Aging of the Organ Systems Nancy V. Karp, Ed.D., P.T. email@example.com
Change Life is a process of continual change. Age-related changes occur at many levels. – Biological level – Physiological level – Psychological level – Functional level During adulthood, there is a slow decline in function. As you age, homeostasis is maintained at a level of decreased function.
Change This presentation will focus on some of the changes that occur in different organ systems as they age. Physical therapists must recognize these changes to: – determine how to objectively measure the extent of the changes; i.e., changes in muscle function. – modify physical therapy interventions to accommodate these changes. – prevent unnecessary therapy complications resulting from functional and structural changes to organs or systems.
Remember “Average” or “Normal” does not imply “Optimal” or “Healthy.” “Average” does not apply to an individual. Elders are a heterogeneous population. On the average, they are a “normal” height.
Age-related Changes In The Cardiovascular System
Normal Cardiovascular Changes Related to Aging The changes I am about to present are considered a NORMAL part of the aging process. These changes occur with age. They are not associated with pathological conditions. There is some controversy over the contribution of aging vs. disease to some of the changes that are presented.
Cellular Changes Alterations of DNA, RNA, mitochondria and other sub-cellular changes are seen with aging. This changes result in decreased cellular activities resulting in: – altered homeostasis – altered protein synthesis – altered degradation rates
Cellular Changes The myoctye cells of the heart increase in size. – This may account for the myocardial wall thickening that is seen with aging. – Some myocytes are replaced by fibrous tissue. Amyloid deposits in the myocardium increase with age. – 50% in persons 70+ – They are not present in ALL older persons. – Often seen in other organs (Alzheimer’s dx)
Cellular Changes There is a decrease in pacemaker cells at the sinoatrial node. – Occurs around the age of 60 – 10% decrease by age 75 A smaller decrease of cells is seen in the atrioventricular node and the Bundle of His
Cellular Changes Thickening and calcification of heart and vessels occur. – Cells become irregular in size and shape. – By age 50, the aorta has thickened 40%. – There is a thickening of aortic, pulmonary and heart valves. – 98% of aortas have some calcification by age 40
Heart Changes Modest increase in left ventricular wall thickness (myocytes). This is exaggerated with hypertension. Slight enlargement of the left ventricular cavity Myocardial stiffness during contractions. The walls of the heart are less compliant
Ventricular Hypertrophy The enlarged left ventricular wall has a decreased ability to expand during diastole. – Results in reduced and delayed filling – The left ventricle contracts less and ejects less blood. There is an increase in left atrium size, secondary to the decline in left ventricle compliance. This increases the work load on the atria.
Vessel Changes Arterial Age causes the walls of the arteries to thicken and to become less flexible. – Thickening results from cellular accumulation and matrix deposition. – Increase in arterial diameter size accompanies thickening and loss of elasticity. – Dilated vessels have a limited ability to dilate in response to increase blood volume.
Vessel Changes Arterial The decrease in the elasticity of vessels results in: – Increased arterial pressure – Increased peripheral resistance – Residual increase in vessel diameter – Vessel wall rigidity – Fragmentation of the internal elastic membrane – Increases in collagen and changes in cross-linking collagen which cause the vessel to be less elastic
Vessel Changes Venous The ability of the vessel to contract is decreased. – Dilation and tortuosity of veins results in decreased venous return. – The Frank-Starling relationship of the heart changes stroke volume which is dependent on venous return. – Little research has been done on the aging veins The electrical excitability and responsiveness to the autonomic nervous system is less rapid and pronounced.
Heart Rate Supine resting heart rate (HR) does not change very much with age. Sitting position HR decreases with age. Respiratory sinus arrhythmia decreases with age. – 104 beats/minute at age 20 – 92 beats/minute at age 45-50
Heart Rate The maximum exercise heart rate decreases with age. – 200 beats/min at age 20 – 150 beats/min at age 80 The decline in maximal heart rate with age is independent of fitness level.
