Life Span Changes

Signs of aging in the muscular system begin to appear in one's forties, although a person usually still feels quite energetic and can undertake a great variety of physical activities. At a microscopic level, though, supplies of the molecules that enable muscles to function—myoglobin, ATP, and creatine phosphate—decline. The diameters of some muscle fibers may subtly shrink, as the muscle layers in the walls of veins actually thicken, making the vessels more rigid and less elastic. Very gradually, the muscles become smaller, drier, and capable of less forceful contraction. Connective tissue and adipose cells begin to replace some muscle tissue.

By age 80, effects of aging on the muscular system are much more noticeable. Nearly half the muscle mass present in young adulthood has atrophied, particularly if the person is relatively inactive. Aging affects the interplay between the muscular and nervous systems. Decline in motor neuron activity leads to muscle atrophy, and diminishing muscular strength slows reflexes.

Exercise can help maintaining a healthy muscular system, even among the oldest of the old. It counters the less effective oxygen delivery that results from the decreased muscle mass that accompanies age. Exercise also maintains the flexibility of blood vessels, which can decrease the likelihood of hypertension developing. However, a physician should be consulted before starting any exercise program.

According to the National Institute on Aging, exercise should be of two types—strength training and aerobics—bracketed by a stretching "warm up" and "cool down." Stretching increases flexibility and decreases muscle strain, while improving blood flow to all muscles. Strength training consists of weight lifting or using a machine that works specific muscles against a resistance. This increases muscle mass and strength, and it is important to vary the routine so that the same muscle is not exercised on consecutive days. A side benefit of strength training is that stronger muscles can alleviate some of the pressure on the joints, which may lessen symptoms of osteoarthritis. Aerobic exercise, which the institute recommends should begin after a person is accustomed to stretching and strength training, improves oxygen utilization by muscles and provides endurance. Perhaps the best "side effect" of exercising the muscular system as one grows older is on mood—those who are active report fewer bouts with depression.

H What changes are associated with an aging muscular system?

Describe two types of recommended exercise.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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