neuromuscular system and exercise Flashcards
1
Q
what is excitation-contraction coupling?
A
- this is the events that lead to an action potential occurring in the sarcolemma, that allows the myofilamnent to slide, resulting in contraction.
2
Q
what are the 3 phases of excitation-contraction coupling?
A
- spread of depolarization
- binding of calcium to troponin.
- generation of force (cross-bridge cycling)
3
Q
discribe cross-bridge cycling?
A
- cyclic events that are necessary for the generation of force or tension within the myosin head during muscle contraction.
4
Q
the nervous system divides into what 2 systems?
A
- somatic nervous system
- autonomic nervous system.
5
Q
what is the somatic and autonomic nervous system responsible for?
A
SOMATIC
- contraction of muscle fibres through the efferent neurons
- controles skeletal muscle.
AUTONOMIC
- controls heart, glands, hallow organs, and maintaining homeostasis.
- controls visceral and smooth muscle
6
Q
what is the sliding filament theory?
A
- this is the force of how muscle contraction generates force, which occurs during concentric force.
7
Q
what are the 3 principle of sliding filament theory?
A
- the force of contraction is generated by the actin filament (thin) sliding over the myosin filament (thick), which exposes the binding site for calcium to bind, allowing for contraction. The force is produced because the actin filament decreases the space between adjacent actin molecules which shortens the muscle fibre and producing contraction.
- length of thick and thin filaments do not change during contraction.
- length of sarcomere decrease as the actin filaments slide over the myosin filaments and pull the z disk towards the center of the sarcomere.
8
Q
name the 4 measurements of studying muscle?
A
- electromyograph
- muscle biopsy
- imagining and spectroscopic techniques
- isokinetic dynamometry & force transducers
9
Q
what is a electromyograph (EMG)?
A
- muscle action potentials that allow for muscle contraction.
- force of static contraction X tension of consistent-velocity contraction.
- this allows for the use of muscle recruitment patterns.
- voltage with the amount of force.
10
Q
what is a muscle biopsy?
A
- muscle is removed from someone in which it is able to be analyzed what type of muscle fibre types are present in a certain muscle.
11
Q
what is imagining and spectroscopic techniques?
A
- CT, MRI, ultra sound.
- this can evaluate how much fat and how dense a muscle is in a certain area.
12
Q
what is isokinetic dynamometry (ID) and force transducers? (FT)
A
ID
- velocity of movement of a limb throughout contraction that is hooked up to a computer.
FT
- measures static endurance and stregrenth, and is based on how long the subject can hold that position for.
13
Q
overview of thick filaments (myosin)?
A
- numerous myosin protein strands
- filament heads that protrude outwards.
- myosin head attaches to active site on the actin filament (thin)
- the myosin head contains mATPase to breakdown ATP and energy to be released.
14
Q
what are 3 thin filaments?
A
- actin
- 2 protein strands twisted around each other. - tropomyosin
- thin strand laying in the actin groove that COVERS the active site. - troponin
- attached to actin and tropomyosin strands: has a strong want for Ca2+.
15
Q
cytoskeletal structural protein?
A
- M-band
- located in middle of thick filament (myosin)
- contains creatine kinase - titan
- connects myosin filaments to z-disks.
- stabilize myosin in the middle of sarcomere - z-disk
- thin filament attchment.
- contains several cytoskeletal proteins
16
Q
what are 2 ways that muscle fibers can be innervated?
A
- a1 which innovates motor neurons of fast twitch fibers (FOG, FG)
- a2 motor neurons which innovate slow twitch fibers (SO)
17
Q
what is a motor unit?
A
- the anterior muscular neuron + all the fibres it innervates (functional unit of movement)
18
Q
what is cross innervation?
A
- this occurs under abnormal conditions
- this is where the alpha neuromuscular units switch. so a1 is now responsible for slow twitch fibres and a2 is now responsible for fast twitch fibres.
19
Q
what is the innervation ratio?
A
- the number of muscle fibres innervated by one motor neuron.
20
Q
name the 3 motor unit classifications?
A
- twitch properiteis
- slow and fast twitch - contractile proteins
- slow or fast fatigue resistance, and fast fatiguable. - contractile and metabolic properties.
- slow oxidative (SO)
- fast oxidative glycolytic (FOG)
- fast glycolytic (FG)
21
Q
what are the force productions of the different fibers?
FOG, FG, SO
(think fatigue, resistance, duration)
A
FOG
- lots of force, high fatigue.
- these fibers can reach peak force very quickly but they also fatigue just as quickly. they have a sort duration. (type 1 fibers.)
