Kin 4433 exercise phys midterm 2

could resistance training be a stimulus for aerobic-like changes to the heart?

\-we saw on past study that there was increase in aldosterone and plasma volume even in high volume low low resistance training

\-so could maybe still act as stimulus for favourable growth of the heart

\-maybe exercise at this level, so muscle strength but more aerobically, could lead to both volume AND pressure stimulus

\-remember pressure stimulus in strength training is an increase in pressure (heart has to continually work against mean arterial pressure), so lead to concentric hypertrophy

explain study comparing the acute changes in ventricular responses during aerobic and resistance exercise? setup

\-study looked at pretty heavy intensity aerobic cycling exercise (90% VO2max)

\-then has leg press, bicep curl, and shoulder press (about 70& 1RM)

study for acute bouts of exercise on ventricular responses: explain response of aerobic training

\-in cycling, there was very little change in mean arterial pressure

\-for HR, they get to about 135bpm, so heart is working harder but pressure doesnt change that much bc we are opening up vessels during exercise and recruiting more vessels too

\-despite increase in pumping action from heart and higher Q, there is vasorelaxation in periphery so TPR isnt changing much

\-the systolic pressure still goes up w acute bout, but mean arterial (so overall) stays the same

\-EF goes up a bit

study for acute bouts of exercise on ventricular responses: explain responses in resistance training

\-smaller increase in HR compared to cycling condition

\-in resistance training (acute bout) there is increase in mean arteriral pressure

\-there was similar increase in systolic pressure compared to aerobic, but MAP increases too here

\-this is probably bc the valsalva maneuver puts pressure on arteries that are leaving the heart, so has to overcome this pressure

\-EF actually drops a bit here, so increase in TPR and afterload is challenging the heart

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explain second study looking at acute changes in pressure bw aerobic and resistance

\-if you constantly putting heart to higher TPR, could this lead to increase in overall BP?

\-study did leg press at 70% 1RM (high volume, low intensity) and compared cycling at 70% peak power

explain second study looking at acute changes in pressure bw aerobic and resistance : what were differences in pressure and Q between the aerobic and resistance?

\-the Q during cycling is almost doubling compared to rest and is much higher than in resistance

\-this would need you really need to increase vasodilation and capillary recruit to mitigate rise in TPR

\-bc TPR in aerobic went even lower

\-there was actually a negligeable change in TPR with resistance training too, so maybe there was vasodilation bc its lower load?

\-so shows dif results from last study, but could be different training that was more similar to aerobic, or dif for dif muscle groups used?

\-**not sure if I need to know the extra info they looked at in the study?**

what is the blood pressure response after consistent resistance training? explain study design

\-looked at hand grip isometrically 5x per week for 8 weeks

\-examined systolic and diastolic BP changes in males and females

\-also looked at dilation ability of vessels in brachial artery

**-this is looking at response to exercise before and after training?**

\-in general, males have larger BP

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what are the results of the study that looked at BP changes after resistance training?

1. there is a drop in males and femaes in systolic and diastolic BP after training
2. this corresponds to changes in dimensions of brachial artery, so they also found increase in flow mediated dilation in brachial artery
3. mean arterial pressure also drops
4. pulse pressure (pressure in vessels0 also drops

overall: with acute bout of resistance training, your BP increase will be different depending on past training, so there is lower BP increase when you are trained?

\-likely dure to that increased ability of vessels to dilate during exercise as a result of training

**-confused: is there a drop after acute bouts of exercise after trained? or is there a drop in resting BP?**

what are the types of resistance training?

there is the more body builder BB tyoe, which prioritizes maximal muscle growth and minimal body fat

\-they do medium-heavy weights using 8-12 reps and multiple sets

\-so more high volume bc they only want to increase hypertrophy

\-then there is powerlifters (PL) or more strength athletes, where their main goal is to increase muscle strength and bone strength

\-so they lift close to 1RM during training and very low rep

what are the changes that occurs to heart paramters during PL type of exercise

\-this is 95% 1RM on bench press, so very high load

\-there is increase in BP during acute bout, which means increase in afterload so makes sense


1. EDV goes down, bc more pressure in thoracic cavity when doing lift


2. drop in SV, so have harder time getting blood back to heart
3. EF actually goes up, so cant contract heart a bit harder
4. drop in ESV, so less volume of blood left bc you have contracted more and EF increased

explain which ventricular geometry is associated with each type of training adaptation

A is normal heart

B is concentric hypertrophy from olympic weightlifter: so we see its thicker but the dimension of heart havent changed (the chamber volume is same)

C is example of remodelling of heart during disease, so there is thickening but causes smaller chamber size is smaller (so wouldnt see in resistance trainers)

D os what you see in BB, so more aerobic adaptations aka eccentric hypertrophy

bottom line: are you able to specifically predict the adaptations of heart based on if they exercise aerobic or resistance?

\-you can’t characterize exactly the type of adaptations that will happen to the heart depending on resistance or aerobic exercise

\-it will always be a mix depending on what you are doing on the spectrum of aerobic or resistance training

what are the factors altering the CV response to resistance training?

