MODULE 6 - PROTEIN & EXERCISE

PROTEINS

Amino acids linked by peptide chains for proteins

The body requires 20 different amino acids

• alanine, arginine, asparagine aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine

Complete vs Incomplete Proteins

Complete - Contain the essential amino acids in the right ratio to maintain nitrogen balance and allow tissue growth & repair.

Incomplete - Lacks one or more essential amino acid

Roles of Protein

1. Protein in nervous and connective tissues do not participate in energy metabolism

2. Amino acid alanine Plays a key role in providing CHO fuel via gluconeogenesis during prolonged exercise

3. During strenuous exercise of long duration, alanine - glucose cycle accounts for 40 - 50% of liver's glucose release.

PROTEIN UTILIZATION

• Protein utilization depends on how well the total energy expenditure is met by the intake of food

• Inadequate total energy intake forces the athlete to burn protein

• This depletes muscle protein which is not desirable

• Protein requirement is about 20% of total calorie intake OR 1.2 to 1.7g/kg body weight

a) PROTEIN REQUIREMENT FOR ENDURANCE AND RESISTANCE EXERCISE

Protein Requirement for Endurance Exercise

Endurance training might need about 1.2 to 1.6 g x kg(-1) x day(-1) (approximately 1.5 times the current RDA)

Serious endurance athletes need protein above the normal adult RDA for:

• maintenance

• growth

• repair

• optimum immune system function

Of LEAN MUSCLE

Not providing sufficient protein will lead to lethargy, anaemia and will cancel beneficial effects of exercise.

In fed individuals protein is meant to contribute 1-8% to the energy expended depending on the sex and the duration of the athletic competition.

• Protein is used in prolonged, continuous, moderate to intense activity (endurance)

• 5-10% of the energy needs for endurance exercise (>90 minutes) may come from protein.

• Protein synthesis is suppressed during exercise and stimulated when physical activity ends.

• Endurance exercise appears to improve the efficiency of the body to utilize nitrogen.

• Amino acids are used to repair muscle trauma that results from repeated muscle contractions and eccentric contractions in particular.

Activity:

Protein Requirement for Strength Exercise

Those involved in strength training might need to consume as much as 1.6 to 1.7 g protein x kg(-1) x day(-1) (approximately twice the current RDA)

Extra protein is needed by strength-trained athletes to repair injuries to muscle fibers and to remodel muscle tissue in response to strength training.

• High intensity, intermittent activity that incorporates strength training in the exercise program.

• Resistance exercise provides the stimulus for gains in muscle size and strength.

• Strength training relies on anaerobic metabolism for energy production. The primary fuel for resistance exercise is muscle glycogen.

• Building muscle is energy intensive.

b) PROTEIN TURNOVER IN EXERCISE

PROTEIN TURNOVER

• Protein turnover (synthesis and degradation) is elevated in strength athletes.

• Protein requirements are increased to supply amino acids to maintain nitrogen balance and to support enhanced rates of protein synthesis.

• Protein turnover depends on the following factors1. Exercise intensity2. Exercise duration3. Training state4. Energy consumed5. Gender

Exercise Intensity

Exercise intensity affects the protein turnover directly, based on the example shown above.

Exercise Duration

During long duration of exercise there is more break down of protein resulting in the increase of by products of amino acid oxidation.

... to put this in perspective

For example, a person who cycles for 60 minutes in a glycogen depleted state might use as much as 2.4 times the amount of protein as those with high initial glycogen levels.

Training State:

• Protein turnover with endurance exercise.

• Protein turnover when there is sufficient energy from glycogen.

Protein-sparing action of carbohydrateWhen there is an adequate intake of carbohydrate, the body

does not need to metabolize muscle protein for energy.Ensuring the energy requirement is met by carbohydrate is vital

to preserve the protein in the body

c) BCAA AND FATIGUE

BCAA AND FATIGUEBranched chain amino acids - Leucine, isoleucine, valine

Serotonin plays a role in the central mechanisms of fatigue

Serotonin is produced from tryptophan

Tryptophan is usually found in the blood bound to albumin or as free tryptophan

The amount of free tryptophan that crosses the blood brain barrier depends on the concentration of BCAA.

Mechanism - BCAA and Fatigue

During long duration exercise fat is broken down to produce energy as a result of which fatty acids are formed.

These fatty acids bind to albumin thus reducing the number of albumin binding sites for tryptophan.

At the same time exercise leads to the breakdown of BCAA which causes an imbalance in the tryptophan:BCAA ratio.

An increase in this ratio causes the free tryptophan to cross the blood brain barrier and INCREASES the amount of SEROTONIN leading to FATIGUE

What does 100 grams of protein look like in food?Food Amount Protein (grams)

Raisin bran cereal 2 cups 10

1% milk 2 cups 16

Bread 2 slices 5

Chicken breast 1 large piece

19

Swiss cheese 1 ounce 8

Lean steak 1 34

Baked potatoes 1 med 5

Broccoli 1 cup 6

Egg white 1 3.6Yoghurt 1 cup 12

d) PROTEIN SUPPLEMENTATION

PROTEIN SUPPLEMENTATION

Many use protein supplements believing that they enhance performance by way of increasing the production of anabolic hormones.

Some research shows that there is no significant effect of amino acid supplements on the

1. Hormone secretion2. Training response3. Exercise performanceHowever, this is a debatable topic and pros and cons will be

discussed.

Effect on Hormones

Whey ProteinWhey protein is the protein contained in whey, the watery portion of milk that

separates from the curds when making cheese.

Whey protein is used for improving athletic performance, as a food supplement, as an alternative to milk for people with lactose intolerance, for replacing or supplementing milk-based infant formulas, and for reversing weight loss and increasing glutathione (GSH) in people with HIV disease.

Uses:

In conjunction with strenght training whey improves:

1. Lean muscle mass2. Strength3. Muscle size

Contraindication:

Whey taken in regulated quantities does not have any known side effects.

If taken in excess can lead to:

1. Nausea2. cramps3. Fatigue4. Reduced appetite

Casein

Casein is the main protein in milk. It is the ingredient in milk that solidifies when milk curdles. When people drink milk, digestive juices break down the casein into protein pieces called casein peptides

Benefits:

1. Improved muscle Mass2. Great Muscle retention3. Greater fat loss4. Helps increase energy5. Improves stamina

Side-effects:

1. Rashes2. Bloating,3. Hives4. Stomach aches and cramps5. Gastro-intestinal discomfort

L- carnitine

PROS:

1. Acts as a vasodilator in peripheral tissues

2. May enhance regional blood flow & oxygen delivery

3. Improves oxygen supply to damaged tissue - May improve DOMS - delayed onset muscle soreness

CONS:

Some research shows :

1. No ergogenic effect

2. Does nto increase anabolic processes

3. No improvement in performance

4. No enhanced recovery

Creatine

Creatine Risks:

Not many risks have been documented after creatine supplementation.

Short term use in healthy men has had no detrimental effect on blood pressure and renal function.

Individuals with poor kidney function should refrain from taking this supplement.

Creatine Benefits:

Activity:

Interpret the following graph with regards to Total Creatine.

Discussion

Your thoughts on the use of protein supplements