Brief intense workouts offer significant health benefits

At this time of year, many people make an extra effort to establish good exercise routines. We know that exercise is good for our health, but it can still be difficult to get started and maintain good habits.

The health authorities' recommendation is to exercise for at least 2.5 hours, and preferably 5 hours, per week. For some people, this may feel just a bit too much to take on.

However, research results from the past 20 years have shown that just 30 minutes per week is enough to improve your health. That equates to 4.5 minutes per day or 10 minutes every other day - but the intensity must be high. This means that you need to really exert yourself so you get out of breath.

If you have a heart rate monitor, your pulse should be approximately 85 per cent of your maximum heart rate. But you don't need a fancy gadget and can use your body to gauge your heart rate. The intensity should be high enough that you can speak in short sentences with a workout partner, but you should be so out of breath that you are unable to sing or talk continuously.

Cardio is key

"The biggest reported challenge regarding exercise is lack of time. But with intense, short workouts, this is no longer a valid excuse," said Ulrik Wisløff, a professor at the Norwegian University of Science and Technology (NTNU) and head of CERG, a research group that conducts research on the health effects of exercise.

A mere 30 minutes of high-intensity exercise per week will improve your cardiovascular fitness - and good cardio fitness is the key to better health.

Cardiovascular fitness is the best indicator of current and future health. Good cardio fitness reduces the risk of over 30 lifestyle diseases as well as premature death by 40 to 50 per cent."

Ulrik Wisløff, professor, Norwegian University of Science and Technology (NTNU)

This was documented in a CERG study back in 2006, which was based on health data from 60,000 people. Since then, many large studies have been conducted both nationally and internationally showing similar effects.

One or more sessions per week?

Does it have the same effect if you do one 30-minute high-intensity session per week, or a five-minute intense session each day? What is best?

"It is best to spread the sessions out a bit, because exercise also has an acute effect that lasts for one to two days, so that way you get the best of both worlds," said Wisløff.

For example, blood pressure and blood sugar regulation are improved for 24-48 hours after a single workout session in which you are out of breath for a few minutes. Therefore, it is best to spread the exercise minutes over two to four days during a week.

Interval training is effective

Do you have to run very fast? Or crank up the incline setting on the exercise bike?

"No. Your own personal fitness level determines what gives you a high heart rate. If you are not very fit, simply taking a brisk walk may be enough. Having said that, you need to walk fast enough that you get quite out of breath. You can then increase the intensity as your fitness improves. Short intervals are effective. For example, this could be bursts of 45 seconds with 15-second breaks. Or like in Tabata workouts, with intense 20 second intervals interspersed with 10 second breaks. Otherwise, 4x4 intervals are recognized as highly effective for increasing oxygen uptake."

Fitness has to be maintained

If you did twice as much exercise last week, can you skip exercising this week?

"No. Fitness is something you have to maintain. Cardio fitness and strength decline quickly when not maintained, especially as you get older," said Atefe R. Tari, a researcher and head of CERG's initiative on exercise and brain health.

What about strength training?

"We know that strength training is important, especially for middle-aged and older adults. There is limited research on how strength training affects lifespan, but a HUNT study exploring this is due to be published soon," said Wisløff.

The Trøndelag Health Study (The HUNT Study) is a longitudinal population health study in Norway that has collected health data over the course of four decades.

New measurement method

AQ (Activity Quotient) is a new concept and measurement method.

AQ reflects the intensity of the activity you are doing, namely your heart rate. AQ is therefore not based on how many steps you take or how many minutes of physical activity you complete each day. These measurements do not always give an accurate picture of whether you are active enough.

NTNU researchers at CERG have developed the algorithm that forms the basis for AQ. They have used data from population studies in five countries, including Norway.

To measure AQ, you need to use the Mia Health app developed by NTNU and Sintef through the spin-off company Mia Health. The app can be connected to a heart rate monitor. If you do not have a heart rate monitor or forget to wear it during a workout, you can enter your activity manually.

100 AQ points per week

You earn AQ points every time your heart rate increases enough to make you slightly out of breath. The higher your heart rate, the faster you will get AQ points.

People who achieve 25 AQ points or more per week significantly reduce the risk of developing lifestyle-related diseases. Optimal effect is achieved when the activity level is 100 AQ points or higher.

In a study investigating the link between AQ and health, the researchers used data from over half a million people in their analyses. The study showed a close correlation between increased AQ, increased cardiovascular fitness and better health:

Association between Activity Quotient and cause-specific mortality - A prospective cohort study of 0.5 million participants in Asia, Progress in Cardiovascular Diseases, March-April 2025

Brain health and dementia

Large studies show that exercise also has a positive effect on how our brain works.

"Physical health and brain health are closely linked, and cardio fitness is key here as well. Exercise leads to the formation of new brain cells," said Atefe R. Tari, who is head of a research group at CERG.

Tari is one of the researchers behind a scientific study on exercise and brain health that was published last year. The publication is among the most read articles in the prestigious journal The Lancet in 2025. You can read a Norwegian SciTech News article about it here: Exercise helps improve how our brain ages.

Micro workouts

Wisløff and Tari are now urging the Norwegian health authorities to change the country's official exercise recommendations. High intensity is the most important factor.

They have written the book 'Mikrotrening' (in Norwegian) which is based on research reviews showing that short bursts of high-intensity physical activity provide greater health benefits than many hundreds of minutes per week of low- to moderate-intensity exercise. (Captions)

"We need a new Dagfinn Høybråten to get the whole population on board with this," said Wisløff, referring to the introduction of the smoking ban.

"In my opinion, Høybråten is the politician who has done the most for public health in Norway since the Second World War," said Wisløff.

"It usually takes 3 to 5 years to see the effects of implemented measures, and since we have general elections every four years, this is not easy to achieve. This should be a cross-party initiative because it would save Norway 2 to 4 health budgets per year, and could be used for prevention and in areas such as elderly care," Wisløff said.

Norway has the advantage of having high-quality health data that have been collected over several decades, enabling us to easily compare and see the results of measures.

"Norway could become a pioneer with regard to health benefits from micro workouts" said Wisløff.