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VO₂ max and marathon time
Your VO₂ max sets the size of your aerobic engine, but it does not decide your marathon time on its own. Two runners with the same number can finish far apart. Here is what the number tells you about your marathon potential, how a race-based fitness score compares, and why the marathon is the race where predictions most often fall short.
Three things decide endurance performance
Sports physiologists describe endurance performance with three linked parts (Joyner & Coyle, 2008):
- VO₂ max: the highest rate at which you can use oxygen. The ceiling.
- How much of that ceiling you can hold: set largely by your lactate threshold. The longer the race, the lower the share of VO₂ max you can sustain; the Daniels and Gilbert equations below build in exactly that drop with race duration.
- Running economy: how much oxygen you need to run at a given speed. A more economical runner goes faster on the same oxygen.
A marathon leans hard on parts 2 and 3, and on a fourth thing the lab test does not measure: having enough fuel and durability to keep going for 42.195 km.
Marathon time and running fitness score (VDOT)
Jack Daniels and Jimmy Gilbert (1979) built equations that turn a race time into a running fitness score, often called VDOT. It works like an "effective VO₂ max" from your races. It assumes average running economy, so it can sit above or below a lab VO₂ max for the same person.
| Marathon time | Pace /km | Pace /mile | Running fitness score (VDOT) | Equivalent 10K |
|---|---|---|---|---|
| 3:00:00 | 4:16 | 6:52 | 53.5 | 38:59 |
| 3:15:00 | 4:37 | 7:26 | 48.7 | 42:17 |
| 3:30:00 | 4:59 | 8:01 | 44.6 | 45:37 |
| 3:45:00 | 5:20 | 8:35 | 41.0 | 48:58 |
| 4:00:00 | 5:41 | 9:09 | 37.9 | 52:22 |
| 4:30:00 | 6:24 | 10:18 | 32.8 | 59:13 |
| 5:00:00 | 7:07 | 11:27 | 28.7 | 1:06:11 |
Want it the other way round? Enter your VO₂ max or a recent race in our race time predictor and you get predicted times for 5K to marathon and five training paces.
Why your lab or watch number may not match
- Lab VO₂ max measures your ceiling directly. It says nothing about economy or how long you can hold a pace, so two runners with the same lab value can have very different marathon times.
- Field tests like the Cooper test estimate VO₂ max from a hard effort. They are useful for tracking change, less so for an exact marathon prediction.
- Watch estimates use heart rate and pace and can be off by several points.
- A recent race is the most useful input for a marathon prediction, because it already includes your economy and pacing.
Why the marathon often falls short of the prediction
A 10K or half marathon predicts a marathon time only if you have trained for the full distance. Riegel's formula (1981) was fitted to world and age-group records, set by runners who had trained for each distance. Common reasons the real marathon is slower:
- Not enough long runs or weekly running. The predicted time assumes marathon training.
- Fuel runs low. Carbohydrate stores are limited. ACSM's position statement suggests up to 90 g of carbohydrate per hour for efforts longer than 2.5 hours, and 30–60 g per hour for 1–2.5 hours (Thomas et al., 2016), practised in training.
- Heat and hills. Both raise the effort for the same pace.
- Going out too fast. A few seconds per km too fast early is easy to pay back later.
How to raise your marathon potential
- Mostly easy running. In studies of nationally and internationally competitive endurance athletes, about 80 % of training sessions were at low intensity (Seiler, 2010). Easy volume is what builds the durability a marathon needs.
- Threshold work raises the share of your ceiling you can hold.
- Some VO₂ max work lifts the ceiling itself, for example the Norwegian 4×4 once a week in the early weeks of a build. Our 8 week VO₂ max plan is a good block before marathon training starts, not during the peak weeks.
- Long runs and fuelling practice. The marathon-specific part. You'll find full plans on our sister site marathontraining.app, from the 16 week beginner plan to the sub-4 hour plan.
- Recovery that matches the load. Fitness is built when training is absorbed. See recovery-guided marathon training for how heart rate, HRV and sleep can steer the hard days.
VO₂ max also falls with age, which is one reason masters runners compare age-graded results. See VO₂ max by age for typical values, and RunPerform's age-grade calculator to compare race times across the years.
A coach's view of the number
Flemming, who runs vo2max.io, came to running after many years as an elite cyclist and now races as a masters runner, mostly over 5,000 m and 10,000 m. When he coaches, the VO₂ max estimate is a starting point; the sessions his athletes log, and how they sleep and recover, decide the next week. If you would like a plan built that way, see personal coaching.
Questions and answers
What VO₂ max do you need for a sub-4 marathon?
By the Daniels and Gilbert equations, a 4:00:00 marathon matches a running fitness score (VDOT) of about 37.9. That is a race-based score, not a lab value, and your lab VO₂ max may be higher or lower depending on your running economy.
Can I predict my marathon time from my VO₂ max?
Roughly. Our race time predictor does it, but a recent race gives a better prediction, because it includes your running economy and pacing.
Do marathon runners have a high VO₂ max?
Elite endurance athletes have VO₂ max values far above those of active non-athletes. But among runners with a high VO₂ max, the lactate threshold (how much of it they can hold) and running economy also decide who is fastest (Joyner & Coyle, 2008).
Why is my marathon slower than my VO₂ max predicts?
Usually because the long runs, weekly distance or fuelling were not enough for 42 km, or because of heat, hills or a fast start. The prediction assumes full marathon training.
Should I do VO₂ max intervals during marathon training?
In small doses, mainly early in the build. In the peak weeks, long runs, marathon pace and threshold work matter more.
Sources
- Joyner, M. J. & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology, 586(1), 35–44. doi:10.1113/jphysiol.2007.143834
- Daniels, J. & Gilbert, J. (1979). Oxygen Power: Performance Tables for Distance Runners. Tempe, AZ: Daniels and Gilbert.
- Riegel, P. S. (1981). Athletic records and human endurance. American Scientist, 69(3), 285–290. (Table 1: men 1.07732, women 1.08283; men over 40 to over 70: 1.05352–1.06370.)
- Thomas, D. T., Erdman, K. A. & Burke, L. M. (2016). American College of Sports Medicine Joint Position Statement: Nutrition and athletic performance. Medicine & Science in Sports & Exercise, 48(3), 543–568. doi:10.1249/MSS.0000000000000852
- Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291. doi:10.1123/ijspp.5.3.276
Related
- Race time predictor · VO₂ max calculator · What is VO₂ max? · Recovery-guided marathon training
- On marathontraining.app: Marathon training plans · Marathon pace calculator
- On RunPerform: Half marathon training plan · Marathon taper
Last updated: October 31, 2026. Written with AI assistance and checked against the sources above.