\-during progressive high volume RT, the responses are in combination of both AT and RT

\-this reflects a combo of both volume and pressure loading on myocardium and vascular system

\-the severity of the pressure depends on:


1. magnitude of resistance (% of 1RM) ex high % will lead to more pressure stimulus (whereas 60-70% 1RM is more BB stimulus)
2. size of the working muscle mass (when bigger = more blood to muscle = more ability to dilate, but more pressure?)
3. duration of muscle contraction( longer contraction = more pressure for extended time)

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how did VO2max change in ET, RT, and combined (CT) pre and post training

\-RT (resistance) here was more BB, and then ET was at 75% VO2maxcycling

\-control had a dip in VO2max, so they were quite sedentary

\-we see an increase in VO2max after training for all groups, even in RT (bc its more aerobic type)

\-CT is cimbined training and they have similar increase in VO2max, do it means heart is not impacted in a bad way when you comined the too

\-the data mirrored the change in EF, so ability to expel blood matched the changes in VO2max

explain study in rats looking at combo of RT and AT

\-combo of training has advantages, and most people prefer to do RT and AT bc there is more variety

\-we know that RT and AT do not impact each other negatively when combined

\-in rats (diabetic), they did combined training and compared to aerobic only (80% VO2max) and resistance only (75% RM)

\-even rats in RT had increase in VO2max

\-then tehy isolated heart and put in appartus to pump it w oxygenated liquid to stimylate blood

\-then did test by removing the oxygen to mimick myocardial infarction, or stop blood flow to certain region of the heart

\-then returned blood in reperfusion phase

\-in heart attac, you never fully get that ability to beat as well again when you reocver (ex get 20% reocovery)

\-so this study was looking at hearts ability to recover from stimulated heart attack in dif types of exercise training

what were results of rat study looking at training and recovery of heart attacks

\-remember in diseased hearts when they have heart attack, they normally only get about 20% recovery in beating ability and ability to build pressure

\-in any of the training (AT, RT, ART) you get to 40% recovery, so double!

\-bottom graphs looking at rates of isovolumic states of contraction and relaxation

\-ART groups improved their rates at getting to these pressure in isovolumic stages

\-so heart is prob better at handling Ca2+ when you combine AT and RT together, so lead to these faster rates?

how quickly does muscle adapt? how are structure and function of muscle connected

\-remember that muscle is a very large organ, so changes to skeletal muscle have a huge change to overall well-being to patients partaking in exercise

\-also adapts pretty quickly, so can change one’s health state quickly and takes a long time to lose these adaptations as well

\-when trying to understand function of muscle, NEED to consider structure, bc structural components link directly to its function - and function determines structure too

how does the local environment affect muscle cells?

\-the environment around the muscle (extracellular region, catecholamines, insulin, and other hormones, inflammation) will affect muscle and how muscle responds

\-does this through cell signalling (communication within and outside of the cell)

\-and also does this through gene expression, which changes quantity and quality of proteins in and around cell, so protein composition of muscle changes and links back to structure and function

do muscle cells have any empty space? how do we make a muscle cell bigger/stronger?

\-muscle cell is jam packed, so any space will be filled w myofilaments

\-to make muscle stronger, make the cell volume bigger and cell will fill in the extra space

\-every nuclei requires a certain space around it, so if satellite cell donates nicleus, then muscle increases its volume and there is more protein expression to fill that empty space

\-we dont know if satellite cell donates its nucleus, does this change the fibre type composition of the muscle?

what is a skeletal muscle made out of?

\-a skeletal muscle is a group of individual muscle cells ( aka muscle fibres, myofibres, or myocytes, use interchangebly)

* some muscle groups have over 1000,000 fibres, some have less than 500

\-muscle cell is not a circular structure, but more a fibre or long strand

\-muscle fibres can differ in size (ex type 2x is larger but there are fewer of them)

\-the whole muscle and myofibres are organized (held together) by connective tissue and it is dispersed throughout the muscle

is a muscle fibre always the same type?

\-CONFIRM IF THIS IS RIGHT

\-along the strand, we see that all dif parts of that strand or muscle cell are different types

\-but maybe majority is what determines what “type” the muscle fibre is referred to?

are muscle fibres arranged in the muscle? explain the classic cat study

\-used to think that muscle fibres all ran from tendon to tendon in a muscle group

\-based on cat study that took a transverse section pre and post training and counted the muscle fibres and found more after training

\-based on this, they determined training led to hyperplasia (generation of more muscle fibres)

\-but ACTUALLY, fibres are interdigitated w other fibres grouped within fascicles and anchored by the connective tissue

\-so maybe section post training was taken at dif part of muscle that had cross section w more interdigitation

\-so now we know that findings were based on randomness of cross section and that hyperplasia doesnt actually happen (hypertrophy does)

what metabolic diseases target muscle?

\-diabetes makes you lose type 1 fibres

\-muscular dystrophy

list the 3 connective tissues on a muscle. Which parts do we each separate?

\-epimysium: surrounds the entire muscle and then fuses w muscles, so separates muscle from each other (ex biceps from triceps)

\-perimysium: divides muscle belly into bundles called fascicles; blood vessels and nerves are found in between fascicles in loose connective tissue

\-endomysium: surrounds each muscle fibre, capillaries are found in between the fibres

what is the connective tissue around muscle made out of?

