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Interval training: A faster route to a stronger heart?

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Short bursts of intense exercise may help build heart fitness. But run the idea by your doctor before you begin.

Want to add some variety to your exercise routine and finish your workout a little faster? Consider interval training, which alternates short, intense bouts of exercise with longer periods of lighter, less vigorous activity. The potential payoff may be enhanced cardiovascular fitness in less time.

“One appealing aspect of interval training is that you may be able to get more bang for your buck, meaning you don’t have to exercise for as long to see a similar improvement in fitness,” says Dr. Meagan Wasfy, a cardiologist at the Cardiovascular Performance Program at Harvard-affiliated Massachusetts General Hospital.

Athletes have long used interval training to optimize their performance during competitions. In recent years, cardiologists have studied the technique as a way to enhance cardiac rehabilitation. These programs—which feature carefully monitored exercise—help people recover from heart-related events.

In these settings, interval training appears to be safe and effective. It boosts cardiovascular fitness at least as well as moderate-intensity exercise for a given amount of distance covered or calories burned, says Dr. Wasfy.

Should you try it?

It stands to reason that people who exercise regularly but have risks for heart disease (such as high cholesterol or high blood pressure) could also benefit from interval training. But you should take a few steps to make sure it’s safe, says Dr. Wasfy. That’s fairly easy in a cardiac rehab setting: the initial exercise stress test assures that you don’t have any symptoms during exertion such as chest pain, which might make intense exercise dangerous. The doctor can also measure your maximum heart rate, defined as your peak heart rate during very strenuous exercise. Your interval training heart rate target is then set to 90% of that value, and the training sessions are closely monitored.

You can estimate your maximum heart rate yourself by subtracting your age from 220 (see table). But if you’re considering doing interval training on your own, ask your primary care physician or cardiologist if an exercise stress test makes sense, just to find out whether you’re at elevated risk for a cardiac event.

“You might not have symptoms during moderate exercise because you’re not pushing yourself hard. We don’t want you to have symptoms for the first time when you try jogging or riding your bike at a higher intensity on your own,” says Dr. Wasfy.

How to add intervals

If your doctor gives you the green light to try interval training, start with a gentle warm-up (such as walking) for at least five minutes to loosen your muscles and get your blood flowing. Then, ramp up to your regular, moderate-intensity exercise (for example, brisk walking). Next, do your high-intensity exercise (which might be jogging or running) for anywhere from 30 seconds to two minutes. During these bouts, push yourself until you feel breathless. Then return to your moderate pace to catch your breath for at least double the amount of time you spent at the high-intensity level. Repeat several times—up to five, if you’re able—and then cool down with a slower, five-minute stroll.

You can try this with other types of exercise, like swimming or cross-country skiing. Exercise machines at gyms, including treadmills, elliptical trainers, and stationary cycles, often have built-in interval training programs to put you through your paces.

Some people like interval training because it saves time and adds variety. Instead of doing a 30-minute moderate-intensity workout, you can shave about 10 minutes off your exercise routine by adding intervals. Others find the extra sweat and effort unappealing. If you’re in the latter camp, don’t fret that you’re missing out. While it’s clear that improved fitness is linked with greater longevity, there’s no evidence that interval training offers any unique benefits in that realm.

“We look forward to more studies to see if this exercise pattern is associated with fewer heart-related events and living longer,” says Dr. Wasfy.

Heart rate targets

Exercising to 65% of your estimated maximum heart rate is enough to build cardiovascular fitness. Adding interval training, during which you exercise at 90% of your maximum heart rate for brief periods, may build fitness faster. A wearable heart rate monitor can help you stay on target, but going by how you feel also works.


Maximum heart rate

65% of maximum heart rate

90% of maximum rate

























Posted by: Dr.Health

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