Sports & Exercise Nutrition

Nutrition

the total processes of ingestion, digestion, absorption, and metabolism of food and the subsequent assimilation of nutrient materials into the tissue.

Nutrient

substance found in food that performs one or more specific functions in the body.

Functions of Nutrients

1. Promotion of growth and development

-proteins

-calcium and phosphorus as building blocks of the skeleton

2. Provision of energy

-carbohydrates and fats

3. Regulation of metabolism

-vitamins, minerals, and protein.

Functions of Carbohydrates

1. Energy to the muscle

2. Energy to the brain

3. Storage form of energy

Functions of Fiber

-Insoluble fiber decreases the transit time of fecal matter through the intestines.

-Soluble fiber lowers blood cholesterol concentration and normalizes blood glucose.

Carbohydrate intake and Health Effects

-Sugar intake is associated with obesity, although this conclusion is debated.

-Concern has been raised about the dramatic increases in the intake of added sugar over the past 30 years.

Fiber intake and Health Effects

-associated with reduced risk of various chronic diseases.

Lipids

compounds that are soluble in organic solvents such as acetone, ether, and chloroform.

-derived from Greek word meaning "fat"

-general name for fats, waxes, and related compounds.

-Oils are liquid at room temperature, whereas fats are solid.

Functions of Lipids

-fuel to most cells and an important fuel for contracting muscles.

-fat protects vital organs such as the heart, liver, spleen, kidneys, brain, and spinal cord.

-the intake of fat soluble vitamins A, D, E, and K and carotenoids is dependent on the daily fat intake, and fats provide the transport medium in the body.

- phospholipids and cholesterol are important constituents of cell membranes.

-Cholesterol is also an important precursor in the formation on bile and is itself an important component of bile.

Lipids as Fuel

-Only some of the lipid forms can be used as fuel- fatty acids, intramuscular triaclglycerols (IMTG), and circulating plasma triacylglycerols (chylomicrons and VLDLs)

Fat intake in Western Countries

-Few people in western countries have a fat intake below 20%, and the average daily intake is 100 to 150 g/day, or roughly 34% of the daily caloric intake.

Protein Characteristics

-20 different amino acids are commonly found in proteins.

-each amino acid consists of a carbon atom bound to four chemical groups: a hydrogen atom; an amino group called a side chain, which varies in length and structure.

-different side chains give different properties to the amino acid.

Functions of Protein

-provide structure to all cells in the human body

-integral part of the cell membrane, the cytoplasm, and the organelles.

-muscle, skin, and hair are largely composed of protein, bones and teeth of minerals embedded in protein framework.

-many proteins are enzymes that speed up chemical reactions.

-amino acids are the building blocks of all proteins.

Protein as a building block

-amino acids are bound to each other in a protein by so called peptide bonds.

-Small proteins are often referred to as peptides of polypeptides.

Protein Intake

-Recommended protein intake varies worldwide from 0.8 to 1.2 g/kg b.w.

-Protein intake in the western world is usually averages 80 to 100 g/day. 100 grams of protein is roughly equal to 400 kcals of energy, so for a 2,000 kcal diet, that is 20%.

-Unlike carbs and fat, protein has not been associated with negative health effects.

-Some amino acids are described as essential because they cannot be synthesized in the body and so must be obtained from food.

Functions of Water

-Transports nutrients in solution.

-Provides protection (lubrication, cleansing, and cushioning)

-Helps regulate body temperature (sweating)

-Participates in biochemical reactions

-Provides the medium in which these reactions take place (by the transport in the blood of nutrients and oxygen to the tissues and the transport of carbon dioxide and waste products away from the tissues)

-Helps get rid of waste products (urine)

Water Intake

-Water intake of an adult is typically 2.0-2.8 L/day

-Rule of thumb: fluid requirements are 1 ml for every 4 kJ of energy expended or 1 ml/kcal.