\-composed mostly of collagen (in muscle tissue) and elastin (tendons)

\-but many other proteins are also involved in connective tissue holding skeletal muscle together

\-connective tissue also has other functions (but dont focus on this?): houses fibres, transmits contractile force, provides protein-to-receptor signals to fibres that modulate intracellular signaling pathways and gene expression

why does muscle fibre look this this?

\-muscle cell is about the same size as a hair strand

\-skeletal muscle is striated (striped), this is due to the sarcomeres

\-the small bumps are nuclei, which are just underneath plasmalemma (cell membrane)

explain the general structure of the skeletal muscle and where everything is placed

\-plasmalemma = sarcolemma = cell/plasma membrane

\-then nucleus is right underneath, and one cell can have multiple nuclei

\-satellite cell is also close, but on outside of muscle fibre

\-inside sarcolemma there is cytoplasm (sarcoplasm), which surrounds individual myofilaments (myofibrils) which are the contractile units within the muscle cell

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explain the structure and function of the T tubules and sarcoplasmic reticulum (SR) in skeletal muscle

\-the transverse tubules are extensions of the sarcolemma which run deeper into the fibre to allow for electrical transmission, and connect to SR

* small invaginations of sarcolemma go into cell to reach inner parts

\-the sarcoplasmic reticulum (SR) surrounds the myofibrils as an elaborate network of tubes so they can release calcium and cause contraction

what is overview of process of AP going into muscle fibre to cause contraction

\-AP goes into sarcolemma

\-AP moves doen T-tubules into more inner parts of cell

\-when T-tubule arrives to SR, there is Ca2+ release

\-the Ca2+ binds to troponin

\-binding site on tropomyosin exposed to myosin now

\-filaments can form cross bridges and ATP mediated contraction occur

what is the difference between myonuclei and satellite cells?

\-these are almost indistinguishable if we just look at muscle

\-nuclei is completely under the plasmalemma; they are very cumerous (1000s per fibre)

\-but there is plasmalemma underneath the satellite cell too

\-the basement membrane is the connective tissue that surrounds the whole muscle and contains these, but satellite cell is basically between basement membrane and sarcolemma

* these are more rare (1-20 per muscle fibre)

how do scientists differentiate between the nuclei and satellite cells?

\-an antibody is specific to a protein, so they tag fluorescence to an antibody that is specific to protein in nucleus, then add to muscle fibre and see where the nuclei light up

\-then put another dif colour antibody to specific protein only in satellite cells (PAX7 protein) and see dif locations of these based on dif colours

\-satellite cells can potentially “roam” around and got adcanent muscle cells

are mitochondria in muscle cell rigid?

\-NO! they are dynamic and branches structures that are below sarcolemma and interwoven bw myofibrils

\-basically they are not stagnant at all and can fuse together and divide to adapt

\-the inner membrane folds are visible with electron microscopy, and this is important for energy metabolism events that occur here

does mitochondria adapt?

\-with training you have enhancement of mito so they get bigger and size and number

\-tehy are constantly fusing and dividing, so more fluid in cell and this is how they can adapt in exercise

\-ex branching off to go towards areas in muscle that are more active?

what are the two mitochondrial pools?

\-a muscle cell has multiple mitochondria

\-there is the subsarcolemmal pool (SS), where we oxidize a lot of fat

\-and the intermyobrillar pool (IMF)

* **the IMF mito have a higher rate of aerobic respiration compared to SS**

Do the different pools of mito have different functions?how do they both react to aging and disuse?

\-each pool has important roles that are needed to support metabolic demands of skeletal muscle

\-both pools lower with disease and disuse and aging, but can be improved with exercise training!

is fat good or bad in muscle?

\-it depends on how active the person is, there is misconception that fat is always bad in muscle

\-there is athelete’s paradox, where athletes actually tend to have some fat in muscle, which is also seen in untrained or disease

\-but this extra fat in athletes is actually good bc they have all the tools (mito) to oxidize it for energy quickly

\-whereas untrained person has same fat, but they dont have the mito or tools to metabolize it quickly, so its just unhealthy

what is the sarcomere?

\-each muscle fibre is composed of several hundred to several thousand myofibrils and these are the contractile units of the fibre

* they lie in parallel with each other to form bulk of the fibre

\-the functional unit of the myofribil is the sarcomere (striated pattern)

\-each myofibril has many sarcomeres (10 -100 thousand) that are joined end to end and very organized

* **they can be aligned/organized w the sarcomered on enighbouring fibrils**

briefly explain how sarcomere contracts

\-the Z line attaches two sarcomeres together

\-actin protein attach to z line and in middle there is myosin

\-so in contraction, myosin attaches to the actin and pulls in towards centre which causes the overall shortening of the muscle

how many thin filaments are associated with thick filaments and how are they organized within the myofibril?

\-each thick (myosin)filament is surrounded by 6 thin (actin) filaments, so very well organized on a cross section

explain the ATPase on the myosin molecule

\-on myosin molecule, there is an ATPase which is an enzyme that hydrolyzes the ATP molecule

\-myosin molecule has head that tilts when it binds to actin and pulls the z line into myosin centre; what allows this tilt is the energy harnesses from ATP molecule to ADP

\-70% od ATP used in exercise and in general in body is used in this manner

are the myosin ATPases the same for every muscle fibre?

