Flanagan has competed at the Boston Marathon three times. Her best finish occurred at the 2013 race when she finished fourth overall in 2:27:08. She recorded the fastest time ever run by an American woman on the Boston course when she ran 2:22:02 for fifth-place in 2014.
Her injury follows a successful 2016 which included a third-place finish at the U.S. Olympic Marathon Trials and a sixth-place finish in the Olympic Games. Flanagan led fellow Team USA Olympians Desi Linden (7th) and Amy Cragg (9th) to top nine finishes in the marathon, which combined to mark the country's best team-wide finish in the event.
"I have shed a lot of tears this past week. I'm injured and have to withdraw from my hometown race, my favorite race, the race that means the most to me, The Boston marathon," Flanagan said in an Instagram post, below. "I fractured a bone in my low back training through a stretch of snowy weather in Portland, OR. I'm heartbroken that I will not get the opportunity to test myself against the greatest runners on the planet."