The Claim: Short, intense workouts are more effective than longer ones.

Woman: “My friends and I run for 30 minutes a day, 3 days a week. But I’ve heard that short interval bursts of training are more effective. How can that be?”

Robert Davis: It sounds too good to be true: spend less time exercising and reap more benefits.

The type of exercise we’re talking about is known as high-intensity interval training, or HIIT for short.

Long used by athletes, HIIT is a becoming a big hit among regular folks…and perhaps for good reason.

The idea is to alternate intense bursts of exercise such as running or biking …with low-intensity intervals.

You go hard for, say, 60 seconds, then easy. Hard again, then easy. And so on, as opposed to going at a steady pace for 30 minutes or more.

Recent studies show that just 20 minutes of intervals, 3 days a week may be even more effective at improving aerobic fitness than continuous exercise, for 60 minutes, five days a week.

It can help lower blood pressure, raise good cholesterol, and control blood sugar.

So, exactly how intense are we talking about?

Ideally 85% to 95% of your maximum heart rate, which you can also achieve with activities such as swimming or stair climbing.

Now you might think this kind of exertion would be risky for people who aren’t young and healthy.

But research shows it can be done safely by those with heart disease or other chronic conditions.

Still, it’s important to talk to your doctor before trying HIIT or any other vigorous exercise program.

And don’t overdo it when you start. To avoid injuries, stick with shorter intervals… say 20 seconds… and increase the length and intensity over time.

Always warm up first.

Of course, you still need to include other types of exercise for Strength and flexibility.

But HIIT can add variety to your aerobic workouts and make them less boring. Plus it helps eliminate a common reason for not exercising: too little time.

For many of us with busy schedules, that’s a benefit that definitely “hits” home.

For the truth about more fitness related claims check out my book, Fitter Faster. You’ll also learn how to slash your workout time and get even better results.

Helping you be a healthy skeptic, I’m Robert Davis.