Of the 25,000 starters, a large proportion will be ill-prepared for this, their ultimate test of endurance. Many will recognise that and be cautious; others will get carried away with the occasion early on, and by the St John's Ambulance Brigade at some later stage. McColgan claimed last week that an awkward footfall in Tokyo left her carrying an injury for the second half of the race. This is a different, more specific form of complaint than the agony of a marathon as conventionally portrayed by the press and experienced by the masses. At the post- race press conference in Tokyo McColgan merely complained of feeling 'tired in the legs'. Now that sounds more like it. After 15 miles she started to slow, and after 22 miles more dramatically so. This is the syndrome that we all recognise: 'tired in the legs' is the least dramatic label for it, 'hitting the wall' the most.
Eleven years ago, when I won the London Marathon, an irritatingly chirpy Bob Wilson was busy interviewing people on the run further down the field. One of the Blue Peter presenters, looking genuinely disorientated, confessed: 'I hit the wall at 18 miles - but in my case it was the floor.' There were other scenes: people crawling over Westminster Bridge on all fours; people propped up between sympathetic fellow runners, legs dragging limply along.
It is this complete loss of energy, motivation and co-ordination that constitutes 'hitting the wall' and which would certainly feel worse for Liz McColgan than the tired legs of which she complained. Fortunately she is unlikely to face such a fate. Training at levels of up to 120 miles per week, allows elite athletes to prepare their bodies for the shock of running out of readily available energy, and draw from other sources in a way not open to the unprepared marathon adventurer. There are proportionately fewer of those around now than a decade ago. The numbers 'bulge' in the finishing chutes on Westminster Bridge now occurs markedly earlier, as overall performance levels have improved, than it did in the early editions of the race.
The agony of the marathon does not always occur in such dramatic forms as on-course injury or the infamous wall. Under more common and predictable circumstances agony reduces to pain or even mere discomfort under the effort of producing peak performances. For some, the peak of performance is simply the completion of the course, in any time. For others it will be a win in under 2 hours 10 minutes. Who suffers more in achieving either of these aims?
Ron Hill, who was Commonwealth and European marathon champion 20 years ago, more recently ran a race in around four hours, and claimed that it felt like harder work. The laws of physics might indicate otherwise. In today's NutraSweet London Marathon, 25,000 people will each transport their own bodyweight 26 miles and 385 yards. For people of the same weight, the same amount of work is done. Alan Storey, general manager of the London Marathon and a longtime national marathon coach, elaborates for the pedants: 'The faster you run, the more wind resistance you face. You also run less efficiently because there is greater vertical movement of the body in the course of each stride. The 2:10 marathon runner is doing slightly more work than the four-hour runner.' Rob De Castella, the former Commonwealth and World champion who runs his last serious marathon in London today, puts the point more poetically: 'being competitive in the last 10 kilometres (of a marathon) shows what there is in your core, what fighting spirit you have. You reach down and find out what is left inside you.'
When every fibre in your body is screaming at you to slow down or stop, the mind has to override all else. Elite marathon runners train themselves to do this, holding the braking mechanism at bay through a concentration of the will, but they do not have to train themselves to do it for periods as long as four hours. The mental effort required by four-hour runners may be less intense, but like the physical effort, it has to be sustained for longer. This all supposes the runners are straining to do their utmost, but some will allow themselves a bigger margin of comfort than others. Those carrying large charitable investments in their stride will probably be most cautious.
But these same runners may be carrying other things as well. The year I won, the pantomime horse costume was the most impressive and cumbersome. This year, the man who will have the biggest burden to carry will be the one sporting a rhinoceros outfit.
When the rhinoceros hits the wall, I know that nothing can feel worse than that.