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Senior Fitness: Aging and the 11 Body Systems

Senior Fitness: Aging and the 11 Body Systems

Table of Contents

Article by Tammy Petersen

Senior Fitness is Important for Successful Aging

In this article we will look at the role of senior fitness in maintaining health as organ systems age.

According to the National Institutes on Aging (NIA) physical activity and remaining fit is an important part of healthy aging. No matter health and physical ability, a person can gain a lot by staying active. So, senior fitness has a lot to do with successful aging.

Low levels of fitness is more to blame than age

In fact, studies show inactivity and low levels of fitness is more to blame than age for the health problems experienced by older adults. Lack of physical activity also can lead to more visits to the doctor. This then leads to more hospitalizations and more use of medicines for a variety of illnesses.

Staying active can help:

Aging and the body systems

With aging changes occur in cells and in organs. How well organs function depends on how well the cells within them function.

Because older cells function less well than younger cells, aging affects all systems of the body. Also, function is decreased because some cells die and are not replaced.

In the remainder of this article we will explore the changes to each body system as a person ages. We will also look at the role of senior fitness in maintaining health and delaying problems experienced in each organ system with advancing age.

Cardiovascular System

The main function of this system is the internal transport of cells and dissolved materials, including nutrients, wastes, and gases.

cardiovascular system lead picture

Changes in the cardiovascular system important to know for senior fitness

Blood

Age-related changes in the blood include a decrease in the volume of packed red blood cells. There can also be a constriction or blockage of peripheral veins by a blood clot. If the clot becomes detached, it might pass through the heart and become wedged in a small artery. This happens most often in the lungs causing a pulmonary embolism.

Blood vessels

Age-related changes in blood vessels are often related to arteriosclerosis, a thickening and toughening of arterial walls. So, the walls become less tolerant of sudden increases in pressure.

Consequently, this can lead to an aneurysm or rupture of the vessel.  The result is a stroke, heart attack, or massive blood loss depending on the vessel involved.

Additionally, calcium deposits can form on weakened vascular walls which increases the risk of a stroke or heart attack. Blood clots can form as plaque deposits. And, there might be pooling of blood in the veins in the legs because valves are not working effectively.

Heart

Age-related changes in the heart include:

  • A reduction in maximum cardiac output.
  • Changes in the activities of nodal and conductive fibers.
  • A reduction in the elasticity of the heart’s fibrous tissues.
  • Progressive atherosclerosis (fatty buildup or plaques) that can restrict coronary circulation.
  • Replacement of damaged cardiac muscle fibers by scar tissue.
Heart atrophy

With aging, the heart can atrophy, remain unchanged, or develop moderate or marked hypertrophy. Atrophy usually coincides with various wasting diseases and is not observed during aging in healthy persons.

A modest increase in left ventricular wall thickness is normal with age. While an exaggerated increase occurs in persons with hypertension.

Other normal age associated changes include enlargement of the left atrium and slight enlargement of the left ventricular cavity.

Aerobic capacity

Aging affects aerobic capacity and cardiovascular performance during exercise. Peak exercise capacity and peak oxygen (O2) consumption decrease with age. But there is great variation from one individual to another.

Aerobic capacity decreases by 50% between ages 20 and 80. This is because maximum cardiac output decreases by 25% and peripheral O2 utilization decreases as muscle mass and strength decrease.

This decrease in muscle mass is not inevitable and why senior fitness is such an important part of aging!

Other possible disorders include inefficient redistribution of blood flow to working muscles. Reduced O2 extraction and utilization per unit of muscle can also occur.

Cardiovascular system facts for senior fitness

Lifestyle and exercise information for senior fitness

Cross-cultural studies suggest that diet, exercise habits, and smoking also affect the blood vessels and hearts of older persons.

For instance, a difference in dietary sodium accounts for some of the differences in age-associated blood pressure changes. However, some changes occur because the sodium sensitivity of arterial pressure regulation increases with age.

Physical conditioning appears to lessen the vascular stiffening associated with aging. Stiffening is increased by only about half as much in endurance-trained older adults as compared to sedentary ones.

Exercise can also improve the aerobic capacity of older adults by increasing cardiac output and O2 utilization.