What is the maximum exercise heart rate ? Not all patients will have a graded exercise test (GXT) to determine the maximum heart rate. Most elderly patients do not have a GXT. “Rule of Thumb” to calculate estimated maximum exercise heart rate: – 220 minus the patient’s age – patients with pathological conditions 200 minus the patient's age with a standard deviation of 10
Stroke Volume No significant changes in resting stroke volume is seen with age. Age may effects stoke volume during exercise. – Reduction in the rate of filling ventricles secondary to diminished diastolic compliance (preload) Filling in early diastole is less and is greater in later diastole – Stroke Volume may be decreased during exercise
Cardiac Output Cardiac Output = Stroke Volume X Heart Rate (ml/min) (ml/cycles) (cycles/min) Declines slightly with age as a function of other age-related changes.
Cardiac Output Stroke Volume Heart Rate SA Node Autonomic Regulation Strength of Contraction End-diastolic Volume
Blood Pressure Changes in blood pressure (BP) caused by aging is difficult to separate from changes in blood pressure caused by cardiovascular disease. There are very few elderly people with no cardiovascular disease in which to study normal BP changes. Blood pressure = Cardiac Output X Total Peripheral Resistance Increases in BP with age is a result of changes in total peripheral resistance and aortic compliance.
Blood Pressure Systolic BP tends to increase with age throughout life – 5-8 mm Hg per decade after 40-50 years of age – an index of arterial stiffness Diastolic BP tends to increase until the age of 60, then it stabilizes or slowly declines Generally increases 1 mm Hg per decade
Summary Slide Aging Effects on the Heart 1.Structural changes at the cellular level 2.Decrease in SA cells and autonomic nerve function 3.Thickening and calcification of heart and vessels 4.Myocardial stiffness 5.Decreased elasticity of vessels 6.Decreased venous return 7.Decreased maximum heart rate 8.Changes in cardiac output,stroke volume and blood pressure
All the changes that have been discussed so far relate to a person at rest.
“Perhaps the single, most salient and age- related difference is the diminishing ability of the body to respond to physical and emotion stress…” Carole Lewis Jennifer Bottomley
Age-Related Changes During Exercise Aging changes (impairments) are seen when the system is stressed. The cardiovascular system must support the exercise by increasing O 2 in working muscles. The Maximum Oxygen Consumption (VO 2 max) is considered an indicator of cardiovascular fitness.
Maximum Oxygen Consumption (VO 2 max) VO 2 max is the maximum amount of oxygen that your heart can pump and your muscles can use in a given period of time. VO 2 max is the product of maximum cardiac output and maximum systemic arteriovenous O 2 difference.
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Changes During Exercise The response of heart rate to exercise is decreased in an elderly heart when compared to a younger heart. This is due to: – reduction of vagal tone – impaired neural activation/release Stroke volume during exercise can be10-20% less in elderly patients compared to younger adults.
Changes during Exercise Cardiac output increases with increasing loads. The reasons for increased cardiac output vary when comparing young adults and the elderly. – In young adults, stroke volume is increased by an increased HR and decreased end-systolic volume due to beta -adrenergic stimulation – In the elderly, stoke volume is increased by an increase in end-diastolic volume (shift in the Frank-Starling relationship).
Maximum Aerobic Power (Aerobic Capacity) Aerobic Capacity declines 1% per year in adults when measured by VO 2 max. The measurement of VO 2 max is dependent on age-related changes in: – Maximum heart rate – Cardiac output – Decreased muscle mass – Decreased skeletal muscle quality Older persons in good physical condition can match or exceed the aerobic capacity of unconditioned younger persons.
