KIN 477 T2

In the protein study, how was lipolysis measured?

In the protein study, how was lipolysis measured?

blood glycerol

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

decrease

Increase

Lipids used during exercise are primarily from _________ why?

Endogenous storage

Ingested lipids take too long to get into system

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

What will upregulate lipolysis in both adipose TG and IMTG

Epinephrine primarily

Glucagon, cortisol, caffeine

What is the primary limiting factor in using fat?

Entry into the mitochondria

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

more

Two primary factors that limit ability to use fat

Mobilization of fat from adipose

AND

Transport into mitochondria

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

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

Increased plasma FFA availability

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

High fat diet periodization will have what effect

Increase lipid oxidizing capacity

Increase plasma FFA availability

Increase FA entry into mitoch

Why is a high CHO meal so low in plasma FFAs

Increased insulemic response

Decreased fat mobilization

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

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

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

What is the problem w pre exercise high FAT meals?

They will enter blood as chylomicrons meanwhile muscle prefers FFA

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

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

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

Why does reduced PDH benefit fat oxidation?

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

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

3-5 days

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

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

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

Fat gets less “MPG”

4.7 kcal/LO2 vs 5.05 kcal/LO2

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

Limited by digestion and mitochondrial entry

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

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

Decreased performance

Inc fat ox-→ dec economy

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

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

LCHF

High CHO

Periodized CHO

Important to note isocaloric

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

Decreased, indicating a shift towards whole body lipox

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

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)

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

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

Significant increase

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

SIgnificant increase pre-post

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

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

LCHF

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)

Unlike CHO and FAT protein body stores are

variable, in a constant state of flux

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

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

High

within hours to days

Structural proteins such as collagen actin and myosin have _______ turnover

Slower

days to months

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

Gut, kidneys, liver

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

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

Which two nonessential amino acids cannot be easily synthesized?

Cysteine and tyrosine

Can be classified as essential in special populations

What are the two purposes of body protein breakdown?

Energy provision from C skeleton

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

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

NO NET

Net

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

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

Oxidative deamination

Transamination

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

Mitochondria of the liver

NAD+

What is produced from the oxidative deamination of glutamate?

Alpha ketoglutarate (TCA cycle intermediate)

NH4 (ammonia)

NADH (reducing equivalent)

Where does transamination occur?

many tissues (including muscle)

Which amino acids undergo transamination?

Alanine, aspartate, glutamate, and the BCAAs

What is commonly produced from transamination?

Alpha ketoglutarate

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

How is nitrogen excreted? Where does this occur??

The urea cycle

Liver

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

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

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

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

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

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.

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

Relative contribution of AA to TEE during exercise is _________

5-15%

increases w cho depletion

Endurance athlete PRO recommendation, why so high

1.2-1.4 g/kg/ day protein

INC protein need bc of inc BCAA ox

PRO recommendations for resistance trained athletes

1.2-1.7g/kg/ day

Keep MPS elevated to keep up with MP turnover elevation

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

Inc muscle protein breakdown

Insufficient energy intake, especially protein

Which athlets are at most risk for protein deficiency

Endurance, combat sport, “artistic sport”

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

sufficient

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

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

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

whey

casein

What maximizes PWO mps

20-30 g pro

8-15 EAAs

2g Leucine

Leucine is key

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

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

Dangers of excess PRO intake

Kidney damage

Hyperlipidemia

Dehydration

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

Where is most of the water wt in the body?

In the LBM (skeletal muscle)

Under what conditions is it difficult to maintain fluid balance

Exercise (especially in the heat)

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

4

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

To the core

Venous blood flow

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

Hypothalamus

initiate sweating and peripheral vasodilation

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

greater increase in core temp

Core temp in celsius

37

Our ability to produce heat ________ the ability to offload it

exceeds

Radiation, conduction, and convection are driven by

a temperature gradient

less effective @ increasing ambient temperatures

When ambient temp< skin temp

Heat is lost to evap, conduction, convection, radiation

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

Sweating/evaporation

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

More difficult to maintain temp

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)

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

decrease

What is counterproductive sweating?

Water loss w/o cooling in hot humid environment

Radiation is the exchange of heat

When objects are not in contact

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

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

What is better at transferring heat, air or water?

Water

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

How is sweat rate calculated

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

/time

Acclimatization to heat results in a ___ sweating threshold

lower AKA pre emptive sweating AKA sweat earlier

Acclimatization to heat results in a _____ sweat rate

increased

APPROX 4 L/H compared to untrained

Due to inc sweat glands

Acclimatization to heat results in a _____ Plasma Volume

Greater

More sweating capacity