\-the ATPases on myosin heads hydrolyze ATP at different rates, so the type of myosin ATPase will determine the fibre type and contraction characteristics

\-ex in type 1, it takes longer to take off P, so slower to contract

which mysoin ATPase do we use at dif intensities of exercise

\-at low levels of intensity(40% VO2max and 20% 1RM), we use mostl type 1 fibres bc we can generate ATP at same rate we are utilizing it

\-at higher intensities, we are using ATP faster than we can generate it, so go into oxidation of glycolytics stores here and more towards type 2a stores that cam break down ATP faster

\-when we go to max lifting/VO2max, we are vert efficient in hydrolyzing ATP and to use anaerobic resources to suppliment this, but can only do for a short duration (using ATP faster than we can make it = deplete stores quickly)

if muscle fibres did change to different types, how would you do this?

\-looking at if fibre type composition changes with training (aerobic vs resistance)

\-to change fibre type, you would have to change the speed at which ATPase hydrolyzes ATP, and we know enzymes can be upregulated/increases within cell

what is the main energy source or pathway for each fibre types (ATPase)

\-SO has more fat in it, so slower but can make more ATP

\-in FOG, there is still ability to generate ATP from fat, but also get ATP from glycolytic resources

\-in FG, you are only relying on glycolysis, so can generate ATP quickly but there is not much

fill in table!

\-rule of thumb, the FOG sides with the FG, except for fatigue resistance, anaerobic capacity, and fibre diameter (when its intermediate)

what is histology? what kind of histological analysis do we do on muscles?

**-the study of a tissues and its cellular/molecule consistuents is called histology**

\-in terms of muscle fibres, we are seeing if they are changing fibre type, if it is fast or slow (what type of myosin), knwoing how much of an enzyme is in the muscle fibre

\-first need to take muscle biopsy, then use other technqiues to look at histology to comparethose in training, those in disease etc

\-using these histological technqiues, we can related function properties to protein expression/activity

what is the function of succinate dehydrogenase? why is this enzyme examined when we look at histological view of muscle biopsy?

\-SDH is an enzyme involved in the electron transfer chain and in krebs, its a rate limiting enzyme

\- and it is **directlt correlated with how much mito exist within a muscle**, so its very common to investigate

\-with aerobic training, we see there is an increase in SDH in muscle and this allows more respiration to occure at higher rate, so beneficial adaptation

what is the most common type of histological stain/picture?

\-the most common picture is called H& E srain of cross section of muscle, which involves specific staining chemicals applied to tissue section

\-hemotoxilin penetrates the nucleus, and when it does, it gives this purple colour

\-eisin penetrates the membrane, and gives this pink colour that marks where cytoplasm it

\-so when looking at cross section, we can see the membrane and nuclei (and some satellite cells)

* cant see cellular contents, so cant determine type of muscle fibre

\-after adding the chemicals, we use microscope to examine it

what type of machine is used to get cross sections of muscles?

\-there is the cryostat machine that will section tissue

\-it basically is a cold chamber that has a big blade, you move the blade and cut off a very small piece of tissue, so kind of like a meat slicer

\-NEED to keep tissue cold, bc freezing will halt the cellular processes in that tissue

* if it was at reg temp, then enzymes would start to function again like ATPase and start hdyrolyzing ATP
* so freezing the muscle allows us to take a “snapshot” of how the muscle currently is
* after, add chemical agent that stops the cellualr processes to stop tissue activity
* this freezing allows us to analyze change in the same muscle at two different time points (ex before exercise and after exercise)

Explain the steps of the conventional way to do a fibre type analysis

1. take a small cross section of muscle tissues (from muscle biopsy), then multipe subsequent sections so all of these are basically in same place on muscle, so they are capturing all the same muscle cells (since one section is consistent in cells as the next section) - normally do 3 bc we have 3 fibre types
2. have antibodies for each of the dif myosin heavy chain ATPases (dif cc will explain how we get the antibodies?)
3. then apply a dif antibody to each of the dif cross sections (ex one antibody to one slide)., so this antibody will only stick to specific enzyme (myosin ATPase) it is designed for
4. then add second antibody that has something you can detect (fluor, or enzyme that performs reaction to show colour) that is sepcifc to the first antibody
5. wash off any excess, bc not all antibody binds and we only want coloured antibody to be on the first antibodies that are bound
6. now depending on the location of the colour shown, we can see which parts are type 1, 2a, or 2x and determine the relative percentages too

what is the fibre type % breakdown of most muscles?

\-most muscles are 50/50 for type 1 and type 2

\-except for postural muscles (like soleus) that is 70% type 1

what is the single step method to fibre type analysis of muscle

\-similar in terms of muscle biopsy and cross section, but only need 1 cross section

\-then you add all antibodies (all with specific fluor) to the same tissue section, so they will all have dif colour and bind to their respective enzymes

\-this is much quicker, and dont need to add secondary antibody to primary antibodies

\-con: antibodies could stick to each other instead of tissue, so could mess up results

\-so conventional method is probably still more accurate

what is histochemistry? and explain basic principle

\-histo = tissue, so chemistry in tissues, older techniques that using antibodies

\-this is a visual evaluation of tissue samples which have been incubated w substrates (chemicals) that undergo a reaction catalyzed by certain enzymes present in tissue

\-then the chemical product in the tissue may be visualized as a coloured precipitate

\-basically requires a functional enzymatic reaction

\-explain different pH optimums for different myosin ATPases

\-we know that myosin ATPase is very important bc it distinguishes what type of muscle fibre it is (based on speed of enzyme), remmeber reaction breaks ATP and releases a Pi

\-different myosin ATPases differ in their function at different pHs

* type 1 works best at pH 7.4, which is more resting and this makes sense bc they are active at low intensity/ rest
* type 2x works best at pH of about 6.5, so much more acidic, which is when it would be more active in higher intensity exercise anyway
* so at rest, type 2 mysoin ATAse is not super functional bc not optimal pH

how do we use histochemistry technqiues to determine fibre type?

