It’s happened at least once to everyone who trains with a GPS watch. You spend months refining your pace to the exact second per mile. You run a virtual race almost every week against your GPS to drill that exact pace into your body. You line up for the race primed to run an exact PR, and then your GPS signals that you’ve completed the race in your exact goal time. YES! But, wait.
There’s a problem. You haven’t crossed the finish line yet and odds are good you can’t even see it. By the time you do cross the finish, your GPS is telling you that you’ve run the race distance plus a quarter-mile or so and your exact PR is history. You’re annoyed, angry, and wondering how on earth your GPS and/or the course could be so very wrong.
The good news? There’s absolutely nothing wrong with your GPS. The bad news? There wasn’t anything wrong with the course, either, assuming that it was a certified course. The problem was with the specific route that you took through the course. You may have been weaving back and forth to avoid other runners, but most likely you didn’t run the tangents around the corners. It’s a small thing, but over the course of a race (especially a longer-distance race like a marathon) it can add up to a significant chunk of distance. In this article we’ll take a look at how race courses are certified, what these “tangents” are, and how you can use that to your advantage in your next race.
How Race Courses Are Certified
In order for a road race course to be certified by USA Track & Field (the governing body of American competitive running), it must be measured or validated by someone specially trained in measuring road courses. When a course has been certified by USATF, it means that “the shortest possible route that a runner could take and not be disqualified” is equal to the advertised distance. Essentially, any valid path through the race course must be at least the stated distance (e.g., 26.2 miles for a marathon). The end result of this is that the path taken by most runners may be longer than the required distance, but it will be impossible to finish the race (unless you’ve cheated) without running at least that far.
What is the “shortest possible route”?
Just as the shortest route around a track is along the very inside of lane 1, the shortest route along a road course takes the inside line of every turn. If there’s two or more turns in a row in the same direction, you stay in that inside “lane” to minimize the amount of weaving back and forth you’re doing.
If there are back-to-back turns in opposite directions, you’ll want to run in a straight line from the midpoint of the first curve to the midpoint of the second curve, as pictured below.
As we all know, though, you can’t always see your next turn in the course. This is where studying the course map and having a good idea of the turn pattern before the race can really come in handy.
Multiple alternating turns and the tangents
What if you’re heading down a road full of s-curves? The shortest possible route in that case is as close to a straight line through the curves as you can run.
This is sometimes called “running the tangents” as your path through the curve isn’t a curved line, but a straight line that runs tangent to the curve. (A tangent is a line that is perpendicular to the curve at the point where the two figures meet.) In some cases, you might even be able to skip several curves by running a straight line through the entire section, depending on the size of the curves and the width of the course.
Benefits of running the tangents
The key benefit to running the tangents of a course is that you’ll cover less distance and, as a result, expend less energy. Not only will that let you run at a faster pace, but you’ll also get to the finish line faster as a result of covering less ground. Clearly this can only be a good thing, right?
Unfortunately, unless you’re in the lead (or bringing up the rear) and are very familiar with the course, running the shortest route every time is next to impossible. Surprise turns may find you on the wrong side of the road to take the most efficient path through the curve and crowded course conditions can result in you needing to weave around other runners to avoid getting stuck in a slower pack.
That said, a little knowledge can go a long way. Seeding yourself appropriately at the race start can help reduce the amount of weaving you’ll need to do (as can entering smaller races), and applying the above principles, even imperfectly, can still reduce the amount of extra distance you run. While it may not add up to much over a 5k, over the course of a marathon you could save yourself up to an extra half mile or so.
Have you ever been upset because your GPS measured a course long? Do you run the tangents?