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In the protein study, how was lipolysis measured?

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In the protein study, how was lipolysis measured?

blood glycerol

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The dec in plasma volume will result in a _______ venous return which will cause a __ in HR



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Lipids used during exercise are primarily from _________ why?

Endogenous storage

Ingested lipids take too long to get into system

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Where do the end products of lipolysis end up?

Glycerol goes to the liver for GNG

FFA into plasma and to muscle to be used as IMTG or beta ox

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What will upregulate lipolysis in both adipose TG and IMTG

Epinephrine primarily

Glucagon, cortisol, caffeine

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What is the primary limiting factor in using fat?

Entry into the mitochondria

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A low glycolytic rate will allow for ______ fat to enter mitochondria


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Two primary factors that limit ability to use fat

Mobilization of fat from adipose


Transport into mitochondria

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What determines the decrease of relative contribution of lipid oxidation to total EE with inc intensity

Decreased adipose tissue blood flow which dec FFA circulation

Dec entry of LCFA into mitoch bc of high glycolytic rate

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What would the effect of having a acute (hours before) high fat meal have?

Increased plasma FFA availability

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Why would it be beneficial to consume SCFA and MCFA w/ respect to exercise?

Their entry into the mitoch is less regulated which will inc FA entry into mitoch

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High fat diet periodization will have what effect

Increase lipid oxidizing capacity

Increase plasma FFA availability

Increase FA entry into mitoch

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Why is a high CHO meal so low in plasma FFAs

Increased insulemic response

Decreased fat mobilization

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Why are plasma FFAs not increased significantly by the FAT-consuming group compared to the placebo group?

Because ingested fats enter blood as chylomicrons not pFFAs

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Will a high fat meal cause the sparing of some muscle glycogen? Even with this in mind, which group performed best?

Yes it will spare some muscle glycogen

BUT the high CHO group still performed best in the time trial

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Will a high fat pre exercise meal reduce CHO ox during intense exercise and improve TT performance in trained cyclists?

Yes it will reduce CHO ox but will not improve TT performance

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What is the problem w pre exercise high FAT meals?

They will enter blood as chylomicrons meanwhile muscle prefers FFA

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What is a method to inc plasma FFA availability (but not really possible during exercise). Will this increase lipox?

To infuse into blood directly w/o having to go through GI system

Yes but it will still be at a lower degree bc of dec entry into mitoch

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What are the two primary factors that will decrease fat oxidation at higher exercise intensities?

Reduction in lipox due to high glyc rate-→ downregulated CAT 1-→ dec entry to mitoch

Reduction in lipox due to dec plasma FFA availability

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A high fat diet will induce the following adaptations

Increased sarcolemmal FA transporters

Reduced PDH (dec glycolytic rate it will then allow more FA entry to mitoch)

Inc beta oxidative enzymes

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Why does reduced PDH benefit fat oxidation?

Decreased rate of glycolysis-→ allows for more lipids to enter mitoch for oxidation

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When can adaptations for lipox be seen in skeletal muscle during a high fat diet?

3-5 days

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What is a good diet strategy for someone preparing for a performance trial?

Periodizing their diet into blocks of high fat to get them fat adapted then High cho day or two before hand to increase muscle glycogen

Fat adapted AND muscle glycogen high

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Higher fat oxidation resulted in a nonsignifianct __________ in TT performance following high fat adaptation + CHO restoration

8% improvement

Nonsignificant due to a large effect of outliers on data

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Why may a high fat diet adaptation decrease efficiency/economy?

Fat gets less “MPG”

4.7 kcal/LO2 vs 5.05 kcal/LO2

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What is the reason that acute nutritional manipulations to increase lipox dont work?

Limited by digestion and mitochondrial entry

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High fat diets can induce favorable changes in protein expression to promote lipox. What is an important consideration of this kind of tactic?

May reduce endogenous CHO

Important to replenish glycogen before race to get best of both worlds

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In elite racewalkers, what was the effect of a LCHF diet on 10km race walk performance?

Decreased performance

Inc fat ox-→ dec economy

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What is the hypothesis in the racewalker study?

LCHF would inc fat utilization during exercise but would impair exercise economy and would not translate into benefitting performance

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How many treatment groups were in the racewalker study? What were they?


High CHO

Periodized CHO

Important to note isocaloric

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in the racewalker study, what happened to RER in the LCHF group?

