Yasso 800s workout planner & predictor
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Yasso 800s calculator
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Method Guide
Yasso 800s workout guide
The Yasso 800s workout is one of the most widely used marathon preparation sessions. While not a scientifically validated predictor, it provides a practical, repeatable benchmark workout that tracks marathon fitness over a training cycle.
The Yasso heuristic
Yasso conversion
Marathon hours:minutes → 800m minutes:seconds
A 3:30 marathon goal maps to 3:30 per 800m repeat. A 4:00 marathon maps to 4:00 per 800m. This is a numerical coincidence, not a physiological relationship.
Accuracy and limitations
Yasso 800s tend to overestimate fitness for faster runners (sub-3:00) and underestimate for slower runners (over 4:30). This is because 800m repeats test anaerobic speed more than marathon-specific endurance. For evidence-based predictions, use the VDOT Calculator or Race Time Predictor.
How to run Yasso 800s
- Warm up 10-15 minutes at easy pace.
- Run 800m at target pace on a track or flat measured path.
- Jog 400m (or equal time) for recovery.
- Repeat for the prescribed number of reps.
- Cool down 10 minutes at easy pace.
Related tools
Compare with VDOT Calculator, Pace Calculator, Race Predictor, and Split Calculator.
FAQ
What are Yasso 800s?
Yasso 800s are a popular marathon workout where you run 800m repeats at a pace that corresponds to your marathon goal time. If your goal is 3:30, you run 800m repeats in 3 minutes 30 seconds each.
How accurate are Yasso 800s for predicting marathon time?
Yasso 800s are not scientifically validated as a predictor. They work best as a benchmark workout for the 3:00-4:30 marathon range. Use VDOT-based predictions for more accurate estimates.
How many Yasso 800s should I do?
Build from 4 repeats up to 10 over your training cycle. Start with 4-5 in the early base phase and progress to 10 repeats in peak training, typically 2-3 weeks before the marathon.
What is the recovery between Yasso 800s?
Jog 400m (or the same time as your 800m repeat) between each repeat. Recovery should be easy enough to complete the next repeat at target pace.
When should I do Yasso 800s in my training plan?
Start the workout 10 weeks before your marathon, doing it once per week. Begin with fewer repeats and build to 10. Reduce or eliminate them during taper.
Why do Yasso 800s work?
The numerical coincidence between marathon hours:minutes and 800m minutes:seconds happens to correlate with the relationship between VO2max and running economy across typical marathon runners. It is a heuristic, not a physiological law.
References
Continue with a related calculator
VDOT Calculator
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Pace Calculator
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Race Time Predictor
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Split Calculator
Plan even or negative splits for race-day pacing.