The Basics: Running Tangents

Posted by Dave on December 4, 2014 | Comments Off

You have probably heard runners speak of “running the tangents” in a race — but what does that mean, exactly, and what’s the best way to do it? Running tangents is just a geeky way of saying “running the shortest legal distance in a race.”

Geometrically speaking, a “tangent” is a straight line that touches a curve but doesn’t cross it, like this:

tangent1

 

The red line is a tangent of the circle. When you “run the tangents,” however, you don’t just touch a corner like the illustration above, you go around it, like this:

tangent2

The tangents are actually the straight lines heading into and out of a corner. In a race with many corners, running the tangents often means crossing from one side of the road to the other:

tangents3

 

Assuming the entire roadway is open to runners, this is entirely legal and expected. When a course is measured and certified for a particular distance — say, 5 kilometers — the certifier measures on the shortest possible route.

In some races, it’s impractical to run the tangents: Large races may simply be too crowded, and at smaller races often the road is not completely closed to traffic, so you may be asked to stay to one side of the road or another. But assuming you are running on a greenway or road that is closed to traffic, if your goal is to complete the race as quickly as possible, you should run the tangents!

But even in races where the road is closed and there is plenty of room, I’ve often seen runners stay to one side of the road, or cross the road all at once instead of on the shortest possible route. In fact, it’s rare to see any runner run perfect tangents. How much time are they losing in doing this? DC Rainmaker did a thumbnail calculation for the National Marathon (now the Rock N Roll USA) and came up with a full half mile, which might be 5 minutes or more for a typical runner! (As an aside, I think he may have gotten it wrong. If you stay to one side of the road, you only run extra distance on half the corners in the race, not every corner — but he also included a fudge factor by not accounting for the wide roads on the course). In any case, everything else being equal, running the tangents means you run the shortest possible route. There are not many occasions when running a longer distance results in a faster time!

So assuming they know to run tangents, how do people go wrong? The most common mistake I see is crossing the street all at once:

tangents4

The runner following the green path thinks he is running tangents — after all, he is switching sides of the road and taking the shortest line around each corner — but he’s clearly traveling farther than the runner following the red path.

The other errors come up when only a portion of the roadway is open to runners. If a part of the roadway is coned off for runners but the other part is open to traffic, some runners seem to think that means they need to run next to the the curb. Not true! You can use the entire width of the road out to the cones, like this:

tangents5

The red runner is following the shortest legal path. By staying next to the curb, the green runner is traveling farther than necessary. And tempting as it may be in some races, the blue path is not legal. Runners must stay on the marked course at all times, and the cones delineate the course boundary. Even running on the wrong side of one cone, say, to pass a crowd of runners, while it might not shorten the course, is not allowed! Notice here that the red runner runs straight lines between the cones. Each cone is like its own mini-corner, and if it is safe to do so, you can save a bit of distance by running straight between the cones, even if the road you are on has a gradual curve.

One scenario where you may want to keep to something more like the green path is when there is a lot of car traffic on the road traveling at a high speed. Though technically you are allowed to run right next to the cones, this may put you at an unsafe distance from cars traveling at 55+ mph!

Another exception: It might not pay to run a precise tangent on an extremely sharp corner or a turnaround. In these cases, especially if you are a fast runner, you may need to swing wide in order to make the turn without slowing down too much. When you do this, however, don’t let yourself drift all the way across the road. As soon as you round the corner, sight the next corner and run straight for it on the shortest diagonal.

Because so many runners fail to properly run the tangents, especially in the situations I show you above, it might feel like you are doing something “wrong” when you are actually running the correct line on a course. If you take care to understand the rules, you can save yourself valuable time, and you might just beat some of those other runners who aren’t as well-informed as you are!

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