Pampered Japanese youth are losing interest in sumo because of the years of rigorous training, writes David McNeill from Tokyo. But foreigners are failing to draw the crowds.

To the uninitiated it may look like fat men in giant nappies horsing around in a tiny ring, but in Japan sumo is a serious business, as big a part of popular culture as hurling or football in Ireland, but many now say the sport is in crisis.

Ticket sales are down, audiences are opting for sexier fare and, with fewer young Japanese men opting to put themselves through what it takes to be a champion, sumo is now, for the first time, dominated by foreigners.

Hawaiian-born Musashimaru and the fiery Mongolian Asashoryu hold the top two rankings, following the recent retirement of the hugely popular Yokozuna (grand champion), Takanohana, part of a trend that has seen the number of non-Japanese sumo professionals treble in the last three years.

It is as though the ranks of Irish hurling were suddenly swelled with Germans, French and British.

The empty auditorium seats at the recent Summer Grand Sumo Tournament, where Asashoryu stormed his way to his first Emperor's Cup as champion, hinted at what the Japanese public thinks of this foreign invasion. With little home-grown talent to support, many are staying home.

"The biggest draws of past sumo contests were bouts between home favorites like Takanohana and foreign-born wrestlers like the Hawaiian Akebono," says Mark Schilling, who comperes sumo for Japan's state broadcaster NHK.

Akebono played the role of the bad guy, and the place fell silent if he won. But now there is no one to root for. It's getting to the point where people are asking, "can we let non-Japanese dominate the sport?".The main problem, observers say, is that too few native Japanese are willing to grind through years of gruelling training in the hierarchical world of sumo stables.

Japanese kids today are bred on luxury, says Clyde Newton, editor of Sumo World magazine. "Foreign athletes are hungrier for success. The average monthly income in Japan is something like $3,500. In Mongolia it's about $55. Other more gradual changes have also taken their toll on the sport."

Weighing in at an average of 350 lb, wrestlers are bigger than ever, even as the ring has stayed about 15 feet across, meaning many are landing more heavily and sustaining serious injuries, further reducing the dwindling ranks.

Faced with this shrinking pool of local talent, the sumo bosses are reluctantly opening up the sport to men from Korea and Mongolia. This too, however, brings problems.

The beefy legs of the country's 700-odd professional wrestlers support a sport marinated in centuries of tradition and culture. Those who grunt their way to the top are showered with money, fame and the sort of adulation doled out to rock stars.

In return, they must strive to live up to the sport's exalted standards of decorum and dignity, collectively know as hinkaku, overseen by the GAA-like traditionalists in the Japan Sumo Association. Foreign wrestlers often struggle to grasp these deep-rooted concepts, and some never do.

Current champion Asashoryu, for example, has enraged the sport's hardcore followers with his loutish antics inside and outside the ring.

Japan's racy weeklies hum with stories of the 22-year-old wrestler's cursing, womanising and cruelty toward junior wrestlers. One alleged that he delights in firing air gun pellets at the buttocks of young trainees, another that he tried to buy the services of a young hostess with his sumo winnings. More seriously, Asashoryu was seen in the summer tournament on nationwide TV angrily disputing a decision by a head judge, an outrageous transgression of sumo rules.

"In Mongolia, having a fiery temper is considered manly," says Schilling. "You're not expected to hide your feelings like you are in Japan. But here, stuff like that will get him in trouble."

Most fans hope the champion will calm down and learn to play by the rules, like other foreign wrestlers before him. In the meantime, some are suggesting that the sport hitch its wagon to his bad-boy antics to improve its ratings.

"There are no stars in wrestling now, that's the problem," says veteran sumo commentator Mark Schreiber. "At least Asashoryu is a star."Schreiber is one of those who believe the foreign sumo invasion is not a bad thing. "It's a godsend to the sport," he says. "It will drag it into the 21st century." Many like-minded folk see it as welcome evidence that the popularity of sumo is growing abroad, offering hope for chunky men with few career prospects everywhere. The next stage, they say, is to make sumo an Olympic sport.

Before that can happen though, the modernists must wage one more battle with the traditionalists. The International Olympic Committee is unlikely to admit a sport that bans women from the dohyo (ring) because their menstrual blood might upset the Shinto gods.

With the fair sex thus holding the deciding vote on whether sumo goes international or stays local, the grey men in the sumo association have reluctantly risked civil war with purists by allowing women to enter the amateur ranks.

"It's a male-dominated sport in a closed, male-dominated society, but it has to change,"says Steve Pateman, president of the British Sumo Federation, who has no doubts that sumo will one day be on the Olympic roster. He says Britain now has 50 sumo wrestlers, including one woman.

Little interest yet from Ireland however, despite the ever-expanding Irish gut. "You need a big heart more than a big stomach," adds Pateman, "and most of the big-hearted guys seem to go into rugby in Ireland."

Training: rigorous regime of eating and sleeping

Calling sumo wrestlers big is a bit like saying Ireland is a bit showery - it doesn't quite do them justice. Current champion Asashoryu weighs in at a relatively svelte 305lbs, but ex-champion Akebono was an intimidating 488lbs before his knees gave out, and the biggest of them all Konishiki was a quivering 624lbs.

Getting this fat might sound about as difficult as sinking that sixth pint of stout, but it takes hard work. Young trainees in about 50 stables around Japan rise at dawn, clean up after the older wrestlers, work like pack horses and stick to a diet centred on a high-calorie stew of seaweed stock, chicken, fish, prawns, tofu and vegetables.

If it weren't for the huge quantities consumed, the regime might be considered healthy, but the fighters also take long naps after meals to slow the metabolism and put on weight. Together with the many gallons of beer they drink, the diet gives wrestlers the characteristic sumo bulk around the belly, buttocks and legs, making them harder to knock down. But it also means they pay later in life with buckled knees, aching backs and perforated livers, with the only comfort being marriage to a Japanese supermodel.