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Why is dietary protein an important concern for athletes?

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Why is dietary protein an important concern for athletes?

b. Protein is needed for new muscle tissue and, in some cases, as a supplemental energy supply during exercise.

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What does nitrogen balance tell you as a scientist?

a. Positive nitrogen balance signals gain in muscle mass.

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What kind of exercise creates the greatest amount of muscle gain?


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Who is most likely to experience inadequate protein intake?

b. Alcoholics in weight loss diet to reduce beer belly

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Which amino acids are most likely catabolized for energy in muscle?

c. Cysteine and methionine

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The central fatigue hypothesis states that performance declines when dopamine in the brain declines due to reduced uptake of

d. Tryptophan

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An intracellular signaling protein that links insulin effects to protein synthesis is

mTOR (mTOR is activated by amino acids, insulin, and growth factors, and impaired by nutrient or energy deficiency. ... mTOR regulates numerous components involved in protein synthesis, including initiation and elongation factors, and the biogenesis of ribosomes themselves. Promotes protein synthesis)

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The role for satellite cells in muscle hypertrophy is...

d. Add more nucleii to the muscle cels.

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Which measurement tells more about the rate of protein synthesis in a muscle after exercise?

b. FSR (remember: 3-methyl histidine concentration in urine, BUN only tell you about the rate of protein breakdown!)

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The quality of a food protein and its ability to restore muscle after extreme exercise is LEAST dependent on a. The concentration of limiting amino acid in the food. b. Digestbility. c. Total amino acid content per gram of food. d. The ratio of essential amino acids to lipids.

d. the ratio of essential amino acids to lipids.

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What data can be used to diagnose a vitamin deficiency?

a. Concentration of the vitamin in a blood or plasma sample. b. Change in activity of an enzyme that requires the vitamin as a cofactor when excess vitamin is added to the in vitro assay c. Comparison of vitamin intake in a diet record to RDA or EAR.

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Multiple B vitamins are needed for the catabolic reactions of that release usable energy as ATP or equivalents from Select one or more: a. monosaccharides b. amino acids c. reactive oxygen species d. fatty acids

a. monosaccharides b. amino acids d. fatty acids

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One of the more important roles of thiamin in energy yielding metabolic pathways is as a component of the _____________ enzyme complex.

Pyruvate decarboxylase

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Pyruvate Decarboxylase

The glycolytic enzyme responsible for converting pyruvate into acetaldehyde under anaerobic conditions during alcoholic fermentation.

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Which of the following statements is the most applicable correct notice for physically active people?

Select one: a. Vitamin K is water soluble, therefore excreted in sweat. b. Vitamin C losses through sweat can be substantial. c. Vitamin D losses through sweat probably does not impact the tissue balance for this nutrient. d. Vitamin A is a water-soluble vitamin, therefore excreted in sweat.

c. Vitamin D losses through sweat probably do not impact the tissue balance for this nutrient.

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In Which of the following group of micronutrients do all compounds have role as part of an antioxidant function?

Select one: a. thiamin, vitamin C, vitamin E, iron b. vitamin A, vitamin C, vitamin E, iron, zinc c. riboflavin, vitamin A, zinc, potassium d. sodium, vitamin B6, vitamin E, zinc e. niacin, vitamin D, copper, magnesium

b. Vitamin A, vitamin C, Vitamin E, iron, zinc

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Anemia is LEAST likely to be caused by a deficiency of...

Select one: a. folic acid b. vitamin B12 c. vitamin D d. iron

c. Vitamin D

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Which of the following is LEAST likely to be true?

Select one: a. Excess water-soluble vitamins are excreted in the urine, so have lower risk of toxicity than fat-soluble vitamins. b. Vitamin C supplementation will prevent infection with cold viruses. c. Prolonged high intakes of vitamin C might result in diarrhea, nausea, and stomach cramps. d. A daily multivitamin and mineral supplement is advisable for athletes on a restricted dietary intake. e. Vitamin and mineral supplementation is not necessary for most athletes consuming a normal varied and balanced diet.

b. Vitamin C supplementation will prevent infection with cold viruses.

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Enzymatic and nonenzymatic antioxidants prevent oxidation initiated by reactive oxygen species (ROS) by ALL of the following EXCEPT:

Select one: a. reducing ROS formation. b. binding metal ion catalysts, such as copper and iron, to prevent initiation of free-radical reactions. c. shutting down the leakage of free electron from the respiratory enzyme chain involved in oxidative phosphorylation in mitochondria. d. providing a favorable environment for the effective functioning of other antioxidants. e. intercepting ROS attack by scavenging the reactive metabolites and converting them to less-reactive molecules.

c. shutting down the leakage of free electron from the respiratory enzyme chain involved in oxidative phosphorylation in mitochondria.

