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KINESIOL 2C03 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

4 mechanisms of SSC Potentiation. Which ones are the most important?

A

80%

  • higher initial force
  • taken up SEC
  • storage of elastic energy

20%
-reflex potentiation

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2
Q

T or F: 0 displacement is possible if a muscle is attached to a tendon

A

T - muscle shortens, tendons stretch - overall 0 displacement

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3
Q

Give 2 examples of reflex potentiation. So how does it add to contraction force?

A

falling asleep in class, knee reflex

during an ECC contraction, the reflex is initiated, muscle CON contracts adding to CON force produced

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4
Q

Fx of V on SSCP

T or F: at higher V, ECC has more to gain and CON has more to give

A

F - v.v.

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5
Q

T or F: V of E affects SSC potentiation even if V of CON does not change

A

T

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6
Q

T or F: Most of the time fast ECC is harder to do than fast CON

A

F - v.v.

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7
Q

greater ________ or % potentiation at higher velocities

A

relative

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8
Q

T or F: It possible to have a ECC submax lead into a CON max

A

T - it is dependent on velocity of the ECC phase

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9
Q

Examples of scenarios…

ECCmax - CONmax
ECCsubmax - CONmax
ECCsubmax - CONsubmax

A

isokinetic dynamometers

jumping, throwing

weight training

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10
Q

SSCP used when we do a squat jump with a counter movement (down than up, vs. up only) resulting in a higher jump height. Similarly, this occurs when we jump off platforms of various heights. However…what if the platform is too high?

A

Too much momentum due to gravity on the way down to the floor, causing a PAUSE = loss of SSCP (golgi tendon - protective fxn)

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11
Q

When is SSC inappropriate? (3)

A

when time needed for ECC phase can’t be spared

  • push off in swimming
  • tip off in bball
  • no telegraphing (give hints to opponent) of punch in boxing

when a rule forbids its use
-competitive weight lifting

when overused = injury
-CN tower example

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12
Q

Fx of training on the SSC and its mechanisms (3)

A

increased ECC force/strength due to increased muscle hypertrophy and neural activation/synchronization

increased storage of elastic energy (stiffer elastic structures)

increased reflex potentiation
-increase neural activation

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13
Q

Study: vball players vs. PE students (M)

A

there was a only a significant difference at 60 cm height

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14
Q

Study: gymnasts vs. PE students (F)

A

training decreased inhibition by the body because they were used to the elevated heights; therefore SSCP was higher/more effective

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15
Q

Calculation for Efficiency?

A

E = Eout/Ein x 100

or E = mechanical power (out)/metabolic rate (in) x 100

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16
Q

T or F: SSC increases Eff

A

T

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17
Q

3 reasons why SSC increases Eff

A

increases EFF force from stretched CBs (no ATP cost) - positive braking force

storage and release of elastic energy

prevention of wasted CB action taking up SEC

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18
Q

T or F: walking is less EFF than running

A

T

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19
Q

T or F: running faster will burn more energy

A

F - same cost despite time and speed of running

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20
Q

FLR is also known as the….

A

length-tension relation (LTR)

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21
Q

What is the difference between active/passive force? What is total force?

A

active - force produced during contraction
passive - resistance of a relaxed muscle to stretch - similar to the positive braking force (note: tighter muscle = higher passive force due to less elasticity)
total force - passive + active

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22
Q

Optimal length (L0) is the length of which the greatest ______ force occurs

A

active

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23
Q

Resting length is the length of which….

A

passive force begins to develop

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24
Q

In anatomical position, resting lengths are limited by….

A

human bone

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25
Q

T or F: relationship between optimal and resting length varies with different muscles

A

T

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26
Q

What are the mechanisms for variation in passive force?

A

elastic structures in the muscle

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27
Q

What are the mechanisms for variation in active force?

A

length of sarcomeres - long, optimal, short

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28
Q

Name the length

Midpoint of one Z line to the other Z line
Length of actin
Length of myosin
Length of the bare zone

A
  1. 6 um
  2. 95 um
  3. 6 um
  4. 2 um
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29
Q

Optimal length….

What is occurring?

A

2-2.2 um - vary because of bare zone

plateau at max force b/c all CBs are bound; plateau is due to the bare zone, no more/less CBs bound

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30
Q

What happens when the length exceeds the optimal length?

