A good exercise program for muscle activity

When you are at rest all the muscles of the body use only about one thirtieth of the oxygen they can use during maximum effort. With a well-rounded exercise program, they can be made to use much more. When they do, the heart will respond, pumping harder to get more oxygen-carrying blood into circulation, and over a period of time, heart pumping efficiency will increase; the heart will pump more blood with each stroke. At the same time, lung capacity-much of it never used in sedentary living-will enlarge to absorb and feed more oxygen into the blood- stream. The higher oxygen content will aid muscle as circulation improves in both quality and body; the capillaries penetrating into muscles will open and become more effective.

A good exercise program also will help to strengthen the muscles around the veins in the lower part of the body, and this is of considerable importance. When you stand, the veins in the legs expand and there may be a tendency for them to become distended with blood which pools in them 50 that less blood is available for circulation through the rest of the body. As less blood returns to the heart from the veins in the lower part of the body, the heart, with less blood to eject with each beat, tries to compensate by increasing its beat rate. But this is not always effective and does impose added stress on the heart. The amount of blood that can pool in the lower veins depends considerably on the amount of pressure by the muscle tissues around the veins. If the tissues are tight and firm, the expansion of the veins is limited.

Soft muscles without tone do not provide much external support to the veins to prevent their expansion. Thus, a good program of exercise can have many admirable effects throughout the body-in terms of health of heart, lungs, muscles, blood vessels. We suggest that you read, in connection with this discussion, the contents of Chapter 8 on exercise.

A word here about nutrition; It, too, is vital in the proper care of muscles. A good diet containing the sources of protein described in Chapter 6 will help you build and maintain strong, healthy muscles. 

Muscle care and Fatigue

MUSCLE CARE

The voluntary muscles are the only ones that require your everyday care. Muscles remain in good condition only when they are used. If they fall The Muscles / 195 into complete disuse, they atrophy or waste away. Short of this, if they are used relatively little, they lose strength and vigor and their tone diminishes. Healthy vigorous muscles are important for many reasons: for good posture, graceful movement, and a sense of well-being. The spring in the step of a healthy vigorous man isn't simply a matter of well-developed muscles, but of the contribution that good muscular health makes to overall body health and even to mental outlook. Also, strong muscles protect the bones, joints, and internal organs more effectively against injury. In our increasingly sedentary way of life, unless we resort to special measures, our muscles are victimized by disuse.

Actually, when muscles are not used, they have relatively little need for blood and nourishment; and as a result most of the capillaries, the tiniest blood vessels which supply them, collapse and remain collapsed, out of business most of the time. The greater the activity of muscles, the more the capillaries opens up and, in fact, the more capillaries may be developed by the body to supply the need. With sedentary living, there is little demand. One famed experiment by Dr. Hardin Jones of the University of California has shown that the average sedentary American man is, in terms of muscle circulation, middle-aged by the time he is 26.

Using Geiger counter tests to follow blood flow through muscles in teen-agers and in 500 industrial workers, Dr. Jones established that between the ages of 18 and 25, the flow drops 40 percent; by the age of 35, it is down 60 percent, at which point, in the sense of physical vigor, the average sedentary man is less than half the man he used to be. Because of our sedentary living, deliberate exercise is essential-and this applies to all of us, women and children as well as men. The objective of the exercise should not be the development of big muscles, for muscle size is not a true measure of fitness. A well-founded exercise program should aim at strengthening muscles and also the circulatory system in the interest of endurance-the ability to sustain activity and keep going without quick fatigue. 

muscle anatomy muscle activity

Muscle Power

Among the many additional muscles are those of expression-small bundles of fibers around the eyes, mouth, and nose which we use to look angry or surprised, to wink, sneer, smile, frown. In the gastrointestinal system, there are voluntary muscles at the top, in the upper part of the esophagus. But in the walls of the lower esophagus as well as most of the stomach and intestines are involuntary muscles that help push food along. Actually, there are two layers of such muscles which work in concert: one, a circular layer, contracts to narrow the gastrointestinal tract; the other, longitudinal, and contracts to widen the tract again and make way for further narrowing.

Between the esophagus and the stomach, and at other points in the digestive tract, are thick muscular rings, called sphincters, which contract at intervals and can remain contracted for extended periods if necessary to regulate the flow of food and liquid. MUSCLE TONE Imagine for a moment that you have a rope fastened to a small wagon. In effect, the rope is a tendon and the wagon is a movable bone. If you pull on the rope, the wagon will move toward you. But if the rope is lying slack on the ground, you first must pull it tight before the wagon can begin to move. If the rope is kept taut, the wagon will move as soon as you pull. Most voluntary muscles of the body keep their ropes tight, so to speak. They are partly contracted at all times. Rarely, for example, does the jaw sag, and you can hold your head and shoulders erect for hours without fatigue. This ability to maintain partial contraction is muscle tone. Tone may be maintained, and the muscles prevented from becoming slack and deteriorated, by regular exercise and proper nutrition.

