AS the first three under-21s in the World Irish Dancing Championships take up their starting positions a hush falls in Glasgow's Royal Concert Hall auditorium. Even from far back in the stalls their almost fluorescent, bejewelled dresses are unnervingly dazzling, their legs are stained a colour that could only come from a bottle and their curly wigs in unnatural colours of white blonde, glossy black, and bright auburn – often topped with a tiara – bounce as they cross the stage.

But as the keyboard and accordion play the opening bars they point their toes in readiness and leap impressively into action. They pirouette, high kick, and perform intricate scissor steps, springing high in the air – fine-turned leg muscles straining – with their arms firmly at theirs sides and as fixed as their smiles. It looks almost effortless but as the dancers move back to their positions and wait while the silent judges mark down their comments their chests are heaving.

This event in Glasgow, say organisers An Coimisiún le Rincí Gaelacha (the Irish Dance Commission), is the Irish dance Olympics. More than 5,000 competitors, aged from eight to 30, are attending this 48th championships from more than 20 countries, including Ireland, England, France, Russia, South Africa, Argentina, Brazil, Japan, Australia and the USA. Is has been running since March 24 and the final champions will be crowned later today. Most, particularly in the older age categories, will have been training for hours every day in preparation, supplementing dance practice with intensive fitness training.

Glasgow was the first city to stage the World Irish Dancing Championships outside Ireland in 2002 and this is the fifth time it has played host, leaving Glaswegians regularly puzzled by the incongruous sight of troops of little girls in full make-up, fake eyelashes and panto-style wigs sauntering in broad daylight through the dreich city-centre streets.

Claire Dolan, 20, who is studying Maths at Newcastle University, understands it might look strange to outsiders, but claims that it's about creating a different world, an escape from the every day. "It's completely different from my normal life," she says. "I'm not exactly going to Maths lectures wearing the wig. It's about putting on a performance."

It's her sixth World Championships and she's still breathing hard having just come off stage in the under-21s solo category. "I'd love to get a recall," she says, her eyes shining at the thought. "The standard is so high. If you get one [a recall] you are amongst the best one percent of Irish dancers in the world.

"It's far tougher than a lot of people think it is. I've been training 15-16 hours a week and it's not just about dancing. I have a personal trainer, I do swimming. It's a real commitment. But I just love it. It gives you fitness, friendship and travel all in one."

McKenzie Weller, also 20 from Colorado, is wearing a black and gold crystal encrusted dress and jewel-studded black wig which altogether cost about $3,000, including international shipping. She says:"My brothers and I saw Lord of the Dance on a TV and said 'we want to do that'." Her mother found a dance class and she "fell in love" with Irish dancing. "I'm really bad at every other sport," she said, showing off some of her steps. "But Irish dancing is something I'm passionate about."

Glasgow-based teacher and adjudicator Kathleen McLaughlin, who has 60 pupils competing says Irish dancing has transformed over the decades. When she started teaching more than 20 years ago many of her pupils had a connection to Ireland and were attending in an attempt to keep links with their culture and heritage. "Now it attracts people with no connection to Ireland at all," she says. "The world of beauty pageants has changed it but the costumes can't camouflage someone who can't dance. Some of the parents will go over-the-top but the girls do feel glamorous. They are going out on to a huge stage with lights. It gives them confidence.

She says standards here in Glasgow are sky high. "Most will be going to classes at least three or four times a week and if you're not prepared to dance every day of your life you're not going to make it here. Judges are looking for extraordinarily beautiful footwork, an easy carriage, strength, grace...and a natural gift." That is something you can't get from a bottle.