Q: Is it true that courses are often longer than the distance advertised? Typically when I run road races, my GPS always says the course is a little longer than I anticipated. Why is that?
This question is one that has frustrated and plagued both runners and race directors since the invention of the GPS watch. Every year I can bank on responding to emails and social media posts in the days after the ODDyssey Half Marathon from runners who ask this very question.
For the most part it is
true that courses are longer than the distance advertised. But,
that most runners run further than the distance advertised.
There are two main factors that cause this issue. The first is the measuring requirements of USA Track and Field for certification. If you are running a certified race, an expert has been hired to measure that course to the inch. The expert measures the course multiple times in creating their certification. So, to the greatest extent that a human can measure, the course is accurate.
But, when the course is measured it is required to be measured in the absolute shortest way that one person could run the course without leaving it. So, every single turn must be measured as if you turned within inches of the curb. Every curve is followed by the shortest line. In reality, no runner actually follows that exact course and every wide turn you take adds distance to your run.
The second reason is the GPS itself measures your path through every diversion you take. So, each time you loop around a runner or a pothole, each time you pull over to tie your shoe or visit a port-a-potty, GPS measures the distance you travel. It even measures your shuffling in line for the port-a-potty. It doesn't seem like a lot, but all of those little steps to the side add up.
When I ran the New York City Marathon, my GPS unit recorded that I ran almost two miles further than a marathon. I found it discouraging and I have not run a big race with my GPS since. I definitely understand how it feels. But, most likely the course is accurate.