Differences between cardiovascular functioning in older and younger persons have been extensively quantified. However, interactions between age, disease, and lifestyle are often overlooked.

The high prevalence of cardiovascular disorders such as hypertension, coronary artery disease, and heart failure might simply be due to aging. But it might occur more frequently in older adults because of a longer exposure to risk. This has not yet been established.

It is reasonable to ascertain, however, that the capabilities of the cardiovascular system gradually decline with age. But this does not mean that a good senior fitness program won’t make a difference.

Summary of age related changes for the cardiovascular system

Age-related changes in the blood

  • A decrease in the volume of packed red blood cells.
  • Constriction or blockage of peripheral veins by a blood clot.
  • Pooling of blood in the veins in the legs because valves are not working effectively.

Age-related changes in the heart

  • A reduction in maximum cardiac output.
  • Changes in the activities of nodal and conductive fibers.
  • A reduction in the elasticity of the heart’s fibrous tissues.
  • Progressive atherosclerosis (fatty buildup or plaques) that can restrict coronary circulation.
  • Replacement of damaged cardiac muscle fibers by scar tissue.

Age-related changes in blood vessels

  • Often related to arteriosclerosis, there is a thickening and toughening of arterial walls.

Muscular System

The major functions of this system are locomotion, support, and heat production. When you hear the words “muscular system” we are referring to skeletal muscle only (not cardiac or smooth muscle).

Skeletal muscular system lead picture

Changes in skeletal muscle important to know for senior fitness

Muscle fibers become smaller in diameter

As the body ages, there is generally a reduction in the size and power of all muscle tissues. In particular, skeletal muscle fibers become smaller in diameter. The overall effect of this is reduced muscular strength and endurance and a tendency to tire rapidly.

Blood flow to active muscles does not increase during exercise as rapidly

Because the performance of the heart also decreases, blood flow to active muscles does not increase during exercise as rapidly as it does in younger people.

Fibrosis makes muscle less flexible

Skeletal muscles also become less elastic. Aging skeletal muscles develop increasing amounts of fibrous connective tissue, a process called fibrosis. Fibrosis makes muscle less flexible so that movement and circulation are restricted.

A lower tolerance for exercise

Tolerance for exertion decreases. A lower tolerance for exercise results partly from the tendency to fatigue rapidly and partly from the reduced ability to eliminate heat generated during muscular contraction.

The ability to recover from muscular injury decreases

The number of skeletal muscle cells/fibers is generally set before birth, and most of these fibers last a lifetime. This means that the average person does not experience an increase in the number of muscle fibers at all during a lifetime.

The dramatic muscle growth that occurs after birth is achieved mainly by enlargement of existing fibers in a process called muscle hypertrophy.

The body does, however, have a limited number of specialized cells called satellite cells. Satellite cells are muscle cells that retain the capacity to fuse with damaged muscle fibers and regenerate functional muscle fibers in an adult.

As a result, the body has a limited ability to repair damaged tissue by replacing aged or worn out skeletal muscle fibers. Unfortunately, the number of satellite cells steadily decreases with age as the amount of fibrous tissue increases.

Because of this, when an injury occurs, repair capabilities are restricted, and scar tissue formation is the usual result.

Muscle mass decreases

Between the ages of 30 and 75, overall lean body mass decreases primarily due to reduced skeletal muscle mass. This loss is called sarcopenia and occurs as the number and size of muscle fibers progressively decrease.

Sarcopenia

Sarcopenia involves several age-related factors:

  • Reduced levels of physical activity.
  • Changes in the central or peripheral nervous system that seem to affect the total number of motor units.
  • A reduced rate of skeletal muscle protein synthesis.

In addition, loss of muscle mass might be accelerated as a result of greater dietary protein requirements. This is because with aging, the body is not as efficient at processing protein. And often protein intake decreases in older adults.

Skeletal muscle system facts for senior fitness

Type II muscle fibers decrease with age

The faster contracting type II muscle fibers decrease with age to a greater extent than do the slower contracting type I muscle fibers. Type II fibers participate in sudden powerful muscle contractions, whereas type I fibers function to maintain posture and to perform rhythmic, endurance-type exercises.

The age-related loss of muscle fibers correlates with a loss of maximum isometric contraction force, which decreases 20% by age 60 and 50% by age 80.

