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Nutrition & the ageing body > Lectures 5 & 6: ageing and muscle mass > Flashcards

Lectures 5 & 6: ageing and muscle mass Flashcards

1
Q

In what unit does the actual skeletomuscle contraction occur?

A

Sarcomere

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2
Q

 Estimated muscle mass loss, after age of 30?

A

3-8% every 10 years

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3
Q

What are the reasons for muscle mass loss when ageing?

A

1: Decreased physical activity
2: Decreased anabolic hormones
3: Anabolic resistance
4: Decreased protein intake

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4
Q

TEE: what happens when increasing in age?

A

when adjusted, it is stable between 20-60 yo
> even during pregnancy
> declines in older adults, to 75% at 100 yo

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5
Q
  1. Decreased anabolic hormones: which hormones are we talking about?
A

Testosterone (large person-to-person variation, inreases with resistance training)
Growth hormone (related to sarcopenia, GH therapy might help to increase lean mass)
Insulin: stimulator of AKT MTOR pathway (important in muscle anabolism)

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6
Q

Anabolic resistance: what is it? What are reasons for anabolic resistance?

A

Attenuated muscle protein synthesis after exercise/amino acid intake

Reasons:

  1. Reduced blood flow and insulin sensitivity
  2. Increased splanchnic extraction
  3. Inflammaging
  4. Decreased satellite cells (L6)
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7
Q

Explain :Reduced blood flow and insulin sensitivity as a reason for anabolic resistance

A

Low capillarization of muscle tissue (decreased blood flow) -> amino acids do not reach muscle cells

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8
Q

Explain: Increased splanchnic extraction
as a reason for anabolic resistance

A
  • Uptake of amino acids before they reach bloodstream
  • Utilised for gut protein synthesis, or oxidized for energy
  • 50% in older adults vs. 23% in younger
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9
Q

Explain Inflammaging as a reason for anabolic resistance

A

Decrease signalling, beakdown muscle tissue, lower build-up, leads to less muscle mass. Chronic inflammation state

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10
Q

Elderly have a decreased protein intake. How much is needed? How should it be consumed?

A

Protein division over the day is important. 25-30 gr per main meal to reach anabolic threshold

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11
Q

What is the average gr of protein for dutch people during breakfast?

A

10 gr average during breakfast, quite low

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12
Q

 Expert papers advice to increase intake to ? g/kg (official recommendations Nordic countries)

A

1.0-1.2

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13
Q

Protein source is important. Quality determined by?

A
  • Amino acid profile
  • Digestibility
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14
Q

Feeding: 3 moments during the day, would it help to add another moment of protein intake right before sleep? What does this do?

A

Yes:
 Extra mTOR stimulation
 Increases muscle mass
 However, accelerates ageing (mTOR)
 Balance is important

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15
Q

What decreases faster: muscle mass or muscle strength?

A

strength

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16
Q

Formula for muscle quality = ?

A

> Muscle quality = function/mass

17
Q

What three main types of determinants of muscle quality are there? Examples per types?

A

Architectural
Capillarization (L7)
Intramuscular fat (L7)
Fiber specific atrophy (= wasting away) (L6)
Satellite cells (L6)

Energetics
Mitochondrial functioning (L7)

Neuromuscular
Decreased voluntary activation
Decreased motor units
Decreased calcium content in muscle fiber

18
Q

Critical life events: increased catabolic rate during?

A
  • Hospitalisation
  • Immobilisation
  • Bed rest
  • Stressful life events
19
Q

Bed rest: how much g lean mass lost in young vs elderly?

A

100 gr vs 600 gr

20
Q

Hospitalisation: Older adults receiving elective hip replacement: average hospital stay: 5.6 d
average quadriceps volume change:

A

-3.4%. Being mobile already helps (walking).

21
Q

What else happens in a hospitalization stay, besides muscle mass loss? in total absence of physical activity?

A

-> also decrease in insulin sensitivity (-29% after 7 days)
-> no changes in capillary density
Increased inflammation

22
Q

Muscle protein turnover: what is the same in elderly vs young and what differs?

A

Breakdown is the same
More synthesis in old vs young, not because of the synthesis an sich, but the response is worse

23
Q

What can overcome this anabolic resistance ageing effect?

A

Lifestyle interventions (resistance exercise, physical activity, protein/EAA supplementation) can overcome this ageing effect. Stimulate via amino acids (e.g. leucine; essential, can directly stimulate muscle synthesis)

24
Q

 Fun fact: X months time muscle rebuilt completely. Breakdown and synthesis happening all the time

A

three

25
Q

T1 vs T2 fibers: what is the difference?

A

T1:High mitochondrial content
Abundance of oxidative enzymes
High resistance against fatigue

T2: Including subtypes IIa and IIb
High glycolytic enzyme activity
More prone to fatigue

26
Q

During ageing something happens with one of the two fibers. Which ones and what happens?

A

specific loss in type 2 fiber size
 No difference in number of fibers!

27
Q

6-month resistance exercise: Increases quadriceps CSA with 9%. To what fiber(s) can this change be explained?

A

CSA increase is fully explained by type II hypertrophy
(CSA = cross-sectional area). T2 fiber size can be increased again.

28
Q

What are satellite cells + what is the function?

A

Precursors to skeletal muscle cells
Responsible for the ability of muscle tissue to regenerate.

29
Q

What happens to satellite cells with ageing, illness, disuse?

A

 The number of satellite cells decrease, making them a potential candidate for contribution towards anabolic resistance

30
Q

What can also happen with ageing with satellite cells, besides decline in number?

A

Function satellite cells is also diminished with ageing.
They sometimes turn into other cells than fibers (fat cells). Less myotube formation.

31
Q

Satellite are dependent on what types of environment?

A

local mirco-environment (niche): younger environment = younger cells

Systemic environment (circulation):
- Parabiosis (connecting a younger organism to an older one: changing its bloodstream) improves satellite cell content
- Inflammation negatively affects SC function

32
Q

Exercise + protein supplementation prior to surgery helps reduce muscle loss

A

ok

Nutrition & the ageing body (15 decks)

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