High-intensity interval training (HIIT) is one of the most exciting trends in fitness, but the word “intensity” can scare away all but the most committed. Exercise is already hard, you may be thinking, and now experts want to make it harder?

Actually, it’s the opposite. Most people find HIIT easier than traditional cardio workouts, such as jogging, swimming or even shoveling snow. Compared with cardio training, HIIT more effectively improves your metabolic rate (for burning calories)…and improves your VO2 max—a parameter associated with cardiovascular health—according to research. In addition, it strengthens the immune system.

What most people don’t realize: Even though HIIT alternates periods of all-out exertion with periods of lower-intensity exercise, the intense segments of the workout don’t have to be too grueling. Facts you need to know to get started with HIIT…


With HIIT, you exercise as hard as you can for 30 seconds to a minute. (The actual exertion level and duration of the “burst” will vary from person to person.) Then you slow down to a lower intensity for a minute or two…then repeat the hard-easy sequence a few more times. The total length of the workout depends on your fitness level and physical abilities.

It’s the “explosive” part of the workout that creates what can only be called “magic.” People who engage in HIIT have better cardiovascular health—including improved cholesterol profiles and less insulin resistance—than those who do conventional endurance workouts, according to research published in Experimental Gerontology.


HIIT is a safe form of exercise, which poses no more risk for sprain/strain injuries than any other exercise regimen. As with any new workout, however, it’s a good idea to get the go-ahead from your doctor before starting HIIT.

I tell people who are elderly or have physical limitations—or are merely new to exercise—to start with a low-intensity version of HIIT.

Example: If you’re a 65-year-old who has mainly been sedentary, you might start out with a slow walk (the easy part of the exercise at up to 3 mph), then pick up your speed—walking at around 4 mph to 5 mph while swinging your arms for the hard part. After 30 seconds or a minute of fast-walking/arm-swinging, you’d drop back to a stroll for a minute or two, then maintain the cycle for four to five rounds. To get started…

• Choose your sport. With HIIT, it doesn’t matter which activity you choose. You can do the exercise/rest cycles in a swimming pool or on a treadmill or an exercise bike—or using your own two feet. All that matters is that the activity allows you to go all-out for a brief period of time…drop down to a slower level…then go all-out once again. For most people, four of these intervals are enough to get an excellent workout.

• Don’t exercise on an empty stomach. If you don’t have enough blood sugar when you exercise, your body will pull sugar from the muscles first. That’s the opposite of what you want to happen. To improve body composition, you want to preserve muscle and burn fat. The best way to do this is to exercise within one to three hours after having a small meal.

Good pre-workout meal choices: A couple of scrambled eggs with a few slivers of avocado and a side of veggies. Or a healthful protein bar such as RXBAR, Oatmega or SimplyProtein Whey Bar.

• Work with your limitations. Many of my patients have some physical limitations. They might be overweight…out of shape…or deal with arthritis, leg pain or other minor (or not so minor) disabilities. You can still engage in HIIT—you just have to find what works for you. A personal trainer can offer advice.

• Go low and slow. To start, I recommend doing an HIIT workout three days a week, for about 10 minutes each time. You’ll slowly increase the total time—by increasing the number of intervals and/or the duration of the exertion/rest components—as you get stronger. Aim to work up to 20 to 30 minutes for each session.

• Don’t forget the warm-up and cooldown. When you start your workout, whether it’s biking, jogging or using a StairMaster, slowly go through these movements for the first few minutes…and shift into low intensity of the same exercise for a few minutes of cooldown at the end of the workout.

Each week, you’ll find that you can gradually increase the duration and intensity of the workouts.

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