Exam 4 Lectures Flashcards
List the three layers of connective tissue surrounding the muscles
Endomysium, perimysium and the epimysium
What does the endomysium surround
It surrounds a single muscle fiber as a thin layer of colalgen
What is the perimysium
It is a layer of connective tissue that serves as the scaffolding for nerves and blood vessels to go through and bundles each muscle fiber into a fascicle
What is the epimysium
The outermost and thickest layer of connective tissue that surrounds all of the muscle fascicles and transmits the force from the contraction to the bone
What is the sarcolema
The membrane of a muscle cell
What is a myofibril
The contractile portion of the muscle
What is a sarcomere
It is the part of the myofibril that contracts
List the cell types found in whole muscle (10)
Myocytes Satellite cells smooth muscle cells endothelial cells neurons schwann cells hemopoietic stem cells fibroblasts adipocytes immune cells
What tissues are important for force transduction
connective tissues
What and where is a satellite cell
It is a precursor myocyte that is between the basolamina and the sarcolemma
What are the types of mitochondria found in muscle cells
Subsarcolemmal mitochondria - beneath sarcolemma and responsible for Energy for transport across the membrane to the nueromuscular junction
Intramyofibrular (IMF) mitochondria - E for work of the muscle
What is the sarcoplasmic reticulum and what is its function
It is the ER of muscle cells surrounding the myofibrils that stores Ca++
What are the primary proteins of the sarcolemma
Actin and myosin
What is the A band
It is the band that spans from myosin to myosin
What is the I band
The end of the A band to the A band of the next sarcolemma
What is the Z disk
It is the length of the sarcomere that is just actin
What is the M line
The attachment protein that joins the myosins together
What is the light band
It is the I band and is actin
What is the dark band
It is the A band and is myosin
How many actin molecules is myosin in contact with
6 - it has a hexagonal shape in reality
What is the sliding filament theory and who discovered it
Huxley discovered that the length of actin and myosin does not change, but they actually slide past one another to shorten the H zone and I band during contraction
Muscle contraction (FIX THIS CARD)
1) Excitation of membrane, depolarization sarcolemma and sarcoplasmic reticulum to activate ryanodine receptors to release Ca++
2) Ca++ binds troponin to expose myosin-binding sites on the actin filaments
3) Myosin heads bind to actin, ADP is released
4) In the power stroke, the myosin head changes conformation, the filaments slide past one another
5) ATP binds to myosin, causing it to release actin
6) ATP is hydrolyzed and the myosin head returns to its resting conformation
7 ) If Ca++ is returned to the sarcoplasmic reticulum, the muscle releases
8) If Ca++ remains available, the cycle repeats and muscles contraction continues
What is the muscle biopsy technique
It is a way of examining a muscle by inserting a needle into the belly of a muscle to extract a chunk of muscle tissue. This is then frozen, sliced, stained, and examined under the microscope.
What are the two possible ways to classify muscle tissue?
1) Activity of the myosin ATPase enzyme - ST, FOG, FG
2) Myosin heavy chain - Type I, Type IIA, and Type IIB/X
What is type I equivalent to
Slow oxidative muscle fibers
What is Type IIA equivalent to
Fast oxidative glycolytic muscle fibers
What is Type IIX/B equivalent to
Fast glycolytic muscle fibers
Where does our fiber type come from?
Mainly genetics but also training
What determines muscle fiber type?
Fiber type is determined by neural activation
What is the cross innervation study and what did it show?
Taking a type I motor unit that innervates Type I fibers and changing it to innervate type IIA fibers instead and vise versa with the Type IIA motor unit. Once crossed, the muscle fibers adapted and changed based on what the neural input was.
What effect can increased endurance training have on muscle fiber type?
Increased endurance training can lead to IIX to IIA.
What is the influence of aging on muscle fiber type?
