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Kines > skeletal muscles mechanics > Flashcards

skeletal muscles mechanics Flashcards

1
Q

strength depends on?

A

muscle force x moment arm

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2
Q

what are the mechanical factors of strength?

A

rotary component of muscle force and length of moment arm

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3
Q

what are the physiological factors of strength?

A

length of the muscle, velocity of contraction, fiber orientation, cross sectional area, and fiber type

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4
Q

what are the 3 types of muscle fibers?

A

type 1 type 2a type 2b

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5
Q

what are type 1 muscle fibers?

A

slow twitch oxidative

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6
Q

what are some characteristics of type 1 muscle fibers?

A

small diameter, red in color, dense in capillaries, seed of contraction is slow, rate of fatigue is slow

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7
Q

what are muscles predominantly type 1 called?

A

stability or postural tonic muscles

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8
Q

what are type 2a muscle fibers?

A

fast twitch oxidative glycolytic

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9
Q

what are some characteristics of type 2a muscle fibers?

A

intermediate diameter, fast speed of contraction, and intermediate rate of fatigue

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10
Q

what are type 2b muscle fibers?

A

fast twitch glycolytic

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11
Q

what are some characteristics of type 2b muscle fibers?

A

large diameter, white in color, sparse capillarity, fast speed of contraction and fast rate of fatigue

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12
Q

what are muscles predominantly type 2 called?

A

mobility, non postural, phasic muscles

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13
Q

________ surrounds the whole muscle

A

epimysium

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14
Q

________ surrounds the fascicules

A

perimysium

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15
Q

________ surrounds the individual muscle cells

A

endomysium

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16
Q

What are contractile elements?

A

contractile proteins (actin and myosin)

17
Q

what are parallel elastic elements (PEC)?

A

peri, ei, and endomysium (fascia)

18
Q

what are series elastic elements (SEC)?

A

tendons

19
Q

T/F with an isometric contraction the contractile element shortens and the series elastic element lengthens

A

true

20
Q

by passively pulling on a muscle beyond rest length will ______ the PEC and they will also contribute to the _________

A

stretch, tension

21
Q

what else will muscle force also vary with in accordance with the length tension curve?

A

muscle length

22
Q

muscle force varies with cross sectional area of the muscle. what is key issue in determining the total cross sectional area?

A

fiber arrangement

23
Q

cross sectional area increases what years? meaning?

A

0-20s max strength is at 20-30 years old

24
Q

what percent of muscle strength do we have at age 65 compared to 20

A

85%

25
Q

key notes with changes with aging

A

loss is reversible or can be minimized
loss of strength is more in legs than arms bc of sitting
males tend to be stronger than females

26
Q

_________ of muscle contraction is a function of the load being lifted

A

velocity

27
Q

speed of shortening of the myofilaments os the rate at which?

A

the myofilaments are able to slide past one another and form/reform cross bridges

28
Q

speed is related to _______ ________ and ________

A

fiber type and length

29
Q

T/F force generated is a function of the velocity of muscle contraction

A

true

30
Q

when does max shortening speed occur?

A

when there is no resistance to shortening, however, no tension is developed in the muscle bc there is no resistance

31
Q

describe concentrics muscle force generation

A

as shortening speed dec tension inc (slower = more force)

32
Q

describe isometrics muscle force generation

A

speed is zero, therefore greater tension generated compared to concentrics

33
Q

describe eccentrics muscle force generation

A

as speed of lengthening inc tension ince (faster= greater force)

34
Q

muscle force with isometric

A

great strengthening but only at that joint angle +/- 10º

35
Q

muscle force with concentric

A

dynamic, but velocity tension relationship often limits strengthening at higher velocities

36
Q

muscle force with eccentric

A

great strengthening, possible tissue damage due to potential for large muscle force production

37
Q

muscle force with isotonic

A

dynamic contractions, but intensity limited by capability in weakest part of ROM (typically end range)

38
Q

muscle force with isokinetic

A

good strengthening throughout the range of motion but not functional

Kines (20 decks)

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