Alongside the Olympic torches on display at Team GB's swish headquarters in central London – one for each competition since 1936 – there is a caption that describes how the average British athlete at the London 2012 Games will have rowed 40,000km, lifted 10 million kilos and eaten nine million calories "to win by a margin of less than one second (hopefully)".
It is that "hopefully" that wrings the heart. After years of punishing training, how appallingly slender is the margin between success and failure. Winning may be hard, but losing is harder.
Dr Ian McCurdie, medical overlord for Team GB, is responsible for ensuring "every athlete gets to the start line able to perform at their best". Some may wonder why elite athletes need dedicated doctors – there will be 17 in the Olympic Village for the British team of 550 athletes and 300 support staff.
But when you think about that slender margin, how much pain and effort has gone into reaching it, how much hangs on achieving it and how much damage might be caused by overdoing it (or falling short), it is not hard to see why medical support is essential. There are threats from every direction – injury, infection, drugs, sex ... fear.
"To perform at the top level you have to train at the edge of injury. There is always the potential to tip over and get into trouble. And some do have to pull out because they can't get over an injury in time," he says.
The worst pain is losing before the race has begun. At the Sydney Olympics in 2000, McCurdie's first as a medic with the British team, he had to look after a rower who had spent "most of his life" preparing for the competition.
"Ten days before the Games began, he tripped and broke his wrist in training on the Gold Coast. It was a freak accident, causing an injury from which there was no possibility of recovery. His family had travelled from England to watch him. They all had to go home."
Sports science has advanced enormously in the past dozen years, and while a broken wrist cannot be fixed in a week, new techniques to speed injury repair are constantly being tried. McCurdie had just returned from Biarritz where research is under way on the use of a cryotherapy chamber to aid healing. "You strip to your shorts and stand inside for two minutes in a temperature of minus 150 degrees. The Welsh rugby team have used it but there is not much evidence that it works."
What does work is the basic stuff, starting with good hygiene. A simple cold could shatter an athlete's chances. In reception at Team GB's headquarters, there are a couple of canisters of hand foam on each table and a notice, "Germs cost medals".
McCurdie created waves a few weeks ago when he said at a press conference that athletes should be careful about shaking hands, because that was the way germs are passed on. The story made headlines next day – "I was on the front page of Metro!" – when it was interpreted as the stand-off English taking health and safety to extremes.
A chastened McCurdie was astonished at the way his message had been presented. The point he was trying to make, he says, was that with the Games being held in London, the "opportunities for interaction" by the home team would be much greater than if they were abroad where they would be living inside a "security bubble".
But he admits now the outcome served his purpose. "It was the best way of getting my message across. To get a bug because you couldn't be bothered to wash your hands is dreadful."
After bugs, there is the threat from drugs. Doping is a major concern for all Olympic medics – both deliberate and inadvertent.
Testing is "massive" compared with what it used to be, he says. All athletes have to inform the authorities where they will be for one hour each day so they can be contacted for random testing. Every member of Team GB will be tested before they go to the Games.
But inadvertent doping is also a risk. He describes the case of Alain Baxter, a Scot who became the first Briton to win a medal in Alpine skiing at the 2002 Winter Olympics in Salt Lake City.
Baxter had developed a stuffy nose before the race and was using a Vick's inhaler from the British team's medical supplies. When he left his hotel room he forgot to take the inhaler, so he bought another from a pharmacy. A few days after the race his drug test came back positive and he was stripped of his medal. It turned out that the US version of the inhaler contained a banned substance not found in the UK version.
Now 52, McCurdie became chief medical officer for the British Olympic Association in 2008 after a career as an army doctor, before becoming a consultant in rehabilitation medicine. "I was halfway through my medical training when I wondered why I wanted to be a doctor. All they did was walk up and down hospital wards."
Today he divides his time between looking after Olympic athletes, dancers at the Royal Ballet School and tennis players at Wimbledon. He expects Team GB to excel at the London Games – any sport does better in front of a home crowd. But there can be a downside if competitors are made more anxious.
When the cyclist Victoria Pendleton won gold in Beijing she did not express delight but relief – "Thank goodness I did what was expected." The weight of expectation could be worse in London. There is also the risk that an enthusiastic home crowd could give an athlete such a boost it disrupts their planning and harms their performance. He cites an example of a cyclist so fired up at the starting gun that he went off too fast.
By the time the Games are over, there will be bruised limbs and bruised egos. But none perhaps to compare with Sarah Stevenson, World taekwondo champion, competing in her fourth Olympics. In Sydney, when she was just 17, she narrowly missed out on a medal. Four years later, she was narrowly beaten again in Athens. In Beijing in 2008 she was fighting a Chinese athlete who was the favourite for gold when she got in a head kick that should have made her the winner. But the judges "didn't see it" and gave the match to her rival. The decision provoked uproar and was later reversed. Stevenson finally mounted the podium to take the bronze medal, but needed crutches to get there.
"The psychological highs and lows she went through are incredible. That medal was earned over 12 years – she could barely walk," said McCurdie.
In six weeks, Stevenson will be going for gold again – and it is McCurdie's job to see she is in peak condition.