THE BLOG
03/04/2014 04:33 pm ET Updated Dec 06, 2017

Get Fit Fast: 5 Reasons to Love Interval Training

I am fortunate to love exercise. It is a part of my daily life that I refuse to compromise, no matter how demanding my schedule is. One reason for my dedication is the mental benefits I get from working out consistently.

I seem to thrive on the endorphin rush I get from exercise, and jogging along the coast has become an active meditation practice. All of which keeps me sane and pleasant to be around. Otherwise I can be a downright moody b-*-ch.

When I'm crunched for time or need to get camera ready after a winter of crepe and Nutella binges, I rely on interval training to get the job done quickly.

NOTE: For anyone who has heart disease or high blood pressure, or major joint problems or is over age 60, please have a chat with your doctor before starting interval training.

In brief, interval training consists of alternating short bursts of vigorous exercise with periods of lighter activity, walking or even rest.

For example, take walking. If you're in good shape, you might incorporate short bursts of jogging into your regular brisk walks. If you're less fit, you might alternate leisurely walking with periods of faster walking.

Anyone in good health may consider interval training once or twice a week after a brief warm up. Joggers can alternate walking and sprints. Swimmers can complete a couple of fast laps, then four more slowly, for example.

While there are numerous combinations of hard to moderate work and resting possible, a general formula is this:

Your high-intensity phase should be long and strenuous enough to make you out of breath. This typically comes after one to four minutes of exercise at 80 to 85 percent of your maximum heart rate.

Your recovery periods should not last long enough for your pulse to return to its resting rate. (*Maximum heart rate can be approximately calculated by subtracting your age from 220.)

It's really not complicated at all. But if you need a little help, there's an app for that!

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Now that you get a basic idea of what interval training entails, here are five reasons why I and so many fitness enthusiasts believe it should be part of your weekly exercise routine, too.

1. Double the results in half the time: Long workouts do not equal better, faster results. Instead, they are often a waste of time and mental effort! With interval training I love knowing that with just 15- 20 minutes per day, a couple of days each week, I can get measurable physical results like fat loss and muscle toning -- read that as, I can slim my tummy and reshape my booty -- in a jiffy.

I personally don't mind doing a 45-minute workout because I love to escape with my hip hop music blaring in my ears. But when time is tight and my bod is not, intervals get the job done.

You get more fat loss with alternating medium or high intensity activity with periods of rest than training for the same time at similar intensity or longer periods at lower intensity. (For example, a 20-minute workout of alternating high/low-intensity periods burns more calories than a 20-minute workout of stead intensity.)

Here's why. By exercising with bursts of vigorous activity that shock the muscles and force the body to nibble away at fat stores along with the easy carbs. This improves with more training over time.

Plus, you generally use large muscles -- like the quadriceps in your legs. So you end up building lean (not bulky) muscle with regular interval training. Believe me, lean muscle looks much shapelier than just skin and bones!

2. Long lasting metabolism boost: Intervals burn calories even when the exercise is done and the fat loss continues even when you switch to lower intensity exercise later in the week. To go hard, the body must use new muscle fibers. Once these new recruits are trained, they are available to burn fuel even during easier training sessions.

When you activate new muscle fibers through exercise, you increase your body's ability to burn carbs and fat. According to fitness model champion and my co-author Toneka Pires of EmbraceU, "Interval training a great fat blaster. When working out at a steady state your body adapts quickly resulting in slower fat burning. Intervals are the best way to trick your body out of a plateau."

3. Mood boost: Most distance runners and cyclists tout the mental high they feel after long periods of exercise. The nice thing about interval training is that high intensity exercise can produce the lovely endorphin rush, too. So if you're not into long periods of activity -- for whatever reason -- but you need a little mood pick-me-up, intervals can do that for you.

4. Increased satisfaction with less resistance: With interval training I don't cringe at the idea of a 20-minute workout, especially when I know I can do it at home, in a park or right in the stairwell of my hotel or apartment. I feel pumped knowing I stuck to my commitment and that confident feeling carries me through a busy day. My clients tell me the same. They feel impressed with themselves for grunting and sweating their way through the sessions and that natural confidence boost spills over into other parts of their lives.

5. It's heart smart: This could have been #1 on the list, but let's face it, we work out (or think about it) for the physical benefits first! The truth is, most serious athletes get into intervals for the cardiovascular benefits and endurance building effects. For me, I rest assured that doing my body-blasting workout is helping reduce blood pressure and tone and clean up my arteries to prevent heart attacks and strokes.

Enjoy!

Dr. Andrea Pennington is an actress, respected mind-body medicine physician, acupuncturist and author. She blends traditional medicine with acupuncture, spiritual direction & empowerment coaching. Featured twice on the Oprah Winfrey Show she is recognized as a medical-wellness expert who teaches how to live with increased vitality & purpose.

She is currently the voice of luxury on Luxe TV, heard in over 100 countries around the world. Dr. Andrea served as the Medical Director and Spokesperson for Discovery Health Channel and Discovery Health Online and has been seen on Dr. Oz, CNN, Fox News, the Today Show, the Early Show - CBS, and many more national television programs.