HOW MUSCLES GROW - Rodale,...
Transcript of HOW MUSCLES GROW - Rodale,...
F or years, the focus of strength-
training science was almost en-
tirely on building bulk. But the
latest research shows that you can’t reach
optimal size unless you bring other factors
into play. Organizing your workouts around
movement patterns, a concept we’ll talk
about throughout this book, is one key
factor. Another is developing the network of nerve fibers that thread through
muscles and eventually snake back to the brain. Every time you lift, the body
releases chemicals that thicken individual muscle fibers so they contract with
more force. Lifting increases the supply of capillaries, the tiny networks of
blood vessels that carry in nutrients and cart away
wastes. At the same time, the endless repetition of
lifting conditions nerve fibers and improves their ef-
ficiency at firing muscles into action. That’s why a
tall, lean man who lifts smart and develops a finely
honed nervous system might be stronger than the
stocky man with tree-trunk legs and a barrel chest.
What you want, of course, is to bring all these
factors into play. Even if you lift for practical rea-
sons—to protect your back, say, or build endurance
for weekend sports—there’s a lot to be said for de-
veloping a physique that not only works well, but
gets noticed. That’s what this book is all about.
B R E A K ’ E M D O W N , B U I L D ’ E M U PEvery man has a mix of slow-twitch and fast-twitch
muscle fibers. Fast-twitch fibers are the ones that
contract powerfully and give pure strength. They fa-
tigue quickly, which is why you might be able to curl
a 50-pound dumbbell just a few times. The slow-
twitch fibers are made for endurance. They can’t
propel the kinds of force generated by fast-twitch
fibers, but they can go just about forever.
Each of your skeletal muscles is made up of
water, protein, fat, and carbohydrates, along with
glycogen (the stored form of blood sugar) and a host
of amino acids and chemical compounds. All of the
usual lifestyle factors—good nutrition, good sleep,
adequate rest between workouts, and so on—are
critically important in any lifting plan. Men who op-
timize these factors while maintaining a tough
workout regimen can achieve steroidlike results
without ever touching those noxious drugs.
There’s another factor, not related to lifestyle,
that can take you from merely fit to built. It’s called
muscle damage. We’re not talking about pain or
H O W M U S C L E S G R O W 3
1HOW MUSCLES
GROW
001-018_MaxMuscle_01PREP 10/4/05 9:52 AM Page 3
post-workout soreness, though those are pretty good
indicators of what’s happening beneath the surface.
At the level of individual muscle fibers, damage and
destruction are your best friends.
Strip away all the scientific jargon. Weight lifting
boils down to what trainers call the progressive
overload of skeletal muscles—in other words,
pushing those muscles harder than they’re accus-
tomed to working.
Every time you lift, you produce tiny tears in
the muscle fibers. Depending on your level of fit-
ness and how hard you work, the tears can be as
small as just a few molecules across, or large
enough to affect entire muscle cells (along with the
supporting connective tissue). The body then re-
sponds to tears in muscle fibers by making bigger
proteins as well as more proteins, which translates
into bigger muscles.
You obviously don’t want to lift yourself into
traction. But you need some damage, and that
means pushing yourself. A man who never taxes his
muscles to their uppermost limits can lift every day
for years without gaining appreciably in size.
Conversely, the man who overloads his muscles the
right way will get bigger much faster.
The process of tearing down and rebuilding
muscle is incredibly complex. Basically, here’s what
happens.
• When you lift, damaged muscle tissues release
signaling factors, substances that attract neu-
trophils, macrophages, and other immune cells
to the damaged site.
• The immune cells trigger inflammation. This
process is designed to remove damaged tissue
from around the torn fibers. If you’ve overdone
it, the inflammation might be painful. If you’re
lifting smart, however, you’ll just feel a pleasant
tightness.
• The immune cells release substances that stim-
ulate the production of cells called satellite cells.
The satellite cells, stimulated by hormones and
other anabolic chemicals, then merge with the
muscle cells as part of the repair process.
At the end of the process, the muscle tear is repaired.
But the muscle itself isn’t quite the same one you had
before because it’s gained additional and larger cells.
It’s like nailing a 2-by-4 to a shaky gate. The struc-
ture is stronger—and bulkier—than it was before.
The traditional thinking was that muscles in-
4 T H E S C I E N C E O F S I Z E
NOKIDDING? M O R E R E P S O R M O R E W E I G H T ?
It’s probably the oldest locker room debate, and still the most common: Do you get optimal results using the heav-
iest possible weight, even if you can only finish 1 repetition? Or is it better to stack up the reps using lower weights?
The definitive answer: It depends.
If your goal is to boost endurance, higher reps at lower weights make sense. But most men want to gain muscle
and definition. To do that, you need to push serious iron.
A recent report compared the effects of different training loads on strength and muscular hypertrophy (increased
size). Men who lifted 80 percent to 95 percent of their 1 repetition maximum—the heaviest weight they could lift
once at full-out exertion—had greater increases in size than those who stuck with lower weights.
