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Exercise Nutrition > Protein > Flashcards

Protein Flashcards

1
Q

What are proteins

A

Chains of amino acids

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2
Q

Protein classification

A
  • Polypeptide
    • Chains of AAs linked by a peptide bond
  • Dipeptide
    • Simplest polypeptide
  • Tripeptide
  • Oligopeptide
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3
Q

Explain essential and non-essential protein

A

Essential - the body cannot synthesis (diet)

Non-essential - body can synthesis

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4
Q

Function of protein

A
  • Synthesis of body protein
  • Structural parts of all cells
    • Muscle, skin, hair
    • Bones and teeth (minerals embedded in protein structure)
      + Deficiency in protein - these structure break down:
      ^ Reduced muscle mass, loss of skin elasticity, thinning of hair
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5
Q

Protein for fuel at rest and exercise

A
  • Estimated contribution of protein to energy expenditure at rest 5 - 15%
  • During exercise ↑ carbohydrate and fat oxidation
  • Contribution of protein to oxidative metabolism in prolonged exercise < 5%
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6
Q

Protein turn over and net protein balance

A

proteins are continually breaking down and synthesizing

Net balance
The area of protein synthesis - the area of protein breakdown = protein gain or loss

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7
Q

Amino Acid pool

A

Small pool of amino acids
- 120g of free amino acids are present in the skeletal muscle of an adult

  • Amino acids are constantly extracted from the free amino acid pool for synthesis of various proteins, and breakdown of protein makes amino acids available for the free amino acid pool
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8
Q

Protein breakdown

- Purpose

A

Serves 3 main purposes:

  • Degrades potentially damaged proteins to prevent a decline in their function
  • Provides energy when some individual AAs are converted to Acetyl CoA – oxidized in the mitochondria
  • Synthesis of other compounds

Protein -> breakdown -> amino acid -> amino acid -> new protein

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9
Q

What is transamination

A

Before proteins can be oxidised:

  • Amino group must be removed
    • This is achieved by transferring it to another molecule called a keto acid
    • Resulting in the production of another type of AA
    • This process is catalyzed by aminotransferase
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10
Q

What is Deamination

A

Before proteins can be oxidised:
- Amino group must be removed
* Amino group can be removed to form AMMONIA
* Ammonia is toxic and is either:
+ Used to form glutamine from glutamate or alanine from pyruvate within the muscle
+ Transported to the liver; converted to urea and excreted

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11
Q

What happens after the removal of the amino group

A
  • The remaining carbon skeleton (the keto acid) is eventually oxidised to CO2 in the TCA cycle

How does it enter the TCA:

  • Acetyl-CoA
  • Alpha ketoglutarate or oxaloacetate – metabolites of glutamate and aspartate respectively
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12
Q

Amino acids to protein

  • Regulatory
  • Structural
A

Regulatory (e.g. enzymes)
- Mins, hrs, days

Structural (e.g. collagen and contractile protein)
- Days, weeks, month

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13
Q

Protein quality

- complete/non complete

A

Complete
- Not deficient

Incomplete
- Deficient in one of more amino acids

Quality of protein
1 (highest) - after digestion of the protein it provides 100% of essential amino acid required
0 (lowest)

Example of high quality

  • Whey protein
  • Egg white protein
  • Casein protein
  • Milk protein
  • Soy protein

We generally refer to the QUALITY of protein as its ability to support the increase of muscle protein synthesis after ingestion.

  • Stimulate muscle protein synthesis
    • Protein digestive capacity
    • Amino acid absorption efficiency
    • Essential amino acid - leucine
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14
Q
  • Protein turn over at rest
  • Protein turnover and diet
  • Protein turnover and resistance training
  • Protein intake and protein synthesis
  • Factors affecting protein synthesis
A

Rest
Negative protein balance

Diet

  • Meal to meal fluctuations in muscle protein synthesis influence gains and losses in skeletal muscle mass
  • Possible to increase net protein synthesis at rest with regular meals containing 10- 20g of protein.