\-manipulate the pH of the cell, so that some of the myosin ATPases are inhibited and others are active, so will be catalyzing reaction that releases Pi

\-then add a colouring agent reacts to the Pi and turns blue (for example)

\-so the cells that turn the darkest blue ar ethe most active, so we can figure out which it is depending on the pH we manipulated

\-the other cells that are not in their optimal pH but still slightly active will have a less intense purple colour

what is immunochemistry?

\-so histochemistry uses pH to figure out fibre types, immunochemistry uses antibodies to determine this (already covered)

\-hardest and most time consuming, but important to see how muscle is structured

what are antibodies?

\-antibodies are synthesized by B-lymphocytes (immune cells) and produced in response to foreign proteins

* so the portion of the antibody is made to fit and bind to target protein

\-then immune cells finds the antibody and engulfes the whole thing to degrade the foreign protein

how are antibodies manufactured for research purposes

company will inject rabbit with fragment of th ehuman type 1 mysoin protein (or any target protein)

\-then rabbit generates the antibodies that target the selected protein (myosin ATPase)

\-then company takes blood sample from rabbit and purifies these antibodies

\-then sell to scientists running experiments for a lot of money!

does every fibre only distinctly express one type of mysoin ATPase? explain using the example study

\-uses immunohistochemistry to stain for type 1, 2a, 2x in three consecutive muscle sections

\-they were interested in determining if some fibres simultaneously expressed more than one MHC isoform (this may indicate if fibre type can transition

\-results: there are fibres that coexpress 1, 2a, and 2x, so showed colour on all different stains

\-these fibres are referred to as transitional or hybrid fibres: means they coexpress different myosin ATPases

do trained or untrained individuals have more hybrid fibres?

\-since they coexpress differente myosin ATPases, people think that they are in this stage of transition to a different type

\-but these fibres also exist in untrained individuals

\-and in post training, these fibres are actyally LOWER (maybe bc they already transitioned to new type bc of training?)

how is the position of fibres types in human muscle different than in rodent

\-in humans, muscle fibre types are nicely spread out, so types are interspersed with each other

\-but rodents have fibres of similar myosin ATPases all within a region

* eg type 2x is closer to bone

\-need to consider these differences when comparing rodent model to humans

which technqiue would you use for an SDH stain? for a capillary stain?

\-SDH stain let enzyme catalyze reaction on tissues and it gives appearance of blue; so use histochemistry

* darker blue = more enzymes in this area, so we can tell where the mito is present

\-capilarry ATPase stains are also used, since there are nuclei in capillaries that have ATPases in them, so find the nuclei in the vessels in between cells; also histochemistry

what are intramyocellular lipids (IMCL)?

\-IMCLs are very important sources of energy for skeletal muscle during exercise, especially when prolonged

\-IMCL are usually stores as droplets, and they are scattered throughout the fibre, but usually located in proximity to the mitochondria

\-in adipocytes, they are one large fat droplet, but in muscle fibre they split into tiny fat droplets

\-they are composed mostly of triglycerides

explain the technique using IMCL to determine fibre type

\-this technique is called “Oil red O”, so adds a fat soluble substance to tissue which then loves to be taken up by fat and it makes this red colour

* basically when you add it to tissue, fat cells will take it up and produce this red colour

\-type 1 muscle love fat (IMCL) bc it is their primary energy source and they store a lot of fat, so they will be more red when the substance is added

\-the SS mito love fat, and these are around the sarcolemma, so will usually have a red O stain right underneath the sarcolemma like a ring around the cell (with some staining within the cell too obviously

\-there is obvi a bit of red in type 2a and 2x but most of IMCL is found in type 1

how is fat placed differently in cell in aerobic trained athlete vs untrained

\-athletes actually have more fat (IMCL) in muscle, similar to T2D, but it is good for health bc they harness this for energy during exercise

\-in T2D this extra fat affects insulin sensitivity, but not in trained bc they are using it up in exercise

\-in aerobic trained, fat is placed right besidre mito in SS area to be more efficient

\-in diabetes, fat is dispered in muscle

what is a western blot? what is the furst step

\-the SDS page is the first stage of the western blot, which looks at the quantity of protein in a muscle

\-first is to take part of muscle from biopsy, and put in blender w solution that has SDS in it

* this breaks up DNA and bonds that hold protein together, so basically seperating the protein from one another; makes blue solution

next step of SDS page: gel electrophoresis

\-add the solution to gel electrophoresis, and send electrical shock through it

* also add stuff that enhances charges, so proteins move away from the charge to the other end

\-the gel is like a web, so has small holes in it

\-if we place protein in lane of gel, the different proteins will move through the gel

\-as proteins go through the web, bigger proteins take longer to get through vs small ones

\-also add a blue protein staining, so it sticks to proteins so that you can see them on the gel

what is the use of the protein ladder in SDS page?