-Of the daily 2.0-2.8 L consumed, 1.0-1.5 L is usually in the form of fluids and the rest obtained from foods.

-Athletes training and competing in the hot conditions may have fluid requirements greater than 15 L/day.

Vitamins, Minerals, and Trace Elements

-vitamins are organic compounds

-minerals and trace elements are inorganic compounds.

-collectively known as micronutrients, these essential compounds have many biological functions.

-all 13 known vitamins have important functions in most metabolic processes in the body.

-vitamins must be obtained from the diet, except Vitamin D, which can be synthesized from sunlight, and vitamin K, which is synthesized by bacteria in the intestine.

Functions of Vitamins and Minerals

-they serve as regulators and links in the processes of energy release from food.

-they are important cofactors in various chemical reactions and as such are important in maintaining homeostasis.

Essential Nutrients terminology:

essential=indispensable

nonessential=dispensable

Dietary Reference Intake (DRI)

-the new standard for nutrient recommendations that can be used to plan and assess diets for healthy people. Think of DRI as the umbrella term that included the following values.

Estimated Average Requirement (EAR)

-nutrient intake value that is estimated to meet the requirement of half of the healthy individuals in a group.

-used to assess nutritional adequacy of intakes of population groups.

-EARS are used to calculate RDAs.

Recommended Dietary Allowance (RDA)

-goal for individuals and is based on the EAR.

-daily dietary intake level that is sufficient to meet the nutrient requirement of 97-98% of all healthy people in a group.

-If an EAR cannot be set, no RDA value can be proposed.

Adequate intake (AI)

-used when a RDA cannot be determind.

-a recommended daily intake level based on an observed or experimentally determined approximation of nutrient intake for a group (or groups) of healthy people.

Tolerable Upper Intake LEvel (UL)

-the highest level of daily nutrient that is likely to pose no risks of adverse health effects to almost all individuals in the general population.

-as intake increase above the UL, the risk of adverse effect increases.

Daily Values (DV)

-term used in food labeling that is based on a daily energy intake of 2,000 kcals and for the food labeled.

-gives the percentage of the RDI and the DRV recommended for healthy people in the U.S.

Practical guidelines for a balanced healthy diet

-there are over 40 essential nutrients. The concept of a balanced diet refers to eating a wide variety of foods in moderation to support normal or optimal functioning.

-mypyramid was developed by the U.S. department of agriculture (USDA) and represents the 2005 dietary guidelines for americans.

Cellular and Subcellular skeletal muscle structure

- Thick and thin filaments

-sarcomere

-sarcolemma

-t-tubules

-sarcoplasmic reticulum

-mitochondria

sarcomere

functional unit of skeletal muscle

sarcolemma

plasma membrane of a skeletal muscle cell

T-tubules

invaginations of the cell membrane of the muscle cell which increases the surface to volume ratio of the cell.

sarcoplasmic reticulum (SR)

-storage depot for calcium

-important for the process of release and uptake of calcium for muscle contractions.

Force generation in skeletal muscle

-action potential across cell membrane

-stimulates the release of calcium from intracellular stores in the SR.

-calcium floods the cytosol (in muscle this is called sarcoplasm)

-calcium binds to troponin-tropomyosin complex

-tropomyosin moves out of the way of the myosin binding site on actin allowing crossbridge cycling to proceed provided there is sufficient ATP for muscle detachment and activation of the crossbridges.

The greater dependence on Aerobic Energy Source will result in ___.

Less maximal power output

Power output during 30 seconds is _____ than power output during 5 minutes.

>

Due to increase in exercise, you will gradually have less power due to need for ____.

More ATP

____ energy metabolism is slower than immediate energy, which is termed ____ energy metabolism.

AEROBIC energy metabolism is slower than immediate energy, which is termed ANAEROBIC energy metabolism.

___ energy metabolism is slowest.

Aerobic

What are the five macronutrient sources of energy for ATP resynthesis during exercise?