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Iron can be characterized by ALL of the following statement EXCEPT: Select one: a. Because iron stores are quite large, female and adolescent athletes need no regular supply of dietary iron. b. Anemia, which is common in athletes, will reduce maximal oxygen uptake. c. About one-fourth (1,000 mg) of the total-body iron content in adult males is in storage. d. Iron is a component of hemoglobin, myoglobin, and cytochromes. e. Iron is essential for both oxygen transport and utilization.

a. Because iron stores are quite large, female and adolescent athletes need no regular supply of dietary iron.

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Which of the following conditions in female athletes is LEAST likely to be associated with increased risk of early osteoporosis?

Select one: a. insufficient calcium intake b. low energy intake c. absence of menstruation (amenorrhea) d. chronically high plasma estrogen levels e. low levels of body fat

d. chronically high plasma estrogen levels

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The natural dietary source that is most rich in vitamin B12 (cobalamin) is ...

Select one: a. broccoli. b. meat. c. whole grain bakery product. d. the new impossible burger. e. a Snickers bar.

b. meat

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The best marker of vitamin D status is the blood plasma concentration of ...

Select one: a. 25 hydroxy vitamin D (calcidiol). b. ionized calcium. c. 1, 25 dihydroxy vitamin D2. d. 1, 25 dihydroxy vitamin D3 (calcitriol).

a. 25 hydroxy vitamin D (calcidiol).

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Magnesium deficiency in both humans and animals is associated with neuromuscular abnormalities, including ALL of the following EXCEPT:

Select one: a. cramps. b. structural damage to muscle fibers and organelles. c. muscle weakness. d. acute diarrhea.

d. acute diarrhea

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Urea Concentration

Tests urine and sweat; easy and relatively inexpensive but only provides a rough estimate of protein turnover. Heavily affected by the diet.

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3-methylhistidine Measurement

-somatic Protein Assessment -AA found in Actin and myosin of muscle -excreted in urine with protein breakdown -test relies on accurate urine collection for 24 hours -specific limitations: rarely used, rough measure, requires strict control of meat intake, does not provide actual information about changes in muscle mass.

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A post-translationally modified AA excreted in human urine - biomarker for skeletal muscle protein breakdown ONLY. No info on synthesis.

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Protein DRI for athletes

Endurance exercise: 1.31 +/- .3 (1.2 - 1.8 g/kg/d) Resistance exercise: 1.35 +/- 1.3 (1.6 - 1.7 g/kg/d)

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DRI for Protein

0.8 g/kg of body weight 10-35% of calories

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Protein use during exercise

  1. AA extracted from blood by tissues for protein synthesis in the cytoplasm of the RER

  2. Deamination or transamination yields keto acids and ammonia or amine groups

  3. Keto acids are used as substrates for gluconeogenesis (substances can also be used as precursors to TCA cycle intermediates, direct oxidation for energy)

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Cori Cycle

The removal and recycling of lactic acid by the liver, Liver converts lactic acid to pyruvic acid, Glucose is released to recharge muscle glycogen reserves

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Central Fatigue Hypothesis

Higher brain centers and/or motor neurons Depletion of excitatory neurotransmitters in the motor cortex Reduced motor output to muscle Caused by the CNS and psychological mechanisms and manifests as feeling "tired" or not wanting to go on

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Used in the synthesis of melatonin and serotonin. Decline of this neurotransmitter in the brain is thought to contribute to central fatigue.

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A hormone manufactured by the pineal gland using tryptophan that regulates the sleep-wake cycle (circadian rhythms).

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An excitatory neurotransmitter. Involved in sleepiness, happiness, fatigue, and pain blockage

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Used to synthesize catecholamines (epinephrine and norepinephrine)

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hormones secreted by the adrenal medulla that affect the sympathetic nervous system in stress response (epinephrine, norepinephrine). Metabolic effects include: stimulating glycogenolysis/lipolysis and increasing metabolic rate.

