breaking from gates - run out

Question
hello sir, when horses break from the gates, few horses which are in the last stall run onto the outer rail and finish the course with difficulty not positioned in the bunch. may i know why?

Answer
HI -- EVERY HORSE RUNS A DIFFERENT RACE . SOME ARE NOT HAPPY TO HAVE THE OUTSIDE POST AND WILL SOMETIMES RUN OUT BECAUSE THEY ARE OUT THERE WITH NO OTHER HORSES TO HOLD THEM IN DURING THE RACE.SOME HORSES HAVE TOO MUCH SPEED AND GO WIDE WHEN THEY CANNOT CHANGE LEADS AT THE RIGHT TIME. THANKS Ed Hess