Phys: Muscle Mass Regulation Flashcards
How many amino acids are there? How many are essential and non-essential?
20amino acids in the human body
11 are non-essential
9essential
Whats the difference between essential and non-essential?
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
What are causes of lack of essential amino acids in the body?
Vegetarianism and veganism can be restrictive if person has lack of knowledge of where to obtain essential amino acids
What is protein turnover?
Complete breakdown and synthesis of proteins
What alters the free amino acid pool in the body?
Depends on starving, fasting, feeding and exercising
How is the liver involved in protein turnover?
Amino acids can be transaminated and lead to fuel in the krebs cycle (gluconeogenesis)
There is a greater rate of gluconeogenesis when fasting
What does positive synthesis mean?
Means there is more protein being created than being broken down which can be linked to hypertrophy
What are the main processes that occur in the liver with amino acids?
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
Why are muscles important?
- Provide structure and shape for organisms
- Determine metabolic conditions
- Contains hormones and neurotransmitters in myokines
- Locomotion
- Fuel store
- Thermoregulation
What are myokines?
cytokine of a muscle (molecular mediators) and become chemoattractants to other cells such as macrophages that come over to repair the muscle post exercise
How much muscle mass do we lose per year?
1% loss after the age of 30
What does the loss of muscle mass lead to?
- 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
What are the three stages of flux that the muscle in constantly in?
Hypertrophy
Atrophy
Balance
When does hypertrophy and atrophy occur?
Hypertrophy occurs when Muscle Protein Synthesis (MPS) is greater than Muscle protein breakdown (MPB)
Atrophy is when MPB is greater than MPS
What does data show about muscle throughout life?
- 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
What happens to the average body composition as you get older?
- Fat mass increases
- Lean mass decreases
Means that BMI doesn’t change indicating that BMI should not be the primary test in older people
What is the average muscle turnover per day?
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
How much protein would be shown to be maximal for protein synthesis?
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
What happens to excess protein in the body?
It is oxidised and urea production is increased when more protein is taken so effectively being excreted
What does Volpi 2003 experiment suggest about just the addition of EAAs?
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
What does Cuthbertson 2004 suggest about the amount of EAA needed to maximise protein synthesis?
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
What does the addition of leucine indicate with muscle protein synthesis?
Increase in just 3g Leucine produced a high stimulatory response to protein synthesis
What does the Churchward-Venne 2013 experiment suggest?
A mix of 5g Leucine and 6g Whey have a similar synthesising effect to the 25g whey
Why does Leucine have such a high stimulatory effect in muscle protein synthesis?
Leucine acts as a trigger for the mTOR pathway which can stimulate MPS
