Lecture 14 Flashcards
The plasticity of skeletal muscle tissue is attributed to 2 dynamic and continuous processes that take place throughout the day. Name them
Muscle protein breakdown and synthesis
T or F: Skeletal muscle is a plastic tissue and is constantly “turning over”
TRUE
T or F: Skeletal muscle hypertrophy is governed by ___
Net protein balance (MPS vs MPB)
What happens if you increase both MPB and MPS when you exercise?
If you don’t have a protein meal after exercise you get more MPB than MPS so risk of injury increases
What is mTOR?
Mechanistic Target Of Rapamycin
increase in mTOR activity comes from 3 options
Resistance exercise
Amino acids
Growth factors
Increase in mTOR activity leads to what effect on MPS?
Increase in MPS
Increase in MPS leads to what consequence for the muscles?
Hypertrophy
Mechanism to activate synthesis: when there is food vs no food
Need specifically amino acids from proteins or you can’t get MPS because you will get the energy from the muscle = increase in MPB
Where does the energy comes from when you have not gotten any proteins in?
Get MPB from the muscles
Is it possible to gain muscle while loosing weight?
Yes, but the window is very small = minimal calorie deficit
When you loose weight, is it normal to loose muscle mass?
Yes normal phenomenon
Where do you get the essential amino acids vs non-essential?
Essential: get it from the diet
Non essential: can synthesize them
Name the 9 essential amino acids
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Muscle protein is ____ slower turnover compared to other organs
20x
Muscle protein accounts for ___ of protein metabolism in the body
30%
What molecule do you need to stimulate to increase MPS?
mTORC1
Can you get an exact measurement of protein synthesis if you get it from the blood?
No, because it happens in the muscle but also in:
- plasma
- urine
- saliva
- CO2
The liver extracts a portion of the AA, letting ___ of AA we ingest into the circulation
30%
AA are used for 3 things
- Used for protein synthesis
- Converted to other amino acids
- Oxidized
Nutritional recommendations for proteins - Adult
0.8-1.0 g/kg of BW
Nutritional recommendations for proteins - Elderly
1.2 g/kg of BW
Nutritional recommendations for proteins - Athletes
1.2 g/kg of BW
Why do elderly need more proteins?
Anabolic resistance - decrease in protein assimilation
How do you measure anabolic resistance?
You measure protein synthesis using stable isotopes
Maximum protein resynthesis rate
25-30g
When can we have high MPS and also MPB?
When we exercise - specifically eccentric training
What happens to MPS if you eat more than 30g of proteins in a single meal?
PLATEAU
The type of proteins consumed will affect what (2)
Tissue repair
Muscle mass gain
T or F: Whey protein contains all essentials AA
TRUE
Proteins recommendations for endurance athlete
1.2-1.4 g/kg of BW
Proteins recommendations for power athlete
1.4-1.6 g/kg
3 possible consequence of excess of proteins
Kidney overload
Excess weight
Adipose tissue
Difference between BCAA and complete protein in the MPS
Complete protein stimulates MPS much longer
What is BCAA
Branded-chain amino acids
What are the 3 BCAA
Leucine
Isoleucine
Valine
Amount of protein needed to stimulate MPS for the young vs the elderly
20g young
40g elderly
in the hours following a workout, MPS is approximately ____ to ____ higher
100 to 150%
Factors influencing synthesis - Acute dietary factors (4)
Protein dose
Protein EAA content
Mixed meal co-ingestion
Alcohol
Factors influencing synthesis - Chronic dietary factors (3)
Protein intake
Fish-oil intake
Energy intake deficiency
Factors influencing synthesis - Non-dietary factors (7)
Resistance type exercise
Physical inactivity
Aging
Female sex (pre-menopause)
Female sex (post-menopause)
Lean mass
Fat mass
T or F: you can’t get all the essential amino acids from being vegan
FALSE (ex: tofu, chickpeas)
Does getting protein from an animal source necessarily correlates with muscle mass?
No, herbivorous animals are strong (ex: elephant, giraffe, bison, hippopotamus, rhinoceros, horse)
In the study that compared 3 strategies (bolus, intermediate, pulse) to assess the impact of timing and distribution of protein intake, what was the conclusion?
Winner is intermediate = get at least 20g of protein to get protein synthesis - long term would be the most beneficial
Recommendation for pre-sleep protein ingestion
40g of protein before sleeping to increase protein synthesis
Consequence of pre-sleep protein ingestion in resistance athletes
Increase in overnight fractional synthetic rate (FSR)
2 impacts of carbohydrates on muscle protein synthesis?
Insulin impacts muscle growth
Carbs + proteins = increase in insulin but no further increase in MPS
Does the timing of protein intake affect mass gain?
Study says no, as long as the daily protein consumption is achieved
