PED 291 - Chapter 3 Notes

Micronutrients- small quantities of vitamins and minerals that facilitate energy transfer and enhance normal growth and development (eat a well balanced meal, vitamin supplements offer little or no physiological benefits and actually are economically wasteful)

Vitamins- required to perform specific metabolic functions. It's their only function. (diet decoder exercise) We take in 12 oz of vitamin per 1800 pounds of food.

 1. Fat soluble- ADEK- you don't need them everyday, the body stores them in the fatty tissues. You eat fat, and the vitamin is dispersed. Sources and function are on table 3.1, page 69

2. Water soluble-table 3.2 page 71.  These are soluble in water and cannot be stored. An excess is excreted through urine. They act as co-enzymes (which aid in chemical processes such as metabolism), with larger protein compounds.

Excess vitamins function as potentially harmful chemicals, especially fat soluble. Hypervitaminosis A are symptoms caused by eating to much vitamin A..Kidney damage can occur by eating to much vitamin D.

The biologic functions of vitamins are listed on page 70. They do not contain any useful energy for the body.

Individuals who exercise do not have to consume special foods or supplements, just increase your well balanced food intake.

Many people however do not consume enough fruits, vegetables, and grains, so they do not get the proper amount of B1 and B6 vitamins. Vitamin B12 you can only get from animal products.

Free radical- a highly chemically reactive molecule carried in cigarette smoke, environmental pollution, and some medications. A build up of free radicals increases the potential for cell damage (oxidative stress). You need oxygen for these to exist and about 2-5 percent of our oxygen combines chemically with hydrogen to make free radicals. The vulnerability of these cells is due to the deterioration in the plasma membranes fatty acids.

These free radicals when built up are responsible for such things like aging, cancer, diabetes, heart disease, and declined immune function.

There is a natural defense against free radicals: there are antioxidant enzymes that are activated when vitamins A,C,E, and vitamin A precursor B carotene are ingested. Free radicals are removed from the process. (foods are listed on page 74)

Again, you don't need supplements. Don't buy megavitamins (10 fold the dosage of some vitamins). The biggest rip off in society is the sale of vitamins. Excess vitamins can act as drugs in your system.

Minerals- 22 metallic elements that make up 4 percent of the body's mass.

Some work like enzymes, hormones, and vitamins; some combine with chemicals (iron latching on to hemoglobin), or they exist alone (calcium)

Trace minerals- need less than 100 milligrams (mg) per day. Major minerals- need more than 100 mgs. Excess minerals can be toxic (poisonous). Page 76, table 3.3.

Minerals serve 3 roles:

a. provide structure in forming bones and teeth

b. maintain normal heart, muscle functioning, and acid base balance

c. they help to regulate metabolism by becoming part of enzymes and hormones (they can synthesize nutrients; proteins from amino acids) They aid in releasing energy from foods.

The synthesis of insulin requires zinc, and chlorine forms acid that allows digestion to occur.

Calcium- the most abundant mineral in the body, combines with phosphorus to form bones and teeth.

The skeleton contains 99% of the body's total calcium. When we are low, the body draws it out of the bone. Prolonged imbalance leads to osteoporosis. 90 percent of the people who get it are women. (mainly due to decrease estrogen after menopause: estrogen enhances calcium absorption). Osteoporosis numbers are reaching epidemic proportions.

It is one of the most frequently lacking nutrients in the body.

We need 1000 mgs per day (8 five ounce glasses of milk).

Exercise slows the rate of skeletal aging, and they have greater bone mass. Weight bearing exercise is the most desirable (running, weight lifting).

Electrolytes- minerals that dissolve in the body as electrically charged particles called ions. (sodium, potassium, chlorine) One of the big functions of electrolytes is that they modulate fluid exchange within the body's fluid compartments and aid in waste product exchange.

1. sodium-exists in blood plasma and extracellular fluid. The electrolyte modulates fluid exchange within the body's compartments, which allows an exchange of nutrients and waste products between the cell and the external fluid environment. Fluid leaves the cells during exercise.

MSG is something very sodium enriched (canned soups)

Regular diet regulates the amount of sodium we have in our body, or need after exercise. You don't need sodium supplements. Excess sodium increases fluid volume and elevates blood pressure (sodium induced hypertension).

Note: sodium restriction does not lower blood pressure.

2. Potassium- the chief intracellular (exists inside of the cells) mineral that regulates nerve transmission.

3. Chlorine- like sodium, an important part of extracellular fluids.

Iron-the body contains about 3-5 grams. 80 percent of it combines with hemoglobin in red blood cells: it increases up to 65 times the oxygen carrying capacity of blood.

A plasma protein called transferrin transports iron from ingested food and red blood cells to the tissues (some people have low transferrin)

Athletes need iron or they will develop a low concentration of hemoglobin in red blood cells (iron deficiency anemia).

Female vegetarian runners have low iron because of

a. the exercise

b. the iron they get from plants (non-heme). The small intestine absorbs only 2-10% of plant iron, where animal sources are 10-35% absorbed. Animal sources of iron also aid in absorbing non-heme sources.

If an athlete's diet is ok, extra iron does not increase hemoglobin or any other measure of iron status.

