From The Desk Of Clarence Bass
HIIT Strengthens the Heart More Than Moderate Exercise
In 2008, I wrote an article titled Intervals for (Almost) Everyone, which included a section explaining that Norwegian researchers had compared high intensity interval training (HIIT) and moderate exercise for rehab of older heart attack patients. The results, reported in the June 4, 2007, issue of the journal Circulation were, to say the least, noteworthy—favoring intervals in virtually every respect.
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Norwegian researchers are back, once again comparing HIIT and moderate exercise for strengthening the heart—with essentially the same result.
Researchers from the Norwegian University of Science and Technology (NTNU) have explored what makes hard exercise so effective in restoring damaged hearts, and reported their findings September 9, 2020, in the Journal of Molecular and Cellular Cardiology. (The study was reported December 11, 2020, in Science Daily.)
"Our research on rats with heart failure shows that exercise reduces the severity of the disease, improves heart function and increases work capacity. And [that] the intensity of the training is really importance to achieve this effect," says first author Tomas O. Stølen.
First authors Stølen and Morten A. Høydal and numerous colleagues, including senior researcher Ulrik Wisloff, went to great lengths to investigate what happens inside tiny heart muscle cells after regular exercise.
"We found that exercise improves important properties both in the way heart muscle cells handle calcium and in conducting electrical signals in the heart. These improvements enable the heart to beat more vigorously and can counteract life-threatening heart rhythm disorders," says Stølen.
Before Stølen gives us the rest of the good news, he notes, "Our results show that intensive training can completely or partially reverse all these dysfunctions."
Beyond that, the details become quite technical.
(The material below was originally written by Anders Reval, Communications Advisor and Web Editor for NTNU, and provided to Science Daily. It is so clear and informative that we are going to use their copy—minus details beyond a laymen's understanding—and then provide a link to the entire Science Daily report, technical jargon and all.)
Normally, a human heart beats between 50 and 80 beats every minute when at rest. This is enough to supply all the organ systems and cells in the body with as much oxygen-rich blood as they need to function properly.
When we get up to take a walk, our heart automatically starts beating a little faster and pumping a little harder so that the blood supply is adapted to the increased level of activity. The higher the intensity of the activity, the harder the heart has to work.
Exercise strengthens the heart so it can pump more blood out to the rest of the body with each beat. Well-trained people have a lower resting heart rate than people who have not done regular endurance training.
At the other end of the continuum are people with heart failure. Here the pumping capacity of the heart is so weak that the organs no longer receive enough blood to maintain good functioning. People with heart failure have a low tolerance for exercise and often get out of breath with minimal effort.
In other words, increasing the pumping power to the heart is absolutely crucial for the quality of life and health of people with heart failure.
Many of the more than 100,000 Norwegians who live with heart failure have developed the condition after suffering a major heart attack -- just like the rats in Stølen and Høydal's study.
In the healthy rats, the heart pumped 75 percent of the blood with each contraction. In rats with heart failure, this measure of pump capacity, called ejection fraction, was reduced to 20 per cent, Stølen says.
The ejection fraction increased to 35 percent after six to eight weeks with almost daily interval training sessions on a treadmill. The rats did four-minute intervals at about 90 percent of their maximum capacity, quite similar to the 4 × 4 method that has been advocated by several research groups at NTNU for many years.
"The interval training also significantly improved the rats' conditioning. After the training period, their fitness level was actually better than that of the untrained rats that hadn't had a heart attack," says Stølen.
The effect was clear when the researchers tried to induce ventricular fibrillation in the diseased rat hearts: they only succeeded at this in one of nine animals that had completed interval training. By comparison, they had no problems inducing fibrillation in all the rats with heart failure who had not exercised.
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This article has mostly considered the effects of high-intensity interval training. But the study also includes a group of rats that trained more sedately.
The rats in this group ran the same distance and thus did as much total training work as the rats in the interval training group. However, they had to exercise longer each time since they trained at a lower intensity. Stolen notes that this form of training also resulted in several health improvements.
But, he emphasizes, the vast majority of improvements were greater with interval training. "For example, we were able to induce cardiac fibrillation in five of eight rats after a period of moderate exercise, and their pumping capacity had only improved half as much as in the interval training group."
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You can read the entire Science Daily piece on line:
Clearly, HIIT is superior to moderate training—vastly superior.
Some believe that interval training is too hard for most people, that they simply won’t do it for long, if ever. My experience - and research - says that is simply not true. Approached properly, most people find intervals more challenging and interesting than boring steady state exercise. That’s important, because few people will stick to a form of exercise they don’t enjoy.
I would not choose the 4 x 4 method used in the Stølen study; way too much time to think. The rats had no choice, but most people would prefer shorter and harder work periods with varying recovery periods.
Carol took this photo of me making a personal record for
McMaster University researchers have striven mightily to find intervals that people will find challenging and motivating.
Here’s a link to an article I wrote about this area of research:
As you probably know by now, Carol and I do intervals going up and down the mountains near our home. The possibilities are practically endless; the only limit is one’s imagination. Experiment and find forms that you find challenging and interesting. When you get tired or lose interest, move on to something else.
To find just about every form of intervals imaginable, Google “The One-Minute Workout by Martin Gibala.”
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We are reposting an article written a decade or so back by Laszlo Bencze. Titled Chaos Training, it’s about varying your training to save your body and stay motivation. Laszlo’s focus is on strength training, but I add a segment on endurance/aerobic training. So, we have both ends of the exercise continuum covered. Taken together, this classic will have you training, changing, training and changing—for the rest of your life.
The gap between you and people who stop training - or never start - will grow wider and wider with each passing year.
Extend your health span beyond your wildest dreams.
PS: You’ll find a link to the “refreshed” version of Laszlo’s classic on our Index page.
April 1, 2021
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