What are the interesting facts about muscles?

*** Types of Muscles
There are three types of muscles in your body. Each performs a different job. One is the cardiac muscle, which pumps the heart. The heart muscle rests half its life, for after each contraction it must relax until the next contraction.
Another type of muscle is smooth muscle. Smooth muscles wrap themselves around most of your internal organs, including blood vessels. Like heart muscle, whose action is involuntary, smooth muscles are not consciously controlled. They perform such vital functions as moving fluids through your kidneys and bladder, pushing food through your digestive tract, regulating the flow of blood through your vessels, shaping your eye lenses, and dilating the light aperture of your pupils.
Most of your 650 muscles are skeletal muscles. These carry out your voluntary movements. You learn to control these muscles from birth. A baby, for example, learns to move its arms and legs so that it can walk and balance. Because muscles can only contract, skeletal muscles work in pairs. When one muscle contracts, the other relaxes. Without this teamwork, every time you scratched your head, you would have to let gravity pull your arm down. Instead, your triceps, the muscle that is the partner of your biceps, contracts, enabling you to straighten out your arm quickly.
Muscles vary in size and shape. Some are long and slender, such as the hamstring muscles of the legs. Others are heavy and thick, such as the gluteus muscles in the buttocks. All are designed to allow you to move. The rib cage would be rigid if it were not for muscles that fill the gaps between the ribs. These enable the chest wall to move like an accordion, helping you to breathe. Much like the layers in plywood, abdomen muscles are arranged in sheets at different angles, to prevent your abdominal organs from falling out.

*** Keep Your Muscles in Shape
“Exercise helps the whole body, inside and out. . . . Muscles exercised regularly do a better job at everything,” states the book Muscles: The Magic of Motion. Exercise produces good muscle tone, which better supports your internal organs and helps your muscles resist fatigue.
Two different types of exercise are beneficial for your muscles. Anaerobic exercise, in which you lift weights a short time each day, strengthens your muscles. Stronger muscles not only store more sugar and fatty acids but can burn these fuels more efficiently, helping your muscles resist fatigue.
Aerobic forms of exercise, such as jogging, swimming, bicycling, or brisk walking, promote overall fitness. This kind of endurance exercise increases blood flow to muscles and increases mitochondria, which create ATP, the energy compound needed to make your muscles contract. Your heart especially benefits from this type of exercise, which may even help prevent a heart attack.
Bending and stretching the muscles before you do strenuous exercise can help prevent sprains or other damage to your muscles. Such warm-up exercises raise the temperature in your muscles, which circulates more blood to them and, in turn, helps enzymes produce more energy, enabling your muscles to contract better. Cooling down with the same exercises you warmed up with helps prevent aches and stiffness by removing the lactic acid buildup.
However, it must be noted that you can damage skeletal muscle by exercise that is too vigorous, especially if you are not trained. Also, if you place too much tension on your muscles by repeated lengthening contractions, as you could when lowering a heavy load slowly or running downhill, you may tear muscle fiber. Even a small tear resulting from strain can cause painful muscle spasms and inflammation.
Take care of your muscles. Give them the proper exercise and rest so that they can continue to serve you like a well-designed engine, your body’s ‘ultimate motor.’

*** Muscles and Nutrition
Good nutrition is a key factor in maintaining healthy muscles. Foods rich in calcium, such as dairy products, and in potassium, such as bananas, as well as citrus and dried fruits, deep-yellow vegetables, nuts, and seeds help to regulate muscle contractions. Whole-grain breads and cereals supply iron and B-complex vitamins, especially B1, which is crucial in converting carbohydrates, proteins, and fats into the energy fuel your muscles need. Drinking plenty of water not only helps to maintain your electrolyte balance but also flushes out lactic acid and other waste products that could interfere with muscle function.