Ryan Hall, one of the few Americans who can compete against the best international distance runners, is going to try to win the Chicago Marathon on Sunday. And he is doing it without a coach, which is almost unheard of in elite distance running, or elite sports for that matter.

Hall makes his own training schedule, assesses his own progress, and runs alone almost all of the time. He has been doing it for a year now, and when he ran the Boston Marathon in April, he came in fourth in 2 hours 4 minutes 58 seconds, the only American in the top 15. He cut nearly four minutes from his 2010 time.

It raises the question: At the elite level, are coaches really necessary? What does an athlete miss when he decides to go it alone?

There are not many examples to go by. Frank Shorter, who won the marathon at the 1972 Olympics, was self-coached. Joan Benoit Samuelson, an Olympic gold medalist in 1984 who still races and set the American marathon record for women over age 50, said that while she has worked with coaches, often at a distance, she has pretty much coached herself for almost her entire career.