Decreased, indicating a shift towards whole body lipox

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in the racewalker study, there was a improved aerobic capacity across all groups, LCHF saw an increase in lipox, what does this mean for economy and performance?

Reduced economy-→ so at same intensity their VO2 is higher

Performance did not improve in the LCHF group like it did in HCHO and PCHO groups

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in the racewalker study, how did the testing take place, how many subjects?

Over two different training camps

21 subjects total but 29 data sets (some repeated)

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in the racewalker study how long was the training block? How long was the testing block?

3 day testing block PRE

2 week training block

3 day testing block POST

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in the racewalker study, what happened w/ respect to blood ketones in the LCHF group

Significant increase

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in the racewalker study, what was the effect of relative O2 cost on exercise in the LCHF group

SIgnificant increase pre-post

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in the racewalker study what did the testing block consist of?

Day 1: A lab treadmill graded economy test (fasted)

Day 2: A 10km race walk to look @ performance

Day 3: a 25km standardized long walk to look at substrate use

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in the racewalker study, which group experienced a greater RPE? Which group saw increased HR post treatment?


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Actin and myosin make up about 80-90% of pro in skel muscle. They are mainly composed of what kinds of amino acids?

BCAAS (Leuicine, isoleucine, valine)

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Unlike CHO and FAT protein body stores are

variable, in a constant state of flux

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as long as you are remaining weight stable the total body protein pool will remain the same because the

rates of synthesis and degradation are equal

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Proteins with regulatory function such as hormones and enzymes have a _______ turnover rate


within hours to days

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Structural proteins such as collagen actin and myosin have _______ turnover


days to months

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Where in the body does the greatest amount of amino acid turnover occur

Gut, kidneys, liver

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Diet only contributes about ________ of AAs that enter free AA pool /day. Where does the rest come from

25%, the rest will come from gut kidney liver turnover

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Which amino acids are primary NH3 carriers in the blood? Why?

Glutamate and glutamine

Play a role in synthesis of nonessential AAs by xferring NH3 to the carbon skeleton of other AAs or TCA intermediates

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Which two nonessential amino acids cannot be easily synthesized?

Cysteine and tyrosine

Can be classified as essential in special populations

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What are the two purposes of body protein breakdown?

Energy provision from C skeleton

Synthesis of compounds (neuroxmitters, hormones, creatine, nucleotides)

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Degradation of protein to create new protein results in _____protein loss. Use of C skeleton as energy will result in a ______ protein loss



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Under which conditions will protein be used as a fuel source? What do these two conditions have in common

Prolonged fasting

Prolonged exercise

both conditions are CHO depleted

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What are two ways that nitrogen can be removed from the amino acid?

Oxidative deamination


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Where does oxidative deamination solely occur? what is used as the oxidizing agent?

Mitochondria of the liver


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What is produced from the oxidative deamination of glutamate?

Alpha ketoglutarate (TCA cycle intermediate)

NH4 (ammonia)

NADH (reducing equivalent)

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Where does transamination occur?

many tissues (including muscle)

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Which amino acids undergo transamination?

Alanine, aspartate, glutamate, and the BCAAs

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What is commonly produced from transamination?

Alpha ketoglutarate

(from glutamate, alanine is produced and can then be used in GNG)

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How is nitrogen excreted? Where does this occur??

The urea cycle


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What two processes feed the urea cycle? Where does the urea go once produced in the liver?

The products of transamination and oxidative deamination

To the kidneys for excretion

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When quantifying amino acid metabolism, what is a weakness of the urea concentration method

It is heavily influenced by hydration and diet status

roughest estimate

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When quantifying amino acid metabolism, what are the benefits and weaknesses of nitrogen balance technique

Strength: pretty accurate

Measure nitrogen intake from diet then subtract excretion (feces, sweat, hair, skin etc) for overall balance

Difficulty measuring, using just urine underestimates a bit

Prolonged sample collection

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When quantifying amino acid metabolism, what is the benefit of using 3-methyl histidine

indicator of myofibrillar protein breakdown

Need to control meat intake, dependent on renal clearance, still rough estimate

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if you are in a positive nitrogen balance, is it an indicator of protein synthesis?

Not always

it can be because of increased synthesis but it can also be because of reduced degradation

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When quantifying amino acid metabolism, describe AV balance method

Theory: diff in arterial and venous AA concentrations represent uptake and release across tissue bed

Highly invasive, tissue specific, and dependent on blood flow measurement.

