Most runners think that a flat course like the one for the Chicago Marathon makes it easier to run fast.

While it definitely makes it easier than a hilly course, a flat marathon course like Chicago presents its own unique challenges.

Specifically, the tendency for runners to fall off pace and have a difficult time picking the pace back up. The flat course often lulls runners into slowly creeping their pace slower.

To prevent this, implement what we call a “pace change” workout in your marathon build-up that will help you prepare physically (and more importantly, mentally) for this unique challenge at London.

Here’s how to do it.

1. Start by running 2-3 miles easy, followed by 2-3 miles at a steady pace (about 10-20 seconds slower than marathon pace).
2. Then, for the next 6-8 miles, alternate between half marathon and marathon pace each 800 meters.
3. Finish with a mile easy. The total workout will be 11-15 miles, depending on your training level.

Obviously, this is a subtle difference in pace each 800 meters, but this accomplishes three things.

Most importantly is that the continual change in pace is a mental challenge. It takes focus to keep dialing the pace back and forth. This combats the “lull” you’ll experience on a flat course like Chicago.

Further, during the marathon, you’ll hit a rough patch where you’ll feel horrible and, at that point, you’ll likely slow down. Most athletes will soon feel a bit better and want to get back on pace. A workout like this helps you practice the skill of dealing with a subtle change in pace as you start to fatigue.

Finally, pacing is critical in the marathon, especially one where you can end up going out too fast. Learning the subtle difference between half and marathon pace in training will make it easier to recognize if you’re running too fast early on.