With age, we decrease our amount of FT to ST due to loss of FT fivers
What levels of the following do we see in Type I fibers: Size Mitochondrial density Capillary density Twitch speed relax time fatigability glycogen lipids glycolytic enzymes oxidative enzymes
Size: small Mitochondrial density: many Capillary density: high Twitch speed: slow relax time: slow fatigability: low glycogen: low lipids: high glycolytic enzymes: low oxidative enzymes: high
What levels of the following do we see in Type IIA fibers: Size Mitochondrial density Capillary density Twitch speed relax time fatigability glycogen lipids glycolytic enzymes oxidative enzymes
Size: intermediate Mitochondrial density: intermediate Capillary density: intermediate Twitch speed: fast relax time: fast fatigability: intermediate glycogen: intermediate lipids: intermediate glycolytic enzymes: intermediate oxidative enzymes: intermediate
What levels of the following do we see in Type IIX fibers: Size Mitochondrial density Capillary density Twitch speed relax time fatigability glycogen lipids glycolytic enzymes oxidative enzymes
Size: large Mitochondrial density: few Capillary density: low Twitch speed: fast relax time: fast fatigability: fast glycogen: high lipids: low glycolytic enzymes: high oxidative enzymes: low
What effect was seen with muscle stimulation of low amplitude and long duration
Shift Ca++ in the Intracellular compartment and increase expression of calcirieurin, activates NFat to increase Type I and Type IIA expression
What effect is seen by giving cyclosporin in the muscles
Blocks activity of NFat so that it is unable to bind, leading to increased Type IIB
What effect was seen with muscle stimulation of high amplitude and short duration
Increased Type IIB fibers
What are the four stages of contractions
1) Cross-bridge detachment (ATP binding)
2) ATP hydrolysis (recocks myosin head)
2b) Weak actin myosin attachment
3) Actin-myosin binding (Ca++ induced actin myosin binding)
4) Power stroke
What is the state of actin and myosin in a concentric contraction?
They are completely overlapped
What is the state of actin and myosin in an eccentric contraction?
They are not overlapped
Define concentric
Muscle shortening
Define static
Unchanged muscle length
Define eccentric
Muscle lengthening
What happens with the cross bridge formation in isometric contractions?
It forms at the same place
What happens with the cross bridge formation in concentric contraction?
Each time a power stroke occurs and it binds, the crossbridge forms with more overlap.
Ex) binding site 1 to 2 to 3
What happens with the cross bridge formation in eccentric contraction?
Each time a power stroke occurs and it binds, the crossbridge forms with less overlap so the powerstroke and formation are in opposite directions.
Ex) binding site 3 to 2 to 1
What are some factors that influence force?
Muscle Type (FT or ST)
Fatigue
Muscle Length
Speed of contraction
What is the ramp-like recruitment of fibers
I -> IIA -> IIX
As you increase force, you increase the type of fibers utilized.
How does fatigue play a role in Force
Different recruitment patterns occur for different athelets, but in general Type IIX fatigue at a higher rate than Type I.
Also, different things ie swim vs jog, utilize different motor units within the muscle which is why there is little overlap in training
How does muscle length play a role in Force
At the longest and shortest sarcomere length, there is not enough force being produced. The optimal overlap occurs where the maximum amount of cross bridges can be formed.
Whole muscle tension vs muscle length
Whole muscle tension is a combination of the active tension from the sarcomere (bell shaped curve) and the passive tension that is developed from muscle stretch (increases at a higher length) to form a combination curve
Velocity and force of contraction: eccentric
A faster movement generates more force due to the increased passive tension
Velocity and force of contraction: concentric
A faster movement leads to a lower amount of tension
Non-weight bearing muscle size in males vs females and reason why.
Males have much larger muscle size due to influence of testosterone
Muscle size and age (child to adolescent)
Muscle size increases proportional to increase in body size, with a sharper rise in males due to the increased testosterone level.
Muscle size and age (older)
A decrease in muscle size and amount of fibers begins around the age of 40.
What is the pathway of central activation of muscles that are also possible areas of fatigue
Intention to move Activity of motor cortex, cerebellum Motor cortex firing Descending pathway activation Motor neuron excitation
What is the pathway of peripheral activation of muscles that are also possible areas of fatigue
NMJ activity Excitation of sarcolemma T-tubules/SR excitation Ca++ release Actin myosin crossbridge
What is the more common cause of fatigue in an untrained individual? Trained?
Central untrained (psychological) Peripheral trained
What are three things that can lead to fatigue in a trained individual?
Low Ca++ availability
Low ATP
Build up of Pi
Is glycolysis a cause of fatigue?
Not on its own - high rates of glycolysis and lactate accumulation are associated with fatigue
Where is ATP needed in the muscle?