FG
- have some force, some fatigue
- these fibers have a longer duration than our FOG fibers but they still to fatigue. (type IIa fibers, intermediate)
SO
- these produce little force but have long duration and are fatigue resistance.
22
Q
name the 2 ways that muscle fibers can be classified?
A
- myosin heavy chain
- myosin light chain
23
Q
how does motor unit recruitment happen with the different neuromuscular and fibre types?
A
- when MU is recruiting it is the small motor neurons that fire first which will then fire the large motor neurons. these neuron fire muscle faster and have a higher innervation rate.
- during the recruitment process the slow oxidative fibers are the first to fire as they use the oxygen up that they need to fire, they then switch to FOG fibers which can be aerobic or anaerobic fibers, then they switch to fast glycolytic fibers which are anaerobic fibers that require high force. these fibers will fatigue very quickly.
every fibre type is used, we have to start at the “bottom in order to get to the top”
24
Q
how can S.O. fibres fatigue during workouts?
A
- drop sets are one way that we can fatigue our slow oxidative fibres.
- starting with our most power exercises at the start and then moving into our small load and high reps will also fatigue our slow oxidative fibres.
25
name the 2 neural activation, in force development in muscle?
1. rate coding
- the frequency of stimulation that allows for the rate of contraction.
- frequency of motor units firing.
2. numbering coding
- the number of motor units that are activated.
26
what are the factors that is needed for force development?
1. neural activation
2. mechanical factors
- length-tension relationship
- force- velocity relationship.
- power-velocity relationship.
- elasticity-force relationship.
27
how does length-tension relationship work in mechanical factors?
- this is dependent on the length of the sarcomere, which then depends on how much tension is used during muscle contraction. as we get more overlap between length of sarcomere and tension we get a increase in cross bridge formation.
28
how does force-velocityrelationship work in mechanical factors?
- velocity (speed) ay which shortening of the muscle occurs.
- with high force, low velocity will happen, and vis versa.
- light load fast contraction.
29
how does power-velocity relationship with mechanical force?
- this is a combination of speed and force.
- the fibres that are used will be fast glycolytic and fast oxidative glycolytic.
- the more FT fibres we can recruit the more power and cross bridges that can be created.
30
why would there be a increase FT which lead to increase force & power? (5)
1. large muscle fibres, which means we get more actin and myosin)
2. faster motor neuron conduction velocites
3. greater/faster Ca2+ release
4. faster mATPase activity & cross ridges.
5. greater reliance on the ATP/PCr & glycolytic systems, which are more power based and therefore are also anaerobic.
31
how does elasticity-force relationship with mechanical force?
- this is stretch shortening cycle which leads to more powerful contractions which and improved efficiency.
- when we are in a lengthened state, it is our central nervous system that sends a message for shortening contraction to occur to prevent injury.
32
what is CSA/ architectural design?
- this is how we use damage muscles, when muscles are damages they change their angle slightly as they repair which then increase power.
33
what factors influence muscle tension?
- muscle length or joint angle
- velocity of muscle action
- elasticity & SSC
- CSA & pennation arrangement
- the number and size of motor units
- muscle fiber properities.
- neural factors (rate & numbering coding)
protective reflexes
+ stretch muscle spinals
+ tension (Golgi tendon organs)
34
what would the neuromuscular adaptations be on muscle function during resistance training?
- increase strength
- increase endurance
- increase power
35
what would the neuromuscular adaptations be on muscle size and structure during resistance training?
MUSCLE FIBRES
- increase CSA
- increase muscle fibre CSA
- increase myofibril protein
- convert FOG to FG
CONNECTIVE TISSUES
- increase collagen synthesis
- = connective tissue to sk muscle
- increase collagen stiffness
36
what training adaptation would someone who is new to training notice, due to neural adaptation?
1. increase in efficient neural recruitment pattern
2. increase in motor neuron excitability
3. increase in CNS activation
4. improved motor unit synchronization and firing rates
5. lowering of neural inhibition reflexes
6. inhibition of GTO reflex (decreased senitivite)
37
how does muscle increase in size?
- hypertrophy or hyperplasia, which is a increase in the amount of muscle fibres.
38
what is the most likely result as to why MF enlarge in width and length?
- stretch mediate tension
- eccentric training
- strength training to long muscle lengths (ROM)
39
what allows for some MU to be converted?
- shifting of the contractile properties & metabolic profiles.
- there can be a co-expression where FT can be expressed as fast MHC and slow MHC.
40
what is disuse in neuromuscular?
- this is when the muscle is immobilized and there is a decrease in CSA of all fibres, and there is a decrease in muscle oxidative capacity which creates general weakness. (muscle atrophy)
