Studied by 17 peopleIn 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
Note
Flashcard