Very few of us can say that we have “extra” time. If something on our to-do list has to be eliminated, it’s usually that hour spent at the gym.

But what if you could significantly pare down your exercise time?

You’ve probably heard of high-intensity interval training (HIIT). With HIIT, you intersperse bouts of intense exercise—say, 30 seconds of all-out pedaling on a bike—with equal or longer periods of recovery (complete rest or low-intensity exercise). Repeat that a few times, and you’re done for the day.

What’s new: Researchers have discovered that with HIIT, you can get significant health benefits even faster than previously thought.


Traditional aerobic workouts, involving continuous low-to-moderate intensity exercise, strengthen the heart…improve metabolism…and reduce the risk for heart disease, high blood pressure, diabetes and other chronic diseases. What’s exciting about HIIT is that it offers the same health benefits as a traditional workout—but in a different way.

Here’s why: Each time you push yourself into high action, you create a disturbance in your body’s homeostasis, which is how the body behaves at rest. Each disturbance forces the heart to beat faster, the lungs to process more oxygen and the muscles to consume more fuel.

Very quickly, your body adapts to these changes. Muscles grow more mitochondria—your cells’ powerhouses—making them more efficient at producing energy. The heart pumps more blood with each beat. You become fitter, and your cardiovascular disease risk goes down.

High-intensity workouts with frequent intervals cause more disturbances in homeostasis than traditional workouts, which push the body into a more constant state of physical exertion.


In a 2016 study, researchers at McMaster University compared two training protocols in sedentary men. One group followed standard exercise guidelines—they rode exercise bikes at a moderate pace for 45 minutes, three days a week.

The second group did a special HIIT workout—a 20-second all-out, hard sprint…followed by two minutes of slow cycling…repeated twice for a total of three sprint-rest cycles. Add in a few minutes for a warm-up and cooldown, and that’s a sweet workout of just about 10 minutes.

Results: After 12 weeks, men in both exercise groups showed similar improvements in insulin sensitivity (the body’s mechanism for regulating blood sugar) and cardiorespiratory fitness. All men also developed stronger muscles.

Bottom line: Men who followed the 10-minute HIIT workout three times weekly had the same health benefits as men who did traditional exercise for 45 minutes three times weekly.


You may assume that high-intensity workouts are riskier than easy ones, especially for people who are out of shape or have a high risk for heart disease. The truth is, any form of exercise, including HIIT, slightly increases cardiovascular risks during workouts…but your overall heart disease risk goes down. In fact, a wide variety of HIIT protocols have been applied to people with many different conditions, including cardiovascular disease, diabetes and metabolic syndrome.

To play it safe: If you have health problems or heart disease risk factors—smoking, high blood pressure, a sedentary lifestyle, etc.—check with your doctor before starting any new exercise program.


Even though an HIIT workout is designed to push exercisers out of their comfort zones, you can adapt it to suit your preferences in a less strenuous way. All that’s required are bursts of exercise followed by lower-intensity activity.

Do you like walking? You can do 30-second fast walks. Start slowly, then push yourself to about 70% of your upper limit—breathing hard, but not gasping for air. Then slow down for a few minutes. Alternate fast/slow for up to 30 minutes (with a short cooldown at the end), three or more times a week.

Those who are healthy, fit and have the all-clear from their doctors, may want to try this 10-minute workout that incorporates just one minute of high-intensity exercise. First, warm up for three minutes with low-intensity exercise. Then…

• Blast through 20 seconds of an all-out sprint (or bike, swim, etc.).

• Recover with light activity for two minutes.

• Repeat the cycle until you’ve done three sprints. End with a two-minute cooldown of light activity.

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