Marathon

A road race of 42.195 kilometres, the longest championship event. It is run on measured city courses, and the course matters: a flat route and cool weather can be worth minutes. A mark counts for records only on a certified course where the overall drop is at most one metre per kilometre and the start and finish are no more than half the distance apart. Times are recorded to the second. The best runners cover the first half close to their half-marathon pace; what happens after 32 kilometres, when the glycogen runs low, decides the race, and it is the reason a marathon debut is so hard to predict from track times.