When you pin on that number, when you enter the appropriate corral, when you cross the starting line, no matter how your training has been over the months leading up to the marathon, you never really know how the morning will unfold, and such was the case on July 27th of this year when I ran the San Francisco Marathon. I ended up with what I call my broken arm PR. I finished my race, but it really wasn’t a big deal. It was just a broken arm.