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High-Intensity Interval Training Is a Better Workout in Less Time

Burn more fat — faster — while building heart health

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En español l Do you have limited time to exercise each week?

Do you yearn to burn more fat in a shorter amount of time?

Have you got the mental toughness to stick with a new exercise program and the will to push yourself?

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If this description fits you, you're a good candidate for high-intensity interval training (HIIT), a workout that punctuates intense bursts of activity with periods of less-intense conditioning. An example would be running as fast as you can on the treadmill for a minute, followed by walking on the treadmill for two minutes. From there, you repeat that sequence several times, say for a total workout time of 20 minutes.

It's the opposite of what exercise experts call "steady-state" cardio: walking, jogging, running or cycling for 30, 45 or 60 minutes at the same intensity.

This type of training is really nothing new, by the way. Playing tennis, for example, is a kind of high-intensity interval training. We sprint around the court in intense bursts, and alternate those with periods that involve less activity.

When I was a tour player, I prepared for matches by doing this type of training, and that was before it even had an official name! My coach would put me on the treadmill, get me running all-out for 30 seconds or for a minute, have me slow down to where my heart rate was below 120 (which would be between one and two minutes) and sprint again. I would do 10 of those sequences. It really challenged me and required a lot of mental toughness to do it. But in the end it paid off — in my conditioning and in my game.

I know you're probably not a tour tennis player, but I know you want to lose body fat and get in great shape. From all I've read recently, high-intensity interval training is the way to do it.

Take this study from Australia, for instance. Researchers reported that a group of women who did a 20-minute HIIT program consisting of eight-second sprints followed by 12 seconds of rest lost a whopping six times more body fat than women who followed a 40-minute steady-state cardio program.

There's a reason this type of training burns more fat, and here comes another technical term: "excess post-exercise oxygen consumption," or EPOC. Basically, EPOC describes how many calories your body burns after your workout ends, as your body returns to its pre-exercise state. Scientists have compared EPOC in high-intensity routines and in steady-state cardio. The high-intensity interval workout burns more fat, hands down. How great is that — burn a lot of calories after the workout is over!

Remembering how effective the high-intensity interval training was for me, I recommend it to anyone who wants to pack more fat-burning exercise into less time. I mean, we're all busy today. Who wants to spend five to seven hours a week (or more) doing regular cardio? If you do the high-intensity interval training three times a week for 20 minutes, you're sure to meet your fitness goals faster.

This type of training works with any type of cardio machine: treadmill, elliptical trainer, stationary bicycle or stair stepper. In fact, some of the more high-tech machines have HIIT programs built into them. It's easy to design your own workout, too: Just pick the type of cardio you want to do. Speed it up for one minute, then slow it down for two minutes. Repeat that sequence.

With high-intensity interval training, less is more. Quality over quantity — I have always loved that. So if you want the most bang for your exercise buck, step up and apply for high-intensity interval training.

Tennis champion Martina Navratilova is AARP's fitness expert.

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