\-the protein ladder is a control sample of artificially designed proteins w known molecular size/weight, so they are used to estimate the experimental protein’s size (normaly dyed red)

\-so all experimental and control proteins run down ladder from small at bottom to big at top, then compare the standard weights (in KDa) to the different lanes

\-the amount of darkness of the stain and thickness also shows you how muc of that relative protein there is

what is SDS page usually used for?

\-can compare in one muscle, so for exmaple differeneces from pre and post training

or compare protein composition from different muscle (ex skeletal vs cardiac muscle vs smooth muscle)

how could we incorporate antibodies into SDS page?

\-add an antibody instead of theblue staining, so will only bind to 1 protein

\-this means we would only see the one band of that one protein, and others wouldnt be visible

\-this is called **a western blot,** so using an antibody specific to a certain protein, which then allows for quantification of protein concentration in each sample

how does SDS page and western blot look like in rodents?

\-remember rodents have 4 types of fibres characteristics

\-in rodent studies, you can see the spread in a lot more tissues bc they are sacrificed, then you can figure out fibre type %

\-in this, you need to use an antibody that binds to the same sequence of all the dif myosin ATPAses, so its consistent and binds to all

\-then seperate proteins based on weight

\-smallest weight is type 1 fibre

\-can also see how postural muscle like soleus has more type 1 (just an example)

\-in rodent you can also only take a biopsy froma certain section of the muscle where mostly 1 fibre type is, or you can take it mixed where it has all types

\-how does SDS page and western blot look in humans from pre to post training?

\-this is for aerobic style training

\-type 2b is largest and heaviest, and then type 1 is smalles and lightest (smallest ATPase)

\-with aerobic training, there is transition of type 2b moving towards 2a

\-may change a bit into type 1, but not as big of a change

how would we normally determine relationship between the myosin type and the contractile properties

\-we combine the reserach on the structure of the muscle (ex which muscle has more type 1 or type 2 etc) with the functional experiments, so looking at ex vivo force measurements on a single fibre

what actually changes in skeletal muscle with training?

\-we dont really know if its fibre type? or fibre CSA?

\-we do know that in disease and age there is negative adaptations, so maybe exercise can help counter this to help functional capacity

\-maybe our body takes advantage of the hybrid fibres, so they are the ones that transition in adaptations

\-hard to make these determinations bc there is not a lot of data in humans

why is it hard to make well-designed human training study on muscle composition?

\-biopsies are uncomfortable and kind of invasive

\-also the length of study required to get the muscle adapations exceeds the patience of most potential subjects

\-there is also variability within the subjects, bc humans have dif genetics and enviro

\-so we mostly rely on rodent studies bc there is shorter time commitment and also less variability

how might muscular changes change aerobic capacity

\-improvements to the muscle will affect our ability to extract oxygen from blood

\-ex more vessels in type 1 fibres will enhance this ability

\-we also get enhancement of mitochondria in muscle

\-DRAW THIS!

what is the metabolic adaptation from resistance training to mitochondria, oxidative enzymes, and myoglobin

\-overall, there is greater oxidative capacity

\-muscle will have larger and more numerous mitochondria especially in type 1 , and type 2a will ehnagce a bit too

* increase IMF mito and increase in SS mito

\-double in size of oxidative enzymes, so this will change the speed it takes to catalyze the reaction (double activity)

\-also increase in myoglobin which is an oxygen carrying molecyle that gets into mitochondria

what is the metabolic adaptation from resistance training in terms of fat oxidation?

\-overall, you enhance ability to oxidize fat

0at 50% VO2max, CHO is at certain value and as we get more intense, we oxidize more CHO

\-in training, there is shift to right, so at a given exercise intensity, the curve kind of dips down to oxidize more fat at the same given intensity

\-this results in glycogen sparing, so you would run out of glycogen stores later so can do exercise for longer

* this is all because you can oxidize fat quciker so you preferentially do this

what is the metabolic adaptation from resistance training to respiratory capacity, blood flow, catecholamine sensitivity

\-enhanced respiratory capacity

\-increased blood flow. in trainied muscle

* there is enhanced vessel capacity around muscle, so adipose stores can be mobilized and delivered to muscle

\-there is increases sensitivity of adipocytes to catecholamines, so release more lipids into blood to be mobilized to muscle (since catecholamine stimulate breakdown of fat)

**-these adaptations all increase the ability to mobilize, deliver, and oxidize fat**

what are the different types of fat found in athletes vs T2D

\-so we know that both pf these populations have elevated fat in their muscles

\-triacylglycerols are more favourable to be stores bc they are readily converted to energy source, and doesnt clog up membrane, stored right next to mito

\-diacylglyceriols is part of signalling pathway in membrane, so it messes up membrane so glut receptors cant get to membrane and take in glucose

* this is found more in disease

what is the central dogma? how can this be applied to why we see training adaptations

\-there is much that we dont understand on how we actually get enhancements to muscle, but cell signalling must be very involved

\-central dogma describes how we go from change in RNA level (transcription) to change in # proteins, then this leads to function changes in exercise performance

\-this all comes from some sort of stimulus (pressure overload or volume overload), so stimulis for msucle will be dif depending on what kind of training we do

what is the stimulus for muscle adaptation in aerobic exercise? what is the stimulus for muscle in resistance exercise?

