An elite endurance coach explains how to boost a key metric for longevity with the 'Norwegian method'

Business Insider

08-05-2025

For Olympic triathlete gold medalist Kristian Blummenfelt, training is a full-time job.
He exercises up to 10 hours a day to keep his heart and lungs in peak shape, and doubles up on tough sessions as part of a workout strategy known as "The Norwegian method."
That same method can help you, a mere mortal, improve your own longevity and fitness spending just a fraction of the time working out, according to his coach, Olav Aleksander Bu.
"We think of elite athletes as freaks of nature. In reality, what we see is working with elite athletes works with everybody," he told Business Insider in an interview tied to a partnership with fitness tech company Core.
Bu, who has coached some of the best endurance athletes on the planet, uses the Norwegian method to dial in workout intensity while avoiding injury or burnout.
The same principles can help you work out more efficiently.
What is the Norwegian method?
At the most basic level, the Norwegian method is about balancing volume — the amount of work you're doing — with recovery. The key principle is alternating periods of high intensity with periods of lower intensity and rest.
To train with the Norwegian method for a higher VO2 max (the ability to circulate and use oxygen effectively) and better endurance, you need the right kind of stress on your body, which means being able to measure intensity.
How tired you feel isn't necessarily an accurate measure of how hard you're working, Bu said. Pace may not be a good measure of intensity either because it varies so much between athletes, and even for the same athlete under different conditions.
Running five miles in 40 minutes might be easy for the pros but crushingly difficult for a newbie.
To stay on target, Bu uses metrics like body temperature and lactate, a byproduct the body produces during intense exercise, to precisely assess how hard athletes can push during training.
While you can buy a device to measure lactate, heart rate can also measure effort, and it's easier to do at home with a smartwatch or fitness tracker.
How to boost your VO2 max
A sample workout plan to increase VO2 max involves three sessions per week of your preferred cardio exercise, such as running or biking.
You'll aim to spend time at your threshold heart rate, the maximum effort you'd be able to sustain for about an hour of work. The pros test their threshold in a lab, but you can estimate it.
One popular technique is to run or bike hard for 30 minutes and record your average heart rate for the last 20 minutes. Your threshold for running or biking may be different.
For threshold sessions, alternate between periods of work at that intensity and rest to recover. Some example intervals from different Norwegian training plans include:
Four minutes of hard effort, followed by three minutes of rest, repeated for four total sets, popularized by coach Ulrik Wisløff.
1,000-meter effort, followed by a minute of rest, repeated 10 times, is a go-to for athlete Marius Bakken.
In one of those sessions, you could incorporate heat training — one of Bu's favorite ways to get the right workout intensity, both in his own workouts and for his athletes. Adding heat also works the heart and lungs while preventing joint pain during exercise.
You can be most precise by using a sensor to monitor your body temperature. Aim for around 101.3 degrees Fahrenheit, building toward 102.2 during your session, but not exceeding that temperature, Bu said. Increase the heat by exercising in warm weather or wearing more layers.
Over time, you can safely challenge your body to keep getting stronger by gradually spending more time at that threshold intensity.
The key is thinking long-term. Working out for an hour or two once a week isn't going to make much of a difference to your fitness. Progress comes from repeating the routine for weeks and months.
"People that find great pleasure in training find a sustainable intensity, and they get to perceive the tremendous effect it has on their physique," Bu said.