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Large Neutral Amino Acid Transporter

A heterodimeric membrane transport protein that preferentially transports branched-chain (valine, leucine, isoleucine) and aromatic (tryptophan, tyrosine) amino acids. LNAA is highly expressed in brain capillaries (which form the blood-brain barrier) relative to other tissues

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BCAA and Central Fatigue

  1. Carb intake during exercise increases insulin

  2. Insulin stimulates uptake of BCAA by the liver

  3. Trp : LNAA ratio increases

  4. Brain uptake of TRP increases

  5. TRP is used to create dopamine, which makes serotonin This may increase or decrease perception of fatigue

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enzyme that controls the rate of protein synthesis within the myofibrils after resistance training. Forms and signals through 2 protein compounds: mTORC1 and mTORC2 (2 is involved in muscle regeneration and growth promotion).

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Interleukin-2 (Muscle Growth)

A cytokine that helps B cells that have contacted antigen differentiate into antibody-secreting plasma cells. Can inhibit mTOR

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AMP Kinase

Activated when there are high levels of AMP during exercise. Activates malonyl CoA decarboxylase and inhibits acetyl CoA carboxylase --> decrease [malonyl CoA] and increase FA oxidation. A decrease in AMPK will result in protein synthesis.

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Increases protein synthesis - high leucine meals seem to trigger protein synthesis

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gene controlling musculature, blocks muscle development. Mechanical action blocks this inhibition.

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Muscle Satellite Cells

Located at the surface of the basal lamina of the myofiber. Normally non-proliferative, but can become activated when a muscle is damaged. Then, they can repair, revitalize, and mediate muscle tissue growth. They will replicate and fuse with the muscle fiber to add additional nuclei to the muscles.

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Nitric Oxide and Muscles

Nitric Oxide is produce from protein breakdown during exercise. It causes bloodflow to the muscles to increase, allowing for muscle growth.

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Muscle protein breakdown is inhibited by


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Muscle protein breakdown is stimulated by

Cortisol and other stress hormones

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Intracellular High Energy Compounds

ATP and phosphocreatine - high intensity, anaerobic power for 1-10 seconds of sustained output.

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Carbohydrates as an Energy Source

Muscle glycogen, blood glucose, and liver glycogen - anaerobic, high energy output (10-120 sec) or aerobic medium output >5 min.

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Fat as an Energy Source

Low-intensity, high endurance, aerobic output over the course of several hours. Efficiency of use increases with training.

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(Conditionally)Essential nutrients that do not yield energy, but that are required for growth and proper functioning of the body.

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Elements found in food that are used by the body. Always essential

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Recommended Dietary Allowance (RDA)

the average daily amount of a nutrient considered adequate to meet the known nutrient needs of practically all healthy people; a goal for dietary intake by individuals

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Adequate Intake (AI)

the average daily amount of a nutrient that appears sufficient to maintain a specified criterion; a value used as a guide for nutrient intake when an RDA cannot be determined

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Estimated Average Requirement (EAR)

the average daily amount of a nutrient that will maintain a specific biochemical or physiological function in half the healthy people of a given age and gender group

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Recommendations from JAMA 2002

  1. All adults should take 1 multivitamin daily

  2. Benefits known/ suspected of supplementing folate, vitamin B12/B6/D: PV cancer, CVD, osteoporosis

  3. 2 ordinary multivitamins daily in the elderly

  4. Increased folate requirement in people with high alcohol intake can be met with 1 multivitamin per day or a folic acid supplement. Pregnant women - add folate 400 micrograms

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Vitamins for Athletes

  1. Vitamin E/C may help athletes tolerate training to a greater extent by reducing oxidative damage

  2. Optimal levels of Vitamin D linked to improved muscle health

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B complex Vitamins

vitamins involved in energy production Coenzyme functions for transketolase and thiamin in RBC

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Metabolic functions: energy production from protein, fat, carbs. Coenzyme for transketolase, pyruvate decarboxylase. Decreases lactate and allows for more recycling of acetyl CoA.

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Part of NAD, NADP - used for energy production from protein, fat, carbs. Can be synthesized from TRP

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Part of coenzymes FAD and FMN in energy metabolism. Involved in energy production from protein, fat, carbs as well as conversion of vitamin B6 and folate to their active forms.

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Vitamin B6

Involved in transamination of amino acids, release of glucose from glycogen, glucose-alanine cycle, gluconeogenesis

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Free radicals

naturally occurring, highly reactive chemicals with unpaired electrons that form in the presence of oxygen.

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Initiation of Free Radicals

Mitochondria takes reducing potential from a molecule like NADH then runs them through the electron chain to pump protons then ATP made, etc. Sometimes pairing to ubiquinone occurs improperly and only one electron is picked up. The other electron is free in solution, and may form a free radical if picked up by oxygen

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  • Biologically active quinone (electron acceptor in photosynthesis and aerobic respiration)

  • Reduced to ubiquinol upon the acceptance of electrons.

