Save time, burn more fat with interval training

Healthy Now

By Greg Rothman, M.S. P.T.

In my last few columns, I introduced the first two parts of any successful fitness program—optimal nutrition and strength training. If you’ve made the suggested changes to your diet, by now they should be habit, so you probably don’t even need to think about them anymore. Your body should be showing the rewards of the small shifts in eating habits, you should have more energy throughout the day, and your clothes should be fitting better as your metabolism improves and you begin burning the fat you stored during the holidays.

If you added strength training to your fitness regiment, you should already feel a little bit stronger. You’re metabolism will also be further enhanced, burning calories at a higher rate to sustain the metabolically active muscle tissue you are adding. Keep it up, and the feeling of success in moving toward your goals will become contagious.

The last piece of the puzzle is one that many people feel most comfortable about: Cardiovascular exercise. Don’t be lulled into thinking that getting on a treadmill and walking or jogging for an hour is a panacea. Performing cardio in this manner will actually hinder you in your progress if your goal has anything to do with a more “toned” body or substantial fat loss. This may seem counterintuitive to most people, so let me explain.

Conventional wisdom states the way to burn a lot of calories is to do a lot of cardio. But conventional wisdom has gotten us where we are today in America—in the midst of an unprecedented epidemic of obesity that is getting worse every year. Many of the least fit people I meet have been doing hours of cardio for years, and they are often the ones that express the greatest dissatisfaction with their bodies.

I have been saying for years, and the latest studies in exercise physiology back me up: Long, steady-state cardio workouts do very little to improve the strength and function of the heart. They are also counterproductive to developing a leaner physique, because muscle tissue gets broken down in order to fuel these workouts. Thus, very little stored fat is burned.

To optimize the effects of cardio, employ “interval training,” which can be done by running, biking or on elliptical machines so that your heart rate fluctuates for intervals of one to several minutes throughout your workout. To find the best range of intensity in which to exercise, calculate your maximum heart rate (MHR) by subtracting your age from 220, then multiplying the resulting number by 0.65 and 0.85 to find your optimal heart rate for the low- and high-ends of the range, respectively.

If you don’t want to monitor your heart rate, you can simplify the process by working very hard for the high interval and letting your heart rate come back down during the low interval. A good way to monitor the high-end of the range is via “the talk test”—carrying on a regular conversation with the person next to you while in this range, which should feel uncomfortable. You should never feel light-headed or short-of-breath when working the high interval, but you should exercise with the most intensity you can muster short of this.

The benefits of interval training versus steady-state cardio are many: They include improving heart-muscle strength, burning more calories from fat (instead of sugars stored in muscle), preserving muscle tissue, and continuing to burn calories for one or more hours following your workout (known as EPOC, or post-exercise oxygen consumption).

Interval training workouts should be no longer than 30 minutes and can be performed every day. Again, longer workouts will cause your body to shift from burning sugars in your blood stream and stored fat to an environment where muscle breakdown occurs, which is counterproductive to the goal of a leaner, stronger body.

There are two times during the day when your cardio workouts will yield the greatest result. The first is within 30 minutes of waking, before you eat anything (but do drink 8-16 ounces of water so your body does not break down muscle to get the liquid it needs for hydration). This is a hard time for many people to exercise, but it yield a better fat burn then working out at any other time of day.

The second optimal time is immediately following your strength-training workout; at this point, you have used all of the sugars in your muscles. If you then perform a short (15-30 minute) interval training workout, you will burn body fat at a greater rate. Keep in mind that you should keep the combined time of these strength and cardio workouts to under 75 minutes. Working beyond this time frame will yield diminishing results from both types of exercise.

Rest assured that this seemingly counterintuitive information is backed up not only by science, but also by the results I’ve seen in hundreds of clients who have developed the bodies they had always wanted. If you’ve been running on a treadmill for countless hours without getting results, find something else to occupy the time you’ll save by trying another activity: a strength-training program, yoga or martial arts.