(The New York Times) -- As any woman who has ventured into a
health club knows, the weight-lifting area is very much a male
domain. Most women steer clear, clustering instead in the group
exercise classes, taking yoga or step aerobics.
And that, medical experts say, can be a mistake, at least for
who want to reshape their bodies. While cardiovascular exercise like
running can help the heart and burn calories, the best way for women
to change their look is to lift weights - heavy weights.
"To really reshape yourself, you have to hypertrophy muscles,"
Dr. William J. Kraemer, a professor of kinesiology at the University of
Connecticut, referring to the medical term for muscle growth.
Kraemer was the principal author of a new position paper on weight
lifting for the American College of Sports Medicine and is the editor of
a leading research journal on weight lifting, The Journal of Strength
and Conditioning Research.
There are also health benefits, said Dr. Claude Bouchard, the
of the Pennington Biomedical Research Center at Louisiana State
University. If men or women work sufficiently hard at weight training,
the muscle they build is more efficient, with more mitochondria, which
are the cell's energy factories. The muscle is also better at using fat
for fuel and better at allowing people to use insulin to clear sugar
from the blood, which reduces their susceptibility to diabetes.
Studies also show that weight lifting can help with problems
Investigators at the National Institute of Aging found that older people
with osteoarthritis of the knee had less pain and improved mobility
when they strengthened their leg muscles, working on those that
support the knee. And, researchers say, weight lifting can stave off
the sort of muscle wasting that forces older people to grab a chair
handle for support when they rise.
One problem that women face, however, is that they are hobbled
myths about weight lifting, expecting the wrong things and,
sometimes, expecting too much, exercise physiologists say.
The worst myth, these researchers stress, is that women who lift
weights risk growing muscles like a man's.
Dr. Gary A. Dudley, an exercise physiologist at the University
Georgia and an author of the American College of Sports Medicine's
statement on weight lifting, says he tries to dispel that notion by
telling women to look around the gym at the women who are lifting
"That's the simplest answer - just look around," he said. "There's
girl who works in my lab who does pull-ups like a yo-yo. She does not
have 26-inch arms like Arnold used to have," he said, referring to
Arnold Schwarzenegger. "They're just not there."
Somehow, that message has not reached the general public, Kraemer
said. Even his 22-year-old daughter believed it, asking Kraemer to
help her and her friends by suggesting a program that would help
them get fit without getting big.
Even women who are genetically capable of growing big muscles
never grow ones as large as a man's, Kraemer said. When
researchers biopsied the muscles of female bodybuilders, who spend
hours each day lifting weights, "They had smaller muscle fibers than
the average male," Kraemer said. "And these were women who were
taking drugs" to increase their muscle mass, he added.
"A lot of women are just sitting there with a 10-pound weight,"
Kraemer said. "It's better than nothing, but they're really taking a
second-class program. A lot of them are dramatically undercutting
Even building bone requires that muscles be stressed, researchers
say. They explain that bones have receptors that respond to demands
on muscle, and weights can signal those receptors.
"Studies showed that stair climbing can help your bones - but
women wore weighted vests," Kraemer said.
If the muscles-like-a-man myth discourages women from starting
lift heavy weights, other myths can discourage women from
continuing, physiologists say. These are the myths that lead women to
expect too much from resistance training and encourage them to give
up when the benefits do not emerge.
One problem is expecting immediate results.
"It takes a lot of time to develop muscle," Kraemer said. "Most
want to have it happen in the first few months, but it takes three
months or longer, usually three to six months," before a person looks
much different, he added.
Forget the idea of spot reducing, researchers say, like "toning"
muscles of the inner thighs, for example, and slimming them. "Spot
reducing is not a real thing," Kraemer said.
Many women also cling to a belief that is almost an act of faith
exercisers: Muscle burns more calories than fat. Therefore weight
lifting, by building muscle, will noticeably increase the body's
Sorry, said Bouchard, who is directing a national study on the
inheritance of an ability to train with aerobic exercises. He said that
weight lifting had virtually no effect on resting metabolism. The
reason is that any added muscle is minuscule compared with the total
amount of skeletal muscle in the body. And muscle actually has a
very low metabolic rate when it is at rest, which is most of the time.
Skeletal muscle, Bouchard said, burns about 13 calories per kilogram
of body weight over 24 hours when a person is at rest. A typical man
who weighs 70 kilograms, or 154 pounds, has about 28 kilograms of
skeletal muscle. His muscles, when he is at rest, burn about 22
percent of the calories his body uses. The brain would use about the
same number of calories, as would the liver, Bouchard said. If the
man lifts weights and gains 2 kilograms, or 4.4 pounds of muscle, his
metabolic rate would increase by 24 calories a day.
Dr. Jack Wilmore, an exercise physiologist at Texas A&M University,
said that the average amount of muscle that men gained after lifting
weights for 12 weeks was 2 kilograms, or about 4.4 pounds. Women,
of course, will gain much less.
A corollary to the hypothesis that you burn more calories simply
adding muscle is the belief that muscle can noticeably change your
body weight. The idea is that when you do resistance training you
may actually be thinner yet weigh the same or a little more, because
muscle is heavier than fat.
That holds a grain of truth, because muscle is more dense than
But, Bouchard said, the problem is that few people put on enough
muscle in proportion to their total body mass to make a noticeable
difference in their weight. The idea that you will weigh the same or
more but you really are thinner may be true if you work hard at
weight lifting for many months, but otherwise it is another myth.
But when it comes to weight lifting, researchers also confess
have not answered some age-old questions. Why, for example, do
muscles feel sore a day or two after they are stressed?
One possibility is that they get damaged, with tiny tears ensuing
the work of lifting weights. But, said Prof. Stanley Salmons, a muscle
researcher at the University of Liverpool, "damage and pain have
different time courses, and they respond differently to repeated bouts
of exercise." He added that delayed muscle soreness remained a
mystery. "At this moment I do not know why muscles get sore, and
no one else does either."
It is also unclear how to prevent soreness. "You hear trainers
very important to stretch before exercise," Salmons said. "But there
were experiments in which people did exercise with or without
stretching, and it didn't seem to make much difference."
As for the techniques of weight lifting - how often, machines
weights, in what order to do the exercises, how quickly to lift a
weight, how long to wait between sets - the research is equivocal.
But, Kraemer said, those are details that should not concern
people. Despite the fervent marketing of programs and the magical
properties attributed to various regimens, there is little difference in
the results of varying resistance-training systems, he said. What
matters is keeping the weights heavy enough to stress the muscles,
exercising consistently and working every major muscle group.
"Think of yourself as being on a continuum," Kraemer said. "At
beginning, when you are out of shape, just about anything can work."
Copyright 2002 The New York Times. All rights reserved.