Dream team

The battling sportswear brands are Nike and Adidas, of course, and the winner of that contest will reign supreme in the all-important Asian market. Adidas is the main sponsor of the games and it has just opened a huge flagship store in Beijing, but Nike will be ramping up its marketing push there too.

The Brits will be decked out in Adidas. So will the Chinese, although their star hurdler (and defending Olympic champion) Liu Xiang is sponsored by Nike. If he wins gold, his Nike running vest will need to be covered by one of the official podium suits, which bear the Adidas emblem. Cue much gnashing of teeth at Nike's Oregon base and cheering in Germany, where Adidas is headquartered.

The British team alone has been supplied with some 120,000 separate items of kit by the sportswear giant. When you factor in all the other national teams Adidas sponsors, as well as the army of workers who will help the Olympics run smoothly (all decked out in the famous three stripes), you start to realise how high the stakes really are.

What this tells us is that sportswear is big, big business. Not because we play more sport - quite the opposite is true in fact - but because sport and fashion have become so inter-dependent they're almost the same organism. We crave sportswear not because it makes our morning workout easier but because we think it makes us look fitter, younger, hipper.

In short, the opening of the Beijing Olympics is the ideal moment for London's Victoria and Albert Museum to be examining the links between the two entities in an exhibition called Fashion V Sport. The exhibition opens this week and draws together some 60 outfits ranging from high performance sportswear to designer collections. It also traces the development of sportswear as an emblem of youth culture and examines how the clothes are advertised, marketed and even collected. One obsessive hoarder of training shoes featured is Kish Patel, a former skateboarder who began collecting trainers in 1988 and now has over 1000 pairs. Most are size nine, all are boxed.

Mostly, the connections between fashion and sport are benign, although the V in the exhibition title is a reminder there are tensions too, as the Cameroon national football team found out when they took to the field in a Puma skin-tight all-in-one Lycra number for the 2004 African Cup of Nations. "Against the laws of the game," shrieked outraged FIFA President Sepp Blatter. Puma, equally outraged, filed a law suit against the team.

For V&A curator Ligaya Salazar, the exhibition is overdue. "I've thought for some time that the influence of sportswear on fashion, particularly men's fashion, was so powerful and important that it needed to be addressed in some way," she says.

Of course sportswear has had a place in fashion for most of the last century, so this is nothing new. Even before tennis players Fred Perry and Rene Lacoste began selling their famous polo shirts, Coco Chanel was decking out the dancers of the famous Ballets Russes in commissioned tennis gear and Jaeger was marketing clothes for both skiing and tennis. The company even made dungaree-style motoring suits "in silk of many pastel colours" and hired pioneering female racing driver Kay Petrie to model them.

Fred Perry began making professional tennis kit in the late 1940s. In partnership with an Austrian footballer named Tibby Wegner, he pioneered the use of honeycomb-weave fabrics to make cotton-pique shirts. The fabric was important - the weave kept sweat away from the body - but the look was iconic too.

Youth subcultures responded in kind, though more out of a spirit of subversion than a desire to play tennis. By the late 1960s, British skinheads and mods were wearing Fred Perry shirts and in America in the 1970s, the Lacoste polo became a staple of the so-called preppy look. A decade on, Britain's dandified football casuals embraced a whole range of sporting labels, from Adidas to Sergio Tacchini. But it was the rise of hip-hop that turned sportswear into a global phenomenon.

Rock musicians, once the drivers of street fashion, were replaced as cultural icons by sportsmen like Shaquille O'Neal and Michael Jordan, who lent his name to Nike's famous Air Jordan trainers. Meanwhile, rappers Run DMC ripped the laces out of their shoes and sang My Adidas in 1986. Two decades on, a million heads are still nodding in knowing agreement.

But what is it about sportswear that is so appealing and has given it such staying power? Functionality is one reason. The Nike windbreaker, for example, was a best seller because of the ease of movement it allowed. "Its popularisation came about through breakdancers," explains Salazar. "The material was slippery enough for them to be able to do their moves on cardboard and because that was seen as cool, other people began to wear them."