Aging Muscles Age-related reductions in muscle mass are a cause of: – decreased muscle strength – disability – gait and balance problems Between 30-75 years old, the number and size of muscle fiber progressively deceases- sarcopenia
Sarcopenia “Healthy” Young Adult 30% of weight is muscle 20% of weight is adipose tissue 10% of weight is bone “Normal” 75 Year Old 15% of weight is muscle 40% of weight is adipose tissue 8% of weight is bone
Aging Muscles There is a decrease in total muscle cross-sectional area. – 40% decrease by 80 years – increase in fat and connective tissue – decrease in protein synthesis The faster-contracting type II fibers decrease at a greater rate than type I fibers. – Loss of maximum isometric contraction force – replaced with fat and fibrous tissue – angulated fibers and atrophy are seen in elderly – Over time, Type I fibers greatly outnumber Type II fibers.
Aging Muscles Blood flow to the muscles is decreased. – Results in decreased endurance capacity. – Capillary density decreases which makes less O 2 available during muscle work. Decreased Enzyme Activity – Aerobic enzymes decrease resulting in mitochondrial decay. – Increased mitochondrial DNA deletions and mitochondrial mutations appear.
Neuromuscular Changes There is a decrease in the number of motor units – Motor neuron innervates more muscle fibers – Seen after 60 years – More come in distal muscle groups The number and diameter of motor axons decreases. – After 60, there is a reduction in spinal cord axons – Surviving segmental neurons branch and display collateral growth.
Changes is Muscle Performance Muscle strength decreases – Beginning at 30, strength decreases 8% per decade. – The rate of decrease is similar for both males and females, – Muscle strength loss is greater in leg muscles than in arm muscles. There is a significant decease in strength by age 70. – 20 -40% decrease in maximal isometric strength – Strength is related to sustainable walking speed
Changes is Muscle Performance Power and Endurance – Power = rapid force generation Decreased power is associated with decreasing walking speed and a decreased ability to climb stairs. – Endurance- stresses the cardiovascular system – Contributes to functional loss – Reduced blood supply – Altered muscle contractibility and metabolism
Changes is Muscle Performance Velocity – The maximal speed of muscle contraction decreases with age – This is seen in “slowly moving” elders. – Also seen as the inability to quickly regain balance resulting in a fall.
.. What happens when you add exercise as your PT intervention to these aging systems So far, two major aging systems have a significant impact on an elderly person’s ability to move.
Fact of Fiction ? Resistive strengthening increases BP. Increasing LE strength will improve walking. Isometric contractions are a good indicator of strength. Active exercises is better than using weights to protect joints. Fatigue is a part of aging. Muscle bulk will never be normal. Decreased endurance is a result of the aging heart. Exercise improves function.
How do you Assess the Need for Exercise ? How do you measure strength? How do you measure fatigue? How do you measure endurance? How do you measure muscle atrophy? How do you measure the success of the exercise intervention? How do you know the type and intensity for exercise?
Age and Exercise Skeletal and cardiac muscle change according to the intensity, duration, and frequency of physical activity. – Changes occur at the cellular, tissue, and performance level – Exercise is one of the few interventions that can restore or improve physiologic capacity once it has been lost.
Age and Exercise – Preserve or improve skeletal muscle strength and aerobic capacity – Improve bone density – Increases insulin sensitivity and glucose tolerance – Reduces resting BP – Normalizes blood lipid levels – Reduces fat – Contributes of mobility and independence – Decreases falls – Reverses decline Regular exercise benefits
Exercise Specificity The type of exercise chosen elicits different changes in metabolic and physiological systems. – Resistance training increases strength. – Aerobic exercise increases endurance. – Isometric exercise increases blood pressure???? Strength and endurance training adaptations may occur independently or concurrently.
Exercise Prescription – Medical conditions – Medications – Response to exercise – Postural or physical limitations – Cardiopulmony functioning – Mental functioning – Functional level – Type of monitoring or supervision – Motivation – Goals Many factors must be considered
Strength Training Increases muscle fiber size and enzyme activity – Hypertrophy – Increase in muscle volume without increase in mitochondria Elderly persons with disuse atrophy can increase muscle size with strength training. Increases bone mineral density
Strength Training The intensity of the training, not the overall fitness level, determines the amount of gain in muscle strength and size. Strengthening exercises need to be performed at least 2 days/week for large muscle groups. Use one-repetition maximum as guide – 60-89 % of max is considered high intensity for the elderly – Under very close supervision high intensity exercise yields good result in the frail elderly.
