Explained by the originators of the Norwegian Protocol
The 4x4 interval training method, also known as the Norwegian Protocol, is a simple but efficient way to improve your VO2max and overall fitness. It involves four minutes of heavy-breathing, repeated four times, separated by three-minute active breaks.
The 4x4 interval method has been extensively researched and validated by experts like Professors Jan Hoff and Jan Helgerud, who are the founders of Myworkout and leading authorities on exercise physiology and medicine. They have published over 200 peer-reviewed articles on PubMed, consulted numerous elite athletes and teams, and applied their training principles to various clinical populations.
The 4x4 interval training method is considered the golden standard to increase your maximal oxygen consumption (VO2max), which is the maximum amount of oxygen your body can use during exercise. Again, VO2max is one of the strongest predictors of cardiovascular health and mortality, and longevity.
As we age, our VO2max decreases by about 1% per year, which means that our physical capacity and health deteriorate over time. However, the 4x4 interval training method has shown remarkable anti-aging effects, improving both your VO2max and your biological age. Biological age is a measure of how old your body is based on your health status, rather than your chronological age. By improving your VO2max, you can reduce your biological age and improve your quality of life.
The purpose of the warm-up is to get you ready for the exercise.
You have to figure out how long you need to warm up, but if you want to stick to the app's formula with a 6-minute warm-up, we recommend that you use the warm-up to build up to the desired intensity. The speed should always be experienced as pleasant.
In the interval strokes, you should aim for an intensity that after a couple of minutes makes you breathe so heavily that you don't feel like speaking in complete sentences. This means that the first minute to a minute and a half of an interval move should be experienced as fairly "easy".
If you use a heart rate monitor, your HR should around 85-95% of your maximum heart rate (MHR).When you are unable to speak in complete sentences after about one minute into the interval, you should not push yourself any further.
At the right intensity, you should be out of breath and not feel any discomfort.A rule of thumb is that you should be able to continue for another minute at this intensity when the active break starts.
Duration: 4 minutes
Incline: Minimum 5% incline is recommended
Intensity: High enough to be challenging but sustainable for 4 minutes
Active breaks are crucial for removing lactic acid and preparing for the next interval. You must reduce your speed so that you can breathe and speak normally again. Make sure the intensity doesn't drop too low, as this will only make it harder for you to get your heart rate back up in the next interval. Get ready to repeat another interval move
Duration: 3 minutes
Intensity: Low enough to recover but not too low to make it difficult to ramp up again
The final active break serves as a cool-down. Slow down gradually and assess whether you could perform another interval. If the answer is "yes," you have completed the workout correctly.
If the answer is “yes” to this, you have completed the workout correctly. If the answer is “no”, you have trained too hard. One interval session per week maintains moderate endurance levels.
Four-minute intervals are at least twice as effective as other endurance interventions
The 4x4 interval training method is as efficient as it is adaptable. You only need 16 mintes of heavy-breathing twice a week to improve your VO2max and biological age.
You can perform the 4x4 intervals with any type of exercise that challenges your cardiovascular system, such as running, cycling, rowing, skiing, or elliptical.
When running uphill, the heart, not the technique, becomes the limiting factor. When training for maximum oxygen uptake, the heart is optimally filled with blood. Active breaks make it possible to keep going for longer, quite simply. You'll get more minutes with a high heart rate and a filled heart, and your workout will be more effective.
The mechanical load is less than when running on flat ground, and this is particularly important when you exercise a lot. If, for example, you struggle with your back or knees, you will notice that the incline is gentle on your joints.
The 4x4 interval method is one of the foundational pillars of our app, Myworkout GO, and it serves as a tool to improve your quality of life and measure your health status with scientific accuracy.
The Myworkout technology and its precision in measuring VO2max and biological age comes from robust scientific research. The published study "Prediction of VO2max from Submaximal Exercise using the smartphone application Myworkout GO" by Jan Helgerud, Håvard Haglo, and Jan Hoff, demonstrated the app's accuracy.
The conclusion that Myworkout GO accurately calculates VO2max and is a practical tool for health risk estimation, potentially increasing physical activity and improving exercise habits in the general population.
With the published study “Smartphone-Assisted High-Intensity Interval Training in Inflammatory Rheumatic Disease Patients - Randomized Controlled Trial” by Jan Helgerud, Håvard Haglo, Eivind Wang, and Jan Hoff, demonstrated that Myworkout GO has the same follow-up effect as a therapist.
The app estimates VO2max and biological age by assessing your performance during a standard 4x4-minute high-intensity interval session.
The app's margin of error is 4.5%, which means that it is very close to the direct measurement of VO2max. Furthermore, the app compares your VO2max and biological age to the average values for your gender and age group, and shows you how you can improve them over time. This approach is safer and more accessible than direct measurements, even for those with health concerns.
When the app knows your VO2max, it can subsequently understand when you're in the right intensity zone for all types of activities. We call this zone HIT (high-intensity training).
You earn HIT points by staying in the correct intensity zone during the intervals, which is based on your capacity and heart rate. You only need 32 HIT points per week to keep your streak, making it an achievable goal for everyone. The app also tracks your progress, rewards your achievements, and motivates you to stay consistent and challenge yourself.
By engaging in our methods, we assure you that you can achieve a biological age of 20 even as your physiological age approaches 70.
For outdoor exercise, the app uses the sensors in the smartphone, GPS and DEM-technology to capture barometer data to calculate your speed and incline. Indoors, on a treadmill, it uses the recorded incline and speed. For devices like rowing machines, bikes, and ellipticals, you can enter your watt level.
No special equipment is needed—just a smartphone. However, if you already use wearables, you can integrate them with our app.
By following the 4x4 interval training protocol, you can maintain and even improve your physical capacity as you age, contributing to a healthier and more active lifestyle.
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