Adaptability is another reason. "Sportswear can be worn in different ways," says Salazar. "It's like a blank canvas. There's lots of things you can do to individualise it." But primarily, the appeal of sportswear is that it is comfortable.

So on the streets, sportswear continues its inexorable rise. Style tribes from Shanghai to Shoreditch mix and match vintage Adidas tracksuit tops with Nike trainers; Tokyo skatekids advertise their love of brands on T-shirts and beanies; Berlin graffiti artists don Northface zip-ups for a night on the tracks.

But if you're not a Glasgow ned, a Tokyo skatekid or a Berlin graffiti artist and you want a bit of the action, you can still wear the same gear. And if you want to take that edginess into the office, you also can, because designers who once concentrated on exclusive lines are now inking lucrative deals with sportswear manufacturers.

Stella McCartney and Yohji Yamamoto design for Adidas, Alexander McQueen creates for Puma and Kim Jones works with Umbro. This means the designer cachet that once resided in a Savile Row suit or a couture dress is now available with an Adidas label - though still at Savile Row prices, of course.

Meanwhile, the same luxury brands that employ such designers are busy recruiting footballers and athletes to peddle their wares. So a buff and bronzed David Beckham models Armani pants, Thierry Henry designs a collection for Tommy Hilfiger, his former Arsenal team mate Freddy Ljungberg strips to his Calvins, and five rugged Italian internationals pose in their smalls to promote Dolce and Gabbana's Intimo range of underwear.

Reflecting on the Dolce & Gabbana campaign, cultural commentator Mark Simpson noted that to grab our attention these days, "the sporting male body has to promise us nothing less than an immaculately groomed, waxed and pumped group session in the showers". Not for nothing has this sub-genre of advertising been christened Sporno.Meanwhile, Italian Vogue can quite happily stick models on bikes for a spread called "Variations on Sport", and Yohji Yamamoto can send models down the catwalk holding footballs and wearing shinguards marked Y-3 - the label he created for Adidas.

And as sport and fashion continue their sexy tango, the fabrics developed for the first will continue to leach into the second. "Fabrics and yarns used in sportswear have become readily available and affordable and people have started to incorporate them into fashionable garments," says Salazar.

So will we all be wearing Calvin Klein Fastskin Y-fronts in a couple of years' time? Having just struggled to get a mannequin into a swimsuit made of the stuff, Salazar thinks not. "But certainly there is a trend towards using more functional fabrics that have resulted from sportswear innovation," she says.

This isn't necessarily bad news for makers of more traditional fabrics either. Hip fashion label Visvim is now taking handwoven Harris Tweed jackets and laminating them with Gore-tex to make high-end fashion items. The V&A exhibition even features a cycling jacket based on a 1930s design but made of Harris Tweed and something called Lumitwill.

The invention of designer Guy Hills, Lumitwill made its debut last year at Pret a Rouler, a fashion show dedicated to cycling apparel. Also showing clothes there was London design team Vexed Generation, whose bullet and knife-proof parka features in Fashion V Sport. It's basically a black hoodie sculpted from neoprene, and was intended as an update on the famous Norfolk jacket so beloved of Highland gamekeepers. In fact it looks like something Christian Bale would wear in the Batman films - or, if they came in white, a fencer at the Beijing Olympics.

It's only a matter of days now until the Games finally open. The athletes will be primed but, come the time, they will also be primped, resplendent in ClimaCool gear made from Formotion compression fabrics, or sleek in their Fastskin all-in-one swimming suits. And we, the watching public, will feast on it all, returning to our lives when it's over with our enthusiasm for sportswear redoubled. That all they offer is the illusion of speed without the need for acceleration is unimportant; what does matter is that sport is, and will for some time remain, the new black.

Fashion V Sport is at the Victoria and Albert Museum, London, from August 5 to January 9, 2009. The Beijing Olympics opens on Friday.