PUBLISHED 10/27/2004
When David Nieman, Ph.D., taught a running class at a small California college 25 years ago, he wasn't surprised that several students caught colds and the flu after their final exam, which was running a marathon. After all, the same thing had been happening to him--usually sore throats that struck after marathons or long runs, especially in the winter and spring.
Running is supposed to make you healthy, so why were so many runners getting sick? Nieman, who is now director of the Appalachian State University Human Performance Lab, has spent the past 20 years leading scores of research projects to find out.
First the good news: "People who exercise contract only one-quarter to one-half as many upper-respiratory illnesses as people who don't," says Nieman. "Regular, moderate exercise like running produces positive changes in the immune system that help you avoid these illnesses." Nieman's research has found that running or cross-training for 30 to 90 minutes a day, several days a week, increases the circulation of immune cells, which enhance the surveillance activity against germs and destroy viruses.
Yet the research has also uncovered the flip side of the running/runny-nose connection--and the reason why Nieman and his students caught so many postmarathon colds. Long runs, the crux of any marathon or half-marathon training program, make you more susceptible to every germ your colleagues bring to work and your kids carry home from school. Nieman's surveys of hundreds of Los Angeles Marathon and Western States 100-Mile finishers have found that an unusually high percentage of them got sick in the two weeks after those races: one in seven runners after L.A., one in four after Western States.