Aerobic Exercise/ Endurance Training Regularly performed aerobic exercise, not the undying fitness level, determines the amount of adaptive response. Adaptive responses include: – increased stroke volume and ventricular end-diastolic volume – bradycardia – improved myocardial contraction – a slowing or reduction in the rate of bone loss (walking, jogging, stair climbing etc.)
Adaptive Responses VO 2 max – Rapid adaptation – Men 2/3 augmented cardiac output, 1/3 to peripheral adaptations – women form the peripheral adaptations Improved Skeletal muscle – increase in number and size of mitochondria, enzyme activity and muscle size – Increase in blood flow Glucose Tolerance
Endurance Training Endurance exercises stresses the cardiovascular system. The American College of Sports Medicine (ACSM) – % of maximum heart rate – rating of perceived exertion
Endurance Training Exercises are continuous, rhythmical, use large muscle groups, and increase O 2 consumption. The “oldest old” need endurance and strength training under close supervision.
How do you determine how much exercise is too much exercise? VO 2 Max is the best guide, but not practical for most situations. Target heart rate – Medication may alter heart rate response. – Cardiovascular disease may change heart rate guidelines. The “Borg Perceived Exertion Scale”- This is a different scale from the “Borg Shortness-of-Breath Scale”
Testing Individual Exercise Capacity Never exceed the person’s approximated, maximum target heart rate. – MD present for maximal stress test – Submaximal tests to assess fitness See Exercise Testing Guidelines Box 15-3 page 251 Monitor the person closely for respiration, HR, BP, pulses and signs of undue stress. Know the patient’s medical history, functional level, mental status, and precautions.
Testing Individual Fitness for Exercise The test should measure the person’s fitness in the method of the exercise, itself. Endurance tests – 6-Minute Walk Test (page 253) – Chair Step Test (page 253) Monitor patient Strength - One repetition maximum (1RM) – Example, 60% of 1RM for no. of reps – Use with Borg’s test Monitor patient
Exercise: A Guide from the National institute of Aging http://www.niapublications.org/exercisebook/index.asp Go over the exercises found on pages 35-53
Muscle Fatigue and Muscle Endurance Fatigue is the reduced ability of the muscle to achieve the same level of force output Endurance is the ability to sustain a force (approx. 50%) for a period of time Clinically endurance and fatigue are used synonymously – If a patient muscle fatigues, then endurance is reduced. – If a patients endurance is low, the muscle will fatigue Motivation is an important aspect for both fatigue and endurance.
Muscle Fatigue Muscle fatigue is a common complaint. – As seen by the inability to maintain ROM – As seen by quivering and shaking The causes of fatigue vary. Lack of muscle strength is a major contributor. – The stronger the muscle, the less fatigue – increasing strength increases muscle mass, function reduces fatigue – increasing strength, decreases muscle anoxia
Muscle Endurance Muscle endurance is related to the aerobic capacity of the muscle, which, in turn, is related to the number of mitochondria and the number of type I fibers. Muscle strength and aerobic condition are major determinants of muscle endurance.
Tests and Measures of Fatigue and Endurance There is no agreement among therapists on one, valid test. Each therapist develops his/her own measure. Examples – Fatigue Test How long a “weighted” upper extremity can climb a finger ladder. – Endurance Test How long a patient can hold a muscle contraction.
Pulmonary Changes Aging lungs are physiologically and anatomically similar to the lungs of patients with mild emphysema. In aging, there is a decrease in lung compliance and chest wall thickness. – There are postural changes and calcification of intercostal cartilage. – There is a weakened muscular force.