Lifestyle and exercise information for senior fitness

Reasons for changes in body composition and isometric contraction force are not completely understood. But contributing factors include a relative deficiency of anabolic hormones. This includes growth hormone, insulin-like growth factor I (IGF-I), dehydroepiandrosterone (DHEA), and testosterone.

Another factor is a decrease in the routine performance of vigorous muscular work. Current research indicates that exercise increases the levels of many hormones that decline with age.

People whose mobility is restricted because of acute illness are at risk of deconditioning and an accelerated loss of muscle mass and strength. This is particularly true for those who are bedridden.

Deconditioning is greatest in the antigravity muscles

The rate of loss is anywhere from 1.5% to 3% per day. Deconditioning is greatest in the antigravity muscles. These muscles are essential for performing activities of daily living, such as sitting up, standing up, and pulling oneself up.

Some geriatricians estimate that for one day of absolute bed rest, two weeks of reconditioning are necessary to return to baseline function.

Despite age-related reductions in muscle strength, muscle functional ability is similar in older and younger adults. Usually, older adults can easily climb stairs, rise from a squatting position, walk along a straight line, hop on either foot, and perform typical activities of daily living.

It would appear that people who continue to exercise into old age will probably not experience such negative changes. So, once again, senior fitness has great advantages.

Summary of age related changes for the skeletal muscular system

  • Muscle fibers become smaller in diameter
  • Blood flow to active muscles does not increase during exercise as rapidly
  • Fibrosis makes muscle less flexible
  • A lower tolerance for exercise
  • The ability to recover from muscular injury decreases
  • Muscle mass decreases (sarcopenia)
  • Type II muscle fibers decrease with age

Skeletal System

The major functions of this system are in structural support, protection of soft tissues, mineral storage, and blood production.

skeletal system lead picture

Changes in skeletal system important to know for senior fitness

Bones become thinner and relatively weaker

The bones of the skeletal system become thinner and relatively weaker as a normal part of the aging process. Everyone begins to lose bone mass between the ages of 30 and 40.

Over this period of time, the number of osteoblasts (bone building cells) begins to decline. At the same time, the number of osteoclasts (cells that break down bone) remains the same.

Osteoblasts and osteoclasts

The balance between the activities of osteoblasts and osteoclasts is very important to the maintenance of bone health and strength. When osteoclasts remove calcium faster than osteoblasts can deposit it, bones become weaker.

Osteoporosis

In addition to this rapid bone loss during early menopause, women accumulate less skeletal mass than men during their growing years. This results in smaller, narrower, more fragile bones with thinner cortices.

In old age, therefore, the consequences of bone loss are greater among women than among men. And the incidence of bone fractures is two-to-threefold higher among women.

Once the number of osteoblasts declines, women lose roughly 8% of their skeletal mass each decade. Men lose about 3% each decade. All parts of the skeleton are not equally affected.

The ends of long bones (like the humerus), vertebrae, and the jaws lose more. This results in fragile limbs, a reduction in height, and the loss of teeth.

skeletal system facts for senior fitness

Lifestyle and exercise information for senior fitness

A significant percentage of women and a smaller proportion of men suffer from osteoporosis. Osteoporosis is a condition characterized by reduced bone mass sufficient enough to compromise normal functioning. While it isn’t reasonable to expect a reversal of osteoporosis, weight bearing exercise can delay or stop bone loss.

Maintaining lower body strength is one of the biggest modifiable risk factors for falling. So programs that focus on weight bearing exercise, lower body strength and balance are important as we age. This is especially true for women with regard to bone loss and fractures. So, again, senior fitness is important!

Summary of age related changes for the skeletal system

  • Bones become thinner and relatively weaker

Digestive System

The major functions of this system are the processing of food and the absorption of nutrients, minerals, vitamins, and water.

Digestive system lead picture

Changes in the digestive system important to know for senior fitness

The rate of new cell growth declines

The digestive system is made up of the mouth, teeth, tongue, salivary glands, pharynx, esophagus, stomach, pancreas, liver, gallbladder, large intestine, and small intestine. Essentially, normal digestion and absorption occur in older adults.