001-018_MaxMuscle_01PREP 10/4/05 8:16 AM Page 4
takes work, a lot of it. But the initial “quick jumps”
in strength when you start lifting, or bump up your
workouts another notch, have relatively little to do
with muscle size. They’re mainly due to neural fac-
tors—alterations in the nervous system that increase
force and power in an astonishingly short time.
Think of these gains as confidence builders. You’ll
move up in weights very quickly. The heavier
weights take you further into the realm of muscle
overload, and that’s the secret to size.
Nothing increases muscle mass faster than
lifting, not even steroids. In a 10-week study that di-
rectly compared weight lifting with steroids for
muscle gain, guys on a lifting program increased
their bench weight by 22 pounds, compared to the
19-pound gain among men taking steroids. The
lifters increased their squat poundage 55 pounds,
compared to a scant 28 pounds in the steroid group.
Nor will combining aerobic exercise and strength
training increase your muscle gains. Aerobic work-
outs can get the heart and lungs working like a bass
variably reached the point at which increases in size
basically stop. New research suggests that doesn’t
happen. It’s possible that once muscle fibers reach
a certain size, they split like twigs on a tree, creating
more muscle fibers. Each of these new fibers will
grow until it reaches maximum size, then it will split
again. This could mean that every man can keep get-
ting bigger, no matter how long he’s been lifting.
B I G G E R , F A S T E RThe ripped physiques and hard-core musculatures
that most men would kill to have don’t come
quickly. But you can get there a lot faster than you
probably think. Scientists have known for almost 50
years that muscular strength increases rapidly when
men start a lifting program. Gains in maximal force
of up to 15 percent have been measured after a
single training session.
Obviously, no one becomes Schwarzeneggeresque
in a few days—or a few months. That kind of build
H O W M U S C L E S G R O W 5
T H E “ T E R M I N A T O R ” G E N EMen are undergoing record numbers of appearance-enhancing procedures these days, but at some point, we might
look back on hair replacement and chest implants as relics from the Dark Ages. On the horizon: the ability to ma-
nipulate a man’s genetic material to create massive size without a hint of sweat.
Scientists have discovered some of the genes that control muscle growth. Some genes limit size; others enhance
it—sometimes to a startling degree. When scientists blocked the myostatin gene, mice and cows developed double
the usual amount of muscle. Other genetic pathways, such as the Akt/p70S6 kinase protein synthesis pathway, may
cause an increase in muscle growth and an accelerated rate of fat burning.
Leaner and bigger without lifting a finger, let alone lifting weights? It’s a tantalizing possibility, though light-years
from reality at this point. The studies have been done on animals, not humans. And genetic tinkering is always risky.
It’s impossible to predict what might happen when genes are artificially switched on or off. The genes that control
muscle growth might turn out to control other things, as well.
So, don’t give up your gym membership yet. Even if it were possible today to get that genetic edge, the men who
work out hard would still be a step ahead.
001-018_MaxMuscle_01PREP 10/4/05 8:16 AM Page 5
drum. Aerobic exercise also boosts endurance, burns
more fat calories, reduces the risk of dozens of dis-
eases, and generally makes you healthier. What it
won’t do is make you bigger. In fact, it has just the
opposite effect.
Researchers looked at gains in strength and
muscle size in three groups of men: those who lifted,
those who did endurance workouts, and those who
combined both. Men in the strength-training group
showed greater muscle gains than those in either of
the other groups. Endurance training actually lim-
ited increases in strength and muscle size.
This is because skeletal muscle can’t adapt to
both strength and endurance training simultane-
ously. Put another way, the muscle changes that you
experience when you run, for example, are the op-
posite of the changes needed for maximum size. The
muscles simply can’t adapt to both activities simul-
taneously. Running before a weight-lifting session
produces muscle fatigue that makes it impossible to
generate the necessary muscle tension to reach peak
power.
This doesn’t mean you should blow off running,
swimming, or other endurance sports. They’re
good for you. But if your primary goal is to get
bigger, focus on the weights first. To keep the heart
rate up and the calories burning, keep moving
when you lift, with nonstop motion from one ex-
ercise to another.
L I F E L O N G P O W E RMost men will never compete on the bodybuilding
circuit or line up to be the year’s top male model.
Guys lift because it makes them look and feel better.
They’re stronger generally, which makes the ho-
hum, practical details of living, like hoisting a 50-
pound bag of dog food out of the car, a little easier.
If you keep lifting—not just this week or next
year, but over the decades—you’ll see payoffs such
as a much lower risk of obesity, diabetes, high blood
pressure, and heart disease. You’ll also have a
physique that other men will envy. The sad truth is
that most men lose a lot of muscle as they age.
Weight lifting is by far the best way to reverse
muscle declines. Older men who lift just a few times
a week don’t lose muscle at all. They gain mass as
well as strength.
Most of us aren’t satisfied with the status quo.
We want more—bigger arms, a stronger chest, that
elusive washboard gut. You can have all this and
more. But there’s no lazy way out. Remember the
term progressive overload. Push your muscles hard,
and push them often. We’ll show you how.
6 T H E S C I E N C E O F S I Z E
001-018_MaxMuscle_01PREP 10/4/05 8:16 AM Page 6