Chapter 8
Muscle System - Notes (Changes and Suggestions in blue and green - 3/6/06)
1. Name and describe the methods by which the muscle system contributes to homeostasis and quality of life.
(1) movement - get goods, avoid harm
(2) support - so parts can work properly (e.g., bones, eyes,
viscera)
(3) heat production - replace lost heat - for fast chemical
reactions
2. Describe the effects of aging on four of the following parameters for muscle cells and describe practical effects on maintaining homeostasis and quality of life from these age changes.
a. ability to be stimulated = slower starting
and stopping of contraction
- decr. efficiency of
motor end plate (smoother) + changes in action potentials (APs) (weaker, slower,
irregular) -> slower starting and stopping of contraction (incr. refractory
period)
b. storing and generating energy for contraction
= decr. energy storage and supply
- decr. storage of ATP,
C-P, and glycogen + decr. oxidative enzymes and mitochondria - > decr.
endurance from decr. energy storage and supply
c. ability to be stretched = decr. ability to be
stretched -> decr. range of motion
- decr. # of
sarcomeres -> decr. strength at stretched condition + decr. range of motion
d. cell thickness
- little age change BUT
decr. exercise -> decr. thickness -> decr. strength, appearance
e. cell number
- decr. # of muscle
cells -> decr. thickness and decr. strength unless exercise hypertrophies
remaining cells
- more rapid loss of
Type II (fast twitch) muscle cells than Type I (slow twitch) muscle cells ->
decreased speed and strength of motions
f. ability to repair when injured
- no age change ->
retain ability to benefit from strength training
g. ability to thicken when exercised
- no age change ->
retain ability to benefit from strength training though slower hypertrophy of
muscle cells
h. proportions of different fiber types
- great decr. in
Type II fibers -> decr. speed and strength
3. Describe the effects of age changes in motor neurons and action potentials on muscle performance.
(1) decr. strength (from decr. # of motor neurons
-> incr. muscle cells are "orphaned")
(2) decr. precision of control (from motor neuron
"adoption" of abandoned muscle fibers -> incr. size of motor
units)
(3) slower peak power, lower peak power, and prolonged
contractions (from slower and more varied motor neuron APs)
- effects = decr. strength,
decr. precision and accuracy of movement, decr. speed of starting motion, decr.
speed at repetitive motions
4. Describe the effects of age changes in neurons other than motor neurons (i.e., sensory, CNS) on muscle performance.
- decr. # and functioning - decr. speed, decr. strength, decr. accuracy, and decr. coordination
5. Describe the effects of age changes and disease changes in the circulatory system on muscle functioning.
- decr. maximum rate of work (from capillaries -
decr. #, thicker, narrower, more irregular, decr. # of pores -> decr.
exchange; From smaller arteries - decr. adaptability)
- atherosclerosis - decr. supply -> great decr.
maximum rate of work, great decr. functioning, great decr. thickness, great
decr. strength
6. Describe the effects of aging on muscle mass and name six effects from these changes.
- gradual decr. in mass, especially after age
50, and especially with decr. exercise (from decr. # of muscle cells and decr.
thickness of muscle cells)
- effects =
(1) decr. strength
(2) decr. speed
(3) decr. coordination
(4) altered posture
(5) altered appearance
and body proportions
(6) need for decr.
calories and diet modification
(7) need to adjust
medications due to altered % body fat vs % lean body mass
- NOTE: great variability
among people and among different muscles in a person because of variable decr.
in exercise
For more details about sarcopenia and aging of muscle, go
to https://www.biologyofhumanaging.com/PPD/Sarcopenia/Sarcopenia_indx.htm
7. Describe the effects of age changes in the muscle system on (1) reaction time, (2) speed of motion, and (3) skill.
(1) incr. reaction time -> slower starting an
action
(2) decr. speed of motion -> decr. speed to
complete and action
(3) little change in skill for practiced motions, but
decr. ability for new skills
8. Describe the effects of aging on the four aspects of stamina; i.e., performing extended vigorous activity.
(1) decr. maximum rate of extended work -> must
"pace" slower
(2) decr. endurance for extended hard work -> must
"quit" sooner
(3) incr. recovery time (e.g., removal of lactic acid)
(4) incr. stiffness and soreness after exercise (from
incr. lactic acid build-up)
9. Describe the effects of aging and changes in exercise on VO2 max and describe the effects from these changes.
- VO2 max = O2 used / kg body
weight / minute
- variable rate but gradual decline beginning at age
20 for men and age 35 for women
- rate of decline related mostly to rate of decline in
exercise
- much of decline due to increase in body fat and
decrease in muscle mass
- little decline in VO2 max / kg muscle /
minute
- possible to slow or temporarily reverse
decline with increased exercise
- many reasons for decr. VO2 max
- normal
- incr. body
fat, decr. muscle mass, decr. cardiac efficiency, decr. speed of cardiac
and respiratory adaptability, decr. cardiac sensitivity to catecholamines,
decr. maximum minute volume, decr. respiratory efficiency (incr. residual
volumes, incr. work of breathing), decr. skeletal efficiency (respiration,
joints), decr. muscle extraction of O2 from blood, decr. capillary exchange
(thicker capillary walls, decr. capillary pores)
- abnormal
- atherosclerosis, heart disease, respiratory disease, skeletal diseases
(arthritis)
- effects from decr. VO2 max
(1) decr. maximum rate
of work
(2) faster onset of
fatigue
(3) with great decr. VO2
max, limitations in ADLs and other ordinary activities
(4) social,
psychological, economic effects from reduced maximum work capacity and, with
great decr. VO2 max, limitations in activities
NOTE: effects amplified by decr. efficiency of
working (decr. efficiency of O2 use by heart, respiration, joint
stiffness), decr. coordination, altered movement patterns. Therefore, a given
decr. in VO2 max has greater effect in an older person than in a
younger person.