However, there are many changes in the digestive system that parallel the age-related changes seen in the other systems. Like other systems, the rate of new cell growth declines and tissues become more susceptible to damage.

Food moves through the system more slowly

Due to a decrease in smooth muscle tone along a majority of the aging GI tract, food moves through the system more slowly as the contractions necessary for the movement and breakdown of food become weaker. Constipation becomes a problem along with hemorrhoids.

Weakening of the cardiac sphincter

The muscle that regulates the flow of food from the esophagus into the stomach, called the cardiac sphincter, weakens. This can lead to esophageal reflux which causes “heart burn.”

Digestive system facts for senior fitness

Lifestyle and exercise information for senior fitness

Because of the large functional reserve capacity of most of the gastrointestinal (GI) tract, aging has relatively little effect on GI functioning. But with age, cancer rates increase, especially in the colon and stomach.

Changes in other systems

Changes in other systems have direct and indirect effects on the digestive system. For example, the reduction in bone mass and calcium content in the skeleton is associated with erosion of the tooth sockets and tooth loss.

When toxins, such as alcohol and chemicals, are absorbed by the digestive tract and transported to the liver for processing or storage, the liver cells are not immune to the effects of these compounds. Chronic exposure leads to damage and disease in the liver and many other organs.

Gastroinstestinal transit time is increased by increased physical activity. So older adults who remain active can decrease the chance of constipation, hemorrhoids and cancer. Another reason to push for senior fitness!

Summary of age related changes for the digestive system

  • The rate of new cell growth declines
  • Food moves through the system more slowly
  • Weakening of the cardiac sphincter

Endocrine System

This system’s major function is to direct long-term changes in the activities of other organ systems through the production of hormones.

Endocrine system lead picture

Changes in the endocrine system to know for senior fitness

A decline in the concentration of reproductive hormones

Overall, the endocrine system shows relatively few functional changes with age. The most dramatic exception, however, is the decline in the concentration of reproductive hormones.

Lifestyle and exercise information for senior fitness

Age-related changes in other tissues affect their abilities to respond to hormonal stimulation. As a result, most tissues become less responsive to circulating hormones, even though many hormone concentrations remain normal.

Endocrine system facts for senior fitness

Because levels of some important hormones decrease with age, restoring low hormone levels might seem logical. However, any resulting improvement in functional status might be gained at the expense of reduced longevity.

For example, increased metabolism, which often results from hormone administration, can lead to tissue damage because of free radical generation. Therefore, hormonal supplementation is usually limited.

Based on recent studies, exercise can have a positive effect on hormone levels. The effects of exercise appears to depend on the type, frequency and duration of the exercises that are being done.

Summary of age related changes for the endocrine system

  • A decline in the concentration of reproductive hormones

Lymphatic System

The major function of the lymphatic system (also called the immune system) is defense against infection and disease.

Lymphatic system lead picture

Changes in the lymphatic system to know for senior fitness

Less effective at combating disease and fighting off infections

With advancing age, the lymphatic system becomes less effective at combating disease and fighting off infections. T and B cells are the primary cells involved with immunity and attack specific invaders as they penetrate mechanical, chemical, and other cellular barriers.

T cells become less responsive

T cells, the cells responsible for cellular immunity and for coordination and regulation of immunity, become less responsive. As a result, fewer T cells respond to an infection or invasion by a pathogen.

B cells become less responsive

B cells, the cells that produce antibodies, are also less responsive. Because of this, antibody levels do not rise as quickly after an infection develops in an older adult. The net result is an increased susceptibility to viral and bacterial infections.

For this reason, vaccinations for viruses like the flu are strongly recommended for elderly people. In addition, the increased incidence of cancer in older adults reflects the fact that surveillance by the lymphatic system declines, and tumor cells are not eliminated as effectively.

Two complementary forms of immunity rid humans of pathogens and cancer cells: nonspecific (or innate) defenses and specific (or adaptive) defenses. Nonspecific immunity provides a rapid but incomplete defense against a variety of threatening agents until the slower, specific immune response develops.

Lymphatic system facts for senior fitness

Lifestyle and exercise information for senior fitness

Nutrition plays a factor in a healthy immune system as well. Vitamin and other dietary supplements can enhance the response of the immune system resulting in fewer days of infectious illnesses.

