Getting fit in 4 minutes: this is the promise of high-intensity interval training, marketed in gyms as HIIT. The idea was thought up by Izumi Tabata and a team of researchers from the National Institute of Fitness and Sports in Japan in the 1990s. Tabata showed that 4-minute workouts, comprising repeated cycles of 20 seconds of all-out work followed by 10 seconds of rest, done four days a week, than an hour’s normal workout done five days a week for six weeks.
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But does it deliver the goods? “The answer to that is absolutely, definitely,” says sports scientist Chris Easton at the University of the West of Scotland, UK. “High-intensity training works: it’s been shown pretty consistently to make you fitter, make you healthier,” he says.
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That’s because pushing the body out of its comfort zone for short bursts forces it to adapt. The higher the intensity, the greater the adaptation, with benefits for your lungs, heart and circulation. “High blood flow through the heart, through the muscle, is the thing that causes those large changes in a short space of time,” says Easton.
That’s not all. In a study published in 2017, at the Mayo Clinic in Minnesota and his colleagues compared muscle samples from younger and older people who had regularly done either HIIT training, a weights workout or both for three months. They found that HIIT reduced, and even sometimes reversed, the effects of old age on mitochondria, the energy powerhouses inside cells. With age, mitochondrial deterioration causes fatigue and can contribute to diabetes. What’s more, high-intensity training helps boost your metabolic rate, which means you burn more energy even at rest.
Sounds great, but full-on HIIT isn’t for everyone, Easton warns: done properly, it is an unpleasant experience. “I do this with my students and invariably after all-out 30 seconds of maximal work on a bike, half of them are physically sick afterwards.” But incorporating some element of vigorous exercise in a longer routine – whether faster-paced walking or jogging, some hills or just a few stairs – will deliver benefits. “In terms of disease risk, what is protective is substantially improved when there’s a higher intensity component,” says Easton.
This article appeared in print under the headline “Is intense exercise better?”
