If skeletal muscles (voluntary) are severed from the nerve fibers in the autonomic nervous system, they atrophy and paralysis results. If smooth and cardiac muscles (involuntary) are severed from their external nerve source, they continue to function.
Smooth muscle tissue is present in the walls of blood vessels, digestive tract, urinary passages, bladder, genital ducts of the womb, trachea, spleen, eye, gall bladder and trachea.
Smooth muscles generally fall into the involuntary reflex category and perform four types of involuntary activity. They are the muscles that are involved in the peristaltic action that moves the chyme through the intestinal tract by contracting and creating wave like motions. They are the muscles involved in eliminating urine and fecal matter from the body and are responsible for regulating the size of openings like the pupil of the eye. They also have the ability to constrict blood vessels and other tubes in the body.
Cardiac muscle is found in the walls of the heart. Cardiac muscle is similar in construction to skeletal muscles except the striations are less distinct. Because of their function and the construction of the heart, cardiac muscles are arranged in bundles or branches of elongated fibers, similar to the skeletal muscles, but they extend in a spiral fashion, especially in the ventricles. The nuclei in the fibers are centrally located and are not encased in a separate membrane. Contractions of the cardiac muscle are involuntary originating in the sinoatrial node of the heart. Impulses are transmitted through the antrioventricular node to all parts of the heart. The junction point with surrounding cells is characterized by dark transverse bands called intercalated discs.
There is not always a clear cut dividing line between the actions of voluntary muscles. Sometimes voluntary muscle function will be involuntary, as in a reflex action, and involuntary muscles may come under conscious control, like slowing the heart rate during deep meditation.
Conditioning is beneficial to all muscles. But, more isn’t always better. It’s been found that walking is better than running and my personal experience is that light weights and lots of repetitions are superior to a few repetitions using heavy weights. In both cases injury is the determining factor.
Running jars the internal organs and pounds the joints. When you have to open your mouth to breathe while exercising, you’ve gone out of your comfort zone, are much less likely to continue with your program and you’re initiating the fight or flight reflex. Fight or flight starts the hormones flowing, including adrenaline and cortisol. Hormones are necessary for life and health but stress in everyday life provides more than sufficient amounts of the fight or flight hormones. Excesses of stress related hormones cause premature aging and have been linked to various degenerative diseases. Brisk walking can provide the same benefits as running, without the problems.
Weight bearing exercise is good for many things including the slowing of osteoporosis. Heavy weights may stroke the ego but can seriously damage the body. Tendons attach the muscles to the bones. Tendons are tough whitish cords, consisting of numerous parallel bundles of fibers composed of collagen. Cigarettes, and some drugs, deplete the body of collagen. Most long-term smokers are easily recognized by the wrinkles in their faces. Collagen is a main component of the skin.
Tendons are flexible but are not made too stretch and that is where problems with heavy weights can arise.
If we lift weight that’s at near or in excess of our limit, we’re taking a chance of pulling the tendon loose from the attachment point. This can result in acute or chronic problems. At best the exercise program is interrupted for a period of time and at worst, it can be the beginning of lifelong misery.
I have a personal friend who tore a tendon loose, sometime in the mid 80’s, while bench pressing heavy weights. The problem wasn’t able to be resolved with rest and inactivity and required a major operation to the shoulder joint. The result of the surgery was loss of range of motion and discomfort, plus not being able to lift even moderately heavy weights without pain.
If we think about the benefits of lifting 100 pounds 5 times we find the total pounds lifted would be 500 and if 100 pounds is our limit, our chances of injury are quite high. If we use 10 pounds and do 100 repetitions we realize our total pounds lifted are 1000. If we begin slowly with light weights, even soup cans will work, and a low number of repetitions and work our way to the 100 figure, we lower our chances of injury many times. Go for the rep’s first and after reaching your goal, then begin increasing the weight.