The New York Times takes a look at the people who start but do not finish the New York City Marathon, about 2% of the field. Remarkably, the fastest runners take up a disproportionate amount of DNFs, with a possible explanation:
For elites who run just half a race, they not only reduce the chance of injury, but could be in top shape to compete again within weeks. Some elite runners are paid appearance fees, and receive a paycheck even if they do not finish. Recreational runners have no such consolation.
The analysis was also extended to international runners:
Among runners who may feel extra pressure to finish, Wittenberg said, are those who traveled from overseas, investing more time and money to get to the starting line. Runners from other countries compose about 60 percent of the field, but they made up only 50 percent of those who did not finish.
Seven runners needed twice as long to run the second half of the marathon as they did the first half, a measure that goes beyond “hitting the wall.” All were from Europe.
The article also takes a look at another demographic, age:
Another group that concerns Wittenberg is men in their 20s with some athletic success, because they may be more likely to undertrain.
Marathon split times from last year’s race show that among United States men, those in their 20s were more likely than older men to post a second-half time that was far worse than their first half. About 2.4 percent of the younger men posted second-half times that were at least 50 percent longer than their first-half times. For the older United States men, the proportion fell to 1.6 percent.