heidi bretscher 's troubles began around mile 17 of the rock n ' roll raleigh marathon .
the 28-year-old runner was so far ahead of the pack it was n't clear to her which way she was meant to go .
after working out her timings and distances she still managed to cross the line well ahead of her closest rival .
before the mishap , bretscher said she was on pace to run her best time ever .