Yasso 800s are a workout-test consisting of 10 x 800-meter repeats, where the average time in minutes and seconds is used as an empirical indicator to predict the final marathon time in hours and minutes.
- Yasso 800s are a famous workout created by Bart Yasso, former Chief Running Officer of Runner’s World.
- The theory correlates the average time for 10x800m (in minutes:seconds) to a potential marathon time (in hours:minutes). Example: an average of 3’40” for the 800s suggests a potential of 3h 40′ in the marathon.
- The recovery is the key to the test: it should last exactly as long as the time it took to run the previous repeat.
- While not a scientifically proven method, it’s an excellent indicator of your fitness level and a powerful workout for your VO₂ max.
- It should be considered a test of potential: it doesn’t account for long-distance endurance, nutrition, or race-day conditions.
What If You Could Predict Your Marathon Time With a Single Workout?
During the journey of preparing for a marathon, there’s a moment when every runner stops and asks the fateful question: “What am I really capable of? What’s a realistic goal time?” You look at past race times, use online calculators, and make estimates based on your long runs. But in the folklore of the marathoner, there exists a workout that is more than just a session: it’s a rite of passage, a prophecy written on the track.
A workout that, according to legend, can predict your final 42.195 km time with surprising accuracy.
It’s not a magic formula from a lab but a brilliant insight born from thousands of miles of experience. We’re talking about Yasso 800s.
Who Is Bart Yasso and How Did He Invent the Most Famous Test Among Marathoners
To understand this workout, you first have to understand who invented it. Bart Yasso is not a physiologist in a white lab coat but a running legend, for years the unofficial “mayor” of the running community in his role as Chief Running Officer for Runner’s World magazine. He is a man who has run races on every continent, in every possible condition, and has spent his life talking to other runners.
It was from these conversations that Yasso noticed a strange and fascinating coincidence. He realized that the time it took for runners to complete a series of 10 x 800-meter repeats, expressed in minutes and seconds, corresponded almost perfectly to their final marathon time, expressed in hours and minutes. It wasn’t science; it was field observation. It was the wisdom of the road. And so, almost by chance, the most loved and debated test by marathoners around the world was born.
The Theory of Yasso 800s: How the “Magic” Works
The principle is disarmingly simple, which is what makes it so brilliant.
If your goal is to run a marathon in 3 hours and 30 minutes, you should be able to run 10 x 800-meter repeats in 3 minutes and 30 seconds each, with a 3-minute and 30-second recovery between each one.
If you can run your 800s at an average of 4 minutes and 10 seconds, your potential marathon time is 4 hours and 10 minutes. If you’re hitting 2 minutes and 50 seconds, well, then you’re aiming for a 2-hour and 50-minute finish. The conversion is direct: minutes:seconds for the 800m = hours:minutes for the marathon.
The Practical Guide: How to Perform the Test Step by Step
This is not a workout to be taken lightly. It’s one of the toughest tests you’ll face in your preparation. It should be performed about 3-4 weeks before your race, when you’re at your peak fitness.
The Warm-Up and Preparation
Don’t even think about starting without a proper warm-up.
- 15-20 minutes of easy running: You need to arrive at the track or your measured stretch of road with your body completely warm.
- 5 minutes of drills and dynamic stretching: Skips, butt kicks, leg swings. Prepare your muscles for an intense effort.
The 10 x 800 Meters: The Heart of the Test
The goal is to run 10 repeats of 800 meters, trying to keep them as consistent as possible and close to your goal time.
- Example (3h 45′ marathon goal): Your target pace for each 800m is 3 minutes and 45 seconds. Try to run each repeat in a narrow range, for instance, between 3:42 and 3:48. Consistency is more important than a single super-fast repeat.
The Active Recovery: The Key to Finishing the Workout
This is the most important and difficult part, the element that makes the test valid.
- The recovery between repeats should be a very slow jog, and it must last exactly as long as the time of the repeat you just finished.
- Did you run the 800m in 3:45? Set your watch and recover for 3:45. Not a second less. This 1:1 ratio between effort and recovery is what simulates the ability to sustain a high intensity, which is crucial for the marathon.
After the last repeat, don’t stop abruptly. Do at least 10-15 minutes of cool-down running to help flush out lactic acid.
Is It a Reliable Method? The Pros and Cons of This Legendary Test
Now for the million-dollar question: does it actually work? The answer is: yes and no.
- Why YES: Yasso 800s are a test of your aerobic fitness and your ability to tolerate fatigue. If you can complete them at your goal pace, it means your “engine” (VO₂ max and lactate threshold) is absolutely capable of sustaining that pace in a marathon. Furthermore, it’s a huge psychological confidence boost.
- Why NO (or rather, with caution): The test measures the power of your engine, but not the size of your fuel tank. It predicts your cardiovascular potential but doesn’t account for your specific muscular endurance over 42 km, a factor that is only built through long runs. A very fast runner with poor endurance might perform an excellent test only to hit the wall at km 30 of the marathon. It also doesn’t consider decisive variables like weather, the course, race strategy, and nutrition.
Consider Yasso 800s not as a crystal ball, but as an insightful check-up. They tell you if your preparation is heading in the right direction and give you a realistic benchmark on which to base your strategy. And, perhaps most importantly, they give you one of the toughest and most rewarding workouts you can do. Whether the prophecy comes true or not, after 10x800m, you will undoubtedly be a better runner.