TYPES OF MUSCLES Muscle Fibers

TYPES OF MUSCLES 

Each muscle is made up of a bundle of fibers, each of which is about the size of a hair and capable of supporting 1,000 times its own weight. All told, there is something more than 6 trillion fibers in the muscles throughout the body. There are three types of muscle tissue. One, when viewed under a microscope, has dark and light bands across the fibers, and is known as striped muscle. It is also called skeletal muscle because it is attached to some part of the skeleton. And it is classed as voluntary muscle because it is under the control of the conscious part of the brain. This is the type of muscle used to walk, write, lift, and throw to perform any movement we actually will to be done.

A second type of muscle, called smooth or involuntary, lacks the dark and light bands. This type of muscle handles the functions of all internal organs except the heart. It is involved in the vital movements of the stomach and intestine, for example. It is called involuntary since we do not have direct control over its action. Its workings are automatic, freeing us from concern over it, allowing us opportunity to concentrate on other matters. The third type of muscle that of the heart is called cardiac. It is striped like the voluntary type but has no sheaths as the voluntary does. It, too, is involuntary.

Muscle fibers vary considerably in length, from as little as 0.04 inch or even less to 1.5 inch or more. The diameter, of course, is very small, as little as 0.004 inch or even less. When a muscle contracts, it becomes shorter by as much as one third to one half, and as it shortens, it thickens. Most skeletal muscles are linked to a bone either at one end or at both ends. The tendons, or sinews, which do the linking, vary considerably in size, ranging up to more than a foot in length. Ligaments, like the tendons, are made up of strong fibrous tissue, but their function is to bind bones together. Tendons join muscle to bone; ligaments join bone to bone. Ligament fibers stretch. Tendons are so strong that a bone may break before the tendon attached to it gives way. When muscles join bones, one of the bones usually functions as an anchor to help move the other bone.

The point where the muscle attaches to the anchor bone is known as the point of origin. The attachment to the bone that does the moving is called the insertion. Before a muscle can contract, it must receive a contract signal. In the case of voluntary muscles, the signal comes from the brain via the central nervous system and is relayed' instantly through tiny nerves that reach each of the fibers involved. Involuntary muscles get their signals from the autonomic nervous sys- tem, which is concerned with the regulation of body functions that do not have to be under conscious control. To be sure, even in the case of voluntary muscles, you are not required to give a direct order-to take the time to stop and think and issue a command for a particular muscle to contract. You simply decide to bend an elbow, move a finger, throw a ball-and the brain and nervous system translate the decision into orders which go to the proper muscle fibers. 

Excercises and Muscle activity - Benefits and precautions.

In addition, the well-exercised body requires a smaller amount of muscle activity for a given physical performance than the untrained body. Many studies indicate not only a lower incidence of heart attacks among the physically active than among the sedentary but also a greater likelihood, when a heart attack does occur, for the physically active per- son to recover. One possible reason is that exercise appears to promote the development of supplementary blood vessels which can take over the burden of nourishing the heart muscle when a coronary artery is blocked in a heart attack. 

In a recent study to try to explain why physical exercise may ward off heart attacks, investigators at the University of Oregon Medical School and radioactively tagged cholesterol to animals. Because of the tagging, they could follow what happened to the cholesterol. (It is a high level of blood cholesterol that is thought to foster development of atherosclerosis, the pile-up of fatty deposits on blood vessel walls that may shut down blood flow to the heart muscle, producing a heart attack.)

The Oregon workers found that the more the animals exercised, the more cholesterol was broken down; the less exercise, the higher the levels of cholesterol in the blood. In Israel recently, a special program of activity has been set up for men who have had actual heart attacks. 

In the program, exercise is gradually intensified until it becomes quite vigorous, including jogs along the Mediterranean Sea. The program is carried out under close medical super- vision. Dr. Daniel Brunner, its director and Associate Professor of Physiological Hygiene at Tel Aviv University, reports that many of the patients now are more fit than before their heart attacks-and more fit than non-trained people of their age who have not had coronary artery disease.

ACTIVITY AT ANY AGE That even elderly people, men in their 70's, can regain much of the vigor and physical function of their 40's through carefully planned physical activity has been demonstrated by a University of Southern California investigator. In the program, in which exercise is prescribed with the same care as a physician prescribes medications, 69 men aged 50 to t\7 have been working out one hour three times a week. 

Their closely supervised regimen includes calisthenics, stretching, swimming, and jog- at the end of one year, these were the results expressed in terms of: blood pressure improved by 6 percent; body fat 4.8 percent; oxygen consumption increased by 9.2 percent;  

 arm strength increased by 7.2 percent; and nervous tension reduced by 14 percent. It would be an invitation to disaster for older people and, for that matter, for younger people to rush pell-mell into vigorous activity after long years of sedentary living without having a thorough physical checkup first and without undertaking activity on a gradual, progressive basis under medical supervision. But there is growing support now for the concept that proper physical activity can help the aged and can even delay the aging process, prolonging the active years, retarding and possibly helping to avoid some degenerative diseases.