Older adults often experience loss and stress. Suppressed immunity has been associated with bereavement, depression, and poor social support. Maintaining an active social life and receiving treatment for depression could boost the older adult’s immune system.

Physical activity may help flush bacteria out of the lungs and airways which may reduce the chance of getting a cold or other illness. Exercise can also cause positive changes in antibodies and immune system cells. And, exercise can help with stress and depression.

So, by now you have to know where this is going? Once again, senior fitness is important for successful aging!

Summary of age related changes for the lymphatic system

  • T cells become less responsive
  • B cells become less responsive

Nervous System

The major function of this system is to direct immediate responses to stimuli by coordinating the activities of other systems.

Nervous system lead picture

Changes in the nervous system to know for senior fitness

The aging process affects all body systems, and the nervous system is no exception. Anatomical changes begin shortly after maturity (probably by age 30) and accumulate over time.

Although an estimated 85% of older adults over the age of 65 lead relatively normal lives, there are noticeable changes in mental performance and central nervous system (CNS) functioning.

A reduction in brain size, weight and number of neurons

Some common age-related anatomical changes in the nervous system include a reduction in brain size and weight. This is due primarily to a decrease in the volume of the cerebral cortex. There is also a reduction in the number of neurons.

Blood flow to the brain is decreased

Fatty deposits gradually accumulate in the walls of blood vessels and reduce the rate of arterial blood flow. This condition is called atherosclerosis and causes problems in more than just the brain.

While reduced blood flow does not cause a cerebral crisis, it does increase the probability of suffering a stroke.

Changes in the synaptic organization

There are also changes in the synaptic organization of the brain. These changes ultimately interfere with the body’s ability to adjust to internal and external stimuli.

The number of dendrite branches and interconnections decrease. At the same time, the rate of neurotransmitter production declines.

Neurons begin accumulating abnormal intracellular deposits or plaques

Abnormal intracellular deposits or plaques begin to accumulate in neurons. There is evidence that when these are present in excess, clinical abnormalities similar to Alzheimer’s disease occur.

Lifestyle and exercise information for senior fitness

These anatomical changes are linked to a number of functional alterations. In general, neural processing becomes less efficient.

For example, memory consolidation often becomes more difficult. Sensory systems, notably hearing, balance, vision, smell, and taste, become less acute. Light must be brighter, sounds louder, and smells stronger before they are perceived.

Exercise

Exercise has favorable effects on the central nervous system and brain plasticity. In addition, exercise increases the production of new neurons in the hippocampus and helps create new brain cells.

It also increases the production of glial cells. These cells are protective and support the function of neurons.

Exercise increases blood flow to the brain and protects brain cells by causing them to make substances that protect them from damage. More blood flow to the brain means that cells have more fuel to operate too.

So one again, senior fitness is very important for successful aging of this body system too!

Summary of age related changes for the nervous system

  • A reduction in brain size, weight and number of neurons
  • Blood flow to the brain is decreased
  • Changes in the synaptic organization
  • Neurons begin accumulating abnormal intracellular deposits or plaques

Reproductive System

The main function of this system is to produce sex cells and hormones.

Reproductive system lead picture

Changes in the reproductive system important to know for senior fitness

The aging process affects the reproductive systems of both men and women

The most striking age-related changes in the female reproductive system occur at menopause, while changes in the male reproductive system occur more gradually and over a longer period of time.

The ovaries stop making hormones

The ovaries stop producing estrogen and progesterone.  This causes menstrual periods to stop and increases the risk of bone loss. As these hormone levels decline a thinning of the urethral and vaginal walls occurs.

The ovaries stop releasing eggs

Menopause is usually defined as the time ovulation and menstruation cease. It typically occurs between the ages of 45-65. Eggs stop being released, so after menopause a woman can no longer get pregnant.

Testicular mass decreases

Aging changes in the male occur primarily in the testes resulting in changes to testicular tissue.

The level of testosterone decreases

Unlike women, men do not experience a major, rapid change in hormone levels as they age. The level of testosterone decreases gradually. Decreased levels of testosterone can cause decreased muscle mass and increase the risk of coronary artery disease.

There is decreased blood flow to the penis

There may be problems getting or keeping an erection.