They can increase vitamin C because ascorbic acid from orange juice increases the solubility of non-heme iron in the small intestine. Women who are child bearing can also develop anemia, and up to 50% of women develop anemia after menstrual blood loss.

Does sports anemia exist? Probably, because of the following factors:

1. iron reserves are taxed during heavy exercise, and hemoglobin synthesis is slowed.

2. iron containing compounds with the cells energy system are reduced (iron drain)

3. iron loss from sweat

4. hemoglobin loss in urine due to cell destruction (blood in the urine) from

a. increased temp

b. spleen activity

c. circulation rates

d. mechanical (foot strike) trauma

40% of American women have iron insufficiency which leads to anemia. Physical activity does not significantly drain iron reserves for most people

260 billion new red blood cells are synthesized daily, unless the iron reserves are stressed. Even though aerobic capacity and exercise performance improve with training, the dilution of hemoglobin still exists.

Mineral loss- the biggest concern is replacing the electrolytes. Water, sodium, and potassium loss in hot weather impairs heat tolerance.

The hormones vasopressin, aldosterone, and the enzyme renin minimize sodium and water loss during vigorous exercise, but when the exercise is completed;

     a.    it's not necessary to ingest sport drinks

b.   potassium can be replaced with an 8 ounce glass of oj or tomato juice, or a banana.

c.    Salt your food at dinner to replace the sodium lost during exercise.

WATER

• UP TO 70 % OF BODY MASS
• WEIGHS 72% OF MUSCLES
• WEIGHS 50% OF FAT

The body contains 2 fluid compartments

a. intracellular- inside the cells (two thirds of your water)

b. extracellular-

1. blood plasma- makes up 20%

2. interstitial fluids- fluid between the cells. Much of the fluid lost through sweating comes from here, predominately blood plasma.

Functions of body water;

a.    helps transport nutrients and waste products

b.   helps diffusion of gases

c.    absorbs heat (when you have the flu your tempter goes up because you lose water)

d.   lubricates joints, and keeps bony surfaces from grinding together

e.    provides body structure and form

In a normal environment we need about 2.5 liters per day.

Active people need between  5 and 10 liters per day.

3 sources provide water: liquids, foods (fruits and vegetables), metabolic processes (breakdown of carbohydrates, fat, and protein...the most coming from fat).

Catabolic reactions (food breakdown) provide metabolic water to our systems.

The body loses water in 4 ways:

a. urine

b. through the skin

c. water vapor in expired air

d. in feces

The kidneys reabsorb 99 % of the water formed each day, and the other 1 percent (about 1500 milliliters) are excreted as urine.

When protein is broken down (it takes 15 ml of water to break down one gram) dehydration actually speeds up during exercise.

Insensible perspiration- water that seeps to the body surface from deep tissues. Occurs through small water droplets in exhaled air- increases during exercise.

Daily sweat rates are about 700 mls. (someone who is in excellent shape will be better at sweating).

Water accounts for about 70 % of fecal matter. With any diarrhea and or vomiting, fluid loss could be up to 5 liters more. The intestinal tract takes up a total daily water quantity of 9 liters.

Note: salt tablets, sports drinks, and protein drinks blunts the rate of water absorption, and can increase gastrointestinal distress (gas)

Comparison of water loss during no/little exercise and heavy exercise in hot weather....page 86.

How much water you lose during exercise depends on : how hard you work out, the temp when you work out, and humidity.

Note: warm muscles are more efficient than cold ones.

The major defense against overheating comes from evaporation of sweat from the skin's surface. Relative humidity (water content of the air) blocks evaporation of fluid from the skin surface to the air, so you cant cool down. The sweat rolls off and does not provide any cooling.. On a dry day the fluid evaporates rapidly from the skin because the air can hold considerable moisture. Here the sweat mechanism works at optimal efficiency to regulate our body temp.

Heat disorders....page 88

You lose around 12 pounds of water during a marathon. Here you must replace fluid while competing to maintain plasma volume so circulation and sweating mechanism work efficiently.

Do not wait until you are thirsty to start drinking water.

Pre-exercise hyperhydration- drink  600 milliliters of fluid 20 minutes before exercise. This increases your sweat mechanism and slows down the rise in body temp during exercise.

The small intestine absorbs fluids after they pass from the stomach. 

Factors that influence gastric emptying:

a.   Fluid temp- cold water empties out of the stomach faster.

b.   Fluid volume- keep a high level in before exercise.

c.    Fluid osmolarity- stomach emptying slows when the fluid has sugar in it. The ideal amount of sugar in a fluid is 5-8 %

d.   Intensity of exercise- after 75% of your max, the stomach emptying becomes reduced.

Dehydration causes hyperthermia- elevated body temp.

(wrestlers, early football practice).

We can consume up to 9.5 liters of fluid per day without problems. More than that could lead to hyponatremia (water intoxication) a condition which dilute our sodium concentration. Marathon runners, ironmen, triathletes occasionally drink too much fluid during their competition and can collapse during or after competition.

Predisposing factors- long duration exercise in hot weather, drinking sodium free fluids, use of diuretics (caffeine).