Week 7 - Protein p2

Question 1

How does exercise/training influence protein synthesis variation in a fed state and a fasted state?

Answer 1

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.

Question 2

Why does an exercised muscle lead to greater muscle protein synthesis after consuming protein?

Answer 2

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

Question 3

Why is the protein synthesis response to the first meal after exercise increased?

Answer 3

the muscle is more responsive to the muscle anabolic properties of protein nutrition in the early phase of post-exercise recovery (muscle anabolic window)

Question 4

What is the greatest anabolic stimulus for muscles?

Answer 4

resistance exercise followed by amino acid ingestion

Question 5

Where is the largest proportion of protein in the muscle cell?

Answer 5

myofibrillar - 60% of all protein in skeletal muscle

Question 6

Site of chronic adaptations in response to
a) weights
b) endurance
c) nutrition

Answer 6

a) myofibrillar proteins (cause hypertrophy)
b) increased number or efficiency of mitochondrial proteins
c) sarcoplasmic proteins

Question 7

Order the following in terms of the % of muscle protein they contain:
- Muscle Collagen
- Sarcoplasmic
- Myofibrillar
- Mitochondrial

Answer 7

Myofibrillar - 50-60%
Sarcoplasmic - 30%
Muscle collagen - 15%
Mitochondrial - 5-10%

Question 8

Order the following in terms of the protein synthesis rates:
- Muscle Collagen
- Sarcoplasmic
- Myofibrillar
- Mitochondrial

Answer 8

mitochondrial
sarcoplasmic
muscle collagen
myofibrillar

Question 9

Does myofibrillar have a high protein synthesis rate?

Answer 9

NO - 0.02-0.03 % per hour (Fractional synthesis rate)

Question 10

Muscle protein turns over at a rate of approximately…

Answer 10

1-2% per day

Question 11

Describe the overall proportion of protein contribution in muscle and the protein synthesis rates of mitochondria protein.

Answer 11

Mitochondrial proteins
- Low contribution to overall protein in muscle (5-10%)
- High rates of protein synthesis (0.08 FSR)

Question 12

Synthesis rate of muscle protein pools

Answer 12

(largest)
Mitochondrial
Sarcoplasmic
Muscle collagen
Myofibrillar
(smallest)

Question 13

How does myofibrillar and mitochondrial protein synthesis rates respond to:
a) endurance exercise
b) resistance exercise

Answer 13

a) Endurance exercise increases the synthesis of energy producing proteins (mitochondria)
b) Resistance exercise increases the synthesis of force producing proteins (myofibrillar)

Question 14

Benefits of taking dietary protein above the RDA of 0.8g/kg/day (recommended dietary allowance)

Answer 14

1. Repair replace and remodel
   damaged proteins (e.g. muscle)
2. Optimal function of
   metabolic pathways using AA’s
3. Support lean tissue
   maintenance and/or accretion
4. Support optimal function of
   the immune system

Question 15

What are the anabolic actions of exercise? In the post-exercise period, what is the effect of protein ingestion?

Answer 15

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.

Question 16

What is the optimal protein dose post-exercise for muscle protein synthesis?

Answer 16

0.25g/kg
In an 80kg person, this is 20grams.

Question 17

To maximize training adaptations, protein intakes for athletes are suggested to be how much (optimal amount)?

Answer 17

1.6 - 2 g/kg/day

Question 18

Nitrogen balance method is a good indicator of muscle protein balance - True or False?

Answer 18

False - good indicator of whole body muscle protein balance not individual tissues such as muscles

Question 19

Net muscle protein accretion is achieved when…

Answer 19

Protein synthesis exceeds protein breakdown

Question 20

Net muscle protein balance is greatest under what conditions?

Answer 20

Following exercise training and protein ingestion

Question 21

In the post-exercise period, the MPS (muscle protein synthesis) response to protein ingestion is enhanced. How long does this enhanced response persist for?

Answer 21

24-48 hours

Question 22

What amino acid is thought to be particularly important in initiating muscle protein synthesis?

Answer 22

Leucine

Question 23

What are the two main properties of dietary protein that are thought to impact its capacity to increase post-exercise muscle protein synthesis?

Answer 23

EAA content and digestibility

Question 24

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?

Answer 24

Early post-exercise feeding + consume 20-30g of protein every 3-4 hours