Week 4 - Muscle Ageing Flashcards

1
Q

What are the impacts of muscle ageing

A

Strength is lost with age
Greater loss in lower body limbs
Muscle power in lower group
Muscle power declines with age.
Older adult has greater subcutaneous fat and intermuscular fat

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2
Q

What underlies the functional decline of muscle mass
(ON SHEET)

A

Average rate of muscle mass loss is approx 8% per decade, until 70 years old where it increases to 15% per decade.
Muscle biopsies can show muscle atrophy - fibres get smaller with age, especially type II. Losses in muscle strength are far greater than muscle loss

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3
Q

What underlies the functional decline of muscle quality

A

Aging increases fat accumulation in muscle - more fat, less muscle within the muscle, more fat in and between muscle
Losses in muscle mass don’t completely explain strength loss

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4
Q

What underlies the functional change in neuromuscular alterations

A

increased age = less motor units

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5
Q

What are the functional consequences of losing motor units

A

Results in muscle fibers becoming denervated
This causes muscle atrophy and potential fibre loss.
However there are adaptive processes that act to rescue force production loss from affected muscle fibers

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6
Q

How does denervation and collateral re-innervation alter muscle characteristics
(ON SHEET)

A

Increase co-expression of myosin isoforms
Decrease force output
Decrease velocity of contraction and thus power

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7
Q

Whats the effects of reinnervation of fibres

A

Increase size of motor units
reinnervation preserves some muscle mass

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8
Q

What are other changes that occur to excitation-coupling process
(ON SHEET)

A

Changes to excitation-contraction coupling leads to decreased Ca2+ release from sarcoplasmic reticulum

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9
Q

Whats the effect of changes in sarcoplasmic reticulum function
(ON SHEET)

A

Decreased Ca2+ uptake

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10
Q

Whats the effect of the slowing of the myosin molecule

A

decreased intrinsic speed of shortening

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11
Q

Whats the effect of reduced acto-myosin cross bridges

A

Decreased force output per muscle fibre

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12
Q

How is fatigue resistance impacted with old age

A

More type II fibres innervated by type I motor units so act more like Type I

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13
Q

What is a master athlete

A

Anyone aged 35 or over, competing in track and field, road running, cross country, or race walking

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14
Q

What are the muscle characteristics of master athletes
(ON SHEET)

A

Lifelong exercise does not minimise motor unit increase or inefficiency.
Fibre loss is inevitable with age but type I better preserved in these master endurance athletes
Same force as someone 30 years younger.
Muscle deterioration not removed but not as severe

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