This session was popularized by American Bart Yasso, the head of the influential Runner’s World magazine. It’s claimed that from a session consisting of 10 repetitions of 800 meters, one can estimate their marathon time. But how does this work, and how accurate is it?
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The Yasso 10x800m session for the marathon
Bart Yasso, renowned for his numerous marathons and a personal best of 2 hours and 40 minutes, integrated a distinct training session into his marathon regimen for 15 years. This session entailed 10 repetitions of 800 meters each.
Yasso observed a consistent pattern: when he averaged 2 minutes and 50 seconds per 800-meter run, he would later finish a marathon in roughly 2 hours and 50 minutes. Correspondingly, while preparing for the marathon in which he set his personal record of 2 hours and 40 minutes, his average time for each 800-meter interval in training was 2 minutes and 40 seconds.
Bart Yasso’s magic rule
Bart Yasso, based on his empirical observations, developed the following ‘magic rule’: If you run these 800 meters in MM minutes and SS seconds, you will likely complete the marathon in MM hours and SS minutes.
To illustrate, here are six examples:
- 800m in 2min30 > Marathon in 2h30
- 800m in 3min00 > Marathon in 3h00
- 800m in 3h15 > Marathon in 3h15
- 800m in 3min30 > Marathon in 3h30
- 800m in 4min00 > Marathon in 4h00
- 800m in 4min30 > Marathon in 4h30
It’s crucial to understand that this is merely an estimation. Completing this workout does not absolutely guarantee marathon performance as predicted.
Does the Yasso session work for fast or endurance runners?
The Yasso test estimation tends to work well for endurance runners. However, for runners less focused on endurance, who can clock impressive times in 800-meter runs due to their speed, the test may be less accurate.
Take, for instance, my experience as a high-level track competitor (with a 1500m best of 3 minutes and 38 seconds). I could easily complete 10×800 meters in 2 minutes and 10 seconds, yet I was far from capable of finishing a marathon in 2 hours and 10 minutes; my best was 2 hours and 30 minutes, achieved without specific marathon training.
Hence, the Yasso session is not a catch-all solution. It can be a useful component in a well-rounded training regimen that includes long runs and marathon-pace workouts.
For endurance-focused runners, the Yasso formula (average time for these 800 meters in MM minutes and SS seconds equals marathon time in MM hours and SS minutes) may hold true. Moderately endurance-capable runners might need to add about 5 minutes to their predicted marathon time. Those with less focus on endurance could consider adding 10 to 15 minutes, particularly if they take longer recovery breaks between intervals.
Optimal recovery duration for the 10×800 meters
In English-speaking forums and websites, it’s commonly advised that the recovery time between each 800-meter interval should match the time taken to run the interval. For example, if you complete 800 meters in 3 minutes, a 3-minute recovery break is suggested.
However, this approach to the Yasso workout might not be the most beneficial from a training standpoint. Allowing the heart rate to drop significantly during extended recovery could be counterproductive, especially for endurance training. Moreover, longer recovery periods may disproportionately favor runners with less endurance focus.
I recommend a maximum recovery duration of 2 minutes. This can be adjusted according to endurance levels:
- Endurance profiles, particularly marathoners who take more than 4 hours, should opt for a 2-minute recovery.
- Moderately endurance-capable runners should aim for 1 minute and 45 seconds.
- Runners with a lesser focus on endurance should limit their recovery to 1 minute and 30 seconds.
With these tailored recovery times, the Yasso formula is more likely to yield effective results. A runner with less endurance focus, facing shorter recovery periods, will naturally pace slower in the 800 meters. This indirectly factors in the crucial endurance aspect necessary for marathon running.
The 15×400 session to estimate half-marathon time
The 15×400 session to estimate half-marathon time
An adaptation of the Yasso session for half-marathon estimation is the 15×400 meters session, totaling 6,000 meters. The principle for calculating the half-marathon time is similar:
Average time for these 400 meters in MM minutes and SS seconds = projected half-marathon time in MM hours and SS minutes.
To illustrate:
- 400m in 1min15 > Half-Marathon in 1h15
- 400m in 1min30 > Half-Marathon in 1h30
- 400m in 1min45 > Half-Marathon in 1h45
- 400m in 2min00 > Half-Marathon in 2h00
- 400m in 2min15 > Half-Marathon in 2h15
- 400m in 2min30 > Half-Marathon in 2h30
Similar to the marathon version, this method does not comprehensively account for an individual’s endurance capacity.
For the 15×400 session, I recommend a maximum recovery duration of 1 minute and 30 seconds. This can be tailored based on endurance levels:
- Endurance-focused runners, especially those targeting over 2 hours, should take 1 minute and 30 seconds of recovery.
- Moderately endurance-capable runners should take 1 minute and 15 seconds.
- Runners with a lesser focus on endurance should limit their recovery to 1 minute.
The 15x200m session to estimate 10K time
For estimating 10km race times, the 15×200 meters session is another effective approach, covering a total distance of 3,000 meters. The formula for the 10K distance is straightforward:
Average time for these 200 meters in SS seconds = projected 10K time in SS minutes.
To clarify, here are five examples:
- 200m in 35sec > 10km in 35 min
- 200m in 40sec > 10km in 40min
- 200m in 50sec > 10km in 50min
- 200m in 1min > 10km in 1h
- 200m in 1min10> 10km in 1h10
For this session, the recovery duration between each 200 meters can match the effort time. For instance, if you run the 200 meters in 45 seconds, a 45-second recovery break is recommended. Given that endurance is less crucial for the 10-kilometer distance, there is no necessity to vary recovery times based on endurance levels.
These sessions can be highly beneficial, especially if you’ve experienced significant progress recently. However, it’s important to remember that they should complement, rather than replace, specific pace sessions tailored to your race. Notably, Yasso sessions are conducted at much faster paces than your target race paces.
For those with recent race results, our performance predictor is a valuable tool. It can assist you in determining your VO2Max and endurance index, both critical metrics for fine-tuning your training.
Good luck with your preparation for your upcoming goals! If you’re looking for a personalized training plan with your own paces, the RunMotion Coach app might be just what you need!