The runner is running along the right side of the path. She sees a curve ahead and runs a straight line that is tangent to the inside of the curve, as shown by the red line. That puts her on the left edge of the path. She follows that curve until she sees the next curve, and she then she runs a tangent to the inside of the new curve, causing her to end up on the right edge of the path. In contrast, a runner not running tangents follows the curve, as shown by the green line. Even though the difference isn't great, the two red tangents are shorter than the green line. In a race that has many curves, the distance saved by running tangents can be significant, and that reduction in distance translates to a shorter time for the race by a number of seconds, perhaps minutes, without running faster. Pretty cool.
As you run the tangents, keep the following suggestions in mind.
- You will be switching from one side of the street to the other side of the street. Only do this if you won't create congestion and you won't endanger yourself, that is, when you're not in a mob of runners and you don't have to run in front of oncoming traffic.
- As soon as you reach a new curve, look ahead for the next curve. When you see that curve, run a straight line to the inside of that curve. Don't just blindly follow the first curve to its completion. This means that you may be in the middle of a curve when you start a new tangent. If the terrain is flat and there are several short curves, you may be able to see more than one curve ahead of you, and you can run a straight line to the most distant curve.
- When running a large curve, you can run a tangent to reach the curve, but you may have to follow the curve until you can see the next curve.
- When going around a curve, run as close to the inside edge as you can, but don't do that if the edge has pot holes, crumbly asphalt, lose dirt, etc. You'll have to maneuver around bad spots as well as other runners who are blocking your way. Because of this, your distance may not be the measured distance, but it will be shorter than if you always run on the same side of the street.
I noticed while watching the 2009 Boston Marathon, that the yellow line that marked the certified course cut to the right when it approached a right-angle turn at an intersection; the line just missed the building.