\-in aerobic, there is strain on metabolism that causes these changes

* ex challenge glycogen stores on a repetitive basis, this is the stimulus to help glycogen metabolism progress so that you deplete it less

\-in strength training, the stimulus is the contractile function, so kinda damage muscle or strain it to a degree to where it wants to become stronger

**-these stimuli change the homeostasis of the cell, this then ultimately leads to transcription of genese and dif levels of proteins**

explain the timeline of the changes in RNA then protein expression to make an adaptation

\-in this case, we have series of days of exercise, then weeks to months

\-in acute exercise right afterwards (within hour), the RNA levels of SDH would be elevated (if untrained = bigger response) and these stay elevated for 3-4 hours

\-there is no change in protein yet, but then RNA is gone and next day we see increase in actual SDH protein

\-then if we exercise again the next day, there is another elevation in SDH RNA levels and then subsequent elevation of the protein the day after

\-every time we exercise, the elevation of SDH RNA levels is a bit less bc the stress is less bc we have more SDH protein to help w exercise

\-so slowly losing this transcription of the gene of interest, bc thsi protein is elevating over time and in weeks and months you see the change in adaptation (change in performance) occur

**-note: there is lots of time between RNA levels and actualy protein expression where we dont know the whole signalling mechanism that happens**

how do we use rodents to check the time points of adaptations? what is the limitations to this?

\-so this is when we are trying to figure out the specific process of how we get to changes in RNA to protein expression to performance changes, and the signalling that goes on throughout this

\-need to pick time to check adaptations since you need to sacrifice the rodents

* so cant monitor at a lot of checkpoints over a long coyrse of time, bc this woul require a lot of rats in the study since you need to sacrfice each one at a specific time

\-so will still have large periods of time when there is gaps in data and we dont know for sure how these changes go from gene level to protein, to performance changes

what is major protein linked to adaptations in aerobic exercise? in resistance exercise?

\-for aerobic exercise, PGC1 alpha is a protein linked to almost all of these processes in aerobic exercise

* so involved in most of the transcription pathways/prpcesses that are associated w alterations in skeletal muscle (ex transcription of mitochondiral genes)

\-for resistance training, the major protein involved in adaptations (building of muscle) in mTOR

* alters protein synthesis and may shut down protein degradation
* mTOR plays even bigger role in more strength training too

\-explain study that looked at muscle adaptation in aerobic training program in old vs young patients

\-did 60% VO2max training program in young and old participants, then did muscle biopsy


1. found size of type 1 fibres increased 10-20%, which is pretty significant sice you use these during the whole period of exercise, so overall contractile ability of muscle will get better and stronger
2. there was also a shift in muscle fibre from type 2x to type 2a, which is pretty common adaptation in aerobic execrise
3. increase in aerobic potential and mito in all fibres; so enhances ability to carry oxygen etc, even seen in type 2x!

in previous study, what were the changes in the actually hypertrophy, anabolic stimulus, and anabolic sensitivity between young and old?

\-the absolite change in size of muscle was the same between young and old

* shows there is benefit of aerobic exercise on aerobic capacity, but also in muscle size increase

\-remember the young and old were working at different absolute intensities, bc it was % VO2max => shows they still had the same adaptations in old even if absolute stimulus was lower

\-this is what anabolic stimulus is, so young had higher anabolic stimulus bc they were exercising at higher rate

\-but since they got the same adaptations in young vs old, the old have a higher anabolic sensitivity (so sensitivity to adaptation was better since they got the same cgange in hypertrophy w a lower stimulus)

what is the most important/ underlying factor being generating muscle mass>

\-so to generate bigger muscle size or an increase in muscle size all comes down to a change in protein balance

\-there are many factors that change transcription of genese and mito content, but all of these factors ultimately lead to changes in muscle protein balance

* so transcribe more than you break down

\-so a positive balance is good bc you have more transcription and more proteins in muscle, whichleads to muscle growth no matter if you are aged or young

example: how does creatine have its effect?

\-creatine is taken up by muscle and changes the msucle cell’s osmolarity, and to balance this, the volume of the cell gets bigger, so balance charges by adding more water to cell

\-when you add more cell volume, then we enhance protein synthesis to fill up empty space with contractile units and SERCA, this then enhances function of muscle

\-also slowing down process of protein degradation

how is creatine’s mechanism similar to how satellite cells work?

\-satellite cells are stem cells and they can be used to enhance muscle growth

\-they donate a nucleus to neighbouring muscle

\-a nucleus in cell demands a certain volume around it, so adding a nucleus will cause cell to get bigger and this empty space will be filled with extra protein

\-speeds up process of synthesis and slows down degradation

explain process of study comparing area of fibres in untrained and different sports (Golnick 1972)

\-this study tooked muscle biopsies of athletes of dif sports(ex long distance vs short distance runners) and untrained individuals

\-they counted the muscle fibres and looked at many sections bc the muscle is interdigited, and did this for whole muscle basically, so very robust

\-looked at area of ST vs FT (didnt differentiate type of FT) and then % ST

what were results of the Golnick 1972 study?

