Musle & muscle function 4 Flashcards
Q: Resistance training increases muscle mass by…
A) Hypertrophy mainly
B) Hyperplasia mainly
C) Both
A)
Hypertrophy = largening of cells, hyperplasia = increase in number
Muscle hypertrophy:
Larger diameter of muscle fibers
More myofibrils per fiber
More myofibrillar protein (oa myosin and actin)
ok
Even without growth (or net protein deposition) high levels of protein synhesis. Why?
to allow maintenance and adaptation
Re-utilization reduces dietary requirement (av intake: 70g/day, WHO: 50 gr/day = minimum)
What is the fractional synthesis rate (k) in protein synthesis and turnover?
- relative intensity of replacement
- 350 g relative to 14000 g (20% of 70 kg) = 0.025
: 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
C: lactation
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
C) Protein synthesis and breakdown occur both in absorptive + postabsorptive state
However, absorptive state: more X than X, post-absorptive state: vice versa
synthesis than breakdown
Q: How many different amino acids exist in nature?
A: more than 500
Muscle protein fractional synthesis rate (FSR) is determined by
monitoring the incorporation of an amino acid tracer (isotope labelled) into muscle protein during a constant-rate intravenous tracer infusion.
Why is there a Bias in studies: everything is focused on synthesis?
- Measurement of muscle protein breakdown is much more complicated…
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?
True
During exercise, there is a(n) increase/decrease in protein synthesis
decrease. Protein breakdown is unknown
You cannot make the protein balance positive during the postabsorptive state, but you can make it less negative
True/false
True
Post-exercise ingestion of more than X g egg protein does not further augment protein synthesis.
20g
Which pathway is a key player in protein synthesis? What is it and what does it regulate?
- mTOR
- protein kinase ((de)phosphorylates other protein)
- regulates cell growth, proliferation, protein synthesis
- Increased protein synthesis before/after exercise is associated with increased mTOR activation (phosphorylation)
after
What inhibits and what activates mTOR?
- 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
IGF-1: induces mTOR activation and protein synthesis. Mostly derived from X.
IGF-1 secretion induced by X
liver
GH
What further increases mTOR phosphorylation (activation) 2 hr after resistance exercise?
Ingestion of (whey) protein
mTOR affects p70S6 kinase, eukaryotic initiation factors, eukaryotic elongation factors. These are factors that influence..
translation (components of ribosomes, among other things)
There is more AMPK activation vs mTOR activation during what type of exercise?
endurance = ampk
mTOR = strength
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?
C) No, because the exercises were different in more than just the recruitment of muscle fibers
The unaltered mTOR phosphorylation after endurance exercise indicates that endurance exercise is insufficient to increase muscle protein synthesis
True/false
False
How is muscle protein synthesis increased with unaltered mTOR during endurance exercise?
There is more mito’s, we need more enzymes, etc. However: its different types of protein: mitochondrial versus myofibrillar protein synthesis
Protein synthesis is /is not the same as protein growth
not necessarily
Effect of resistance exercise training on muscle mass and strength well-proven, but effects of additional protein supplementation?
- Many studies
- Many different setups.. (protein source, training protocols, duration, subjects, etc)
-> large inter-individual variation.
To what (aerobic capacity vs hypertrophy) do these pathways belong?
- mapk p38y
- PGC-1a
- mTOR
1 & 2: aerobic
3: mTOR
