Note: This article is in no way meant to disrespect Bart Yasso as a runner or as an individual. I have no doubt that this workout works very well for him. However, as with most things running, this isn't everything for everyone. While this workout may work well for some runners, devoting ten workouts to this training method for a marathoner is not as effective for most marathoners as a predictor or training tool than other options.

Show me a marathoner who hasn't heard of Yasso 800s and I'll show you someone who hasn't been paying much attention recently. The concept sounds great, doesn't it? Want to run a 3 hour marathon? Train to run 10x800 in 3 minutes. Want to run a 4:00 marathon? Train to do the 800s in 4:00. 2:30 marathon? 2:30 800s. What could be more simple than that? Not much. The best part is, if you read some articles I've read on Yassos, you'll be convinced that Yassos are the key to getting your marathon time goal. Of course, do your long runs but definitely don't skip the Yassos because they are what will get you to the finish line in your goal time. Unfortunately, no matter how much we would like this to be true, running simply isn't that simple. Especially marathon running.

In some senses, Yassos seem to have some merit. Try some training pace calculators (like this one on Hillrunner.com) and you'll see that a 3:00 marathoner's suggested VO2max interval pace would be about 2:58/800. A 4:00 marathoner's suggested VO2max interval pace would be about 3:56/800. That seems quite close, doesn't it? Well, theoretically, yes.

There are a number of factors we have to keep in mind when considering whether Yasso 800s are really a good idea. First, remember what energy systems the workout is stressing most and what energy systems the marathon is stressing most. Second, note the differences in those paces. Third, is there a better workout you could be doing?

What energy systems do Yasso 800s stress most? The energy system in question is called the VO2max system. What about the marathon? That would be a primarily aerobic event, run at paces lower than your lactate threshold. So you are trying to determine your performance potential at a very stamina oriented event by doing a much more speed oriented workout. The simple fact is most marathoners these days have not developed their aerobic systems as well as they have developed their speed. You can nearly maximize your speed very quickly. It takes many years to fully develop your aerobic system.

For a good visual of the differences here, just consider the paces. Running 800s in 3:00 means you're running about 6:00/mile. A 3:00 marathon is a little under 7:00/mile, over 50 seconds per mile slower than the workout. As your times increase, so does the spread. a 4:00 marathoner would be running Yasso 800s over 1:00/mile faster than goal marathon pace. That's a pretty significant difference in paces when trying to predict what you are capable of in one by doing the other. The difference is very significant when we figure that most runners are more well trained for the shorter events than they are for the longer events. Don't believe me? How many 18:45 5k runners do you know who can run a 3:00 marathon? How many 25:00 5k runners do you know who can run a 4:00 marathon? Those are equivalent performances if one would be equally well trained for both events. The simple fact is most people are more well trained for the shorter events and hence Yassos than they are for the longer events like the marathon.

But Yassos still make a good workout, right? Yes, they make a good workout. However, are they the best workout that a marathoner can do? No. A marathoner would be more well served by doing longer repeats. Repeats at around the pace of Yassos but of distances more like 1200-1600 meters would be better. Tempo runs and repeats of 1-2 miles with short recoveries are even more important. Aerobic running, of course, can not be overlooked and a significant amount should be done before even considering any other workouts. Doing 800s at times in a training plan is not a bad idea. However, devoting a workout every week for 2 months, give or take, to 800s is taking time and energy away from workouts that can be much more effective in preparing for the demands of a long event like the marathon.

I have heard many stories of people trying to use Yassos to predict their marathon performance. The typical result is that they fall 10-20 minutes short of what the Yassos predicted, sometimes even more. If you are one of these people and you actually go out at the pace that your Yassos predict that you could do the marathon in, you will be going through the half 5-10 minutes faster than you should be. Some people say that, for every minute fast you are at the half, you end up losing at least 2-5 minutes in the second half. That means you could be costing yourself 10-50 minutes in the second half and 5-40 minutes overall. That adds up to two things: a time much worse than you were capable of and a very painful second half.

Do Yasso 800s make a good workout for someone training for a marathon? In moderation, yes. Do Yasso 800s make a good predictor of marathon performance? In the large majority of cases, absolutely not.