- effects of exercise
- decr. exercise ->
decr. VO2 max
- incr. exercise ->
slower decr. in VO2 max or temporary incr. VO2 max
followed by slow decr. VO2 max
- most incr.
VO2 max from exercise from incr. O2 extraction by muscles
(other factors from above also improve)
10. Describe effects on the muscle system and three other systems - circulatory system, skeletal system, endocrine system; on quality of life; on diseases; and on life expectancy from staying physically active - i.e., maintaining high level of exercise.
muscle system
(1) slows decline in stamina
(maximum rate of work, endurance, post-activity soreness and stiffness,
recovery time
- due to (1) slower decr. in energy storage (ATP, C-P, glycogen), (2) slower
decline in oxidative enzymes, (3) slower decrease in muscle perfusion
(2) slows decline in muscle
mass
(3) slows decline in strength
(4) slows decline in insulin
sensitivity
- # 2-4 due to (1)
slower decr. in muscle cell thickness, (2) slower loss of muscle cells
(especially Type II fast fatiguable fibers), (3) slower incr. in muscle fat
(5) slower decline ability for
fast movements
- from (1) slower increase in reaction time and (2) slower decline in speed of
motion
circulatory system
-
decr. risk of atherosclerosis
- decr. BP or slower rise in BP
- decr. LDLs, decr. cholesterol, incr. HDLs
skeletal system
- slows decline in minerals,
maintains joint mobility
endocrine system
- slows decline in insulin
sensitivity, maintains GH levels
quality of life
- retain physical ability plus
non-biological benefits derived therefrom
diseases
- decr. risk of developing
some diseases - e.g., atherosclerosis, heart disease, strokes, diabetes,
osteoporosis
- decr. severity of diseases
life expectancy
- little increase in life
expectancy currently demonstrated, though increase is expected
11. Describe the effects from reducing levels of physical activity.
- no "bank account" from exercise
- "use it or lose it"
12. Describe effects on the muscle system and three other systems -
circulatory system, respiratory, nervous, skeletal, endocrine system; on
quality of life; on diseases; and on life expectancy from increasing activity
when older.
muscle
(1) incr. muscle mass
(2) incr. strength
(3) incr. speed of motion
(4) incr. stamina - all four parts including VO2
max
- NOTE: same proportion of improvement as in
young person
-due mostly to incr.
cell thickness
circulatory
(1) incr. cardiac output,
incr. cardiac efficiency, incr. HDL/LDL ratio, incr. vessel diameter, decr. BP,
decr. arrhythmias
(2) incr. organ perfusion
(3) probably decr. risk of
atherosclerosis
respiratory
(1) slows decline in
respiratory functioning
(2) helps reduce effects from
COPD (incr. mucous clearance, incr. respiratory muscle function, decr. airway
collapse, decr. smoking)
nervous
(1) incr. speed of CNS impulse
processing
(2) incr. short term memory
(3) improves sleep
(4) improves motor neuron
functioning -> incr. speed and strength
skeletal
(1) slows bone
demineralization
(2) reduces risk of
osteoporosis
(3) improves joint function =
easier movement, incr. ROM
endocrine
(1) incr. insulin sensitivity
- incr. glucose tolerance. decr. risk and severity of NIDDM
(2) slows decline in growth
hormone
- slows decline in organ size and function
quality of life, diseases, life expectancy (as above)
miscellaneous
(1) weight regulation, incr.
nutrition by incr. amount and variety of foods eaten
(2) incr. independence
(3) improves, psychology
- e.g., incr. mood, incr. well-being, decr. boredom, decr. anxiety, decr. stress
(4) incr. social contacts
(5) improves economic status
13. Explain why exercise programs for older people must be individualized.
- increased heterogeneity as age increases
14. Name six important steps or considerations in planning an exercise program for elders.
- set goals
- evaluate participants before beginning and after
participation in the program for a while (e.g., several weeks)
- individualize the program for each participant
- adjust the program according to the progress
of the participants
- include modifications in nutrition in the program to
accommodate for the increase in physical activity and altered metabolism
- take steps to minimize injuries and risks from
possible abnormalities or diseases present in the participants
- alter the nature of the exercises to avoid boredom
and maintain interest
- provide positive feedback to maintain interest and
motivation
- consider implementing "alternative
practical" exercises such as activities of daily living (ADLs), hobbies,
etc.
15. Describe effects of age changes and abnormal changes on ability to drive motor vehicles.
- slower and weaker responses
- increasing difficulty solving complicated or novel
problems
- declining vision
- declining hearing
- decreasing ability to stay mentally focused on tasks
16. Explain why driving a motor vehicle is important to many elderly.
- important for quality of life, psychological health, social well being, economic efficiency, access to needed services
17. List ways by which adequate transportation can be retained longer in spite of age changes.
- ongoing education, training, and evaluation of
motor vehicle driving skills
- providing alternate sources of transportation for
non-driving elders
Copyright 2020: Augustine G. DiGiovanna, Ph.D., Salisbury,
Maryland
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Copyright 2020: Augustine G. DiGiovanna, Ph.D.,
Salisbury University, Maryland
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