenient to decouple the press studs 54, which permits easy removal of the cooling or heating layer 42. Others forms of releasable engagement means, such as Velcro (RTM), buttons or zips, might be contemplated.

Figure 5 shows a garment 60 for cooling down or warming up which provides cooling for warming to the upper legs, more especially the quadriceps muscles.

The garment 60 is of a'chaps'design.

To make up the design into a wearable garment, patterns for the garment were created with a view to ensuring acceptable freedom of movement for the wearer.

The pre-shaped and articulated chaps design garment was therefore developed with a pattern consisting of ten pieces; front cut, back cut, front lining, back lining, front knee piece, front lining facing, backlining facing, front crotch facing, back crotch facing, and front and back shanks. These patterns were drawn up to suit a medium sized athlete, although it will be apparent that the dimensions of the garment 60 can be chosen so that the garment 60 will fit a wearer of any given size. The multiple layer material which permits cooling and heating is only disposed in the upper portions 61,62 of garment 60, ie, above the knee. The garment 60 further comprises articulated knee portions 63,65 permitting freedom of movement for the wearer.

Figure 6 is a view of the multiple layer material used in the embodiment shown in Figure 5. The multiple layer material comprises a shell layer 64, a lining layer 66 and an innermost layer 69. The multiple layer material further comprises a cooling or heating layer which is not shown in Figure 6, but which in practice is housed by the lining layer 66 by way of inserting the cooling or heating layer in between folds 70,72 formed by the lining layer 66. The cooling or heating layer is further retained by way of releasable engagement means 74,76, such as press studs. In this embodiment, the press studs extend from the shell layer 64 to the innermost layer 69. In addition to retaining the cooling or heating layer, the press studs 74,76 also enable the entire multiple layer material to be retained in place. An articulated knee portion 78 is retained against the fold 72 and a fold 80 formed in the innermost layer 69. A fabric with low thermal conductivity was used for the shell layer 64 to minimise heat flux between the inside and outside of the cooling down/warming up garment; a fabric with reasonable flexibility and moisture absorbency was used for the lining layer 66 to hold the cooling system; a fabric with high wicking capability was used for the innermost layer 69 to counteract any perspiration or condensation of vapour on the cooling system that could compromise the garment's temperature regulation capability. For the rest of the garment 60, polyester knitted fabric was chosen for the shank region below the knees, and cotton woven fabric was used for the articulated knee portion. The specifications for the fabrics which might be used in the garment 60 are shown in Table 1. All fabrics are easily obtained through commercial sources.

The cooling or heating layer comprises re-usable frozen super-absorbent sodium polyacrylate pads. The pads were commercially purchased and used to provide the mechanism through which temperature is regulated. The specification of the super- absorbent material is shown in Table 2.

Table 1. Specifications of the fabrics used in the cooling down/warming up garment Section Material Weight Thickness Special (g/m2) (mm) Characteristics Outermost Layer Metallised 71 0.99 Thermal polyester conductivity: 0. 023 W. rri lk-1 Inner Layer 100% cotton 140 0.36 Sateen weave (37 x 31/cm2) Innermost Layer 100% polyester 213 0.69 Hydrophilic finished warp knitted mesh Shanks 100% Polyester 252 1.09 Interlock knitted Knees 100% cotton 140 0.36 Sateen weave (37 x31/cm) Table 2. Specification of the cooling system used in the cooling down/warming up garment Absorbent Cross-linked sodium polyacrylate polymer Covers Polythene Polyester Dry weight 315 g/m Dry thickness 0.64 mm The garment 60 was constructed according to a pre-shaped and articulated chaps design using Nm75 ballpoint needle and No. 120 polyester core-spun thread on a lockstitch sewing machine with a stitch length of 2. 5mm.

The design of the garment and the nature of the material used are all highly important factors permitting the provision of cooling or warming of a desired muscle function without restriction of the wearer's movement and maximising comfort for the wearer and garment performance, especially in relation to maintaining optimal thermal balance.

Although the foregoing relates to trouser garments, it will be apparent to the skilled reader that other garments, such as jackets, vests and headwear, might be produced using the principles described herein.

Also within the scope of the invention are various forms of blanket which comprise the above described multiple layer material.

Figure 7 depicts a blanket 100 which comprises a layer of wicking material 102 which serves as an innermost layer, intended to be positioned against the body of a wearer. The adjacent side of the blanket 100 comprises a shell layer 104. In the intended use, the shell layer 104 is the outermost layer from the body of the wearer covered by the blanket 100. As shown in Figure 7, the shell layer 104 extends to the innermost side of the blanket, forming a three sided panel 104a. The layer of wicking material 102 is attached to the panel 104a such as by stitching. A lining layer 106 and cooling or heating layer 108 are disposed within the cavity formed by the wicking layer 102 and the shell layer 104. This cavity is closed by way of press-studs 110. It will be apparent to the skilled reader that there are many other ways in which the blanket of the present invention might be constructed. For example, the wicking layer might be attached to the shell layer in a different way, such as by press-studs or, indeed, may comprise part of an insert in a similar manner to that shown in Figure 4. The lining layer and cooling or heating layer might be retained between the wicking layer and shell layer by alternative means, such as a zip. Alternatively, the shell layer may form a four sided panel on the innermost side of the blanket. One side of this four sided panel might not be in attachment with the wicking layer, thereby permitting removal of the cooling or heating layer. Instead, this side of the panel would serve as a"lip", retaining the lining layer and cooling or heating layer in place. In any event, the lining layer is optional. The blanket 100 as shown in Figure 7 is rectangular, but could be any other shape, such as square of circular.

Figure 8 shows a shaped horse blanket 111. The horse blanket is constructed generally in accordance with the principles described in respect of Figure 7.

Shown in Figure 8 is the outermost shell layer 112, which is attached via press-studs 114 to the innermost, wicking layer 116. Enclosed between the wicking layer 116 and shell layer 112 are a lining layer and a cooling or heating layer (not shown). Straps 118 having buckles 120 are provided for securing the blanket 111 against the torso of a horse. it is also possible to provide other garments suitable for animals, especially mammalian animals, such as body warmers for dogs.