Week 7 - Protein p2 Flashcards
How does exercise/training influence protein synthesis variation in a fed state and a fasted state?
With exercise, variations in protein synthesis are greater in the fed state and decline less in the fasted state.
Therefore, muscle protein synthesis > muscle protein breakdown and we are in a positive net protein balance.
Why does an exercised muscle lead to greater muscle protein synthesis after consuming protein?
more sensitive to the anabolic properties of protein that is consumed meaning its better able to make use of the amino acids derived from protein ingestion
Why is the protein synthesis response to the first meal after exercise increased?
the muscle is more responsive to the muscle anabolic properties of protein nutrition in the early phase of post-exercise recovery (muscle anabolic window)
What is the greatest anabolic stimulus for muscles?
resistance exercise followed by amino acid ingestion
Where is the largest proportion of protein in the muscle cell?
myofibrillar - 60% of all protein in skeletal muscle
Site of chronic adaptations in response to
a) weights
b) endurance
c) nutrition
a) myofibrillar proteins (cause hypertrophy)
b) increased number or efficiency of mitochondrial proteins
c) sarcoplasmic proteins
Order the following in terms of the % of muscle protein they contain:
- Muscle Collagen
- Sarcoplasmic
- Myofibrillar
- Mitochondrial
Myofibrillar - 50-60%
Sarcoplasmic - 30%
Muscle collagen - 15%
Mitochondrial - 5-10%
Order the following in terms of the protein synthesis rates:
- Muscle Collagen
- Sarcoplasmic
- Myofibrillar
- Mitochondrial
mitochondrial
sarcoplasmic
muscle collagen
myofibrillar
Does myofibrillar have a high protein synthesis rate?
NO - 0.02-0.03 % per hour (Fractional synthesis rate)
Muscle protein turns over at a rate of approximately…
1-2% per day
Describe the overall proportion of protein contribution in muscle and the protein synthesis rates of mitochondria protein.
Mitochondrial proteins
- Low contribution to overall protein in muscle (5-10%)
- High rates of protein synthesis (0.08 FSR)
Synthesis rate of muscle protein pools
(largest)
Mitochondrial
Sarcoplasmic
Muscle collagen
Myofibrillar
(smallest)
How does myofibrillar and mitochondrial protein synthesis rates respond to:
a) endurance exercise
b) resistance exercise
a) Endurance exercise increases the synthesis of energy producing proteins (mitochondria)
b) Resistance exercise increases the synthesis of force producing proteins (myofibrillar)
Benefits of taking dietary protein above the RDA of 0.8g/kg/day (recommended dietary allowance)
- Repair replace and remodel
damaged proteins (e.g. muscle) - Optimal function of
metabolic pathways using AA’s - Support lean tissue
maintenance and/or accretion - Support optimal function of
the immune system
What are the anabolic actions of exercise? In the post-exercise period, what is the effect of protein ingestion?
Demanding exercise stimulates a prolonged elevation of muscle protein synthesis (MPS)
In the post-exercise period, the MPS response to protein ingestion is enhanced. This augmented fed-state MPS response may persist for 1-2 days post-exercise.
What is the optimal protein dose post-exercise for muscle protein synthesis?
0.25g/kg
In an 80kg person, this is 20grams.
To maximize training adaptations, protein intakes for athletes are suggested to be how much (optimal amount)?
1.6 - 2 g/kg/day
Nitrogen balance method is a good indicator of muscle protein balance - True or False?
False - good indicator of whole body muscle protein balance not individual tissues such as muscles
Net muscle protein accretion is achieved when…
Protein synthesis exceeds protein breakdown
Net muscle protein balance is greatest under what conditions?
Following exercise training and protein ingestion
In the post-exercise period, the MPS (muscle protein synthesis) response to protein ingestion is enhanced. How long does this enhanced response persist for?
24-48 hours
What amino acid is thought to be particularly important in initiating muscle protein synthesis?
Leucine
What are the two main properties of dietary protein that are thought to impact its capacity to increase post-exercise muscle protein synthesis?
EAA content and digestibility
If you wanted to maximise muscle protein synthesis throughout the day, following resistance exercise performed in the morning, when would you commence protein feeding and at what frequency would you continue to provide protein?
Early post-exercise feeding + consume 20-30g of protein every 3-4 hours
