Changing the Way You Exercise

HAVE YOU EVER seen a gym at rush hour? Everyone hovers around
the treadmills, elliptical trainers, and stationary bikes. Signs
warn you of 20-minute maximums so that the next sweat seeker
can have his turn. It seems like everyone wants a cardiovascular,
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aerobic workout. The more you sweat, the more calories you burn,
the more weight you lose, right? In a way, yes, the headphoneand-
Lycra set is right. Cardiovascular exercise—steady-state endurance
exercises, like running, biking, and swimming—burns a
lot of calories. In fact, it often burns more than other forms of exercise
like strength training or trendier workouts like yoga or Pilates.
But when it comes to weight control, aerobic exercise is
more overrated than the fall TV lineup. Why? For one reason: Aerobic
exercise builds little (if any) muscle—and muscle is the key
component of a speedy metabolism. Muscle eats fat; again, add 1
pound of muscle, and your body burns up to an additional 50 calories
a day just to keep that muscle alive. Add 6 pounds of muscle,
and suddenly you’re burning up to 300 more calories each day just
by sitting still.
Here’s the problem with low-intensity aerobic exercise. Just
like a car can’t run without gas or a kite can’t fly without wind,
a body can’t function without food. It’s the fuel that helps you
run, lift, and have the legs to make love all night long. Generally,
during exercise, your body calls upon glycogen (the stored
form of carbohydrate in muscles and the liver), fat, and in some
cases protein. When you’re doing low-intensity aerobic exercise
like jogging, your body primarily uses fat and glycogen (carbohydrates)
for fuel. When it continues at longer periods (20 minutes
or more), your body drifts into depletion: You exhaust your
first-tier energy sources (your glycogen stores), and your body
hunts around for the easiest source of energy it can find—protein.
Your body actually begins to eat up muscle tissue, converting
the protein stored in your muscles into energy you need
to keep going. Once your body reaches that plateau, it burns up
5 to 6 grams of protein for every 30 minutes of ongoing exercise.
(That’s rougly the amount of protein you’ll find in a hard-boiled
egg.) By burning protein, you’re not only missing an opportunity
to burn fat but also losing all-important and powerful muscle. So
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aerobic exercise actually decreases muscle mass. Decreased
muscle mass ultimately slows down your metabolism, making it
easier for you to gain weight.
Now here’s an even more shocking fact: When early studies
compared cardiovascular exercise to weight training, researchers
learned that those who engaged in aerobic activities burned more
calories during exercise than those who tossed around iron. You’d
assume, then, that aerobic exercise was the way to go. But that’s
not the end of the story.
It turns out that while lifters didn’t burn as many calories during
their workouts as the folks who ran or biked, they burned far more
calories over the course of the next several hours. This phenomenon
is known as the afterburn—the additional calories your body burns
off in the hours and days after a workout.When researchers looked
at the metabolic increases after exercise, they found that the increased
metabolic effect of aerobics lasted only 30 to 60 minutes. The
effects of weight training lasted as long as 48 hours. That’s 48 hours
during which the body was burning additional fat. Over the long
term, both groups lost weight, but those who practiced strength
training lost only fat, while the runners and bikers lost muscle mass
as well. Themessage: Aerobic exercise essentially burns only at the
time of the workout. Strength training burns calories long after you
leave the gym, while you sleep, and maybe all the way until your
next workout. Plus, the extra muscle you build through strength
training means that in the long term, your body keeps burning calories
at rest just to keep that new muscle alive.
That raises a question. What aspect of strength training creates
the long afterburn? Most likely, it’s the process of muscle repair.
Weight lifting causes your muscle tissues to break down and
rebuild themselves at a higher rate than normal. (Muscles are always
breaking down and rebuilding; strength training simply accelerates
the process.) That breakdown and rebuilding takes a lot
of energy and could be what accounts for the long period of calorie
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burning. In fact, a 2001 Finnish study found that protein synthesis
(the process that builds bigger muscles) increases 21 percent
3 hours after a workout.
The good news is that you don’t have to lift like a linebacker to
see the results. A recent Ohio University study found that a short
but hard workout had the same effect as longer workouts. Using a
circuit of three exercises in a row for 31 minutes, the subjects were
still burning more calories than normal 38 hours after the workout.
(The Abs Diet Workout is designed along similar principles, to
mimic these results.)
As I said earlier, building muscle increases your metabolism so
much that you burn up to 50 calories per day per pound of muscle
you have. The more muscle you have, the easier it is for you to lose
fat. That’s why one of the components of the plan includes an exercise
program that will help you add the muscle you need to burn
fat and reshape your body. And it also points to one of the reasons
why you should deemphasize cardiovascular, aerobic exercise if
you want to lose fat: because it depletes your body’s store of fatburning
muscle.
Now, before you think I’m some sort of anti-aerobics fanatic,
let me clarify a few things: I run almost daily, and I’ve even completed
the New York City Marathon. Aerobic exercise burns calories,
it helps control stress, and it improves your cardiovascular
fitness. It also helps lower blood pressure and improve your cholesterol
profile. If your choice is aerobic exercise or no exercise, for
Pete’s sake get out there and run. But when it comes to long-term
weight management, I’ll take gym iron over road rubber any day.