Reproductive system facts for senior fitness

Lifestyle and exercise information for senior fitness

Reduced estrogen levels have been linked to osteoporosis and a variety of cardiovascular and neural effects including “hot flashes,” anxiety, and depression.

There is currently much debate over the use of hormone replacement therapy in women. Research shows that detrimental effects might outweigh any benefits of the therapy. Some clinicians are now tentatively suggesting the use of testosterone therapy for older men.

Getting regular exercise and having a healthy diet can help the aging process go more smoothly, especially for women dealing with menopausal symptoms.

So once again, senior fitness is important for successful aging of this body system too!

Summary of age related changes for the reproductive system

The aging process affects the reproductive systems of both men and women

  • For women the ovaries stop making hormones
  • For women the ovaries stop releasing eggs
  • For men testicular mass decreases
  • For men the level of testosterone decreases
  • For men there is decreased blood flow to the penis

Respiratory System

The major function of this system is the delivery of air to sites in the lungs where gas exchange can occur between the air and circulating blood.

Respiratory system lead picture

Changes in the respiratory system important to know for senior fitness

The effects of aging on the lungs are physiologically and anatomically similar to those that occur during the development of mild emphysema. Aging affects ventilation, gas exchange, compliance, and other parameters of lung function. It also affects the defense mechanisms of the lungs. But, pure age-related changes do not lead to significant airway obstruction in the nonsmoker.

Elastic tissue deteriorates

Many factors interact to reduce the efficiency of the respiratory system in elderly individuals. Elastic tissue deteriorates throughout the body and reduces the lungs’ ability to inflate and deflate.

Arthritic changes

The rib cage does not move as freely because of arthritic changes. This, in combination with the changes in elasticity, causes a reduction in chest movement which limits respiratory volume. These changes contribute to the reduction in exercise performance and capabilities seen with increasing age.

Respiratory membrane is lost

On average, roughly 1 square foot of respiratory membrane is lost each year after age 30. However, the extent varies widely depending upon the lifetime exposure to cigarette smoke and other irritants.

Respiratory system facts for senior fitness

Lifestyle and exercise information for senior fitness

When a person has reduced lung function they use a large part of their breathing reserve. Regular exercise can increase the strength and function of muscles. Because of this, muscles will require less oxygen to move and they will be producing less carbon dioxide.

This increased efficiency makes them work less hard as it decreases the amount of air that is needed to breathe in and out. Exercise also improves circulation and strengthens the heart.

Summary of age related changes for the respiratory system

  • Elastic tissue deteriorates
  • Arthritic changes
  • Respiratory membrane is lost

Integumentary (Skin) System

The major functions of this system are protection from environmental hazards and temperature control.

Integumentary system lead picture

Changes in the integumentary system to know for senior fitness

Skin thins

In general, aging skin thins as cell activity declines and as the network of elastic and collagen fibers supporting it decreases. This makes older people more prone to injury and recurring skin infections. It also causes the sagging and wrinkling notorious of aging, and slows skin repair.

Decrease in melanin

Aging results in a decrease in the melanin pigment in skin, which means older people are more sensitive to the sun and tend to avoid it. Avoiding sunlight can cause the production of Vitamin D to decrease by as much as 75%.

Vitamin D is necessary for functioning of both the muscular and skeletal systems. So, this can then result in muscle weakness and a reduction in bone strength.

Glandular activity decreases

Glandular activity in the skin decreases and leads to dry, scaly skin. Sweat glands also become less active, and at the same time blood supply to the skin is decreased.

This combination makes older adults less able to lose body heat. So overexertion or exposure to extreme temperatures can cause dangerously high body temperatures.

Integumentary facts for senior fitness

Lifestyle and exercise information for senior fitness

Exercise raises your heart rate and increases blood circulation. This increase in circulation provides extra oxygen and vitamins and nutrients to the skin.

From a health standpoint, healthier skin can help with heat modulation. It can also improve infection rates and cause healing to occur faster in the case of an injury.

Summary of age related changes for the integumentary system

  • Skin thins
  • Decrease in melanin
  • Glandular activity decreases

Urinary System

The major function of this system is the elimination of excess water, salts, and waste products.

Urinary system lead picture

Changes in the urinary system to know for senior fitness

Renal function declines

Although renal function declines substantially with age, it usually remains sufficient for removing bodily wastes.

