The Norwegian 4×4 interval training method, widely promoted since a 2007 study, is often claimed to be the best way to improve VO2 max. However, a detailed review of the original research reveals it only shows that high-intensity interval training improves VO2 max more than low or moderate training in moderately trained men, with no superiority of 4×4 over other interval structures. The popular narrative oversimplifies and misrepresents the study, ignoring long-term sustainability and injury风险.
In 2007, a study on the Norwegian 4×4 interval training method made waves in the endurance training community. It was widely hailed as scientifically proven to increase VO2 max by 13%, and the 4×4 intervals became a global phenomenon. Coaches prescribed it extensively, and athletes embraced it as a revolutionary way to improve cardiovascular fitness.
However, upon closer examination of the original study and its communication, the reality is more nuanced and less definitive than popularly believed. This article explores what the study actually showed, how the 4×4 method was marketed, and what this means for endurance training.
The Norwegian 4×4 method consists of running four intervals of 4 minutes each at high intensity (around 90% of maximal heart rate), interspersed with 3 minutes of easy running or rest. This session is repeated three times per week.
It was promoted as a universal endurance training solution, effective for everyone from elite athletes to patients, and as the key to improving health and performance.
The two professors behind the original study framed the 4×4 intervals as revolutionary and the gold standard for endurance training. Their claims were repeated in books, interviews, TED Talks, and media articles for nearly two decades.
Examples of such claims include:
These strong claims were all linked back to the 2007 study titled "Aerobic high intensity intervals improve VO2 max more than moderate training."
The study involved moderately trained young men who already trained at least three times per week. They were randomly assigned to four groups for eight weeks, with all other training outside the study removed.
All groups trained roughly the same total time weekly (~2 hours).
This means the study did not prove that the 4×4 method is superior to other high-intensity interval training (HIIT) methods.
The study only shows that, for moderately trained runners with low weekly training volume (three short sessions), high-intensity interval training improves VO2 max more than low or moderate intensity training.
4×4 sessions at 90% max heart rate are physically and mentally demanding. Doing multiple such sessions weekly over long periods is unsustainable and increases injury and burnout risk.
The popular narrative that low-intensity training offers little benefit is misleading. Low-intensity training allows higher total volume and better long-term adaptation.
The author, a physiotherapist and coach, shares that building training around frequent 4×4 intervals contributed to years of running injuries.
The marketing of the 4×4 method, wrapped in scientific authority, overshadowed the importance of balanced training and long-term sustainability.
Contrary to popular belief, the Norwegian method used by elite athletes like Jakob Ingebrigtsen is not centered on frequent high-intensity 4×4 intervals.
Instead, it emphasizes:
This approach aligns better with long-term adaptation, durability, injury prevention, and sustainable progression.
The 2007 study on Norwegian 4×4 intervals showed that high-intensity interval training improves VO2 max more than low or moderate training in moderately trained men with low weekly volume. However, it did not prove the 4×4 method is superior to other interval structures or suitable as a universal training solution.
Endurance training should balance intensity and volume, prioritize sustainability, and consider individual needs. The real Norwegian method reflects these principles better than the oversimplified 4×4 hype.
Train smart, enjoy your workouts, and focus on long-term progress rather than quick fixes.
