As summer approaches, many people are looking to get back into healthier exercise habits. Most of us already know that physical activity is important, but it can still feel difficult to stick to a routine, especially when time is limited.
Current health recommendations recommend exercising for at least 2.5 hours each week, with 5 hours considered even better. For many, that goal may seem daunting.
However, research over the past 20 years suggests that the amount of exercise needed to achieve meaningful health benefits may be much lower than many people assume. Researchers say just 30 minutes of high-intensity exercise per week can improve your health. This works out to about 4.5 minutes per day, or about 10 minutes every other day. What matters is strength. This activity should be intense enough to leave you breathless.
Researchers say if you’re using a heart rate monitor, your heart rate should reach about 85% of its maximum value. However, no special equipment is required. An easy way to judge strength is by how difficult it is to speak. Although they can speak in short sentences, they cannot sing or carry on a continuous conversation comfortably.
Why cardiovascular fitness matters
“The biggest reported exercise challenge is lack of time, but for high-intensity, short-duration training, this is no longer a valid excuse,” said Ulrik Vislov, a professor at the Norwegian University of Science and Technology (NTNU) and head of the research group CERG, which studies the health effects of exercise.
Researchers say that even small amounts of high-intensity activity can improve cardiovascular fitness, which plays a big role in long-term health.
“Cardiovascular health is the best indicator of your current and future health. Good cardiovascular health reduces your risk of over 30 lifestyle diseases and premature death by 40 to 50 percent,” Wislov explained.
CERG first documented these effects in a 2006 study that analyzed the health information of 60,000 people. Since then, additional large studies from Norway and other countries have reported similar results.
Is it better to spread out training?
Is it just as effective to do one 30-minute intensive workout each week as opposed to several short sessions spread over multiple days?
“It’s best to spread out your sessions a bit. Exercise also has an acute effect, which lasts for one to two days. That way you get the best of both worlds,” says Wisløff.
Researchers say that after a few minutes of strenuous exercise, blood pressure and blood sugar control improve for 24 to 48 hours. Because of these short-term benefits, experts recommend splitting your exercise into two to four days a week whenever possible.
Short interval training is effective
That doesn’t necessarily mean sprinting at full speed or using the highest resistance setting on your stationary bike.
“No. A high heart rate is determined by your personal fitness level. If you’re not very fit, simply walking briskly may be enough. That said, you need to walk fast enough that you’re out of breath. Then, as your fitness improves, you can increase the intensity. Shorter intervals are best, for example, 45-second bursts with 15-second breaks in between. Or, like Tabata training, you can do intense 20-second intervals. “Otherwise, 4×4 intervals are recognized to be very effective at increasing oxygen uptake,” Wisloff said.
fitness must be maintained
If I skipped exercise this week, can I make up for it by doing extra exercise the week before?
“No, fitness is something that must be maintained. Aerobic fitness and muscle strength decline rapidly if not maintained, especially as we age,” says Atefeh R. Tari, researcher and director of the CERG Initiative on Exercise and Brain Health.
Strength training is also considered important, especially for middle-aged and older people.
“We know that strength training is important, especially for middle-aged and older adults. There is limited research on how strength training affects longevity, but the HUNT study investigating this is expected to be published soon,” Withroff said.
The Trøndelag Health Survey (HUNT Survey) is a long-running population health survey in Norway that has been collecting health data for over 40 years.
Track your exercise intensity with new AQ measurements
The researchers also introduced a new measurement system called AQ (Activity Quotient).
Unlike traditional activity tracking methods that primarily focus on steps or training time, AQ measures exercise intensity by monitoring your heart rate. Researchers say this could give them a better idea of whether someone is getting enough activity to improve their health.
Scientists from NTNU and CERG developed the AQ algorithm using population data from five countries, including Norway.
AQ can be measured through the Mia Health app created by NTNU and Sintef through their spin-off company Mia Health. The app connects to a heart rate monitor, but users can also enter activity manually if they are not wearing a heart rate monitor.
How AQ points work
AQ points are earned every time your physical activity increases your heart rate and leaves you slightly out of breath. The harder your heart works, the faster you accumulate AQ points.
Researchers found that people who reach at least 25 AQ points per week significantly lower their risk of lifestyle-related diseases. According to the researchers, the strongest health benefits occurred when AQ points were 100 or higher.
Click here to learn more about AQ.
In a study investigating the relationship between AQ and health, researchers analyzed data from more than 500,000 people. This study found a strong association between improved AQ scores, improved cardiovascular function, and improved health outcomes.
Association between activity index and cause-specific mortality — Prospective cohort study of 500,000 participants in Asia, Advances in Cardiovascular Disease, March-April 2025
exercise and brain health
Extensive research also suggests that exercise not only benefits your body, but your brain as well.
“Physical health and brain health are closely linked, and aerobic fitness is key here too. Exercise leads to the formation of new brain cells,” said Atefeh R. Tari, head of the CERG research group.
Tali helped lead a scientific study on exercise and brain health published last year. The paper became one of the most widely read articles in the world. lancet In 2025.
Researchers promote ‘micro-workouts’
Mr Wislov and Mr Tali are now encouraging Norwegian health authorities to revise the country’s official exercise recommendations, arguing that more emphasis should be placed on exercise intensity.
The researchers also wrote a book, Mikrotrening (in Norwegian), based on a research review showing that short bursts of high-intensity activity may have greater health benefits than hours of low- to moderate-intensity exercise each week. (caption)
“We need a new Dagfin Højbroten to get the whole population on board with this plan,” Wislov said, referring to the man behind the introduction of smoking bans in Norway.
“In my opinion, Mr. Hjbroten is the politician who made the greatest contribution to public health in Norway after World War II,” Mr. Wislov said.
“It usually takes three to five years to see the effects of implemented measures. This is not easy to achieve, as there are general elections every four years. This should be a bipartisan effort, as Norway can save two to four health budgets per year, which can be used in areas such as prevention and elderly care,” Vislov said.
Researchers say Norway’s large long-term health database will make it easier to assess how physical activity policies affect public health over time.
“Norway has the potential to be a pioneer when it comes to the health benefits of microtraining,” Wislov said.
