Protein

Question 1

essential nutrients for humans

Answer 1

• water
• amino acids
• fatty acids
• minerals
• trace minerals
• electrolytes
• vitamins
• ultra-trace elements

Question 2

protein metabolism

Answer 2

• proteins provide structure to all cells in the human body
• many proteins are enzymes that increase the rate of metabolic reactions
• amino acids have central roles in the metabolism of many organs and tissues
• amino acids are precursors for the synthesis of body proteins
• amino acids are precursors and regulators of the synthesis of neurotransmitters, hormones, DNA, and RNA

Question 3

amino acids (protein) are a source of nitrogen in the body

Answer 3

1g nitrogen = 6.25g protein

Question 4

calculating nitrogen balance

Answer 4

1) determine nitrogen excretion (e.g., urine, faeces, sweat)(in grams per 24h period)
2) determine nitrogen intake
- protein intake (as grams per day) divided by 6.25
- N balance = 2 minus 1

Question 5

limitations of nitrogen balance

Answer 5

• no information of tissues
• lack of sensitivity
  
  • only gross measures of intake and excretion
• zero balance on low intake may reflect accommodation (similar to low EA concept)
• positive balance may not relate to lean body mass

Question 6

basis of skeletal muscle remodeling

Answer 6

• at meal times, the rate of muscle protein synthesis (MPS) drops
• at meal times, the rate of muscle protein breakdown (MPB0 increases
• with exercise, variations in protein synthesis are greater in the fed state and decline less in the fasted state
• with resistance exercise, variations in protein synthesis are greater in the fed state and decline less in the fasted state

Question 7

distinct muscle protein synthesis response to different modes of exercise

Answer 7

• resistance exercise increases the synthesis of force producing proteins
• endurance exercise increases the synthesis of energy producing proteins

Question 8

optimizing protein requirements beyond the RDA

Answer 8

• 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

Question 9

synergist anabolic actions of exercise plus protein

Answer 9

• 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 10

optimal protein dose for MPS in young healthy adults

Answer 10

ingestion of 30g protein is sufficient to maximise MPS rates during recovery from a single bout of endurance exercise

Question 11

how important is dietary protein quality for muscles

Answer 11

on a relative basis, animal proteins contains more essential amino acids, particularly the branched chain amino acid, leucine