A

force decreases linearly

Less CBs bound

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31
Q

What happens when the length is below the optimal length (1.7-2 um)?

A

force decreases - actin filaments overlap one another (blocking myosin binding)

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32
Q

What happens when the length is below the optimal length (<1.7 um)?

A

decrease in force - Z disks compress myosin filament, preventing shortening

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33
Q

T or F: when comparing two species such as a frog and a human, there is little variation in the actin filament length and a large variation in the myosin filament length

A

F - vv - more variation in actin - this explains the larger length of a human sarcomere (4.24 um) - proportional to the size of the species

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34
Q

How does a human FLR graph compare to a frog’s?

A

shifted to the right

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35
Q

What are the two main factors affecting the shape of strength curves?

A

FLR

Muscle MA

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36
Q

In terms of the FLR relationship, order the muscles in low to high active force.

A

hamstrings, calf muscles
biceps, quadriceps
triceps

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37
Q

How does MA length vary the FLR (aka strength curve) relationship?

A

Every muscle has its own FLR or strength curve, and has it’s optimal MA and angle

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38
Q

T or F: the MA, strength and FLR have similar curves

A

T

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39
Q

Give in an example where the force produced is dictated more by the FLR since the MA doesn’t change by much

A

Quads

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40
Q

Cost of smaller MAs

A

lower torque and strength,, increase risk of injury (avulsions)

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41
Q

Advantage of smaller MAs

A

increased ROM and speed

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42
Q

For two muscles of the same CSA,

B’s MA is twice of A’s therefore double the torque but….

A

B has half the ROM - B has to shorten twice as much as A for a given change in joint angle

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43
Q

3 other factors of the strength curve shape

A

training
fatigue
injury

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44
Q

2 adaptations due to training in the first 6 wks

A

neural and muscle adaptation

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45
Q

T or F: if there was muscular adaptation, there would be a uniform increase in strength

A

T

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46
Q

T or F: neural adaptations increases at only certain joint angles

A

T

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47
Q

For all men, regular or body builder, the optimal joint angle for the bicep was higher than it was for women..why?

A

in men, bicep bulge comprises the LOA of the muscle at smaller JAs, therefore the force produced

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48
Q

If you are looking at a graph, how do you tell the difference between fatigue and an injury?

A

injury - most likely one JA is affected; fatigue lowers the whole strength curve

49
Q

T or F: during training you want to match the load with the strength curve

A

T - not being too high or low

50
Q

Alternative, when you are doing shoulder abduction to better match the strength curve of the deltoids?

A

lay on your side

51
Q

What is a cam pully? why was it flawed?

A

a type of machine that varies the resistance by changing the ratio of the radius of the pully (2x length = 2 force)

they thought the angle and % max relationship was negatively linear - their system did not match the strength curves of every muscle

52
Q

So what is the best system or machine to match strength?

A

isokinetic devices

53
Q

2 components of a motor unit

A

motor neuron + innervated muscle fibre

54
Q

Fibres/MU decreases with (increase/decrease) complexity of movement/fxn

A

increase

55
Q

of varies with the _______ of the muscle and ______

A

size of muscle and size of MU

56
Q

T or F: Med Gastroc would have more fibres/MU than FDI

A

T

57
Q

T or F: Med Gastroc would have less MUs than FDI

A

F

58
Q

What does it mean when we say that the MU territories produce a mosaic?

A

branches of MUs overlap each other and intermingle; there is no sectioning in terms of with MU is in charge of which section of the muscle

59
Q

What are the advantages of having MU territories? (2)

A

smoother contraction - more MU force distributed over a larger area

may help delay fatigue - inactive and active fibres, or different fibre types sharing metabolites and capillaries

60
Q

Type I - also known as (2)

Type 2 - also known as (1)
-2 subtypes (2 names for each)

A

slow twitch (ST) or slow oxidative (SO)

fast twitch (FT) – fast oxidative glycolytic (FOG) or IIA and fast glycolytic (FG) or IIX/IIB

61
Q

IIX > IIA > I for:

motoneuron soma size
axon diameter
fibre size
?

A

fibre number

62
Q

In male body builders, what affect does testosterone have? Effects of training?

A

increased muscle growth - larger muscle fibre, increase in type II fibres esp

fx of training - increase in type II as expected (compared to the untrained group)

63
Q

What are units of ABS and REL force? Another name for REL force?

