There’s nothing radical in this session, it was defined back in 2001 by Amby Burfoot of Runners World. So why are we looking at it here? Well, it certainly has its merits, but there is also a degree of misunderstanding, possibly leading to false expectations in the marathon — and we know where that can lead.
Amby liked it because of its simplicity and seemingly its accuracy; this is not just a training session it can also be a predictor of your current marathon speed potential.

The Yasso 800 session

Lets look at the session first, then examine the implications for the marathon runner.
Unsurprisingly, Yasso 800s involve running repetitions of 800m, the other part of the name comes from the creator Bart Yasso. The theory is this: if you run 10 x 800m with equal time recoveries to a consistent time, the time (of the rep) predicts your marathon potential. Thus, 10 x 800m at 3mins 30, will predict a marathon of 3hrs 30; 10 x 800m at 3mins 50, will predict a marathon of 3hrs 50. So the concept is certainly simple and very easy to remember.

Of course the Yasso 800 is only measuring your ability to run 10 x 800, and not your ability to run 26.2 miles without stopping. The two workouts (if you can call a marathon a workout), use different energy systems and so there’s no real reason there should be any correlation. But, the evidence does seem to indicate that the session serves as a useful guide.

What’s important to remember though, is that Yasso 800s assume a firm endurance base has been laid and that the required long runs have been part of the marathon training. The danger of course is that the aspiring sub 4 marathon runner gets on the track, trains to run their Yasso 800s in 3:59 and falls apart in a very ugly way in the marathon because there is no solid marathon training to support this aim.

Marathon training is complex. It is of course an endurance event, and yes, we want to run it as fast as possible, but we must train in a way to increase our speed endurance and not just our speed or endurance.

Yasso 800s are useful and if run regularly during our marathon training, they will show us how we are progressing. But, they are not an ideal marathon training session. Most coaches would agree that the recoveries are too long and the repetitions are too short to be marathon specific. Nevertheless, Yasso 800s remain a motivating session to run, and any session that encourages runners out on to the track to experience some mixed pace running has a place in the schedule of those wanting to explore their potential.