Resistance training

  • Resistance exercise (of sufficient intensity) stimulates mixed muscle protein synthesis and breakdown
  • Protein synthesis is stimulated more than breakdown
  • Net muscle protein balance is improved
  • EXERCISE improves muscle protein synthesis (MPS) but… NOT enough to enter a NET POSITIVE MPS state
  • RT volume: best - Unilateral 8 x 10 @ 80% 1RM

Protein intake and protein synthesis

  • Hours after exercise - Protein synthesis may exceed protein BREAKDOWN BUT… Only after AA feeding
  • Strongest stimulus = training + protein intake

Factors affecting protein synthesis

  • Co-ingesting of other nutrients
  • Amount of protein
  • Timing of intake
  • Type of protein
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15
Q

Co-ingestion of other nutrients

  • CHO
  • Milk
A

CHO

  • CHO alone doesn’t stimulate protein synthesis
  • CHO combined with protein had the greatest effect net protein balance
    • Increase in insulin levels
    • Reduction of protein breakdown (from CHO)
    • Small increase in protein synthesis

Fat free milk vs Whole fat milk

  • Fat free milk delayed the delivery of amino acids
  • Whole milk is best
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16
Q

Amount of protein

A

Recommended intake
- General populations: 0.8g/kg

Athletic populations

  • Strength athletes: 1.5 - 1.7g/kg
  • Endurance athletes: 1.2 - 1.6g/kg
17
Q
  • Timing of intake

- strategies of consumption

A

There was a common belief that there was an narrow anabolic window (for building muscle). However, through evidence this window was shown to be larger
- 3hr is best but still have a 48hr winder

Strategies

  • Bolus: 2 meal with 40g of protein over 12hrs
  • Intermediate: 4 meals of 20g of protein over 12hrs (produces best results)
  • Pulse: 8 meals of 10g of protein over 12hrs
18
Q

Type of protein

A

Digestive properties of proteins influence the anabolic response at rest and exercise

  • SLOW: takes the body longer to breakdown and absorb
  • FAST: body digests and absorbs rapidly

Milk

  • Whey (20%) - fast
  • Casein (80%) - slow

Soy protein
- fast

Milk vs soy protein
- Milk based has a larger protein synthesis rate

Whey vs Casein 
- Whole body protein
synthesis is
stimulated with whey
and supressed with
casein

Whey vs Casein vs soy
- Muscle protein synthesis the greatest following whey. Soy higher then casein

19
Q

Leucine

A

Stimulates the mTOR, a key signalling protein and triggers a rise in muscle protein synthesis
Protein high in LEUCINE is beneficial

  • Whey: 10g per 100g
  • Casein: 8.2g per 100g
  • Soy: 5.9g per 100g
  • Leucine threshold that stimulates muscle protein synthesis appears to be about 3g leucine per meal.
  • Consideration in determining protein recommendations
    • 0.4 g.kg.meal (4 meals)
20
Q

Training stimulus TYPE

A

Metabolic response of individual proteins may respond differently to training stimulus
- Different training different amount of protein synthesis in a different area

Different areas for protein synthesis

  • Myofibrillar proteins
  • Mitochondrial proteins
  • Sarcoplasmic proteins

Resistance training
- Higher myofibrillar protein synthesis rate
Endurance training
- Higher mitochondrial protein synthesis rate

21
Q

Supplementing with BCAAs

  • Types of BCAA
  • BCAA claims
  • Glutamine
A

BCAAs

  • Leucine, Isoleucine, Valine
    • Not synthesized in the body (essential AAs)
    • Oxidised during exercise
    • Must be replenished in the diet

BCAA
- Fuels during exercise and spare glycogen
- Increase protein synthesis following exercise.
- Reduce net protein breakdown in muscle during exercise.
- Reduce muscle damage and soreness
Reduce fatigue.

Glutamine
Non-essential AA
- Many very important roles:
    * Nitrogen transport 
    * Acid-base regulator  
    *Used by white blood cells
Normal intake: ~3 to 6 g/day

Supplement claims for Glutamine:

  • Fluid absorption
  • Muscle protein balance
  • Muscle glycogen synthesis
  • Muscle damage and soreness
  • Immune system

Exercise Nutrition (9 decks)

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