Marathon Training Corner: Yasso 800s

As I begin, or rather continue, through this marathon training program, I would like to talk about some of the things that can improve (or deter) my training. I figure that if I write about it, then I can incorporate it into my training plan. Keep in mind, that most of the time I do not know what the hell I am talking about.

The first topic in this series will be Yasso 800’s


From my limited reading and understanding, these workouts should “predict” your marathon finishing time by running ten 800 meters intervals with equal time between each 800. More specifically, one would convert the predicted marathon time from hours and minutes to minutes and seconds. If you want to run a 4 hour marathon, then you should be running 4 minute 800 intervals

Ok, when I first found information about this technique, I really gave it a side eye.tenor (1) Actually, I’m still side eyeing this predictor. Perhaps, there are other implicit factors that were used to develop this predictor, but I would think that longer runs would be a better indicator of a marathon finish time. Since I used to be a biomedical researcher, I come from the line of thought that predictors are closely related to potential outcomes. Like if want to test the effect of a drug on in a particular cancer, I would induce the cancer in an animal model and give the animal the drug with the appropriate controls, of course. Same for marathon training. Wouldn’t an 18-mile run be a better indicator of a marathon finish than running ten intervals that pretty much equal five miles? If that’s the case, then why not run a bunch of 400s, and half the number?

Also, I am a little confused about the workout itself. Is one supposed to take the average of all ten intervals or is one supposed to the use the slowest time (more than likely interval 7, 8, 9, or 10) as the predictor?

In my limited search, it has been hard to find some of the background/theory behind this training regimen. Most of the information seems to point in the direction of coincidence than an actual theory. Buuuuut, I could be wrong. Hey, I was kind of lazy in my search. A couple of reports mention the role Yasso 800s have in VO2 max, but those reports really do not expand on the topic. Other reports mention that one should add 5 minutes to the predicted time.

Obviously, I am not going to completely write off Yasso 800s, since Burt Yasso clearly is more of a long (or any) distance expert than I. It appears that these are great interval workouts to complement a regular marathon training program. Sometimes I neglect the importance of interval training days, because I get so focused on making sure that I meet my distance goals . . . which I often do not. It take it that these could be great workouts to monitor how a runner’s speed improves (rather than predicting a marathoner’s finishing time) during a training program.

There are some other recommendations that can be used in lieu of or in conjunction with Yasso 800s

A fast finish long run: Pretty much is as simple as it sounds. A runner will run the first 12 miles of an 18-mile long run at regular pace, but finish the last 6 miles at marathon pace. I have a feeling that this method would work best for me.

A long distance race: I kind of mentioned this earlier in my post. Typically you will see this type of run/race associated with the McMillan Calculator ( *** ). Some even mention that you could take your half-marathon time, double it, then add 5 minutes. I take it that this method is more for intense runners, because I always seem to f-up the second half of a marathon . . . by a lot.

I figure that there are soooo many variables and conditions could affect a person’s performance that one, two, three, or even four methods of prediction.

Since this entry is more or less about my marathon training thoughts, you can take them with a grain of salt. The grain of salt you may have sweated out during a long run.

Do you utilize any marathon predictors workouts? If so, how close were they to your finishing times?


  1. You’re right about Yasso 800’s being more of a coincidence than actual scientific-based theory. Bart Yasso just noticed that there was a correlation between his 800 meter times and his marathon finish times. As you know with your scientific background, correlation does not imply causation. Most people use Yasso 800’s as a predictor for marathon time but there are many other factors on race day like weather, course, and just how you’re feeling that can effect your finish time.

    Liked by 1 person

    • So true. For example today, I was doing mile interval work outs and my average pace was around 8’20”. However, for the Yasso 800’s I was averaging 3’58” pace. Yes, I’m extrapolating two data points (time and the interval distance); but technically, my Yasso 800 pace should, more or less, match the pace for the mile pace. I’ll pretty much use my Yasso results to compare how fast (or slow) I have gotten over the course of my training program.


  2. I hear ya on this – I don’t understand how speed work can predict a marathon time. That said, I do sometimes input things into the “predictor” apps to see if they might be accurate – so for instance, I’ll put in data for a random run I did the week before a race and then see how closely it got to my actual race time. Honestly – it’s been pretty accurate (within a minute or two) for the half marathon distance on roads. It’s terrible, though, at predicting anything trail running!

    I also use the “pro” tools on Smashrun – they have a thing called “PRs You Can Beat” and “PR Progress” which takes data from all of your runs in the preceding 30-90 days and gives predictions for future performance. So far, these tools seem to be very accurate – it’s unclear what data they’re using from the runs (they have everything that Garmin records) but they also tell you details about the training that you were doing (distance, frequency, HR, etc) that led up to your very best performances which is kind of neat too.

    But as you’ve said, too, all these are basing the predictions on the very best possible race conditions on the day of and THOSE are the things that derail you!

    Liked by 1 person

    • I’ve been playing around with Smashrun for about a week . . . yes, I’m late. My main issue was trying to figure out how to export my data from strava and my Apple Watch. It seems like it is a great analysis program. Hopefully, I’ll utilize it more in the future.


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