“The Simulator” is the name given to a very precise workout created by brothers Keith and Kevin Hanson, who coach the Hansons-Brooks Distance Project. The appellation refers to the workout’s purpose of simulating an upcoming marathon race as closely as possible without stressing the runner to the point of ruining the flow of his or her training. It is intended to put the finishing touches on the runner’s marathon-specific fitness and demonstrate his or her ability to achieve a time/pace goal for the marathon.

The format couldn’t be simpler. The Simulator consists of running 26.2 kilometers (roughly 16.3 miles) at one’s goal marathon pace. Why 26.2 kilometers? Two reasons. First, at 62 percent of the full marathon distance, 16.3 miles is long enough to challenge and increase one’s capacity to sustain a targeted marathon pace and to provide a legitimate indication of the realism of a marathon goal. Yet it’s not so long that it will destroy the runner’s legs for the next three days.

The second rationale for the 26.2-kilometer distance is purely psychological. The difference between running, say, a 16-mile marathon-pace run and a 26.2 km Simulator is almost entirely symbolic, but the symbolism is important. Consciously approaching the Simulator as a “metric marathon” enhances the runner’s awareness of the workout as proof of his or her readiness to run 26.2 miles at a desired pace in a few weeks. It makes the workout just a bit more confidence-boosting than a virtually identical workout lacking that layer of symbolism.

In marathon training it’s vitally important to arrive at the starting line feeling confident in your ability to achieve your goal. Such confidence is built on proof of this ability gathered in training. The more familiar you are in training with the test facing you, the more confident you will be–and the more confident you are, the more likely it is that you will achieve your goal. It’s nice to be able to stand on that starting line and think, Yeah, I’m nervous, but I’ve all ready run the pace I want to run today for 26.2….kilometers.

The Hansons usually have their runners perform the Simulator five weeks before a marathon. That works for elite runners who run such high mileage that they need three full weeks to taper for their race, but for us mortals it’s probably better to run the Simulator closer to race day—four or even three weeks out. Again, the idea is to put the finishing touches on your marathon fitness.

The Hansons runners don’t rest up for the Simulator. They do it at the end of a normal training week, on less-than-fresh legs, on the grounds that this makes the Simulator even more marathon-simulating by “making up” for the fact that the workout is 38 percent shorter than a marathon. I prefer to run the Simulator on relatively fresh legs, however, because it allows me to perform better in the run and thus makes the workout more confidence boosting. Specifically, I take it easy for two days before running the Simulator.

Before you start the Simulator you’ll want to do the same warmup you plan to do before your marathon. I recommend a mile of jogging, a few mobility exercises, and a few strides (20-second runs at 5K race pace). Try to do the workout on a course that’s very similar to the course of your upcoming marathon. When it came time for the Hansons team to run the Simulator ahead of the 2008 men’s Olympic trials marathon, held in New York City, they took a nine-hour bus trip to the Big Apple and ran it in Central Park. Ideally, you’ll also run your Simulator at the same time of day as your marathon.

It’s very important to drink during your Simulator. Find out which sports drink will be available in your marathon and make the same product available to yourself throughout the workout. You can carry your fluid, but I find this to be a major annoyance, so I like to recruit a friend to accompany me on a bike and hand me the bottle when I need it.

Since pacing is a critical element of this workout, you need to be able to monitor your pace throughout it. One option is to run on a marked course or on a route with known mile landmarks, wear a stopwatch, and check your splits as you pass the markers or landmarks. A second option is to wear a speed and distance device. A third option is to have your fluid support cyclist use a bike with a cyclometer that measures time, distance covered, and average speed.

Two final notes: First, it should go without saying that this challenging workout requires that you train appropriately toward your marathon goal for many weeks before you do it. You should have plenty of high-mileage weeks, long runs, and shorter marathon-pace runs in your legs before you take on the Simulator. Second, the Simulator is not relevant to runners whose marathon goal is just to finish. The Simulator is intended only for runners who are fit enough to race a marathon at a much faster pace than they would run a marathon merely to finish. If your goal is just to reach the finish line, the best workout to put the finishing touches on your fitness and provide that last bit of confidence is the traditional 20-miler.