Muscle Ageing Flashcards

1
Q

Does strength loss appear greater for upper or lower body?

A

lower body - 40% decline
upper body - 33% decline

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2
Q

Muscle power decreases, what does this mean in older people?

A

Fall likelihood increases.

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3
Q

What underlies the functional declines with age?

A

1) A loss of Muscle mass -sarcopenia /muscle atrophy
2) Muscle quality is reduced
3) Neuromuscular alterations

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4
Q

The average rate of muscle mass loss after 40 years old is approximately?

A

8% per decade or 0.5 to 1% per annum until 70 years old

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5
Q

What is the average rate of muscle mass loss past 70 years?

A

~15 % per decade

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6
Q

When does the regression line slope start (age)?

A

∼45 years old for both men and women
declines more rapidly after 70 years old

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7
Q

Is the muscle relative to body mass slope of regression steeper in women or men?

A

Men

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8
Q

What atrophies faster, type I or type II fibres?

A

Type II

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9
Q

What is greater, losses in muscle strength or muscle loss?

A

Losses in muscle strength are FAR greater

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10
Q

What happens to % of muscle in muscle with ageing?

A

Ageing increases fat accumulation in muscle, more fat less muscle WITHIN muscle!

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11
Q

What happens to motor units with age?

A

Increased age = less motor units

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12
Q

What does less motor units = ?

A

Less motor units = less force

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13
Q

What is denervation?

A

Where what was previously a type II fibre, is now innervated by a type I fibre. Therefore this type II fibre starts to behave more like a type I fibre

Complete denervation = type II fibre loss

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14
Q

Does a larger MU = more efficient?

A

No, less efficient

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15
Q

Can atrophying fibres be reinnervated by remaining MU’s?

A

Yes but it creates larger MUs.

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16
Q

How does denervation and collateral re-innervation alter muscle characteristsics?

A
  • increased co-expression of myosin isoforms
  • decreased force output
  • decreased velocity of contraction and hence power
17
Q

Other than denervation… what other changes occur the excitation-coupling process?

A
  • changes to excitation-contraction coupling
  • changes in SR function
  • slowing of myosin molecule
  • reduced acto-myosin cross bridges
18
Q
A