Podcast
Questions and Answers
Which process is associated with sarcopenia?
Which process is associated with sarcopenia?
- Improved muscle contractile speed
- Increased muscle mass
- Loss of skeletal muscle mass (correct)
- Enhanced muscle strength
What leads to larger motor units in older individuals?
What leads to larger motor units in older individuals?
- Motor unit jitter
- Increased physical activity
- Collateral reinnervation (correct)
- Motor unit death
Which factor can attenuate ageing-related motor unit remodeling?
Which factor can attenuate ageing-related motor unit remodeling?
- Sarcopenia
- Decreased physical activity
- Increased muscle contractile speed
- Physical activity (correct)
In ageing-related motor unit decline, what is a potential limit on physical activity's capacity?
In ageing-related motor unit decline, what is a potential limit on physical activity's capacity?
What is a characteristic of motor unit jitter in some diseases?
What is a characteristic of motor unit jitter in some diseases?
Which age group is likely to have a higher number of motor units in the tibialis anterior muscle?
Which age group is likely to have a higher number of motor units in the tibialis anterior muscle?
What is one of the functional consequences of aging in relation to muscle fibers?
What is one of the functional consequences of aging in relation to muscle fibers?
Which type of fiber area increases as a result of decades of aging?
Which type of fiber area increases as a result of decades of aging?
What is a contributing factor to sarcopenia and whole muscle strength loss in aging individuals?
What is a contributing factor to sarcopenia and whole muscle strength loss in aging individuals?
Which type of muscle fibers are typically associated with slowed contractile response in older adults?
Which type of muscle fibers are typically associated with slowed contractile response in older adults?
In terms of fatiguability, which age group generally experiences less fatigue in isometric tasks according to the text?
In terms of fatiguability, which age group generally experiences less fatigue in isometric tasks according to the text?
What is one of the factors influencing fatiguability according to the text?
What is one of the factors influencing fatiguability according to the text?
What is a possible factor contributing to sarcopenia?
What is a possible factor contributing to sarcopenia?
What is a characteristic of muscle weakness in old age?
What is a characteristic of muscle weakness in old age?
How do old adults differ from young controls in terms of muscle activation?
How do old adults differ from young controls in terms of muscle activation?
Which neurotransmitter level is NOT decreased in individuals experiencing sarcopenia?
Which neurotransmitter level is NOT decreased in individuals experiencing sarcopenia?
What is a consequence of cortical hypo-excitability in the context of muscle function?
What is a consequence of cortical hypo-excitability in the context of muscle function?
What factors does not cause sarcopenia?
What factors does not cause sarcopenia?
Flashcards
Sarcopenia process
Sarcopenia process
Loss of skeletal muscle mass associated with aging.
Motor unit size in older adults
Motor unit size in older adults
Larger motor units due to collateral reinnervation.
Attenuating aging's impact on motor units
Attenuating aging's impact on motor units
Physical activity can reduce changes in motor unit structure.
Physical activity's limit
Physical activity's limit
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Motor unit jitter
Motor unit jitter
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Tibialis anterior muscle units (age)
Tibialis anterior muscle units (age)
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Aging's effect on muscle contraction
Aging's effect on muscle contraction
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Type I fiber area change
Type I fiber area change
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Sarcopenia and muscle fiber relationship
Sarcopenia and muscle fiber relationship
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Aging's effect on muscle fiber type
Aging's effect on muscle fiber type
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Fatigue and age
Fatigue and age
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Fatiguability factor
Fatiguability factor
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Potential sarcopenia factor
Potential sarcopenia factor
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Muscle weakness in old age
Muscle weakness in old age
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Muscle activation in older adults
Muscle activation in older adults
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Hormone NOT decreasing with sarcopenia
Hormone NOT decreasing with sarcopenia
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Cortical hypo-excitability impact
Cortical hypo-excitability impact
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Factors not causing sarcopenia
Factors not causing sarcopenia
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Study Notes
Aging and Motor Unit Remodeling
- A motor unit (MU) consists of a motoneuron and the muscle fibers it innervates
- Aging leads to a decline in the number of MUs and an increase in the percentage of Type I (slow-twitch) fibers
- Collateral reinnervation: an intact MU can reinnervate fibers orphaned by the death of another MU
Functional Consequences of Aging
- Sarcopenia: age-related loss of skeletal muscle mass, strength, and power
- Slowed contractile response in older adults
- Decreased muscle strength and speed with aging
Age-Related Decline in Motor Units
- Number of MUs declines with advancing age, with an accelerated decline after 60 years
- Case study: a 92-year-old with a single MU, demonstrating denervation 5 weeks later
Motor Unit Discharge Rate
- Motor unit discharge rate (Hz) decreases with age
- Average motor unit discharge rates for different muscles (e.g., First Dorsal Interosseous, Biceps Brachii, Triceps Brachii, etc.)
Motor Unit Jitter
- Motor unit jitter is increased in some diseases and with aging compared to healthy young adults
- Assessing motor unit jitter by overlaying many action potentials and aligning based on the 1st muscle fiber
Estimates of Motor Unit Numbers
- Estimates of motor unit numbers in male tibialis anterior of young, older, and masters runners
- Number of motor units decreases with age, with some attenuation in masters athletes
Take-Home Points
- Sarcopenia is an age-related loss of skeletal muscle mass, strength, and power with central and peripheral components
- Motor unit death and collateral reinnervation lead to larger and perhaps slower motor units
- Physical activity can attenuate age-related motor unit remodeling, but may have limitations in very old age
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