Mind Over Manner : Expert Insists That You Need to Use Your Brain, Too, If You’re Going to Exercise Efficiently

Pam Deegan likes to think of herself as a red Ferrari.

And when she’s explaining the mechanics of exercise physiology, she urges her listeners to think of themselves as cars, too. A sturdy Mercedes, a sleek vintage Porsche, or even a reliable little Volkswagen--whatever they can identify with, says Deegan, an exercise physiologist who chairs Irvine Valley College’s department of health science, physical education and athletics.

It’s a technique that works especially well here in auto-obsessed Orange County, where even people who consider themselves fitness-conscious often understand more about the functions of the internal combustion engine of a car than they do about the workings of their own bodies.

For example, we all know that cars run on gasoline. But not many of us could name the human body’s equivalent fuel: adenosine triphosphate, or ATP, which is simply three phosphate molecules bound together chemically.

Everything we eat, whether it’s fat, protein or carbohydrate, must be broken down into ATP to provide energy to the body’s cells, Deegan explained last Thursday at an Irvine Medical Center seminar on “Maximizing Your Exercise.”

And like the gears of a car, the body has a series of systems for obtaining and burning ATP. Only one of those systems--the highest gear--uses fat, Deegan said. But simply working out fast and hard doesn’t necessarily ensure efficiency, either. Overexertion can deprive the body of the oxygen it needs to keep the chemical process going, so it shifts back into a lower gear and the fat stays put.

In Deegan’s words: “If I take my red Ferrari up the Grapevine, I’m not going to make it in third gear.”

The misconceptions so many of us--even athletes--have about how our bodies work can leave us exercising far less efficiently than we could, Deegan said. And when putting in all that energy produces less-than-expected results, too many well-intentioned exercisers simply become frustrated and give up.

That fat-burning gear is better known as the body’s aerobic state, meaning “with oxygen.” But although the word “aerobic” may have found its way into common usage over the last decade or so, it’s more likely to evoke images of sweaty folks in Spandex than the bodily process it describes.

“I have people who come up to me all the time and say, ‘I play volleyball three times a week, or softball, and I’m still overweight and out of shape. What’s wrong?’ Or they’ll say, ‘I do sit-ups ever day. Why do I still have all this fat around my waist?’ ”

When the body is in first gear, it uses the 15 to 20 seconds’ worth of ATP that is found in the muscles themselves. That system is quick but inefficient, she explained.

The next gear is the lactic acid system, which breaks down blood glucose, or sugar, molecules, each of which produces two molecules of ATP and a byproduct of lactic acid. Lactic acid buildup in the muscles is the cause of the soreness that can occur after exercise.

But in third gear, or the aerobic state, the heart is pumping more oxygen to the cells. After three to five minutes of sustained exercise using the large muscle groups, the body is able to break down fat to obtain 38 ATP molecules from the same amount of glucose that produced only 2 molecules of ATP in the previous stage.

Brisk walking, running, swimming, cross-country skiing, jumping rope, using a stair machine or exercise bike, and the most active parts of aerobics classes are all considered aerobic exercises, if they are done continuously without interruption, Deegan said.

Football, baseball, volleyball, weightlifting, and doing sit-ups or leg-lifts are considered anaerobic, or without oxygen. The exception is circuit training, which speeds up the process of weightlifting to bring it into the aerobic range.

Studies have shown that the people who are most likely to lose weight and keep it off exercise aerobically at least four days a week, for more than 40 minutes each time. The minimum length of exercise to obtain results is 20 minutes at a time.

To determine whether you are exercising aerobically, you’ll need to check your pulse. The simplest method is to press gently with three fingers--not your thumb, since it has its own pulse--on your neck on either side of the larynx to feel the carotid artery. Press on one side of the neck only, because if you compress the arteries on both sides you could cut off the oxygen supply to your brain.

Your target heart rate will depend on age. A 20-year-old, for example, needs to work up to a heart rate of 140 to 170 beats per minute, while for a 40-year-old, the range is 126 to 153. At 65, the rate decreases to 108 to 131.

If the rate is too high, Deegan explained, “your heart will be beating so fast it can’t do its job and circulate your blood. You’ll feel like you’re going to pass out or throw up.

“How many of you have exercised so much you had to go home and take a nap?” Deegan said. “Proper aerobic exercise should give you energy, not drain you.”

One reason aerobic exercise feels good is that it releases endorphins, the morphine-like chemicals produced naturally by the brain. “People accuse me of using cocaine because I’m feeling up all the time,” Deegan said. “But it’s not true. I just exercise appropriately.”

Another advantage is the increase in the proportion of HDL, or high-density lipoprotein, cholesterol, considered “good” cholesterol because it reduces the risk of heart disease.

Regular aerobic exercise also raises the body’s overall metabolic rate, so that even when you aren’t exercising, you burn more calories, Deegan said. It also increases your body’s insulin efficiency and reduces the risk of diabetes. And it decreases your appetite, she said.

But aerobic exercise does have its downside. It has become the leading cause of injury in the United States as more and more Americans have begun to exercise, Deegan said.

One important way to minimize the risk of injury is warming up. “When you start, you should very slowly increase your heart rate,” Deegan says. “Muscles have a better chance of ripping if they’re cold. And the heart is also a muscle, so it needs to warm up, too. There was a study of long-distance runners, people who were in very good shape, and if they didn’t warm up, they had abnormal EKGs (electrocardiograms).”

Stretching, however, may not be as essential as trainers once thought. “Most of the research now says you don’t avoid a lot of injury by stretching,” Deegan said. “If you do stretch, use a static stretch rather than bouncing. And don’t go until you feel a burning sensation, because that means you’re getting microscopic tears in your muscle.”

Cross-training, or mixing different forms of aerobic exercise, may not only make the process more interesting, but it also can help prevent injury. Deegan knows that from experience. “I was teaching aerobics, two classes a day five days a week, and I ripped my gluteus muscle right off the bone because of overuse. It took me three years to recuperate.”

Cooling down is also important. “When you exercise, 80% of the blood volume is in your arms and legs. If you stop suddenly, it will tend to stay there, and that can leave you feeling faint.”

If any exercise hurts, stop immediately, Deegan says. “If you get those looks from your instructor or from the people around you, scoff back. Do what’s best for you and don’t worry about what anyone thinks.”