  • Long alkyl chain = lipid soluble = act as an electron carrier within the phospholipid bilayer.

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Propagation of Free Radicals

The single electron is passed from molecule to molecule in a chain reaction of oxidants

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Superoxide Radical

toxic form of oxygen that is detoxified by superoxide dismutase

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Superoxide Dismutase (SOD)

An enzyme that destroys superoxide: O2- + O2- + 2H+ --> H2O2 + O2

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Hydroperoxide Radical


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Hydrogen Peroxide

Chemical compound of hydrogen and oxygen; a colorless liquid with a characteristic odor and slightly acid taste. H2O2

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Hydroxyl Radical

results from ionizing radiation and from incomplete reduction of Hydrogen Peroxide

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Termination of Free Radicals

Various enzymes and antioxidants work to "quench" the free radical by removing the lone electron from the molecule.

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Glutathione Peroxidase

a selenium-containing enzyme that protects cells from oxidative damage by neutralizing peroxides

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Vitamin E as an Antioxidant

Halts lipid peroxidation by interacting with cell membranes as a stabilizer

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Accessory pigments that broaden the spectrum of colors that can drive photosynthesis. Lipid soluble, can stay in cell membranes to act as an antioxidant

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reduced form of ubiquinone after it accepts electrons. Can act as an antioxidant because it scavenges peroxyl radicals.

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naturally occurring water-soluble plant pigments that act as antioxidants. Can inhibit inflammatory enzymes, and scavenge superoxide, hydroxyl, and peroxyl radicals.

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Vitamin E

•tocopherols and tocotriends; alpha-tocopherol most readily absorbed •Found in food sources high in saturated fats •High CHO, low fat diets more likely to be deficient •Therefore athletes may be deficient without supplementation

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Vitamin C

•Regeneration of Vitamin E •Most abundant water soluble antioxidant •Chronic megadosingmay be hazardous

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Selenium as an Antioxidangt

Acts as part of the GPX system

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Copper and Zinc as Antioxidants

Part of the Cu-Zn SOD system

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Iron as an Antioxidant

Part of the catalase enzyme system

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•Most widely studied of carotenoids •Other carotenoids may be more important as antioxidants •Quenches superoxide anions and singlet oxygens

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Regenerating Vitamin E

  • Ascorbate and ascorbic acid can be used

  • Vitamin C can be used

  • DHLA and LA

  • Ubisemiquinone to ubiquinone

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Oxidative Stress

a condition in which the production of oxidants and free radicals exceeds the body's ability to handle them and prevent damage. Damage to DNA can cause cancer or premature aging. Damage to proteins can cause cataracts and reduce enzyme activity. Cholesterol oxidation can cause CVD, hypertension, reduced bloodflow.

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Lipid Peroxidation

the destruction of polyunsaturated lipids through oxidation, leading to membrane damage and increased permeability

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ROS and Exercise

Exercise increases ROS because it increases the amount of ATP made and the amount of O2 consumed. Athletes are encourages to eat a variety of antioxidants from fruits and vegetables.

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Augments insulin action; forms part of glucose tolerance factor.

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Chromium AI

(19-50) Men = 35 ug, Women = 25 ug/day; (50+) Men = 30 ug, Women = 20 ug

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Glucose Tolerance Factor

A biologically active complex of chromium and nicotinic acid that facilitates the reaction of insulin with receptor sites on tissues.

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Promotes normal iron absorption, oxidative metabolism, connective tissue formation, hemoglobin synthesis, acts as a cofactor for superoxide dismutase

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RDA for Copper

900 micrograms

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Deficiency results in goiter, reduced metabolic rate. Excess causes depressed thyroid gland activity.

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Transports oxygen as hemoglobin and myoglobin. Forms cytochromes and metalloenzymes, promotes immune function. Excess = hemochromatosis, liver cirrhosis, heart disease, increased infections.

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hereditary disorder with an excessive buildup of iron deposits in the body

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Iron RDA

men: 8 mg/day women: 18 mg/day

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Deficiency causes impaired growth, impaired healing, increased infection rate, anorexia

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Zinc RDA

Men: 11 mg/day Women: 8 mg/day

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Over 300 Mg containing enzymes in glycolytic pathways. Beta-oxidation of fat, ATP hydrolysis, protein synthesis

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