Yes, they had to get themselves up a structure which resembled a nightmare trompe- l'oeil - upside-down steps which defied the very idea of ascent. And, yes, they had to pause regularly to shake their arms and legs back to life. But they were able to do so to the emollient, atmospheric strains of Enya. Some consolation.
A crowd of around 4,000 gathered at one end of the arena as if watching a snooker championship, with a hush of concentration, broken periodically as the spectators, many of them climbers themselves, showed their appreciation of a particularly bold or brave manoeuvre on the part of the human fly before them.
The wall, 18 tonnes of lunar landscape resin, loomed back and over each climber as they stepped forward to address it. It entailed a long approach climb of around 12 metres, six metres of horizontal roof and a final pull round a lip to finish with a 30-degree overhanging section.
Once they began their ginger progress, stopping regularly to grab handfuls of gymnasts' chalk from the bags which dangle from their belts, the competitors had quarter of an hour to complete their work. The handholds - some large, some tiny - were bolted along a route decided by an official from the Swiss-based international alpine climbing body, the UIAA.
And, excruciatingly, the competitors had just six minutes to study their latest challenge before climbing. They stood like tourists on the spotlit stage, viewing the routes with binoculars, reaching out their arms to perform imaginary manoeuvres 30 feet above their heads, before being shooed off the stage.
It is this constant variation, allied to the mind-defying task of operating in an upside-down world, that moved one professional sports psychologist, David Gilbourne, to declare: "This sport was developed by total sadists. It is one of the worst sports in the world that I have seen from a competitors' psychological perspective."
Ian Vickers, the 21-year-old British champion, clearly has a psyche that is as fit as his body. A minute after dropping from the wall face on his rope, having been unable to work out a route along the wicked, pockmarked ceiling that forms the central section of the climb, he lolled against a wall and slid back into his trainers.
Despite strenuous physical efforts that had raised the audience to murmurs of approval and bursts of support, he looked no more tired than if he had lost a chess match.
Pale and bespectacled, with tousled fair hair, Vickers faintly resembles a schoolboy playing hookey. Supported partly by his parents, with whom he still lives in Darwen, Lancashire, and sponsorship by equipment companies Petzl and Beal, he ... does his own thing. "I have a car and I drive around," he said. "I just kind of like to go climbing a lot."
Vickers finished seventh in a men's final - the third of four in the overall competition - which earned the winner Francois Petit, of France, pounds 3,000. Not towering money, but more than anyone can earn on real rock faces, where competition is now banned on environmental grounds. The women's title went to the American world champion, Robyn Erbesfield, who at 5ft 1in is considerably shorter than most of her rivals, but whose thin arms and legs clearly have a tenacity of almost superhuman proportion.
Since the National Indoor Arena first put on an event of this kind four years ago, a new commercial climbing centre has opened in the city and there are plans for 47 such centres to open around the country in the next year. Enya must be delighted.