1-Muscle Glycogen

2-Liver Glycogen

3-Muscle Triglycerides

4-Adipose Triglycerides

5-Carbon skeletons

What are the first 2 sources when beginning a workout?

1-Muscle Glycogen

2-Blood Glucose

What percent contribution(%) do Fats, Glucose+Glycogen, and Protein give to Energy Metabolism at REST?

%FATS- 60%

%GLUCOSE+GLYCOGEN- 35%

%PROTEIN- 2-5%

What percent contribution(%) do Fats, Glucose+Glycogen, and Protein give to Energy Metabolism at LIGHT-INTENSITY?

%FATS- 55%

%GLUCOSE+GLYCOGEN- 40%

%PROTEIN- 2-5%

What percent contribution(%) do Fats, Glucose+Glycogen, and Protein give to Energy Metabolism at HIGH INTENSITY SPRINT-TYPE EXERCISE?

%FATS- 3%

%GLUCOSE+GLYCOGEN- 95%

%PROTEIN- 2%

What percent contribution(%) do Fats, Glucose+Glycogen, and Protein give to Energy Metabolism at HIGH INTENSITY ENDURANCE EXERCISE?

%FATS- 15%

%GLUCOSE+GLYCOGEN- 70%

%PROTEIN- 5-8%

Why should athletes not eat right before a race? (3)

1-GI distress

2-Will directly fuel source available

3-Insulin immediately affected-possibly produce fatigue

___ is the response to hyperinsulinemia.

Rebound Hyperglycemia

Hyperinsulinemia does what? (3)

1-Blunts long-chain fatty acid oxidation by skeletal muscle

2-Blunts FFA liberation from adipose tissue

3-Inhibits hepatic glucose release during exercise--Which inhibits liver glycogen

40-45 minutes after eating an insulin spike is seen and our bodies become dependent on?

1-Muscle glycogen

2-Blood Glucose

3-Short & Medium Chains

Carbohydrate availability depends on?

1-Carbohydrate Availability controls its use

2-Intake affects availability

Long chain fatty acids need ___ transmitters.

CAT-trained

1 Hour of strenuous exercise uses up to ____ of liver glycogen.

55%

2 hours of strenuous exercise depletes glycogen in _____ & _____.

Liver & Exercised Muscles

After about 10 minutes after activity _____ is affected.

Glycogen

What happens if the liver can't keep up with blood glucose use by active muscle?

1-Blood glucose decreases to hypoglycemic levels

2-Serum FA increases dramatically

3-Plasma AA increases dramatically (coming from muscle)

4-Exercise intensity decreases to about 50% of starting intensity

What is the guideline for hypoglycemic level?

< 45 mg GLU per 100 mL/dL of blood

It takes the body twice as long to make ATP using ____ versus Carbohydrates.

Fats

If fat breakdown is slower, it must be from processes that occur prior to the ____.

Citric Acid Cycle

What are the 4 processes are specific to fat breakdown?

1-Beta Oxidation

2-Fatty-Acid Activation

3-Intracellular Transport (from the blood into the Cytosal)

4-Mitochondria Transport

The presence of carbohydrates will prevent ____.

"Bonking" or "Hitting the Wall"

The Training Effect does what?

1-Greater ability to oxidize Pyruvate

2-Greater glycogen stores

3-Greater use of fat as a fuel source

Training helps conserve the ____.

Glycogen reserves

Females tend to have a greater reliance on ____ & ____ is constrained.

Lipolysis & Glycolysis

Other than training, how can someone increase their glycogen store?

Eat a high carbohydrate diet

What are the 5 Potential Sites for ENDOCRINE REGULATION of Substrate Use?

1-Substrate Availability (via effect on Nutrient Storage)

2-Substrate Mobilization from Body Tissue Stores

3-Substrate Uptake at Tissue Site of Use

4-Substrate Uptake within Tissue itself

5-Substrate Trafficing among Storage, Oxidation, and Recycling

List the 3 hormones that stimulate Glycogen Phosphorylase during strenuous exercise?

