Workouts that take minutes attract fans and critics

Not long ago, Trevor Speed, 34, of Kelowna, British Columbia, was a busy professional and expectant father who never found time for exercise. Today, he has a demanding but time-efficient routine: Three times a week, he hops on his stationary bike or treadmill and powers through a 25-minute workout that includes 10 one-minute bursts of sweaty effort, broken up by one-minute rests, plus a warm-up and cool-down.

“It’s tough, but definitely worth it,” Speed says. With a baby now in the house, a quick workout “fits in really well with my life,” he says.

Hardcore gym rats will recognize Speed’s workout as high-intensity interval training, or HIIT — a trendy style of exercise that calls for alternating hard and light efforts. In their most extreme forms, such workouts can leave even the fittest humans gasping for breath.

But some exercise experts believe HIIT has great potential to reach the less-fit majority, with the promise of quick but effective workouts, modified for various fitness levels. Others see HIIT as a fad too unpleasant and demanding to catch on widely or improve public health.

Leading the charge for interval training is Martin Gibala, a professor of kinesiology at McMaster University, Hamilton, Ontario, and author of a new book, The One-Minute Workout.

That somewhat misleading title refers to an extreme workout that actually takes 10 minutes, including 60 seconds of lung-searing all-out-effort, broken into three 20-second sprints. But Gibala insists that “there’s a style of interval training that is right for just about everyone.”

Gibala says he was a young father himself when he first tried HIIT cycling workouts more than a decade ago. “I found that interval training was a way to maintain my fitness despite limited time for working out.”

The idea behind HIIT: Bursts of hard exercise strung together in relatively brief workouts can have equal or greater effects on cardiorespiratory fitness than longer bouts of moderate continuous exercise. You get a big dose of exercise in a short time and may benefit from adaptions your body makes each time you pump up the intensity, Gibala says.

Short-term studies have found physiological benefits, even in people who are overweight or dealing with diabetes or heart disease.

But critics say the real question is not whether the workouts work — it’s whether people will like them enough to keep doing them and will get enough exercise along the way to improve their health without hurting themselves. Widely accepted guidelines call for either 75 minutes of vigorous aerobic exercise or 150 minutes of moderate aerobic exercise, plus some strength training, each week.

It’s misleading to suggest exercise “is really something you can do in a minute and sit down and forget about it,” says Stuart Biddle, a professor of public health at Victoria University, Melbourne, Australia. What’s needed instead, he says, are ways to get people moving more throughout the day, with activities that “keep them coming back for more.”

When it comes to HIIT, he says, “I just don’t think enough people will stick with it.”

Studies differ on whether people like HIIT. Speed was among 100 participants in a study looking at how many people stick with HIIT for a year, and those results are just being analyzed, says Mary Jung, an assistant professor of health and exercise psychology at the University of British Columbia. But she says previous smaller studies found promising results.

One appeal, she says, is that “you start feeling fitter faster.” And, she says, changes in tempo keep workouts interesting.

Unknown: whether HIIT workouts come with extra heart risks. The American College of Sports Medicine says any vigorous exercise has more immediate heart risks than light or moderate exercise, especially for unconditioned individuals — but that the risks of not exercising at all are much higher. Guidelines from the college say studies of interval training “show promise.”

“The best exercise is the exercise you will do,” says guideline co-author Carol Ewing Garber, professor of biobehavioral sciences at Columbia University. “If you like doing HIIT, I would encourage you to do it rather than no exercise at all.”

Gibala recommends checking with your doctor first. Here are some workouts he suggests, with intensity levels rated on a 10-point “perceived exertion” scale where 1 is “very light,” 5 is “starting to breath hard,” and 10 is “almost max”:

The Beginner: Aptly named, this one has been studied in out-of-shape older adults. Walk at a warm-up intensity of 1 for 3 minutes, then pick up to level 3 (breathing deeply but still able to converse) for 3 minutes and drop back to 2 for another 3 minutes. Repeat through a 30-minute walk (or less to start).

The Norwegian: This one has been tested in people with heart disease and type 2 diabetes. To reach the peak intensity level, you may need to run, walk uphill or cycle uphill. Warm up at level 1 for 3 minutes, then go hard at level 6 for 4 minutes and drop back to level 3 for 3 minutes; repeat three more times, then recover at level 1 for 2 minutes. Total time: 30 minutes.

The Ten by One: This has been tested in cardiac rehab patients.  Warm up lightly for 3 minutes, then exercise at level 5 for 1 minute, go back to level 1 for 1 minute, then up to level 6 for 1 minute, back down to level 1, up to level 7 and so on, up to level 9. Cool down for 2 minutes. Total time: 24 minutes.