Phys: Muscle Mass Regulation

Question 1

How many amino acids are there? How many are essential and non-essential?

Answer 1

20amino acids in the human body

11 are non-essential
9essential

Question 2

Whats the difference between essential and non-essential?

Answer 2

Essential means they can’t be synthesised in the human body so have to come from the diet
Non-essential can be made in the human body

Question 3

What are causes of lack of essential amino acids in the body?

Answer 3

Vegetarianism and veganism can be restrictive if person has lack of knowledge of where to obtain essential amino acids

Question 4

What is protein turnover?

Answer 4

Complete breakdown and synthesis of proteins

Question 5

What alters the free amino acid pool in the body?

Answer 5

Depends on starving, fasting, feeding and exercising

Question 6

How is the liver involved in protein turnover?

Answer 6

Amino acids can be transaminated and lead to fuel in the krebs cycle (gluconeogenesis)

There is a greater rate of gluconeogenesis when fasting

Question 7

What does positive synthesis mean?

Answer 7

Means there is more protein being created than being broken down which can be linked to hypertrophy

Question 8

What are the main processes that occur in the liver with amino acids?

Answer 8

Oxidation: -Leads to production of CO2 and Ammonia

Ureagenesis: -Removal of Urea after stripping it from all the useful carbons

Gluconeogenesis: - Repackages amino acids as useful glucose to help maintain homeostasis

Lipogenesis: -Making fats from a non-fat substance

Question 9

Why are muscles important?

Answer 9

• Provide structure and shape for organisms
• Determine metabolic conditions
• Contains hormones and neurotransmitters in myokines
• Locomotion
• Fuel store
• Thermoregulation

Question 10

What are myokines?

Answer 10

cytokine of a muscle (molecular mediators) and become chemoattractants to other cells such as macrophages that come over to repair the muscle post exercise

Question 11

How much muscle mass do we lose per year?

Answer 11

1% loss after the age of 30

Question 12

What does the loss of muscle mass lead to?

Answer 12

• Decrease in muscle function
• Increase in falls
• Decrease in cardiovascular and respiratory function in old due to large muscle mass loss

Therefore leads to the conclusion that maintaining muscle mass will increase lifespan and functionality

Question 13

What are the three stages of flux that the muscle in constantly in?

Answer 13

Hypertrophy
Atrophy
Balance

Question 14

When does hypertrophy and atrophy occur?

Answer 14

Hypertrophy occurs when Muscle Protein Synthesis (MPS) is greater than Muscle protein breakdown (MPB)

Atrophy is when MPB is greater than MPS

Question 15

What does data show about muscle throughout life?

Answer 15

• Men have significantly more muscle mass than women
• Decrease in lean body mass after 50 (especially in male thigh muscle)

-Maintaining physical activity may reduce the amount of reduction per year

Question 16

What happens to the average body composition as you get older?

Answer 16

• Fat mass increases
• Lean mass decreases

Means that BMI doesn’t change indicating that BMI should not be the primary test in older people

Question 17

What is the average muscle turnover per day?

Answer 17

1-2% per day (roughly 300-600g muscle)

• This occurs as the body is trying to repair injuries and protect the body so that we are always able to have fully functional proteins
• Fluctuations occur throughout the day in response to each meal

Question 18

How much protein would be shown to be maximal for protein synthesis?

Answer 18

20g protein at rested states
-The amount required is greater in the elderly as the stimulus is required to be greater

Average 75kg individual response shows no more then 30g is needed

Question 19

What happens to excess protein in the body?

Answer 19

It is oxidised and urea production is increased when more protein is taken so effectively being excreted

Question 20

What does Volpi 2003 experiment suggest about just the addition of EAAs?

Answer 20

Volpi added 18g of EAA in mix of 40g AA or just an 18g EAA supplement
-No additional benefit from the AA the benefit achieved the same with just EAA

Question 21

What does Cuthbertson 2004 suggest about the amount of EAA needed to maximise protein synthesis?

Answer 21

10g EAA produced a maximum rate in both young and elderly and no further effect from increasing the dosage

-Only limiting factor was the synthesis rate of the elderly people but it still hit maximum at 10g

Question 22

What does the addition of leucine indicate with muscle protein synthesis?

Answer 22

Increase in just 3g Leucine produced a high stimulatory response to protein synthesis

Question 23

What does the Churchward-Venne 2013 experiment suggest?

Answer 23

A mix of 5g Leucine and 6g Whey have a similar synthesising effect to the 25g whey

Question 24

Why does Leucine have such a high stimulatory effect in muscle protein synthesis?

Answer 24

Leucine acts as a trigger for the mTOR pathway which can stimulate MPS