This earlier post noted development of research indicating that long distance running over a long term may be hazardous to your health.
Thus, this article from earlier in the week about arguably the greatest American marathoner caught my eye:

Alberto Salazar, the former champion marathoner who collapsed over the weekend, had his condition upgraded Monday from serious to fair.
A cardiologist at Providence St. Vincent Medical Center said tests now indicate that Salazar had a heart attack while coaching distance runners Saturday at the Nike campus outside Portland, said Lisa Helderop, a hospital spokeswoman.
Salazar, who is alert and talking with his family, told a doctor at the hospital that he has a family history of heart conditions, Helderop said. [. . .]
Salazar, a University of Oregon graduate, won the New York City Marathon three straight years (1980-82) and the 1982 Boston Marathon. He has set six U.S. records and one world record. He is a longtime Nike employee and consultant who trains elite distance runners and has a building named for him on campus.

This recent University of Maryland Medical Center study addresses another health risk of long-distance running. And none of the foregoing even touches on the heightened risk of joint and ligament damage that results from long distance running. Take note, runners.