Musle & muscle function 4

Question 1

Q: Resistance training increases muscle mass by…
A) Hypertrophy mainly
B) Hyperplasia mainly
C) Both

Answer 1

A)
Hypertrophy = largening of cells, hyperplasia = increase in number

Question 2

Muscle hypertrophy:
 Larger diameter of muscle fibers
More myofibrils per fiber
More myofibrillar protein (oa myosin and actin)

Answer 2

ok

Question 3

Even without growth (or net protein deposition) high levels of protein synhesis. Why?

Answer 3

 to allow maintenance and adaptation
 Re-utilization reduces dietary requirement (av intake: 70g/day, WHO: 50 gr/day = minimum)

Question 4

What is the fractional synthesis rate (k) in protein synthesis and turnover?

Answer 4

• relative intensity of replacement
• 350 g relative to 14000 g (20% of 70 kg) = 0.025

Question 5

: net protein deposition (g/day) is the highest..
A) During early postnatal growth
B) During compensatory protein synthesis after injury (e.g. skin loss)
C) During lactation
D) When following a strenuous resistance training protocol

Answer 5

C: lactation

Question 6

Q: what is true?
A) Protein synthesis only occurs in the absorptive state
B) Protein breakdown only occurs in the postabsorptive state
C) Protein synthesis and breakdown occur both in absorptive + postabsorptive state

Answer 6

C) Protein synthesis and breakdown occur both in absorptive + postabsorptive state

Question 7

However, absorptive state: more X than X, post-absorptive state: vice versa

Answer 7

synthesis than breakdown

Question 8

Q: How many different amino acids exist in nature?

Answer 8

A: more than 500

Question 9

Muscle protein fractional synthesis rate (FSR) is determined by

Answer 9

monitoring the incorporation of an amino acid tracer (isotope labelled) into muscle protein during a constant-rate intravenous tracer infusion.

Question 10

Why is there a Bias in studies: everything is focused on synthesis?

Answer 10

• Measurement of muscle protein breakdown is much more complicated…

Question 11

High dosages of essential amino acids stimulate muscle protein synthesis. Ingestion of essential + non-essential amnio acid composition vs essential amino acids does not give a different effect (only the essential!) True/false?

Answer 11

True

Question 12

During exercise, there is a(n) increase/decrease in protein synthesis

Answer 12

decrease. Protein breakdown is unknown

Question 13

You cannot make the protein balance positive during the postabsorptive state, but you can make it less negative
True/false

Answer 13

True

Question 14

Post-exercise ingestion of more than X g egg protein does not further augment protein synthesis.

Answer 14

20g

Question 15

Which pathway is a key player in protein synthesis? What is it and what does it regulate?

Answer 15

• mTOR
• protein kinase ((de)phosphorylates other protein)
• regulates cell growth, proliferation, protein synthesis

Question 16

• Increased protein synthesis before/after exercise is associated with increased mTOR activation (phosphorylation)

Answer 16

after

Question 17

What inhibits and what activates mTOR?

Answer 17

• AMP-activated protein kinase (AMPK) inhibits mTOR (amp/atp ratio up = ampk up, also during exercise/fasting)
• Activation of insulin/IGF-1 receptor activates mTOR

Question 18

IGF-1: induces mTOR activation and protein synthesis. Mostly derived from X.
IGF-1 secretion induced by X

Answer 18

liver
GH

Question 19

What further increases mTOR phosphorylation (activation) 2 hr after resistance exercise?

Answer 19

Ingestion of (whey) protein

Question 20

mTOR affects p70S6 kinase, eukaryotic initiation factors, eukaryotic elongation factors. These are factors that influence..

Answer 20

translation (components of ribosomes, among other things)

Question 21

There is more AMPK activation vs mTOR activation during what type of exercise?

Answer 21

endurance = ampk
mTOR = strength

Question 22

Strength exercise (3 leg exercises, 4 sets, 12 RM) vs endurance )120 min cycling at 60% VO2)

Q: From the higher AMPK phosphorylation by endurance exercise, can we conclude that T1 muscle fibers exhibit a faster depletion of ATP?

Answer 22

C) No, because the exercises were different in more than just the recruitment of muscle fibers

Question 23

The unaltered mTOR phosphorylation after endurance exercise indicates that endurance exercise is insufficient to increase muscle protein synthesis

True/false

Answer 23

False

Question 24

How is muscle protein synthesis increased with unaltered mTOR during endurance exercise?

Answer 24

There is more mito’s, we need more enzymes, etc. However: its different types of protein: mitochondrial versus myofibrillar protein synthesis

Question 25

Protein synthesis is /is not the same as protein growth

Answer 25

not necessarily

Question 26

Effect of resistance exercise training on muscle mass and strength well-proven, but effects of additional protein supplementation?

Answer 26

• Many studies
• Many different setups.. (protein source, training protocols, duration, subjects, etc)

-> large inter-individual variation.

Question 27

To what (aerobic capacity vs hypertrophy) do these pathways belong?

• mapk p38y
• PGC-1a
• mTOR

Answer 27

1 & 2: aerobic
3: mTOR