Nevertheless, reduced renal function decreases the elderly person’s ability to respond to various physiological and pathological stresses. In general, an increased incidence of kidney problems is associated with aging.

A decline in the number of nephrons

There is a decline in the number of nephrons by about 30-40% between ages 25 and 85. Nephrons are the basic functional units of the kidneys and are made up of a renal corpuscle and renal tubules.

Reduction in filtration rate

A reduction in filtration rate occurs due to cumulative damage to the urinary system. Reduced filtration also involves a reduction in blood flow to the kidneys.

Renal blood flow progressively decreases

Urine is formed by the kidneys through three processes: filtration, reabsorption and secretion.

Blood is the ultimate source of urine and a large amount of blood is transported to the kidneys for filtration by way of the renal arteries. Renal blood flow progressively decreases from 1200 mL/minute at age 30 to 40 years to 600 mL/minute at age 80.

The glomerular filtration rate decreases

There is a marked decrease in the glomerular filtration rate. This is the rate at which blood is forced through and filtered by the renal corpuscle in our kidneys. Decrease in glomerular filtration rate is the most important functional defect caused by aging.

The kidneys receive up to 25% of the resting cardiac output through the renal arteries. This means a large portion of total blood volume is filtered through the renal corpuscle each day. At this rate, it wouldn’t take long to totally deplete the body’s entire blood volume if there was not some form of “recapture” or “return”.

Reabsorption is the process that returns necessary items from the filtrate back into the blood.

Reduced nephron sensitivity

Reabsorption is responsible for returning 99% of filtrate back to the circulatory system. Reduced nephron sensitivity which occurs with age, however, results in less reabsorption of water.

So urination becomes more frequent while daily fluid requirements increase. At the same time, there is usually a loss of thirst which compounds the problem.

The muscles that help regulate the release of urine become weaker

The muscles that help regulate the release of urine become weaker. This leads to problems with incontinence and often involves slow leakage of urine. This is usually a more common problem in women.

Chronic inflammation of the prostate gland

In males, urinary retention might develop due to chronic inflammation of the prostate gland. Swelling of the gland prevents the flow of urine as it puts pressure on the urethra.

Urinary system facts for senior fitness

Lifestyle and exercise information for senior fitness

Physical activity can help prevent urinary problems by improving overall health:

  • Diabetes can damage nerves around the bladder that help with control.
  • People who are overweight may be at a higher risk of leaking urine.
  • Constipation can cause too much stool to build up in the colon which can block the expansion of the bladder.
  • High blood pressure can cause kidney failure.

Exercise can improve renal functions by improving plasma lipids, blood glucose levels, blood pressure, and body weight. It can also help with gastrointestinal transit time. And finally, it improves renal tissue.

Bladder problems are more common among people who smoke. Smoking can also increase the risk for bladder cancer.

So once again, this is another body system for which senior fitness is important!

Summary of age related changes for the urinary system

  • Renal function declines
  • A decline in the number of nephrons
  • Reduction in filtration rate
  • Renal blood flow progressively decreases
  • The glomerular filtration rate decreases
  • Reduced nephron sensitivity
  • The muscles that help regulate the release of urine become weaker
  • Chronic inflammation of the prostate gland

In Summary

As you just learned by reviewing aging and the body systems, senior fitness is important for all eleven systems.  So, there exists a great opportunity to work with older adults who want to age successfully.

The American Academy of Health and Fitness is here to help you with the all-important training you will need to be a safe and effective trainer of older adults. Therefore, we offer a varied selection of in-depth, advanced continuing education courses.

You will find training in areas such as senior health and fitness, fitness assessment, senior strength training, back stability, nutrition for special dietary needs, lifestyle wellness coaching and cancer exercise. The home study continuing education course SrFit Mature Fitness is definitely one not to miss! Certainly everything you need to create your niche in senior fitness!

References

Petersen, T. SrFit: The Personal Trainer’s Resource for Senior Fitness, Second Edition. The American Academy of Health and Fitness, 2008.

Petersen, T. SrFit: The Personal Trainer’s Resource for Senior Fitness, Third Edition. The American Academy of Health and Fitness, 2018.

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