Part 1: Proteins - The Role In Exercise

Current understanding of protein dynamics in exercise comes from study that determines protein breakdown through urea excretion.

As exercise progresses, the concentration of blood urea also increase coupled with increase in nitrogen excretion (from protein breakdown) in sweat.

With low carbohydrate (depleted state) intake the amount of nitrogen excreted in sweat is much higher compared to an with high carbohydrate loaded state. Thus carbohydrate is an important protein sparer in exercise as if there is inadequate carbohydrate, the body will breakdown the protein into glucose.

Athletes in protracted and intense training should conserve adequate carbohydrate to conserve muscle protein.

The RDA for protein intake in adults is 0.83g per kg of body mass.

A continuing area of controversy concerns whether the initial increased protein demand when training commences creates a true long-term increase in protein requirement above RDA. A definitive answer is elusive, but protein breakdown above resting levels does occur during intense weights and cardio training to a greater degree than previously thought.It may be only slighly more than sedentary people.

It is recommend that people who train intensely consume between 1.2 and 1.8g of protein per kg of body weight daily. For most there is no need for protein supplements.

Part 1: Proteins - The Vegetarian Approach

True vegetarians, or vegans, consume nutrients from only 2 source - the plant kingdom and dietary supplements. Eating a variety of grains, fruits and vegetables supplies all of the essential amino acids. For example, a vegan diet contains all the essential amino acids if the RDA for protein contains 60% of protein from grain products, 35% from legumes, and 5% from leafy vegetables. A 70kg man will satisfy the essential amino acids requirement by consuming about 56gm of protein from approx. 1 1/4 cup of beans, 1/4 cup of seeds or nuts, 4 slices of wholegrain bread, 2 cups of leafy veggies and 2 1/2 cups of grains (brown rice, cracked wheat, oats).

A lactovegetarian diet provides milk and related products such as icecream, cheese, & yoghurt. This approach minimises the problem of consuming insuffucient high quality protein, and increases the intake of calcium, phosphorous and vitamin B12. Adding an egg ot the diet (ovolactovegatarian) ensures intake of high quality protein.

Part 1: Proteins - Sources

Sources of complete protein include eggs, milk, meat, fish, and poultry. High quality protein sources in nutritional supplements include whey, colostrum, casein, and milk and egg proteins.

Egg provide the optimal mixture of essential amino acids among food sources; hence egg receives the highest quality rating (100) for comparison with other foods.

Animal protein provide almost two thirds of dietary protein in the diet in a modern society; 80 years ago plant and animal sources contribute equally to protein consumption. Reliance on animal sources for dietary protein accounts for the relatively high cholesterol and saturated fatty acid intake in the major industrialized nations.

The biological value of a food refers to how well it supplies essential amino acids. High quality protein foods come from animal sources; vegetables remain incomplete in one or more essential amino acids.

Biological Value (Rating)
Eggs 100
Fish 70
Lean beef 69
Cow's milk 60
Brown rice 57
White rice 56
Soybeans 47
Peanuts 43
Potatoes 34

Part 1: Proteins - Kind of proteins

The body cannot synthesize eight amino acids so one must consume foods containing them. These make up the essential amino acids – isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. The body manufactures the remaining nonessential amino acids.

Animals and plants manufacture proteins that contain essential amino acids. An amino acid derived from an animal has no health or physiological advantage over the same amino acid from vegetable source. Plants synthesize amino acids by incorporating nitrogen from the soil (along with carbon, hydrogen and oxygen from the air and water). In contrast animals have no broad capability to synthesize amino acids; instead, they consume most of their protein. Just look at the elephant and gorilla who are vegetarians - they are strong and muscular.

Synthesizing a specific protein requires the availability of appropriate amino acids. Complete proteins, or higher quality proteins, come from foods containing all these essential amino acids in the quantity and correct ratio to maintain nitrogen balance and to allow tissue growth and repair. An incomplete protein, or lower quality protein, lacks one or more essential amino acids. A diet of incomplete protein eventually leads to malnutrition, whether or not the food source contains an adequate amount of energy or protein.

Part 1: Proteins - The Nature of Proteins

An average adult contains about 10 – 12 kg of proteins, with 60-70% of it located within the skeletal muscles.

Typically we get 10-15% of our calories each day from proteins. During digestion proteins are broken down into amino acids constituents for absorption.

Proteins are made of peptides of amino acids. Two amino acid joined produce a dipeptide. Combination of 50 or more amino acids form a protein. In total, roughly 50,000 different protein-containing compounds exist in the body.

TO THOSE WHO BUY COLOSTRUM
A newborn baby has no antibodies - but within a few days on breast milk, the baby suddenly has a fully functioning immune system! A miracle.