A

N

N/cm2 - specific force

64
Q

Compare ST and FT fibres in terms of force

A

FT - are larger and more numerous therefore generating a greater ABS force

65
Q

How is it possible that 20% of the muscle forces are unused in the triceps brachii?

A

Triceps - 750 fibres/MU

IIX fibres are difficult to recruit unless it is a very high force demand

66
Q

75% of the MUs can be type I however it can makes up around 33% of the muscle fibres. How is it possible for 50% of the muscle fibres be type II when it only makes up 21% of the total # of MU?

A

Type II are larger in size and have more branches (muscle fibres)

67
Q

T or F: ST fibres generate a lower ABS force because they are smaller in size and, but a similar SPECIFIC/REL force compared to FT

A

T

68
Q

Why does type II produce a greater specific force? (3)

A

stronger CBs - greater F/CB

more # CBs attached - assumes max activation - saturating Ca

similar myofilament density, similar myofibrillar density- packing

69
Q

T or F: SO have a lower peak in force than FG and FOG

A

T

70
Q

T or F: Looking at tetanic ISO and CON contractions, SO has a higher ISOmax force but a lower Vmax value.

A

F

ISOmax - FG>FOG>SO
Vmax - FG>FOG>SO

71
Q

Describe the shape of the velocity vs. power graphs for type I, IIA, IIX

A

all upside down Us that have different magnitudes and ranges in x and y axis

72
Q

What possibly accounts for differences in velocity vs. power?

A

genetics

73
Q

What’s the advantage of having a mixed muscle, in terms of power?

A

the muscle can be active over a wider range of velocities; nervous system recruits them consecutively

I - slower Vs - quick peak, slow fall
II - faster Vs - slower peak - slower fall

74
Q

List the 3 determinants of contraction speed. Describe each and what’s the trend among the types?.

A

Myosin ATPase activity determines speed of CB cycling (avg 50ms); IIX>IIA>I

CB power stroke speed - we don’t know this mechanisms for sure; IIX>IIA>I

Ca release and uptake - IIX>IIA>I; larger/more extensive SR = more rapid release & uptake of Ca = INCREASED rate of contraction/relaxation of the muscle

75
Q

T or F: for CON contractions, the difference in force between Type I and II increases as velocity decreases

A

F - velocity increases

76
Q

T or F: for ECC contractions, the difference in force between Type I and II increases as velocity increases

A

F - force decreases

77
Q

T or F: Type II have a higher ISO max as well as Vmax

A

T

78
Q

Compare the soma, axon, and muscle fibre size of FG and SO

A

SO<FG in size

79
Q

T or F: FG has a faster conduction velocity

A

T - think of it as water flow in a pipe diameter

80
Q

T or F: muscle fibres conduct faster than nerve axons

A

axons are myelinated and have Nodes of Ranvier at allow SALTATORY conduction

81
Q

T or F: increased diameter = decreased resistance and increased conduction velocity

A

T

82
Q

Another reason why MAP maybe slower….

A

T-tubules with the MAP may slow it down

83
Q

Why do we have small stores of ATP?

A

ATP are large and heavy

84
Q

Duration of the PC system?

A

~10 seconds

85
Q

In terms of METABOLIC power…FG have a greater…(2)

A

CK, myosin ATPase, glycolytic ENZYME ACTIVITY

SUBSTRATE STORES of PCr and glycogen

86
Q

Differentiate mechanical and metabolic power, for each fibre type.

A

mechanical - P = Fv; FG>FOG>SO
metabolic - activation of and fuel for engine (demand)

FG>FOG>SO

87
Q

T or F: isolated muscle fibre type contractions is possible in humans

A

F - impossible to isolate due to the mosaic

88
Q

Compare the MF types in terms of fatigue resistance. What is the reason behind his?

A

SO> FOG >FG

OXIDATIVE

89
Q

T or F: SO contraction force can go on “indefinitely”

A

T

90
Q

4 determinants of fatigue resistance. Describe each

A

mitochondrial size - larger mito = >ox enzyme activity = >utilization of O = > fatigue resistance
Mb concentration - Mb helps carry and store O, >Mb = >O utilization
MF diameter - smaller the fibre = less distance travelled to the center of fibre
capillarization (technically external to MU) - SO have more capillaries around it for higher O delivery and utilization

91
Q

T or F: IIB or IIX is only recruited with very high forces, otherwise the body would recruit SO

A

T - IIs are recruited as backup to compensate for what the Is are lacking

92
Q

What is recruitment threshold (RT)?

