More than 500,000 people finished at least one U.S. marathon in 2015, the last year for which the group Running USA has released its annual report. Almost half of those runners were at least 40 years old, a record high percentage. Anyone can run a marathon, says exercise physiologist Susan Paul, but beginning runners should take it slowly — injuries are common among novices and experts alike. Here & Now‘s Jeremy Hobson talks with Paul, training program director and coach at Track Shack (@trackshack) in Orlando, about how newcomers can prepare for their first marathon. Copyright 2017 NPR. To see more, visit http://www.npr.org/.