Lecture 6

Question 1

functions of proteins

Answer 1

• all biological enzymes are made of protein
• makes hormones (like insulin and glucagon
• actin and myosin
• collagen
• all antibodies
• carriers of fatty acids, oxygen, iron, vit A, copper
• in blood
• energy source when carbs are limited

Question 2

What are the 9 essential amino acids

Answer 2

• leucine
• isoleucine
• valine
• tryptophan
• threonine
• histidine
• methionine
• lysine
• phenylalanine

Question 3

Rationale for glutamine supplements

Answer 3

• appears to be conditionally essential when the body is exposed to metabolic stress or trauma
• muscle glutamine concentrations associated with rates of MPS in animal models
• prolonged exercise and periods of heavy training are associated with a decrease in the plasma glutamine concentration
• using the idea that

Question 4

Goal for glutamine supplements

Answer 4

to replenish stores in order to increase muscle mass accretion and enhance immune function after intense and repetitive resistance exercise

Question 5

What happens in the stomach to proteins?

Answer 5

• HCl from cells in the stomach unfolds proteins
• pepsinogen becomes pepsin with the help of HCl
• pepsin digests protein into large peptide fragments

Question 6

What happens in the small intestine to proteins

Answer 6

• CCK triggers the pancreas to secrete digestive enzymes once digestion products leave the stomach
• digestive enzymes are activated and continue to break down peptides into di/tri and free a.a’s which are taken up by intestinal cells

Question 7

Whey

Answer 7

• rapidly digested and results in quick rise in plasma AA’s

- stimulates protein synthesis to a greater extent than casein

Question 8

Casein

Answer 8

• forms a curd and takes longer to empty from the stomach

- casein reduces muscle protein breakdown better than whey protein

Question 9

Soy protein

Answer 9

• digested faster than whole milk protein which contains whey and casein
• overall more like a fast protein but slower than whey

Question 10

What is protein turnover

Answer 10

• constant flux between making new muscle and breaking down muscle protein
• goal is for increasing muscle size is for muscle protein synthesis

Question 11

What are the 3 branched chain amino acids

Answer 11

• leucine
• isoleucine
• valine

Question 12

HMB

Answer 12

• derived from breakdown of leucine
• hypothesized to inhibit muscle protein breakdown and increase muscle synthesis especially with resistance training
• 3g/day may be effective and more benefits with creatine
• HMB may provide greater benefit to untrained people who start weight training compared with previously conditioned athletes

Question 13

Complete protein

Answer 13

contains all essential AA’s in amounts that meet or exceed the amounts needed by humans
ex. animal proteins or soy protein

Question 14

Incomplete protein

Answer 14

-too low in one or more of the essential AAs to support human growth and development
cannot serve as a sole source of protein in the diet

Question 15

Fatigue

Answer 15

inability to maintain a desired level of intensity

Question 16

Central Fatigue Hypothesis from Newsholme

Answer 16

• fatigue during endurance exercise is related to an over-abundance of serotonin in the brain
• serotonin causes drowsiness and fatigue
• serotonin is synthesized from 5-OH tryptamine which is derived from tryptophan

Question 17

Central Fatigue Theory 1

Answer 17

• during exercise BCAA’s are taken up by muscle and oxidized for energy
• when muscle glycogen stores are depleted BCAA uptake is accelerated
• greater uptake of BCAA’s late in exercise leads to lower blood BCAA levels levels and an increased ratio of tryptophan/BCAA
• as a result tryptophan enters the brain in greater amounts and more serotonin produciton

Question 18

Central Fatigue Theory II

Answer 18

• as exercise progresses more free fatty acids are liberated from triglyceride stores and blood level of FFA goes up
• FFA’s and tryptophan are both transported in the blood albumen
• as FFA levels goes up more tryptophan is displaced from binding sites to albumen and the “free” tryptophan concentration rises leaving even more tryptophan available to enter the brain

Question 19

Central Fatigue Theory III

Answer 19

• increased tryptophan into brain=more serotonin=central fatigue=stop exercise
• used as a rationale for development and sale of BCAA supplements
• large doses of BCAA touted as a means to “bump” tryptophan off carriers decrease tryptophan and serotonin levels in the brain and prevent fatigue

Question 20

RDA for protein

Answer 20

0.8g/kg/body weight/day

Question 21

Protein recommendations for endurance athletes

Answer 21

1.2-1.4g/kg/day

Question 22

Protein recommendations for strength athletes

Answer 22

1.2-1.7g/kg/day

Question 23

Protein recommendations for vegetarian athletes

Answer 23

1.3-1.8g/kg/day

Question 24

Downside to high protein diets

Answer 24

• increase urinary output due to high protein load may increase chances of dehydration
• diets high in protein may lack appropriate amounts of carbs, fibre and some vitamins and minerals (which could impair exercise performance)
• excessively fatty protein sources could increase risk of CVD
• protein rich diets are high in phosphorus which can be harmful to individuals with kidney disease
• may increase calcium loss in urine

Question 25

When does the body use protein for energy?

Answer 25

only in conditions of starvation or extreme energy requirements
-commonly used as a fuel source in certain situations (during endurance exercise which can deplete carb stores in muscles)

Question 26

law of diminished returns

Answer 26

when gains tend to decrease over time even with consistent training

Question 27

What conditions are required to promote muscle growth

Answer 27

• anabolic environment
• energy surplus
• positive nitrogen balance

Question 28

What conditions are required for fat loss?

Answer 28

• energy deficit

- catabolic environment