Lecture 23 - Nutritional interventions and skeletal muscle Flashcards
What is the 4 aims in sports nutrition?
To optimise body substrate stores before exercise
To enhance substrate availablilty during exercise and spare muscle glycogen stores
To increase the rate of glycogen synthesis in the recovery phase
To increase muscle protein repair synthesis and reduce muscle damage
If there is not a significant difference from nutritional interventions that does not always mean…
that thereis no effect
placebo effects
multiple suppliments
difference between winning and losing can be extremely small
True or false
You need food intake to be in a positive protein balance after resistance exercise
true
true or false
CHO intake affects protein synthesis
false
CHO intake does not result in a positive protein balance
How is CHO thought to interact with the net protein balance indirectly?
Via insulin
The level of insulin that causes protein synthesis is at the very start of release - low levels
will signal GLUT 4, more glucose uptake
Insulin can stimulate the mTOR pathway
potentially more important in regulating MPB
The intake of ______ AAs stimualtes protein synthesis
essential
these are the main stimuli to protein synthesis
Which signalling pathways does essential AAs use to stimulate protein synthesis?
mTORC1
The plateau of protein intake vs. Muscle Protein sythesis rate is at?
about 20-30g
True or false
~25g protein is enough to maximally stimulate muscle protein synthesis
true
The stimulatory effect of increased AA availability on protein synthesis is how short?
back to basal levels after around 4-6 hours
What is the protein makeup of Milk?
3% protein, so 30g/L
80% is casein protein
20% is whey protein
True or fasle
Whey protein is more rapidly digested than casein
true
AA derived from dietary protein hydrolysate appear quicker in the circulation resulting in…
high protein synthesis
Why is Whey protein better than casein?
need to look at the AA composition of the proteins
Whey protein contains much more Leucine
Why is Leucine so special?
It stimualtes muscle protein synthesis and inhibits proteolysis
Leucine administration inhibits protein breakdown
- including indirectly through increasing insulin
Leucine can directly stimulate mTORC1 though the Leucyl-tRNA synthase. This enzyme changes GDP –> GTP on the Rags which stimulates the mTOR pathway
Recmmended dietary intake represents the …
minimal intake - not optimal
Current American College of sports medicine position stand on dietary practices for athletes recommends protein intake of ….
1.2-1.7 g/kg/day
What effect does increased protein intake during weight loss have?
reduces loss of muscle mass
Diet and exercise-induce weight loss with higher protein and increased dairy product intakes promotes more favourable body composition changes in women characerised by …
Greater total and visceral fat loss and lean mass gain
_______ is low in protein and represents the biggest opportunity to increase protein intake in frail elderly
Breakfast
An issues is that the acute studies into the effects of protein ingestion do not translate into …
long term studies
Chronic leucine treatment does not increase msucle mass
Glycine supplimentation reduces_______________ expression and helps maintain the protein synthetic machinery
Atrogin-1 mRNA expression
Metabolism of glycine has a massive effect intracelluarlly on ..
ROS, Glutathoine, changes methylationof DNA,
