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
2
Q
Behavioral changes with aging
A
- weakness
- slowness
- higher variability
- larger postural sway: delayed APAs
3
Q
Central Changes
A
- longer RT
- slower movements
- higher antagonist cocontraction
- higher safety margins
- changed synergies
4
Q
Decline in the number of _______.
A
alpha-motoneurons
5
Q
Muscle fiber ____ and _____.
A
denervation and atrophy
6
Q
_________ by surviving motoneurons
A
Reinnervations
7
Q
_______ innervation ratio
A
Higher
8
Q
Lack of ______ motor units
A
smaller
9
Q
Consequence: fewer ______.
A
motoneurons
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
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
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
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
14
Q
Effects of training
A
Higher Forces
Lower antagonist co-contraction
Small changes in cross-sectional area; importance of neural adaptations
15
Q
Posture and Postural reflexes: Flexed in neck and trunk, extended in _____.
A
knees and elbows
