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Kinesiology > muscle mechanics > Flashcards

muscle mechanics Flashcards

1
Q

purpose of muscles

3 of them

A
  • enable boens to move at joints
  • provide strength and protection to skeleton
  • absorb shock and distribut loads
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2
Q

muscles properties

A
  • extensibility
  • elasticity
  • contractility
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3
Q

connective tissue surrounding muscle fiber

A
  • epimysium: covers muscles
  • perimysium: covers fasicles
  • endomysium: covers fibers
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4
Q

structures within muscle fiber

A
  • sarcolemma: muscles cell membrane
  • myofibril
  • sarcomere
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5
Q

structures within a sarcomere

A
  • actin

- myosin myofilaments

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6
Q

6 things affecting muscles funtion

A
  • muscles actions
  • joint structure
  • muscles structure
  • contraction type
  • muscles mechanics
  • neuromuscular
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7
Q

factors affecting muscle force production

A
  • cross sectional area
  • fiber type
  • type of contraction
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8
Q

ratio of actin to myosin

A

6:1

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9
Q

what happens to cross sectional view of myofibril during muscle damage

A
  • increases

- more actin and myosin added by proteins

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10
Q

mechanical properties that determine fiber type

A
  • contraction force
  • contraction time
  • time to 1/2 relaxtion
  • fatigue rate
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11
Q

what is an isoform and how does it affect muscle fiber types

A
  • deviation from set protein

- changes mechanical properties

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12
Q

how many total isoforms are there

A
  • 86 myosin
  • 6 action
  • 516 total
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13
Q

what is the size principle

A

fibers recruited slow to fast

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14
Q

what is selective recruitment

A

-send out signals for high amp/high freq fibers and bypasss slow twitch

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15
Q

what is rate coding

A

amplitude + frequency

-every muscles fibers of same MU has same rate coding

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16
Q

what is the mechanical model of the musculotendinous unit?

A
  • contractile component: active
  • series eleastic component: passive (eligned end to end)
  • parallel elastic component: passive (elignd on top of eachother)
17
Q

anatomical structures represented in mechanical model of MTU

A
  • CE: muscles fibers
  • SEC: tendons
  • PEC: epi-, peri-, and endomysiums
18
Q

contribution of CE/SEC/PEC in concentric contractions of a constant load (ex405lbs)

A
  • CE= 100%

- PEC and SEC = 0%

19
Q

contribution of CE/PEC/SEC in ecentric contraction of a contant load (ex405lbs)
-what does this tell you about the diff btwn 2 conctractions

A
  • CE= 80%
  • SEC= 15%
  • PEC= 5%
  • require less energy to eccentrically contract a constant load
20
Q

contribution of CE/SEDC/PEC in concentric contractions of a constant intensity (1RM)

A
  • CE= 100%

- SEC and SEC= 0%

21
Q

contribution of CE/SEDC/PEC in ecentric contractions of a constant intensity (ex 1RM)
-what does this tell you about the diff btwn the 2 contractions

A
  • CE= 100%
  • SEC= 15%
  • PEC= 5%
  • can manage more load during eccentric contraction during constant intensity
22
Q

why does the force potential production decrease as muscle length shortens?
-why does it eventually reach 0?

A
  • # cross bridges formed decrease
  • b/c actin overlap on eachother and bottom one will block top one from binding to myosin
  • 0 b/c: myosin acts as barrier to Z discs
23
Q

why does the force potential production decrease as muscle length lengthens?
-why does it eventually reach 0?

A
  • # of cross bridges formed decreases
  • b/c actin doesnt have any overlap with myosin
  • 0 b/c: no overlap at all
24
Q

what happens to the tension and speed of contraction as the load increases in a concentric and eccentric contraction

A

con: -tension increases
- speed drecreases
ecc: -tension increasees
- speed increases

25
Q

when can the max force be produced in a muscle in relation to veolcity

A
  • isometric contraction

- velocity = 0

26
Q

what happens to force produced by an eccentric contraction as velocity increases

A

-force increases

27
Q

what happens to force produced by a concentric contraction as velocity increases

A

-force decreases

28
Q

why does force decrease w/ concentric contractions as velocity increases

A
  • greater load so need mroe cross bridges
  • more time needed to form more crossbridges
  • if you go too fast the actin and myosin do not have time to make cross bridges as they slide past eachother
  • increased latency period to transmit tension
29
Q

equation of power

if decreased force what will power be?

A

P = F x V

-deceased power

30
Q

factors affecting force production of the MTU

6 of them

A
  • CSA
  • fiber type
  • type of contraction
  • muscle fiber architecture
  • force length relationship
  • force velocity relationship
31
Q

factors affecting velocity of contraction

4 of them

A
  • muscle length
  • shortening rate per sarcomere or muscles fiber (dependent on muscle fiber type)
  • fiber arrangement
  • the load needed to be moved
32
Q

factors affecting muscles torque production

A
  • all factors affecting force prodcution by MTU

- moment arm length

33
Q

what happens to the force length curve as velocity increases

A
  • curve gets smaller

- aka max point goes lower

34
Q

what happends to force as velocity increases and length increases/decreases from rest length

A

-decrease

35
Q

what happends to muscle length and moment arm length as jnt angle decreases

A
  • muscle length decreases

- moment arm length increases, peaks, then decreases

36
Q

factors affecting strength curve

A
  • muscle length
  • moment arm length
  • velocity of contraction
37
Q

what happens to strength curve as:

  • concentric contractions get faster
  • eccentric contractions get faster
A
  • con:decreases
  • will have less torque at a set jnt angle
  • ecc: increases
  • will have more totque at set jnt angle

Kinesiology (18 decks)

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