Pulmonary Changes Airway size decreases – The proportion of collapsible airways increases. – There is a loss of elastic recoil. – There is decreased air flow. Deceased diffusion of gases – After 20 years, gas diffusion declines at a rate of 1.47 to 2.03 ml/minute/mmHg/decade – estrogen?
Aging Changes Skin Skin – The skin wrinkles, looses elasticity and a decline in cell replacement occurs. – The skin tears and blisters easily. – There is a loss of dermal thickness (20%), especially in sun-damaged skin. – Skin neoplasms (benign and malignant) increase. – Vitamin D production declines.
Aging Changes Skin – Touch (Meissner’s corpuscles) – Pressure (Pacinian’s corpuscles) – Temperature (Krause’s corpuscles) A gradual decline is seen in:
Aging Changes Eye Ptosis, wrinkling and loss of orbital fat Lens- grows during life span, increasing in density and weight – There is a progressive decrease in lens elasticity, so that by 40-50 years, you con no longer focus (presbyopia) and have to use reading glasses. – Corrective lenses Aqueous humor- Increased introcular pressure as you age may lead to glaucoma.
Aging Changes Ears Hearing loss accompanies aging – 10% of U.S. population has hearing loss – 33% of persons 65-75 years have hearing loss – 50% of persons over 75 have hearing loss Presbycusis- aging of middle ear – Ear drum loses elasticity – Decreased 8 th nerve sensitivity due to noise exposure – Decline in hair cells of the cochlea – Joints of the bones of the ear become stiff – Mechanical blockage- earwax, effusion
One note about oral health… You do not loose teeth as a result of aging. With proper oral hygiene and regular dental visits, your teeth will last your entire lifetime. Gum disease (periodontal disease) does not occur as a result of aging. If an older person has trouble, manually, when brushing and flossing to prevent periodontal disease, there are many oral hygiene assistive devices available for use by older persons. If a patient has dentures, the dentures need to be evaluated on a yearly basis by a dentist and replaced frequently. As gum tissue changes with aging, dentures will not fit correctly, making chewing difficult. Altered salivary flow may necessitate the need for drinking more frequently when eating. There are also artificial saliva’s available for use.
The following slides are a quick review of normal aging and some pathological conditions associated with aging. Source: The University or California, Academic Geriatric Resource Center
Area of Exam Common Non-pathologic Changes Common Pathologic Changes General appearance May move more slowlyKyphosis Being unkempt SkinWrinkles Seborrheic Keratoses Pigmentation Thinning and/or graying of hair Actinic keratoses Skin cancers EyesArcus senilis Slower dark adaptation Presbyopia Cataract formation Glaucoma Macular degeneration Marked decreased visual acuity EarsCerumen impactionMarked hearing loss
Area of ExamCommon Non-pathologic ChangesCommon Pathologic ChangesOral CavityYellowing or greying of teethPeriodontal diseases Oral mucosal diseases Dental caries Altered salivary flow NeckTransmitted sclerosis murmurCarotid bruits Multinodular goiter Cardiovascular exam S4 Aortic sclerosis murmur Increased ventricular ectopy Systolic Hypertension Aortic Stenosis murmur Lungs Rales that clear with cough may be present in bedbound patients due to atelectasis. Rales that do not clear Abdominal exam Enlarged abdominal aorta
Area of ExamCommon Nonpathologic ChangesCommon Pathologic ChangesFemale GU exam Decreased vaginal lubrication Smaller uterus and ovaries on bimanual exam (often not palpable) Male GU examEnlarged prostate on examPalpable bladder after voiding Neurologic exam Frontal release signs Decreased vibratory sense in toes More difficult to elicit ankle jerks Mild increase in leg tone or rigidity Mild difficulty with word finding Decreased arm swing and increased lateral sway Shorter stride length Asymmetric exam Musculoskeletal exam Mild loss of strength common (patient should be able to get out of chair) Loss of function due to weakness Kyphoscoliosis Decreased joint ROM Joint deformities
Aging of the Organ Systems The End Next time we will look at the skeletal system and osteoporosis.