By Sarah Edmonds
LONDON (Reuters) - A generation remembers the day in 1976 when Nadia Comaneci scored the first-ever 10 in gymnastics, breaking Olympic scoreboards not calibrated to handle perfection.
Now the sport of dressage, essentially the equine equivalent of the gymnastics floor exercise, is seeing a similar grading revolution after decades where judges viewed 80 percent as an insurmountable barrier.
And it is entirely possible the London Olympics could witness the toppling of yet more records when the multi-phase dressage contest gets underway on Thursday.
"It's absolutely correct that the top marks have gone up. We have seen new world records coming in a string," said Trond Asmyr, Director of Dressage and Para-equestrian Dressage at the Federation Equestre Internationale, the sport's governing body.
Nor, he says, are the rising marks the result of inflation.
"We have a fantastic breed of good horses. We have never, ever had the level of horses we have today. It's amazing."
Riding, training and horse management have also improved to unprecedented levels, he said.
Two horses - Germany's Totilas and Great Britain's Valegro - have set new records in the past three years and some in the equestrian world say with the quality young horses now climbing the ranks, this is only the beginning.
Between them, Totilas and Valegro have earned record scores in each of the three top-level dressage tests - the grand prix, the more difficult grand prix special and the freestyle, which is set to music and not pre-set like the other two.
Totilas, knocked out of the London Games by rider Matthias Rath's glandular fever, earned a record 84.09 percent grand prix score in August 2009 and 92.30 percent - the first mark above 90 percent - in the freestyle four months later.
In dressage, judges seated at various points around the arena rate each movement - such as the halt, the extended canter, the difficult on-the-spot trot called the piaffe - out of 10. These scores are then collated to produce a percentage.
In dressage, 10 means excellent, not perfect.
Charlotte Dujardin of Britain only started riding at the top level of international dressage last year, but she and Valegro immediately landed in the record books with the highest-ever grand prix debut score of 74 percent.
In April this year, they posted the highest-ever mark in a grand prix special of 88.02 percent.
Carl Hester, mentor and teammate of the record-breaking Dujardin is delighted at the bursting of the 80 percent dam.
"It was almost like you couldn't use 10, you just didn't dare use 10. Now the judges can be persuaded to give 10. What could be better?" he said. "I'm all for it."
Valegro, he said, deserved his lofty grades.
"The horse has not yet had a flaw or shown anything that we could say wasn't going to make him a champion," he said, adding that Dujardin's incredible focus and determination is also key.
"She'd climb over her mother to win this thing," he said with a grin. "She would. She's that determined."
Catherine Austen, Olympics correspondent for Horse and Hound magazine, agreed that horses and riders had improved immeasurably.
"In British dressage ten years ago, if you got 65 percent, you were a national hero. And now suddenly we have broken all barriers," she said.
"I think it's addictive and also catching, like a cold. Once a judge is brave enough to start awarding nines and 10s, then everyone gets brave enough as well."
With Totilas out of the Games, London will be deprived of a showdown between the two great horses - a battle of beauty Hester thinks Valegro, nicknamed Blueberry, would win.
But even without Totilas, Asmyr thinks these Olympics are likely to produce some impressive scores.
And with a new format that has cut team sizes to three and made all scores count, there are likely to be some gasp-inducing moments over the four days of competition.
"I think we will see a number of performances both in the grand prix and the grand prix special above 80 percent," Asmyr said. "I would be happy and not surprised if we had at least one result above 90 percent in the freestyle."
He smilingly declined to say which horse he saw hitting that high watermark.
The four days run like this:
Over the course of Thursday and Friday, all 50 horse-rider pairs will perform a grand prix test.
The top seven teams and the top 11 individual riders after the grand prix go through to the grand prix special on August 7. This decides the team medals.
The grand prix special also serves as a qualifier for the August 9 freestyle where the leading 18 horse-rider pairings - a maximum of three per country - contend for individual Olympic glory.
(Editing by Nigel Hunt)