Chapter 8
 Muscle System - Notes  (Changes and Suggestions in blue and green - 3/6/06)
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 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 http://www.biologyofhumanaging.com/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

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© Copyright 1999 - Augustine G. DiGiovanna - All rights reserved.
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