Lecture 24: Aging Flashcards

1
Q

General changes in the neuromotor system

A
  • strength decline
  • longer reaction time
  • impaired control of posture/gail
  • impaired accurate control of force/movement
  • unintended force production
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2
Q

Behavioral changes with aging

A
  • weakness
  • slowness
  • higher variability
  • larger postural sway: delayed APAs
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3
Q

Central Changes

A
  • longer RT
  • slower movements
  • higher antagonist cocontraction
  • higher safety margins
  • changed synergies
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4
Q

Decline in the number of _______.

A

alpha-motoneurons

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5
Q

Muscle fiber ____ and _____.

A

denervation and atrophy

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6
Q

_________ by surviving motoneurons

A

Reinnervations

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7
Q

_______ innervation ratio

A

Higher

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8
Q

Lack of ______ motor units

A

smaller

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9
Q

Consequence: fewer ______.

A

motoneurons

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10
Q

Consequences of Changes in Motor Units with Age

A
  • Smaller MUs are absent; poor control of low forces
  • poor smoothness of force production
  • inability to develop force quickly
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11
Q

Changes in Strength with Age

A
  • Reduced Muscle Mass
  • Reduced Cross sectional Area
  • Reduced Normalized Force
  • Neural Activation: depends on the muscle
  • Coactivation of antagonist muscles increased by 30%
  • Not all muscle shows similar force losses; typically, more distal muscles are more affected
  • Consequences for multi-muscle synergies
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12
Q

Changes in Reflexed/Reactions with Age

A
  • H-Reflex amplitude slightly reduced
  • Tendon tap reflex slightly reduced
  • Polysynaptic reflexes reduced
  • Simple reaction time increased
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13
Q

Changes in Posture/Gait with Age

A
  • postural sway increased
  • APAs: loss of asynchronous involvement; delayed
  • preprogrammed reactions decreased and delayed. Switch from ankle to hip strategy
  • greater coactivation of antagonist muscles
  • higher variability
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14
Q

Effects of training

A

Higher Forces
Lower antagonist co-contraction
Small changes in cross-sectional area; importance of neural adaptations

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15
Q

Posture and Postural reflexes: Flexed in neck and trunk, extended in _____.

A

knees and elbows

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16
Q

Posture and Postural reflexes: _____ are exaggerated.

A

spontaneous and induced sway

17
Q

Posture and Postural reflexes: recovery after perturbation is ______.

A

imparied

18
Q

Posture and Postural reflexes: postural reflexed are impaired in ___ of elderly over 80 years of age.

A

70%

19
Q

Gait abnormality, gait apraxia: ______ strides; wide base

A

short, slow

20
Q

Gait abnormality, gait apraxia: ____ of those one 60 have gait problems, reduced arm swing, stiff turns, tendency to fall.

A

15%