A

% of max force/effort at which a MU is recruited/activated

low threshold - recruited at low % OF MAX
high threshold - recruited at high % OF MAX

93
Q

What’s the size/Henneman principle? What’s the order of recruitment?

A

MU are recruited in order according to the size of the MU’s soma

SO, FOG, FG - larger size = larger RT

94
Q

T or F: SO fibres have smaller somas therefore less resistance to excitatory input.

A

F - more R

95
Q

T or F: depol threshold or voltage is increases with cell soma size

A

T

96
Q

What’s Ohm’s law? Explain it in terms of MU recruitment

A

V = IR

I = input
V = threshold
SO = smaller soma = more resistance, greater V when reaching excitation - more likely to fire
FT = larger soma = less resistance lesser V when reaching excitation - less likely to fire
97
Q

So which fibre type would be more likely to fire, for the same I (input)?

A

SO!!!!

98
Q

T or F: FT generate a larger action potential than SO

A

F - same AP due to all or none principal

99
Q

T or F: larger soma = harder to excite = harder to recruit = lower activation (I) needed to reach threshold

A

F - higher

100
Q

Depolarization threshold is the same for all MUs, so what differentiates them as low/high threshold MUs?

A

differ in degree of activation required (I) to cause them to reach threshold in order to fire

101
Q

What is the Central Wisdom principle? Differentiate low excitation/effort with the high

A

CNS matches MU recruitment with the demands of the task

low excitation/effort levels prefer to small motor neurons (type I) first
high excitation/effort levels recruit larger motor neurons (type II) in addition to type I

102
Q

Name examples of when you’d use low and high excitation recruitment.

A

low - endurance

high - sprinting, lifting, jumps

103
Q

Define gradation of contraction.

A

varying force of contraction

104
Q

2 ways contraction force is graded?

A

MU recruitment

MU firing rate

105
Q

MU recruitment mechanism is based on…

A

central wisdom + size principle

106
Q

MU firing rate is…

A

nerve impulses/second

sent from soma to muscle fibres

107
Q

T or F: 20 impulses/s = 10 MAPs/s or Hz

A

F - its a 1 for 1 relationship

108
Q

T or F: minimum MU firing rate (FR) for FG>FOG>SO

A

F - SO> FOG> FG

109
Q

Why do faster MUs require a higher FR?

A

stimuli must be closer together to form a tetanus (summation) or else force gradation cannot occur

110
Q

T or F: SO have a lower FR but hits its max faster

A

T - because it is slower in rising and falling

FG need a higher FR to hit its max force and plateau

111
Q

Below 50% MVC it is the _______ mechanism dominants.

Above 50% MVC it is the _______ mechanism
dominants.

A

recruitment

FR

112
Q

T or F - %MVC vs. # of MU recruited = linear relationship shape…

A

F - increasing curve - non linear

note: both mechanisms are at play throughout contraction

113
Q

How is muscle unit activation measured?

A

EMG

114
Q

How do we quantify an EMG?

A

of recruited MUs + FR = size of fibre MAPs = quantity

115
Q

Differentiate between sustained MVC and submax contraction (to failure)

A

signal starts larger and gets smaller (negative linear)

signal starts smaller and gets larger (positive linear)

116
Q

MUA and exercise…3 fxs

A

fx of exercise on intensity
fx of contraction type
fx of contraction V

117
Q

3 types of intensity of exercise - describe and give an example

brief, max effort
submax effort
progressive/incremental

A
  • 100% MUA; lifts/throw/jumps and sprints (longer duration)
  • <100% MUA - walking, jogging, running
  • aerobic power tests (VO2max) - % MUA increases in steps
118
Q

T or F. In lifting the same weight, the CON phase of the lift has a higher % MUA/magnitude of signal than the ECC phase

A

T - because

CON = # CBs required = >muscle fibres required = >MU needed therefore >signal

119
Q

T or F: during a max CON or ECC contraction, there is a same a REL force and EMG signal

A

T - BECAUSE IT IS AT MAX!

KINESIOL 2C03 (2 decks)

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