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When quantifying amino acid metabolism, DESCRIBE using tracers

Stable or radioactive tracers

Dilution= amino acid production/ protein breakdown (because the concentration of tracer in blood is diluted)

inclusion in skel muscle = PRO synthesis

Appearance in breath = oxidation

Invasive + expensive

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Relative contribution of AA to TEE during exercise is _________


increases w cho depletion

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Endurance athlete PRO recommendation, why so high

1.2-1.4 g/kg/ day protein

INC protein need bc of inc BCAA ox

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PRO recommendations for resistance trained athletes

1.2-1.7g/kg/ day

Keep MPS elevated to keep up with MP turnover elevation

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Why does someone who goes from sedentary =-→ active go into a negative nitrogen balance

Inc muscle protein breakdown

Insufficient energy intake, especially protein

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Which athlets are at most risk for protein deficiency

Endurance, combat sport, “artistic sport”

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In most athletes, if energy intake is sufficient, the protein intake is


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High protein diets, AA supp, and RT all stimulate protein synthesis? Are these effects additive

Yes because in response to RT MPS > breakdown for about 24H post

The multiphasic nature of MPS peaks and lows will greatly benefit from a high protein diet and AA supplementation

Need to provide sufficient protein to avoid negative nitrogen balance

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What is the best recommendation for postworkout supp

After the workout consume a mix of CHO + AAs

Ideally 3:1

Promotes insulin which promotes synth and inhibits breakdown

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Not all proteins are built the same, some hit the blood faster than others. For example ________ hits fast meanwhile ______ hits slow



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What maximizes PWO mps

20-30 g pro

8-15 EAAs

2g Leucine

Leucine is key

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What is more important, daily protein intake or acute PRO supp

Daily protein intake is more effective

As training status increases and PRO intake is sufficient, the acute supps have less of an effect

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Who benefits most from acute PRO supp, a untrained older individual or trained younger individual?

Older untrained individual

More room for adaptation

Also beneficial for weight loss to spare LBM

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Dangers of excess PRO intake

Kidney damage



Purified amino acids developed for clinical use -→ megadoses should be avoided as safety is unknown

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Where is most of the water wt in the body?

In the LBM (skeletal muscle)

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Under what conditions is it difficult to maintain fluid balance

Exercise (especially in the heat)

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How many kcal of heat are produced for every L O2 consumed?


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Where is the majority of heat produced transferred to? How is this transferred?

To the core

Venous blood flow

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The increase in core and skin temp is sensed by ______ which then will


initiate sweating and peripheral vasodilation

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As a general rule of thumb, movements using a greater amount of muscle mass will result in a

greater increase in core temp

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Core temp in celsius


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Our ability to produce heat ________ the ability to offload it


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Radiation, conduction, and convection are driven by

a temperature gradient

less effective @ increasing ambient temperatures

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When ambient temp< skin temp

Heat is lost to evap, conduction, convection, radiation

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When ambient temp> skin temp what are the routes of heat loss?


No temp gradient for radiation, convection, conduction to work (will actually cause heat GAIN)-

More difficult to maintain temp

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What is a primary factor influencing evaporative cooling?

Relative humidity and ambient temperature

Other factors: surface area exposed and convective air currents (this will provide air that is less saturated w water to the skin which will inc evap cooling)

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The ability of sweat to evaporate will ______ as ambient vapor pressure approaches that of moist skin


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What is counterproductive sweating?

Water loss w/o cooling in hot humid environment

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Radiation is the exchange of heat

When objects are not in contact

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What are the two competing CV demands when exercising in the heat?

Increased need for oxygen and nutrient delivery to muscle

Heat delivery to periphery for cooling

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Why does the HR have to increase when dehydrated even if same pace is maintained?

Decreased stroke volume but inc HR to maintain cardiac output to maintain intensity and delivery to muscle

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What is better at transferring heat, air or water?


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Sweat rate is highly related to ___ and may be as high as ____ in the unacclimatized

1.5-2L /hour

must be 2L to dissipate all heat produced if reliant on evap alone

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How is sweat rate calculated

(Body weight change + (fluid consumption-urine production))


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Acclimatization to heat results in a ___ sweating threshold

lower AKA pre emptive sweating AKA sweat earlier

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Acclimatization to heat results in a _____ sweat rate


APPROX 4 L/H compared to untrained

Due to inc sweat glands

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Acclimatization to heat results in a _____ Plasma Volume


More sweating capacity

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