Protein Metabolism + Nutrition in Endurance Performance Flashcards
Define protein
chains of amino acids, arranged into primary, secondary and tertiary structures which contain nitrogen.
What are the 3 processes of protein production
transcription, translation (initiation, elongation and termination) and post-translation modification
Give 3 functions of proteins
- Provide structure
- Hormones
- Antibodies
- Transporters
- Enzymes
- Movement
Define Muscle) protein synthesis
o The creation of new proteins from amino acids (as a result of initial transcription of the DNA).
Define Muscle) protein breakdown
o The degradation of whole proteins back to constituent amino acids.
Define (Muscle) protein balance
o The net result of muscle protein synthesis and muscle protein breakdown (Synthesis-Breakdown).
Define Amino acid oxidation
o The breakdown of intracellular amino acids for energy production.
Define Amino acid uptake
o The rate of transport of amino acids from one pool (e.g. the plasma) to another (e.g. the muscle cell).
Define Amino acid utilization
o The amount of dietary amino acids (obtained from dietary protein) that is used by the tissue and organs of the body for the above processes.
What are the 3 possible classes of proteins
Essential
Non-essential
Conditionally essential
Define primary structure of protein
Sequence of amino acids
Define secondary structure of protein
Local folding of polypeptide chain
Define tertiary structure of protein
three dimensional folding pattern of a protein- side chain interactions
Define quaternary protein structure
protein consisting of more than one amino acid chain
What is deamination
removal of amine group (NH3) in liver
In the average person,how much protein is synthesised each day?
350g/day
In the average person, what is the protein synthesis rate?
1-2% a day
What is a stable isotope
Isotopes function identically, but can be marked, so act as a tracer to measure net nitrogen balance.
give 3 factors affecting protein turnover
- Habitual diet
- Protein intake
- Energy intake
- Hormones
o Insulin
o Steroids e.g. testosterone - Exercise
Give 3 potential roles of dietary protein in sport and exercise
Muscle hypertrophy Muscle strength Immune function Central fatigue Glycogen re-synthesis Additional energy during exercise Specific function of individual amino acids Effects on muscle damage
Bowtell et al 1998 found that leucine oxidation increased most when after exercise
1 hour post-exercise
Hulston et al 2011 found what sort of protein balance during exercise
negative net balance, but exercise increased both protein synthesis and breakdown
Protein ingestion before, during or after exercise promotes what sort of balance
positive net balance
Protein ingestion is associated with which synthesis rates? A) increased myofibrillar B) decreased myofibrillar C) Increased mitochondrial D) decreased mitochondrial
A) increased myofibrillar
In the trans-alp challenge, which group improved their performance?
o 7.6% cho-e solution and cho bars (placebo)
o 7.2% cho-e, 1.8% wp solution and cho/protein bars.
o 7.2% cho-e, 1.8% wp solution and cho/protein bars.
What is central fatigue theory
Fatigue may be associated with inadequate central nervous system “drive” to the working muscle e.g. by neurotransmitters
What is the serotonin central fatigue theory
Increased brain 5-hydroxytryptamine (5-HT) (Serotonin) concentration causes a deterioration in performance
Describe the central fatigue theory mechanism
the selective transporter poses competition with branched chain amino acids (increasing tryptophan and serotonin) so... • reduced [BCAA] and increased [fTryp] • increased fTryp : BCAA • increased fTryp transport into brain • increased serotonin synthesis • impaired CNS function
Did Blomstrand et al 1991 show BCAA supplementation to improve mental and physical performance
- some evidence of improved mental performance
* slower runners (3.05 - 3.30 h) improved performance
Did Van Hall et al 1995 show BCAA/tryptophan supplementation improved physical performance
• No difference in time to exhaustion despite increased fTryptophan:BCAA.
True or false: A hypocaloric diet decreases body mass, lean body mass and fat mass
False, Lean body mass increased
What is the recommended protein dose?
RDI = 1.2 – 2.0 g/kg
What is the timing consideration for protein ingestion?
o Protein ingestion in close proximity to exercise may facilitate muscle reconditioning
o Protein feeding during exercise does not appear to enhance exercise performance assuming adequate CHO is consumed.
True of False: Tarnopolsky et al 1992 suggested a RDA for sedentary subjects to be 0.89 g/kg/day and 1.76g/kg/day for strength trained subjects.
True
What is the anabolic stimulus for muscle production in the diet?
Protein
Why does exercise cause an immediate reduction in muscle protein synthesis?
the priority is ATP for muscular contraction at the time
What is more important in Rex training: intensity or carrying it out to failure
carrying it out to failure
What is more important in Rex training: eccentric or concentric exercise
eccentric
Why do we see an increase in MPB following exercise
protein breakdown replaces protein fibres with stronger, faster fibres
If protein turnover is around 300-600g per day.. what can this increase too post-exercise
around 600-900g per day
True or false: there is a golden 30 mins post-exercise
False-
protein synthesis is increased for up to 2 hours post. Plus, the body is sensitive to protein for all meals within this 2 days
What does net protein accretion result in
Hypertrophy
When should whey protein be ingested
ingested and absorbed faster than casein- so post-exercise
When should casein protein be ingested
pre-bed
What is leucine better at than other amino acids?
Faster FSR
True or false: CHO can improve MPS
There was an increase in MPB with CHO and exercise, but CHO reduced MPS with exercise
What is the RDA for protein? Sedentary
0.89 g/kg/d
What is the RDA for protein? ReX trained
1.76 g/kg/d
How much protein post-exercise will induce an optimal anabolic response
20-30g
