Buzz
Individuals with a high VO2max—a key indicator of cardiovascular health—often enjoy better health as they age and may have the potential for a longer life. With this in mind, some advocates of longevity have been praising the 'Norwegian 4x4' workout, which focuses on improving your VO2max. So, how exactly should you do it? And is it really the ultimate solution for fitness and longevity? Let’s explore.
What is the Norwegian 4x4 workout?
I’ll break it down in detail shortly, but at its core, it's a cardio workout (typically done while running) involving four-minute intervals. You complete four of these tough four-minute sessions, which gives the workout its '4x4' name. There’s also a warm-up at the beginning, a cool-down at the end, and a three-minute rest period between each interval.
If you're a runner, you'll recognize this as a typical VO2max interval workout. (Usually, VO2max intervals last for three to five minutes, with a recovery time equal to or slightly shorter than the work time.) Can’t I just do any random VO2max interval workout? You might wonder. Yes, that would work too.
The Norwegian 4x4 workout is a great example of a VO2max interval, but it’s not the only option. In fact, there are other ways to improve your VO2max besides targeting it through intervals. So, the 4x4 isn’t particularly unique; it's simply a straightforward protocol that’s easy to recall, and it's been tested with a variety of people, including elderly individuals with heart conditions.
What are the benefits I can gain from the Norwegian 4x4 workout?
By incorporating this workout regularly (for instance, twice a week) over the course of several weeks to months, you can expect improvements in your cardiovascular fitness, including measurements like the ‘cardio fitness’ or ‘VO2max’ data on your smartwatch. If you participate in races, you’ll likely notice you can run faster. You’ll also find it more difficult to become winded when hiking or running around with your children in the backyard.
Your heart health is likely to improve; this exercise aligns with the exercise guidelines for heart health and overall well-being. Cardio workouts in general, including these intervals, help reduce the risk of heart disease, enhance mental health, and more. Of course, you can achieve similar results through other forms of exercise as well. However, the 4x4 is one excellent choice among many.
How to perform the Norwegian 4x4 Workout
The 4x4 gets its name from the four repeats of four-minute-long intense intervals. The primary source on this workout is the Cardiac Exercise Research Group at the Norwegian University of Science and Technology (NTNU), which features a video with researcher Anja Bye explaining the workout's structure. For further details, refer to that source, not influencers or podcasters who may try to reframe it into zones or alter the work and rest periods. If you want to try the 4x4, make sure to follow it as intended. (Then feel free to experiment on your own, if desired.)
Although the 4x4 was initially intended for running, the researchers suggest it's acceptable to perform it with other activities like “swimming, biking, or skiing.” (Apologies if I’m not equipped with skis.) Here’s the step-by-step protocol:
Warm-up: Start with 10 minutes of moderate-intensity jogging or brisk walking.
First interval: 4 minutes at a hard pace. It might take 1-2 minutes for your heart rate to reach your target (85-95% of your tested max HR), and that's completely fine. If you don't have a heart rate monitor or aren’t sure of your max, push yourself enough that you can no longer speak in full sentences. As Bye explains, “the intensity in the final minute should be high, but not so draining that you can't finish the interval.”
Recovery: 3 minutes of moderate-paced jogging or brisk walking. Try to bring your heart rate back to 60-70% of your max heart rate.
Repeat: Do the intervals until you've completed all four.
Cooldown: Finish with 5 minutes of moderate intensity once again.
In total, this adds up to 40 minutes:
10-minute warm-up
4-minute hard interval
3-minute recovery
4-minute hard interval
3-minute recovery
4-minute hard interval
3-minute recovery
4-minute hard interval
5-minute cool-down
Remember, there’s a three minute recovery between each hard interval, not four (this is a common mistake). Also, don’t skip the warm-up. It’s important to raise your heart rate to properly prepare for the first interval.
How often should I perform the Norwegian 4x4 workout?
The NTNU recommends doing the workout twice a week, in addition to one longer cardio session where you maintain a moderate pace. They also suggest that if you’re working out four or more times a week, the interval sessions should make up no more than half of your total training. This typically means two 4x4 workouts per week, along with two to four sessions of other types of exercise.
What heart rate zones should I aim for?
This is not a zone-based workout, as it's a trick question! If you're tracking with a heart rate monitor, you’ll have specific numerical targets:
85-95% of your maximum heart rate during the final 2-3 minutes of the 4-minute intervals
60-70% during the warmup, recovery, and cooldown phases.
The 85-95% range typically spans zones 4 and 5, depending on the system with five zones. Your recovery heart rate may fall within zones 1 or 2, based on how your device calculates it. (As mentioned earlier, the zone limits can vary between devices.)
If you're using heart rate as a target, ensure you know your true maximum heart rate. Don't rely on your device's calculation; individuals differ, and the default formula can be off by 10 beats or more. NTNU suggests using a modified 4x4 test to measure your max. Start with the same intervals, but for the third one, push it to an all-out effort. The highest reading on your device during this test should be your max heart rate.
Is this a workout targeting zone 5?
You may hit zone 5 at some point during the intervals, so in that regard, yes. However, the goal is not to aim for zone 5, but to adhere to the protocol.
Is this a VO2max workout?
Indeed, this is a typical set of VO2max intervals. That said, it's not the only method to enhance your VO2max! Cardiovascular fitness improves through training across different ranges, including longer, slower workouts, and intervals of varying lengths and intensities. All of these contribute to improving your VO2max and, even better, your overall cardiovascular fitness.
The concept of a VO2max workout originates from athletic training, where coaches consider various components of running performance and schedule diverse workouts throughout the season to enhance athletes' strengths and address weaknesses. “VO2max” intervals are an integral part of this process.
In a separate line of thought, researchers focused on heart health and longevity have discovered that VO2max is a measurable and repeatable fitness component. Those with superior cardiovascular fitness tend to be healthier and live longer, meaning that VO2max is linked to overall health. But this is not because improving VO2max alone leads to better health; it's because overall fitness improvement boosts health, and VO2max naturally increases as a result.
Am I doing this correctly?
I often come across Reddit threads from fans of various biohacking podcasts, wondering if they completed their 4x4 workout correctly. Here's a checklist to help you out:
Did you check the protocol from the original source at NTNU? Some influencers may not explain it accurately, or mix it with other exercise methods, which can lead to confusion about the actual protocol.
Did you include the warmup and cooldown? The warmup prepares you for the first interval. Starting from complete rest means you're spending too much time in that initial interval just getting your heart rate up.
Did you take three-minute rests? Not four minutes. Three minutes. (While four-minute rests wouldn’t be bad, they aren't part of the 4x4 protocol.)
Did you reach 85-95% of your maximum heart rate during the last two minutes of each interval? Your heart rate needs time to climb, but by the last half of each interval, you should be at your target.
Did you stay under 70% during most of the recovery periods? Your heart rate will take time to drop, but the goal is to keep it around 70% since that’s where your body clears lactate most effectively (so you’re ready for the next round).
Did you finish feeling like you could’ve done at least one more round? The goal isn’t to completely exhaust yourself, but to challenge yourself in the workout.
If the workout didn’t go perfectly, don’t be hard on yourself—just make a note of what you can improve next time. Any form of cardio is beneficial and builds a foundation for progress.
