The
Miracle of Muscle
By
J.D.RATCLIFF
Events that take place when a dog wags its tail, a baby toddles across the
floor or you scratch your nose with your forefinger dwarf in complexity the
workings of a hydrogen bomb. All are
examples of muscular contraction—so commonplace we pay it no heed, yet so
mysterious that it has baffled the most gifted scientists.
More than half of the human body is muscle—“the most
remarkable stuff in nature’s curiosity shop,” as one scientist had said. From birth to death, muscles play a critical
role in everything we do. They propel
us into the world in the first place—when the womb suddenly empties
itself. They provide nearly all our
internal heat. They push food along the
digestive tract, suck air into lungs, and squeeze tears from lachrymal glands. And finis is written for fails and us when
the heart muscle, after beating two and half billion times in a 70-year life
span, flatters.
We speak of “muscles of iron.” Yet the working or contractile element in
muscle is a soft jelly. How this jelly
contracts to lift 1000 times its own weight is one of the supreme miracles of
the universe. An elaborate series of
chemical and electrical events, which would require hours of days to duplicate
in the laboratory, occur almost instantaneously when a muscle contract—the
twitch of an eyelids, for example.
There are three types of muscle in the human
body. One is the striated muscle, which
looks like a sheaf of hair-sized filaments.
These are the muscles of motion—that propel us when we walk, that lift a
forkful of food, that nod our heads.
Next come the “smooth” muscles.
These control such involuntary actions as the churning of intestines
during digestion, the dilation of the pupil.
A third type is found in the heart.
In structure, it is midway between the other two. All types of muscle are startlingly
efficient machines for converting chemical energy [food] into mechanical energy
[work].
Hundreds of books and scientific papers have been
written on muscles—but none explains fully the process by which muscles
contract, how you wiggle a tow. “It is
essential that we understand these puzzles,” said Dr. Albert Szent-Gyorgyi,
Nobel Prize winner and scientific director of the National Faundation for
Cancer Research. “In one was or
another, failure of muscles to contract porperly accounts for the vast majority
of deaths—from heart failure, high blood pressure and other diseases.”
It is the riddles such as these that Dr.
Szent-Gyorgyi and his co-workers went years seeking to solve. Fiber by fiber and molecule by molecule they
have taken muscles apart, and then fitted them together again trying to discover
the mechanics of muscular action.
Research suggests that muscle is never thoroughly
relaxed. Because it is partially
tensed—something like a taut spring—it is ready for almost instantaneous action
when an electrical message from the brain orders it to contract.
TWP proteins, Dr. Szent-Gyorgye has found, are
mainly responsible for the contraction—actin and myosin. Alone, neither is contractile. But when an electrical impulse from the
brain orders the batting of an eye, or the wrinkling of a nose, actin and
myosin combine to form actomyosin, which is contractile.
In a sense of actomyosin is the muscular
‘engine.’ Its fuel is a remarkable
chemical substance, adenosine triphosphate—ATP for short. ATP is a submicroscopic bombshell of energy. Actomyosin fibers contract violently on
contact with it. At death, ATP
disintegrates rapidly and muscles become hard, inelastic. This is rigor mortis.
To demonstrate the critical importance of ATP, Dr.
Szent Gyorgyi stored rabbit muscles, which had been washed free of the
chemical, in freezers for periods up to a year. Taken out, thawed and touched with ATP, the hard, brittle muscles
spring to life; once again they show the elasticity they had when they
propelled a rabbit in its hopping gait.
Creating ‘living’ tissue in the laboratory has been
something of a scientific will-o-the-wisp.
But muscle researchers have come close to it. Dr. Szent-Gyorgyi mixed jelly-like actin with jelly-like
myosin. Then, with the aid of a tiny
glass nozzle, he spun this material into gossamer filaments. Watching through a microscope, he added a
droplet of ATP to the fluid surrounding the filament. There was violent contraction!
He had created artificially perhaps the most fundamental of all life
processes—muscular contraction. “It
was, “he says, “the most exciting moment of my life.”
Where are such experiments leading? They may open a new frontier of attack on
some of mankind’s greatest ills. There
is no logical reason why the human heart should beat two billions times during a
lifetime, the suddenly fail. Almost
nothing is known about the cruel crippling of muscular dystrophy; or why
muscles in blood-vessel walls should tighten to produce the misery of
hypertension; of why the uterine muscles of many women become crumply contracted
each month to cause painful distress.
Once the mechanics of muscular action are thoroughly understood, we may
be at the beginning of a new biology, a new medicine.
Meanwhile, there is a great deal all of us can do to
keep our muscles functioning well.
First, they must be promptly fed.
Generally speaking, the average diet includes all the protein needed for
muscle repair, and all the carbohydrate required for muscle fuel. But muscles can starve through lack of
exercise—witness hospital patients who eat perfectly balanced meals and get out
of the bed too weak to walk. Reason:
muscles are nourished by thousands of miles of hairline capillaries, which
transport food and carry off wastes. In
the sedentary adult, large numbers of these capillaries are collapsed, out of
business, nearly all the time. Exercise
alone can open them up and provide better muscle nutrition.
A number of studies have shown the beneficial
results of exercise on the heart muscle.
A study in London bus drivers, for example, showed that drivers, who sat
all day, had far more heart trouble than conductors, who were constantly on the
move. Similar checks have shown office
workers more prone to heart disease than postal workers.
Often, muscles become unduly fatigued when required
to work at too fast a rate. One
housewife rushes at her chores and is worn out by noon, while her more
leisurely sister accomplishes just as much and finishes the day still
fresh. A series of treadmill
experiments tells why. In one, subjects
were paced at 140 steps a minute.
Gradually speed was increased to 280.
At the doubled rate, oxygen requirements of muscles increased eightfold
supplying such demands are fatiguing in it.
All work and exercise should be paced to get the most of our muscles.
Like all other body organs and tissues, muscles must
have rest. Millions of people sleep the
traditional eight hours, and then get up exhausted. The most likely explanation: one set of muscles has been cramped,
tensed all night—wearing out the rest of the body. The best way to avoid this is to become acquainted with your own
muscles.
Lie quietly in bed, legs straight, and arms at the
side. Contract one set of muscles at a
time, and consciously relax them. Start
with the feet and work upward. In a
matter of minutes, real relaxation can be achieved—leading to more restful
sleep.
Overburdened or weakened muscles sometimes require
additional support. This is
particularly true of the back muscles, whose chief function is to hold the body
erect. Often, low-back pain can be
traced to weakness of these muscles. Every physician has his favorite set of
exercises to provide new strength. But
until exercises are well under way, extra support is sometimes necessary. A strong extra-wide belt is useful for this
purpose.
It is best, of course, not to wait until muscles are
weakened before giving them the care and consideration they deserve. For, to a great degree, we are what our
muscles make us—sick or well, vigorous or droopy, alive or dead.