ATP needs to bind the myosin head for a power stroke to occur
What happens with high rates of ATP hydrolysis
Build of of Pi which eventually leads to decreased contractions and more potential for injury because it will bind the Ca++ in the cell, diminishing the reuptake
What is DOMS
Delayed onset muscle soreness is the muscle soreness that occurs 24-48 hours after resistance training
What is the primary cause of DOMS
Heavy eccentric contractions is the primary cause
What is the mechanism of damage in DOMS
Structural damage to lead to inflamm and increased interleukins and then DOMS:
Myosin and actin filaments
SR
Z line streaming
What is strength
Maximum force a muscle or group can generate
What is power
Product of strength and speed of movement
What is muscular endurance
The capacity to sustain repeated muscle action
Equation for power
weight x distance x time
What are the factors of strength, power, and endurance
Genetics : fiber type
Physical activity (type of training)
Nutritional status (diet, caloric, protein)
NS activation
Environmental
Endocrine influences (gender differences, growth factor, GH, testosterone)
What is transient muscle hypertrophy
It is muscular hypertrophy from an acute exercise bout due to an increase in pressure in the tissue, interstitial fluid accumulation that causes muscles to get larger
Define fiber hypertrophy
an increase in the muscle fiber size
Define fiber hyperplasia
an increase in muscle fiber numbers
Define chronic muscle hypertrophy
An increase in muscle size due to hyperplasia or hypertrophy after a long amount of time
What is a key part of fiber hypertrophy
Higher intensity training
What occurs in muscle fiber hyperplasia
the fibers will split in half with intense weight training - in avian models, NOT in humans
What is the primary form of chronic muscle hypertrophy in humans
It is the increase in the muscle fiber SIZE - typically in Type IIX fibers with resistance training
What is the early gain in strength due to with resistance training
Neural activation
What are the neural changes that occur with resistance training
Recruitment pattern
Contraction of autogenic inhibitors that allow for greater force production
Reduce coactivation of agonist and antagonist muscles
What is Constant resistance training
An isotonic form of training where the load and resistance does not change through the ROM and is limited by the weakest point
What are examples of constant resistance
Free weights, most machines
What is variable resistance training
An isotonic form of training where the resistance is changed through the ROM so that the muscle can be maximally trained at all points
What are examples of variable resistance
Resistance bands, cyrex machines
What is constant velocity resistance training
An isokinetic form of training where the speed of movement is constant and the machine maintains the force produced through variable resistance
What is isometric resistance training
An isometric form of training where the muscle length is fixed and you simply hold the movement for a period of time
What are examples of isometric training
Holding a squat, holding a wall press
What kinds of resistance training show greater gains?
Isotonic and isokinetic are greater than isometric
How do you maximize strength training?
Low reps, high resistance 1RM-6RM
How do you maximize endurance
Many reps with low resistance
How do you maximize power
Several sets of few reps and moderate resistance - Emphasis on SPEED
How do you maximize size
More than 3 sets of 6RM to 12RM loads - short rest periods
How many sets for beginners? is it the same as int or advanced?
1 set is the same as 2-3 for beginners. Otherwise 2-3 sets
What is periodization
Varying phases of training to have variable amounts of reps and intensity to focus on different changes in strength and power
What are the stages of periodization
I: hypertrophy II: strength III: power IV: Peaking Active rest
What are key factors in strength training
Overload
Progression
Specificity
What are the effects of muscular inactivity
Muscular atrophy
Decrease in muscle protein synthesis
Rapid strength loss (Type II fivers larger decrease)
What are the 6 aspects of specificity ACSM
1) muscle actions involved
2) speed of movement
3) ROM
4) muscle groups involved
5) Energy system used
6) Intensity and Volume
Action: recommendation ACSM
greater force is produced with an eccentric contraction, but a combo of all three should be utilized
Loading: recommendation ACSM
60-70% RM for 8-12 reps
Volume: recommendation ACSM
1-3 sets/exercise
Type: recommendation ACSM
unilateral and bilateral single and multiple joint exercise included with an emphasis on multiple joint exercise to maximize strength
Machine type: recommendation ACSM
Utilize both machines and free weights - machines stabilize joints better but free weights have more neural input
Order of exercise: recommendation ACSM
Large muscle groups before small muscle groups (weak). Can do whole body, upper/lower, or muscle groups.
Rest periods: recommendation ACSM
At least 2-3 min heavy, 1-2 light
Velocity: recommendation ACSM
Untrained: slow and moderate
Trained: slow and fast
Frequency: recommendation ACSM
novice: 2-3 d/wk
advanced: up to 4-5 d/wk
how to get muscle hypertrophy: recommendation ACSM
70-85% RM for 8-12 reps, 1-3 sets
2-3 d/wk novice, 4 int w/upper lower split
gains in power: recommendation ACSM
vary light to moderate (30-60 % RM) 1- 3 sets, 2-3 d/wk
gains in endurance: recommendation ACSM
low loads, 10-15 reps or 10-25 reps
Gains in performance: recommendation ACSM
4-6 d/wk, combo of heavy and light
Heavy and ballistic are key
What do you want to have before increasing power?
Joint stability and strength and muscle strength