1-Epinephrine

2-Norepinephrine

3-Glucogon

Energy contribution ranges from ____ for muscle triglycerides.

15-35%

Carbohydrates & lipids use identical oxidation pathways once this product is produced?

Acetyl-CoA Oxidation

Training increases plasma levels of ___.

Hormone-Sensitive Lipase

What 4 hormones that activate Hormone-Sensitive Lipase?

1-Epinephrine

2-Norepinephrine

3-Glucagon

4-Growth Hormone

Fat use is proportional to ______.

Blood Flow

Subcutaneous Abdominal Adipocytes have a much > ____ than Gluteal Femoral region.

Vascular density

____ is released from the VISCERAL ADIPOCYTES from adipose tissue.

Adipokines

Fat use @ 25 % and 85% of VO2 Max:

1-No difference in fat usage @ low intensity vs. high intensity exercise--Fat usage slightly decreases

2-Fat usage does not from low intensity to moderate intensity

3-If your looking to burn fat-- Long duration exercise @ moderate intensity

RQ value ____ overtime.

Decreases

Classification of RQ value:

0.7 (100% fat burn) - 1.0 (100% Carb burn)

0.85= Combination of burning fat & carbs

What specific type of amino acid is oxidized within the skeletal muscle rather than the liver?

Branched Chained

What are the 3 branched-chained amino acids used for protein during exercise?

1-Leucine

2-Isoleucine

3-Valine

During exercise there is a ____ in protein synthesis.

Decrease

During recovery, protein can increase between ___ following exercise.

10-80%

Sir Prescott Joule announced the ___ of work raises the temperature of a pound of water by 1 degree F.

838 ft/lb

____ is the quality of heat necessary to raise the temperature of 1 liter of water 1 degree C.

kilocalorie (kCal)

____ is the description of energy transfer.

Heat

Energy = _____

Kilojoule (kJ)

Movement (work) added energy, raising the temperature: 1 kcal--____

4.184 kJ

What is the definition of Heat of Combustion? (Energy Intake)

Heat liberated by oxidizing a specific food; it represents the food's total energy value.

What is Heat of Combustion for Carbohydrates, Proteins, and Lipids?

Carbohydrates- 4.2 kCal/g

Proteins- 5.65 kCal/g

Lipids- 9.4 kCal/g

Energy liberated ____ energy available to body.

Doesn't equal

In protein, nitrogen atoms must combine with hydrogen atoms to form urea-furthermore ___ of the potential energy is lost.

19%

___ & ___ have the same fuel values.

Carbs & Lipids

What is the definition of a Coefficient of Digestibility?

Digestive efficiency represents the percentage of food digested and absorbed to serve the body's metabolic needs.

What are the ranges for the Coefficients of Digestibility for Carbohydrates, Proteins, and Lipids?

Carbohydrates- Ranges from 90-98%

Proteins- Ranges from 78-97%

Lipids- Ranges from 90-95%

The more ___ available, the lower the coefficient of digestibility.

Fiber

____ are calculated using at water general factors.

Calories

The standard for calculating calories is ___ for carbohydrates & proteins.

4 kCal/g

The standard for calculating calories is ____ for lipids.

9 kCal/g

Dietary calorimetry is:

1-Highly theoretical

2-Timely

3-Expensive

4-Engineering Expertise

_____ is based on the assumption that all energy releasing reactions depend on O2 use.

Indirect Calorimetry

The blend of Carbs, Proteins, and lipids in 1 liter of O2 resulted in ____ released when burned.

4.82 kCals

The value is rounded to 5.0 kCal/L of O2 consumed for any ___ activity.

Aerobic

The measurement of O2 is done with either a ___ or ___.

Closed-Circuit Spirometry & Open-Circuit Spirometry