City marathons are a tricky business for organisers, having to be competitive for professionals, a challenge for amateurs and enjoyable for fun runners. All the while, they have to be safe, with education programmes and training months before the race and medical help close at hand throughout for every person taking part. This year's record-breaking Standard Chartered Marathon ticked all those boxes, if the reactions of the finishers and also-rans are any guide. But one runner's death and the taking to hospital of 38 others, two in critical condition, clouded what would otherwise have been considered a resounding success.

Why the 26-year-old man, a participant in the half marathon, died, is not yet known. But all manner of ailments can affect runners during marathons, billed as the ultimate test of mental and physical fitness. Exhaustion and dehydration are the most common, although stress to heart and lungs and even drinking too much water can cause problems. As a result, deaths are not unheard of, although rare; a man died a day after collapsing during the 2006 race and among the dozens of marathons elsewhere each year, sporadic incidents occur.

Amateurs run marathons for a host of reasons, but a frequently-heard explanation is for better health. Sunday's death gives prospective participants pause for thought. Studies of the health effects of long-distance races do not point to them being riskier than other forms of strenuous exercise. With tens of thousands of runners, organising committee chairman William Ko Wai-lam's rejection of suggestions that medical approval be needed in future is justified.