X-Bionic PK-2 Energy Accumulator Leg Warmer : Black

With years of technical fabric development that began with ski and motorbike socks, and with countless design awards and hundreds of patents across many sports, X-Bionic are at the forefront of technical cycling apparel. You may or may not have heard of them, though if you have it is probably through their famous X-Socks.

The Swiss company are focused on producing apparel that gives a real and quantifiable performance advantage and this is evident from the moment you pick up a product. For starters the box of each item has more technical information on it than most websites and once liberated from the packaging the distinctive feel and look of each piece screams R&D, from the humble sock through to jackets designed in conjunction with Lamborghini.

Much of X-Bionic's focus is to do with minimising the body's wasted energy. As much as 97% of our energy expenditure is directly involved in Thermo-regulation (the regulation and maintenance of our biologically optimal operating temperature) and as such, any help we can give ourselves in avoiding excess heat loss or gain will quite obviously lead to big advantages when it comes to exercise: even a 1% energy saving will increase our potential by 25%.

It is to this end that X-Bionic have gone about developing complex, knitted fabrics that assist the body in rapidly reaching and maintaining the optimal temperature and they combine this with differing levels of compression to help stabilise muscles to avoid oscilations that lead to early fatigue and increased recovery times. Their PK-2 Energy Accumulator Summer Light warmers are no exception. The heavier weight version of the PK-2 Summer Light warmers, these will suit riders with less body fat or those that are susceptible to cold.

A freezing headwind can quickly chill your legs. The X-Bionic PK-2 Energy Accumulator Leg Warmers protect your muscles from the cold to help avoid injuries. The high-tech knit technology warms exactly where you need it since the legs lose warmth in specific areas and at differing rates. When the knee bends, a system of chambers and ducts opens out like an accordion to maintain insulation. The knitted fabric of the ExpansionRib folds apart based on the accordion principle, insuring that cold air doesn‘t cool down the knees. Even when sharply bent, the insulating effect is maintained through warm air stored closer to the skin. In contrast the knee hollow (fossa), perspires very quickly and heavily; to allow for this X-Bionic have used a fine, circular knitted fabric in this area so that perspiration dissipates and is pushed outward with the aid of body warmth but without the risk of chilling. The flexibility of the ExpansionRibs and the elasticity of the yarn allow a frictionless freedom of movement. When your body is working harder, various knitted structures distribute sweat over a large surface across the leg and a thin film of perspiration evaporates and therefore cools whilst excess sweat is immediately dispersed outwards.

Away from the joint and surrounding the muscles of the upper and lower leg,  graduated compression lends improved performance through reduced muscle oscillations, muscle and joint support and optimised nutrient supply. X-bionic's compression is almost always partial. The reason for this is that heavily compressed muscles suffer greater temperature irregularities which leads to a greater energy expenditure from the body - the antithesis of X-bionic's guiding design principle. Partial compression allows for optimal support, blood-flow and nutrient delivery without having an effect on the thermal output of the body, thus helping to maintain optimal performance. 

An additional feature of the X-bionic leg warmers is the Air-Conditioning Channel. This is effectively a system of channels that flow around the garment, continuously carrying away moisture and warmth. The nature of the design of the leg warmer means that air is able to flow to body regions not normally accessible by fresh air circulation.

In addition to all these features, the leg warmers - like the bulk of X-Bionic products - are of a seamless construction and the knitted fabric yields an impressively comfortable, low bulk warmer that never irritates and that all but disappears when on; a self adjusting cuff means that the warmer stays put. 

These leg warmers (like all the X-Bionic clothing) are only evident at the end of your ride when taking them off, when you realise that your temperature has barely fluctuated throughout the course of your training or racing, despite what the ambient temperature may have been doing.