\-there was not a big dif in the area of the ST fibres between untrained and distance runner

\-but they DID see a sig increase in % ST fibres in marathon runner (from 34% to 75%)

\-could this genetic difference between the two? so did the distance runners become distance runners bc they were predisposed? or was there a transition and adaptation that occurred with muscle?

in Golnick 1972: what was the relationship between those that increase in type 1 fibre CSA and those that increase their type 1 fibre %?

\-the study took points for all different athletes, and plotted them to see if there was a correlation between these two: does type 1 fibre CSA and % type 1 fibre increase at same time? so tow different types of training responses

\-two pockets were formed: lower pocket is more untrained (aerobically) and then higher pocket was aerobically trained

\-there was a negative correlation in both pockets: so as fibre get bigger, the % of type 1 fibres goes down

* was different in dif sports, ex a cyclist had larger type 1 firbes but % of type 1 is lower compare to a swimmer that has opposite reaction

\-basically shows that training does not lead to specific adaptations, so some increase in size of ST fibres, and some increase in % of ST Fibres (maybe genetic effect on how you individual adapt?)

**-in general, there is a shifting of either size OR % in training, bc all trained have more of one of these factors and is higher than the pool of untrained**

* as whole, we cant predict which one will increase more in trained

explain the concept of relative CSA, so how this can increase without the actual fibres getting bigger?

\-in the Gollnick 1972 study, the distance runners had greater type 1 fibre % and relative type 1 fibre area, but NOT larger fibres

\-so fibres are not getting bigger, but contribution of type 1 fibres as a whole gets bigger?

\-so dont change in size, but if there are more type 1 fibres, then the relatice fibre area increases bc there is a higher % of the area of the whole muscle that is made out of type 1

\-this effect could be because they genetically have a higher % of type 1 fibres, BUT it has been shown in animal studies that chronic stimulation of a motor nerve results in shift towards more type 1 fibres (but stimulus needs to be frequenct for a long time)

explain premise of bodybuilding study and what they were looking at

\-compared bodybuilders and powerlifters to untrained individuals to see if there was differences in fibre size(looked at area) and % fast twitch

\-like golnick study, they counted the fibres and found area that way, so very robust

\-when comparing trained to untrained, there is a difference in the FT area, so in general resistance trained have a greater FT area

\-when looking at % ST fibres between trained and untrained, there is lower % is reistsnace training a bit, so suggests that they have more FT fibres if the % ST is decreasing

Back to Golnick study, what was the relationship when they compares type 2 firbe CSA and type 2 fibre %?

\-again, there were two pockest of data: the untrained aerobically (could include untrained in general and the resistance) and then endurance trained

\-endurance tend to have small CSA and lower % type 2 fibres (which makes sense)

\-in untrained/resistance, there have higher type 2 fibres % and higher CSA

* there is correlation here, so as you move from untrained to weightlifeter, the CSA increases and could have slight change in type 2%
* overall heavy lifters had the largest type 2 fibres, and slight indication that type 2 % can increase w training

\-whereas in endurance, there is very little corelation, so no real training effect (bc not really stressing type 2, so doesnt change)

what is the interpretation of data on past study? basically what is the training effect in resistance training?

\-weightlifters aim to induce muscle hypertrophy (getting bigger muscles)

\-the data here suggests that this was acheived through gains in type 2 fibre CSA, so fibres got bigger

\-there was minor gain in the type 2 fibre % (so actually generation or transition of fibres to type2)

* not clear if this change is significant though

how does the mode of training change the relative fibre area of type 1 muscle?

\-this graph is looking at relative type 1 CSA, so an increase in this could be from more fibres OR each of the type 1 fibres is getting bigger (so this basically ignores how it gets to this bigger CSA, could be one or other or both)


1. weightlifters have the lowest relative CSA of type 1 (bc area is more type 2), and also lower type 1 %
2. then at the higher section of type 1 relative CSA, there are swimmers and more aerobically trained
3. in the middle of this, there is untrained => shows you can adapt in either direction depending on what training you do

\-if the graph was looking at type 2 relatice CSA and %, then this graph would be flipped, so endurance would be on bottom and diagonal and resistance would be on top

Give the summary of training effects

\-the past data indicate that training can induce changes in FT% or CSA (or some combination of the two)


1. **an endurance athlete gains relative type 1 fibres area** - functionally, does it matter if it happens via FT% or CSA (or some combo?)
2. **resistance training appears to result in greater relatice type 2 fibre area** - mostly as a result of increase type 2 CSA - unclear if there is also changes in Type 2 %

\-have to remember that there is some difference in people bc of genetics, so some may replicate fibres to increase %, and some may just grow the already existing

* also training methods will differ the adaptations (ex resistance vs powerlifting) and just in general variability between people

explain the evidence of fibre type shifting from type 2x to 2a

\-extra note: there is some circumstances where there is changes from type 2 to type 1, but depends on person and less research on this

\-there is more consistency with evidence of fibre shifting within the type 2 type, so shifting from Type 2b to 2a

\-western blot data shows that there is shift from 2b to 2a from pre and post training, but little change in type 1

\-this was in training that is more endurance resistance training (low weight high rep)

* **power lifters would want to generate most power and so train 2x fibres, but resistance training without any explosice movement may result in type 2x to type 2a shift**

\-study also did histology count of fibres, we see there is drop in % of type 2b and increase in 2a (no change like this in untrained)