Two things: first, he took it extremely easy for a month following Houston; second, he has never gotten hurt from marathon training.
Graeme McDowell wrote:
Running Chicago is a good financial decision for Ritz but after the year he has had you have to wonder if it's the smartest decision for his health. He has to be fried...trials Marathon in January...all the track races including 3 all out 10,000's and then Chicago in October. Seems like a lot within 10 months.