The race simulation is a “dress rehearsal” done 2-3 weeks before the competition, faithfully replicating pace, nutrition, and gear to test your strategy and reduce unknowns.
- What it is: It’s a specific workout that mimics race conditions (pace, time of day, breakfast, gear, nutrition) over a reduced distance.
- What it’s for: It’s a “dress rehearsal” to validate your race strategy, not a test to see how fast you are.
- What to test: Race pace (is it sustainable?), nutrition (do the gels cause problems?), gear (do the shoes or shirt cause issues?), and the mental management of the effort.
- Why it’s essential: It turns hopes (“I hope I can do it”) into certainty (“I know what to do”) and allows you to correct mistakes before it’s too late.
- When to do it: Generally 2-3 weeks before a half marathon or 3 weeks before a marathon.
You Don’t Test the Race on Race Day. You Test It Before.
Remember Colonel Hannibal Smith from the A-Team? “I love it when a plan comes together.” He’d say that after the mission was accomplished, but the point is, he had a plan. And that plan worked because, one way or another, it had been tested.
For us runners, race day is the execution of the plan. It’s the moment when all the pieces—the long runs, the repeats, the strength work, the rest—have to fit together perfectly. But how do you know if the plan is correct? If the pace you have in your head is sustainable? If the gels you bought won’t wreck your stomach at kilometer 30?
You can’t find out on Sunday morning with your bib pinned on. That would be like showing up for a university exam hoping you know the answers.
You don’t test the race on race day. You test it before. And that test has a specific name: the simulation.
What Is the Simulation and Why Is It the Most Important Workout (After the Long Run)
The simulation isn’t a workout like the others. It’s the dress rehearsal. It’s the last big test, physical and mental, before the final taper.
It’s usually scheduled two or three weeks before the goal race (depending on the distance) and consists of replicating all the conditions you’ll find on D-Day as faithfully as possible, but over a shorter distance.
It’s the workout that combines the endurance built with long runs with the speed honed by intervals. It’s the moment you verify if your engine has the reliability to hold the RPMs you’ll ask of it, for the entire time needed. But above all, it’s a test that goes far beyond your legs: it’s the dress rehearsal for your gear, your stomach, and, more than anything else, your head.
What to Test During the Simulation: The Complete Checklist (Pace, Nutrition, Gear, Mind)
The goal of the simulation isn’t to “win” the workout, but to gather data. It’s a test, and like any test, it’s meant to find problems so you can solve them.
Here is the complete checklist of things to try:
- The Time and Breakfast:
Wake up at the same time you will for the race. Eat exactly the same breakfast you’ve planned. Three hours before? Three hours before. That toast with jam? That toast. This is where you find out if digestion is a problem, not while you’re in the starting corral. - Gear and Shoes:
Wear all your race gear. The shirt, the shorts, the socks, and, above all, the shoes. This is the workout where you discover if that annoying tag irritates your skin after an hour or if that sock seam gives you a blister. If it happens, you have three weeks to fix it. - Race Pace (The Engine Test):
This is the heart of the test. If you’re training for a 5:00 min/km marathon, the simulation involves running a large portion exactly at that pace. Not one second faster, not one second slower. You need to understand if that speed is your “cruising pace” or if it’s redlining your engine. You need to learn to feel it in your legs. - Nutrition and Hydration:
You don’t improvise this. You must test your entire nutrition strategy. Try the same gels or bars you’ll use in the race, at the same time intervals (e.g., one every 40 minutes). It’s the only way to know if your stomach tolerates them, if they give you energy, or if they send you into a crisis. - The Mind:
What happens when fatigue sets in? When your “inner voice” starts listing all the reasons you should slow down or stop? The simulation is the ultimate mental workout to prepare your answers for that voice.
How to Structure Your Simulation: 2 Practical Examples
The structure depends on your goal. Here are two classic examples.
1. Simulation for the Half Marathon (21K)
- When: 2-3 weeks before the race.
- Workout: 3-4 km warm-up + 14-16 km at Race Pace + 2 km cool-down.
- Focus: It’s an almost full-distance test. The goal is to feel if your target race pace is correct. If you finish the 16 km feeling like you “still have more,” the pace is right. If you’re crawling by the end, you were probably too optimistic. Test your breakfast and one gel halfway.
2. Simulation for the Marathon (42K)
- When: 3 weeks before the race (never later, recovery would be insufficient).
- Workout: 2-3 km warm-up + 28-32 km with long stretches at Race Pace + 1-2 km cool-down.
There are two main approaches:- Steady: Do all 30-32 km at marathon pace (MP). It’s an extremely tough test, both physically and mentally, but it gives you incredible confidence if you nail it.
- Progressive: 10 km at MP+10” (easy) + 15 km at MP + 5 final km at MP-10” (progression). This better simulates the reality of a race, where you start controlled and finish (hopefully) strong.
- Focus: Nutrition is everything here. You must test your entire fueling strategy (e.g., 4-5 gels, depending on your plan) and your mental fortitude over the long distance.
The Goal Isn’t to Hit a Time, but to Gather Information
I want to be crystal clear on this point: the simulation is NOT a race. You aren’t there to set your 30 km Personal Best.
If something goes wrong, the simulation is a success.
You read that right. If the gel gives you cramps, if the shoes hurt, if the pace is unsustainable: you’ve won. You found a problem while you still have time to fix it.
If you had discovered that problem at kilometer 25 of your marathon, your “plan” would have failed miserably. Instead, you gathered data. Now you can switch gel brands, put on the right bandages, or recalibrate your pace goal.
You will arrive at the starting line not hoping everything goes well, but knowing what you need to do for your plan to work. And that, believe me, is the best feeling in the world. Take it from a control freak.