Myth : Yasso’s 800s can predict your marathon time

There is a popular misconception that a workout regimen “10x800m” can predict your marathon time. But to what level of accuracy?

The reliability of a Yasso’s 800 to predict the marathon, when assessed over a wide group of people, is suspect and works more as a coincidence rather than for mechanistic reasons.

The issue is that it’s about an individual’s inherent muscle quality. The fast twitch predominant long distance sprinter can hammer out Yasso’s without a sweat in probably 2:00–2:30 each. The ultra-runner, because of their superior economy, might also be able to hammer out some consistent 2:30–3:00 intervals.

Do we expect these two runners to complete a marathon in 2.5 hours? And what errors in judgement do we make if we carry that idea into a training plan?

Running endurance time according to various distances mile to marathon follow a mathematical power law. And at an individual level, the power law signature is unique to the athlete. The ultra runner is most likely the ultra runner due to their superior economy and have a far better capability to “hold pace” when the distances double, triple etc. On the other hand, the long sprinter might have a steeper power law curve indicating that their fiber makeup do not allow them to carry on a fast speed to longer distances.

So we can say that the ultra runner might have a greater chance finishing the marathon in close to the Yasso’s outcome but there is no reliability for someone naturally good at 800’s to finish a marathon in 2:30 hours.

So these realities must be borne in mind when coaching athletes.