Which VO2max intervals actually work?
Reps of 3–5 minutes at roughly 3–5 km race effort have the firmest evidence. In 48 well-trained men, 4 × 4 minutes raised VO2max by 8.1%, more than sprint intervals did. Longer reps at a slightly lower intensity and short 30/15 reps also work. For short reps, judge the effort by pace, not heart rate.
What to do
- Make 4–6 × 3–5 minutes at about 3–5 km race effort your core session, with 2–3 minutes of jogging between reps and 12–24 minutes of hard work in total.
- For variety, try 4 × 6–8 minutes at about 90% of maximum heart rate with 2 minutes of recovery, or 2–3 sets of 10–13 × 30 seconds on, 15 seconds off.
- Control 30-second reps by pace or effort, not heart rate, and don't run them faster than the speed you reach VO2max at.
- One VO2max session a week is plenty in the final marathon block, and one or two in the build phase. That cap is a suggestion based on weaker evidence.
- If your plan is mostly threshold work, keep one short, hard session every 7–14 days.
What VO2max sessions are for
VO2max is the most oxygen your body can use per minute. It sets the ceiling for your aerobic engine. VO2max intervals are hard reps that push you close to that ceiling for several minutes at a time.
For a marathoner they are a supporting act. Most of your training should still be easy (see how much of your running should be easy). But when it comes to how to design the hard session, the evidence is firmer than for most training questions.
One term first. Maximal aerobic speed (MAS, also called vVO2max) is the running speed at which you reach VO2max. For most runners it sits around 3–5 km race effort.
The trials
Four-minute reps. In 48 well-trained men, four 4-minute reps at about 95% of maximal aerobic speed raised VO2max by 8.1%. That was more than the sprint-interval protocols in the same study achieved (Hov and colleagues, 2023). This fits older work on 4 × 4 minutes and 15/15 formats (Helgerud and colleagues, 2007).
Longer reps, slightly easier. In trained recreational cyclists, four 8-minute reps at about 90% of maximum heart rate beat four 4-minute reps at about 95% (Seiler and colleagues, 2013). So a bit more time at a slightly lower intensity can work at least as well.
Short reps. In cyclists, short 30/15 intervals (30 seconds hard, 15 seconds easy) outperformed long intervals (Rønnestad and colleagues, 2021).
None of these trials measured marathon times, and two of them were in cyclists.
Heart rate lies on short reps
A study in highly trained runners compared 30-second reps with 4 × 3 minutes. The short reps gave less time above 90% of VO2max: 201 seconds against 328. Yet they showed more time above 90% of maximum heart rate (Fleckenstein and colleagues, 2024).
In other words, on short reps your heart rate can look like a great session while your body gets a smaller stimulus. Judge short reps by pace and effort. The same caution about wrist sensors applies here; see how accurate your running watch is.
A session library
The research report behind this site turns these trials into three session types. It grades the library B overall:
| Session | What it looks like | Main source |
|---|---|---|
| Core | 4–6 × 3–5 min at about 95–100% of MAS (3–5 km effort), 2–3 min jog between, 12–24 min of work in total | Hov 2023, Helgerud 2007 |
| Longer reps | 4 × 6–8 min at about 90% of maximum heart rate, 2 min recovery | Seiler 2013 |
| Short reps | 2–3 sets of 10–13 × 30 s on / 15 s off, 3 min between sets | Rønnestad 2021 |
An example of fitting the core session to the work limit: 5 × 4 minutes gives 20 minutes of hard running, inside the 12–24 minute range. 4 × 3 minutes gives 12, the bottom of the range.
The rule for short reps is graded B: control them by pace or effort, and never prescribe 30-second reps faster than your MAS.
How many per week?
Two further rules have weaker support and are graded C:
- A dose cap. At most one VO2max session a week in the marathon-specific phase and one or two during the build. For recreational runners, that comes to roughly 24–32 minutes of hard work a week.
- Keep a touch of it. If your plan leans on threshold sessions, as the Norwegian method does, keep at least one short, hard session every 7–14 days.
Treat these numbers as sensible defaults, not tested limits.
Does the overall plan model matter?
Less than you might think. Trials comparing polarized and pyramidal training found no difference in time-trial results (see polarized vs pyramidal training). Easy running alone is also not the best route to a higher VO2max for runners with little time (see is Zone 2 overrated?). What matters is that the hard sessions are well designed and the easy running stays easy.
Age is no barrier
High-intensity intervals raised VO2max by 9–13% in every age group studied, from people in their 20s to those over 70 (Støren and colleagues, 2017). Older runners respond too. See training as a masters runner.
What we don’t know
- No trial has tested VO2max sessions against marathon performance. The outcomes are VO2max and short time trials.
- The key trials were mostly in men, and two were in cyclists. Whether 30/15 reps beat long reps in runners is unclear; the runner data on heart rate point the other way on stimulus.
- The weekly dose cap is not tested. It is extrapolated from observational data and the overall intensity mix.
- The percentages are approximate. “About 95% of MAS” assumes you know your MAS. Most runners will use 3–5 km race effort instead.
Sources
- Hov et al. (2023). Four-minute intervals vs sprint intervals for raising VO2max in well-trained men.
- Helgerud et al. (2007). Aerobic interval formats, including 4 × 4 minutes and 15/15.
- Seiler et al. (2013). Longer intervals at lower intensity vs shorter, harder intervals in trained cyclists.
- Rønnestad et al. (2021). Short 30/15 intervals vs long intervals in cyclists.
- Fleckenstein et al. (2024). Time near VO2max in short vs long intervals in highly trained runners.
- Zrenner et al. (2021). Training data and improvement in 6,771 marathon finishers.
- Oliveira et al. (2024). Meta-analysis of polarized vs other intensity distributions.
- Filipas et al. (2022). Switching from pyramidal to polarized training in well-trained amateurs.
- Støren et al. (2017). VO2max response to high-intensity intervals across age groups.
Last reviewed 13 November 2026.