Antibodies ingested through the mouth
Antibodies are proteins of more than 1,000 amino acids and the new baby could not possibly get them through the mother's milk which went into the baby's body through the mouth and stomach. The antibodies are digested into amino acids and can never be absorbed into the blood as a complete ANTIBODY. The intestines can only absorb peptides of 15-30 amino acids long.

The IgG antibody in the colostrums milk is too big to be absorbed. It is digested into amino acids before absorption. Colostrum is a good source of protein, calcium and minerals. The only useful antibody is the IgA a mucosal antibody to protect the mucosal lining of the intestinal tract and it is never absorbed as it is TOO BIG!

The basic unit of each antibody is monomer. An antibody can be monomeric, dimeric, trimeric, tetrameric, pentameric etc. The monomer is a "Y"-shaped molecule that consists of two identical heavy chains and two identical light chains connected by disulfide bonds.

There are five types of heavy chain: γ, δ, α, μ and ε. They define classes of immunoglobulins. Heavy chains α and γ have approximately 450 amino acids, while μ and ε have approximately 550 amino acids.

There are only two types of light chain: λ and κ. In humans they are similar, but only one type is present in each antibody. Each light chain has two successive domains: one constant and one variable domain. The approximate length of a light chain is from 211 to 217 amino acids.

Part 1: Lipids - Exercise training & Fat Use

Fat contributes 50 to 70% of the energy requirements during light and moderate exercise. Stored fat (intramuscular and those in the adipose fat cells) plays an increasingly important role with prolonged exercise. Fatty acid molecules (mainly circulating FFAs) provide more than 80% of the exercise energy requirements.

Carbohydrate depletion reduces exercise intensity to a level determined by the body’s ability to mobilize and oxidize fatty acids.

Aerobic training increases long-chain fatty acids oxidation (combustion), mainly fatty acids from triglycerides from within active muscle during mild-to-moderate intensity exercise.

Enhanced fat oxidation with training spares glycogen (the more powerful fuel); this allows trained individuals to exercise at a higher level of submaximal exercise before experiencing fatigue effects of glycogen depletion.

Part 1: Lipids - Role of Lipid in the Body

1). Energy Source and Reserve

Fat is a ideal fuel for cells coz:
a).carries a large quantity of energy per unit weight.
b).transport and stores easily.
c).a ready source of energy. Provides 80% of energy at rest.

2).Protection of Vital Organs and Thermal Insulation

Up to 4% of body fat protects against trauma to vital organs
(heart, liver, spinal cord, spleen etc).

The fat beneath the skin provides insulation, providing protection against extremes of cold. Excess fat hinders body temperature regulation during heat stress during sustained exercise when heat generation could be 20x usual, as it hinders heat dissipation.

3.Vitamin Carrier & Hunger Depressor
Consuming 20g of dietary fat daily is enough to transport and store fat -soluble vitamins A,D, E & K.

Part 1: Lipids - Kind and sources (3)

3.Derived Lipids

Simple & Compound lipids form derived lipids.

Cholesterol the most common derived lipid, exist only in animal tissue. It is from eaten source (exogenous) or through liver synthesis (endogenous). More endogenous cholesterol forms with a diet high in saturated fatty and trans-fatty acids. Endogenous synthesis usually meets the body's needs.

Functions of cholesterol

• Building plasma membranes
• precursor in synthesizing vitamin D, adrenal gland and sex hormones

Part 1: Lipids - Kind and sources (2)

2.Compound Lipids.

Are triglycerides components combined wit other molecules are about 10% of body's total fat.

a).Phospholipids - water soluble end and a fat soluble end (thus found in cell membranes to modulate fluid movement across cell membrane); found in nerve sheath; important role in blood clotting

b). Glycolipids - fatty acids bound with carbohydrate.

c). Lipoproteins - protein capsules used for carrying lipids in the blood.
i).Chylomicron - emulsify fats and carry fats from the intestine into the lymphatics. Transport fat-soluble vitamins like A,D,E & K. Able to absorb larger molecules than normal absortion route.
ii). HDL (good cholesterol)
iii).LDL (bad cholesterol)

Part 1: Lipids - Kind and sources (1)

Lipids is the general term for a group of compounds, includes oils, fats, waxes, and related compounds. Oils become liquid at room temperature, whereas fats remain solids.
We can classify lipids to 3 main groups. 1) Simple Lipids 2) Compound Lipids 3) Derived Lipids

1).Simple Lipids Consist primarily of triglycerides. It is the major storage form of fat in the fat cells that resides in the adipose depots under the skin. Consist of a glycerol molecule and 3 fatty acids.
Saturated fatty acids:
Chemically when the carbon is maximally bonded with hydrogen.
Primarily in animal products such as beef (52% saturated fatty acids), lamb, pork, chicken, egg yolk and dairy fats of cream, milk, butter (62% saturated fatty acids), and cheese.

Unsaturated fatty acids: Chemically the carbon atoms have double bonds.