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Sverre Kirtsæther, one of the original participants in the Generation 100 study, runs on a treadmill in 2012 so that Øyvind Eian, a master’s student in exercise physiology, can measure his maximal oxygen uptake. The photo is from the beginning of the study, which ran from 2012-2017.

Rethinking recovery: How high-intensity interval training can aid heart attack patients

We all know that exercise is good for us, but how much, how hard, and for how long? 

Ulrik Wisløff, left, watches as a runner undergoes VO2max testing as part of his research on the health effects of exercise.

Ulrik Wisløff was convinced that the training techniques he had used helping Olympic athletes could help heart attack patients too. 

He had seen how quickly cross-country skiers improved their cardiac fitness by training at high intensity for short intervals — an approach called high-intensity interval training.

When he started as a PhD candidate at the Faculty of Medicine in 1997, Wisløff asked his supervisors if this might be a good research project. At the time, cardiologists knew that it was good for heart attack patients to exercise, to improve their quality of life and possibly reduce the risk of additional heart attacks.

But the conventional wisdom in 1997 was to prescribe moderate exercise — not high intensity training. Nevertheless, Wisløff thought his idea made perfect sense.

His colleagues? Not so much.

Podcast: Running rats and healing hearts

In 1998, a young Norwegian exercise physiologist found that a technique he had used to help Olympic athletes could help heart patients too. But his idea made doctors sweat. One famous cardiologist told him that if he used his technique in human heart attack patients, he "would kill them."

Listen to the episode here.

“I asked the cardiologists, couldn’t we use the same principles as we do in athletes in heart failure patients? And they said yes, let’s do that. But you are crazy. You can’t do it in humans. You have to start in rats,” he says in NTNU's English language podcast 63 Degrees North.

From rats to humans

“I had never seen a rat. At least not a laboratory rat,” Wisløff says. 

Soon he was busily building little treadmills, specially outfitted with equipment to allow him to measure the rats’ VO2 max, which is the maximum amount of oxygen a body can use during intense exercise. It is a standard measure of cardiovascular fitness.

The results were so promising he got approval to conduct trials in humans.

A white laboratory rat does its part for science, running 5 days a week, two hours a day to help a young researcher understand how high intensity training could help heart attack patients. The pay for this effort — one small piece of Crispo chocolate bar.

From heart attack patients to ageing well

Wisløff went on to study high intensity training in patients with heart failure. He recruited 27 patients whose average age was 75. 

One-third of them did moderate training, one-third did high intensity training, and the last third served as the control group, and was just given the standard advice regarding physical activity. 

The results were incontrovertible: High intensity training was best. 

The paper he published in 2007 has been downloaded more than 105,000 times.

One question Wisløff and his colleagues wanted to answer was how high intensity training might affect ageing. The Generation 100 project provided some encouraging answers.

That success led Wisløff to explore other areas where high intensity interval training could make a difference — whether it was ageing well, or in his latest efforts, to see how it might help Alzheimer’s patients — but not the way you might think.

You can learn more about Wisløff’s journey in the podcast episode below. 


Rognmo et al. Cardiovascular Risk of High- Versus Moderate-Intensity Aerobic Exercise in Coronary Heart Disease PatientsCirculation, vol. 126, 2012. DOI: 10.1161/CIRCULATIONAHA.112.123117

Stensvold et al. Effect of exercise training for five years on all cause mortality in older adults—the Generation 100 study: randomised controlled trialBMJ, 2020. DOI: 10.1136/bmj.m3485

Tari et al. Safety and efficacy of plasma transfusion from exercise-trained donors in patients with early Alzheimer’s disease: protocol for the ExPlas studyBMJ Open, vol. 12, 2022. DOI: 10.1136/bmjopen-2021-056964

Tari et al. Temporal changes in cardiorespiratory fitness and risk of dementia incidence and mortality: a population-based prospective cohort studyLancet Public Health, vol. 4, 2019. DOI: 10.1016/S2468-2667(19)30183-5

Wisløff et al. Intensity-controlled treadmill running in rats: VO(2 max) and cardiac hypertrophyAmerican Journal of Physiology Heart and Circulatory Physiology, vol. 280, 2001. DOI: 10.1152/ajpheart.2001.280.3.H1301

Wisløff et al. Superior cardiovascular effect of aerobic interval training versus moderate continuous training in heart failure patients: a randomized studyCirculation, vol. 115, 2007. DOI: 10.1161/CIRCULATIONAHA.106.675041

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