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Strength and Conditioning > Ch. 4 - Biomechanics > Flashcards

Ch. 4 - Biomechanics Flashcards

0
Q

How do muscles transmit force to the environment?

A

Muscles do not act directly to exert force on ground or other objects

They function by pulling against bones that rotate about joints and transmit force through the skin to the environment

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1
Q

Musculoskeletal system consists of …. and is configured to…

A

bones, joints, muscles, and tendons

allow variety of movements

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2
Q

How many bones in the human body?

A

approx 206

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3
Q

function of skeleton

A

provides leverage, support and protection

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4
Q

portions of the skeleton

A

axial skeleton and appendicular skeleton

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5
Q

axial skeleton components (4)

A

consists of skull (cranium), vertebral column, ribs, and sternum

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6
Q

appendicular skeleton components (8 groups)

A

shoulder (pectoral) girdle, bones of arms, wrist, and hands, pelvic girdle, and bones of legs, ankles, and feet

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7
Q

joints definition

A

junctions of bones

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8
Q

3 types of joints

A

fibrous joints
cartilaginous joints
synovial joints

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9
Q

fibrous joints

A

virtually NO movement

ex. sutures in skull

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10
Q

cartilaginous joints

A

allow little movement

ex. intervertebral discs

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11
Q

synovial joints

A

considerable movement

ex. elbow and knee

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12
Q

important features of synovial joints

A

low friction and large ROM

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13
Q

sport and exercise movements mainly occur about which type of joint?

A

synovial joints

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14
Q

how are joints characterized?

A

by # of directions about which rotation can occur

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15
Q

categories of joints (3)

A

uniaxial joints
biaxial joints
multiaxial joints

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16
Q

uniaxial joints

A

operate as hinges
rotate about ONE axis
ex. elbow joint (NOT knee joint)

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17
Q

is the knee joint a uniaxial joint?

A

NO

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18
Q

biaxial joints

A

allow movement about 2 PERPENDICULAR AXES

ex. ankle and wrist

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19
Q

multiaxial joints

A

allow movement about ALL 3 perpendicular axes that define space
ex. shoulder and hip ball + socket joints

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20
Q

vertebral column components

A 
7 cervical vertebrae
12 thoracic vertebrae
5 lumbar vertebrae
5 sacral vertebrae
3-5 coccygeal vertebrae
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21
Q

cervical vertebrae

A

7

neck region

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22
Q

thoracic vertebrae

A

12

middle-upper back

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23
Q

lumbar vertebrae

A

5

lower back

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24
Q

sacral vertebrae

A

5
fused together
make up rear part of pelvis

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25
Q

coccygeal vertebrae

A

3-5
“vestigal internal tail”
extending down from pelvis

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26
Q

skeletal musculature

A

system of muscles that enables the skeleton to move

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27
Q

origin and insertion

A

skeletal muscle attached to bone with connective tissue
origin = proximal attachment
insertion = distal attachment

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28
Q

origin

A

proximal attachment

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29
Q

insertion

A

distal attachment

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30
Q

fleshy attachments

A

muscle fibers directly attached to the bone
usually over wide area so force is distributed rather than localized
most often found at proximal end of muscle

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31
Q

where are fleshy attachments most often found?

A

proximal end of muscle

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32
Q

are fleshy attachments usually localized or over a wide area?

A

wide area

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33
Q

fibrous attachments

A

blend into and are continuous with both the muscle sheaths and the connective tissue surrounding the bone
additional fibers that extend into the bone itself for strong union
ex tendons

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34
Q

agonist

A

muscle most directly involved in bringing about a movement

aka prime mover

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35
Q

agonist aka

A

prime mover

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36
Q

antagonist

A

muscle that can slow down or stop the movement

assists in joint stability and in braking the limb toward end of fast movement

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37
Q

antagonist portects…

A

“gamentous and cartilaginous” joint structures from potentially destructive forces

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38
Q

triceps and biceps during baseball throw is an example of…

A

triceps agonist and biceps antagonist

during baseball throw (fast movement) biceps work to slow the arm and protect from destructive forces

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39
Q

synergist

A

muscle assisting indirectly in movement

ex. muscles stabilizing the scapula are synergists in arm movement

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40
Q

synergists are required to control body motion when…

A

the agonist is a muscle that crosses 2 joints (ex. rectus femoris flexes hips and extends knee with contraction)
so, ex. synergist would be gluteus maximus counteracting hip flexion during rectus femoris facilitated knee extension for upward movement of squat

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41
Q

synergist for upward movement of squat

A

gluteus maximus

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42
Q

body movements in sports/exercise act through…

A

bony levers of the skeleton

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43
Q

lever (def)

A

rigid/ simerigid body that, when subjected to a force whose line of action does not pass through its pivot point, exerts force on an object impeding its tendency to rotate

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44
Q

fulcrum (def)

A

pivot point of a lever

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45
Q

moment arm (def)

A

perpendicular distance from the line of action of the force to the fulcrum

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46
Q

torque aka

A

moment

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47
Q

torque (def)

A

degree to which a force tends to rotate an object about a specified fulcrum.
defined quantitatively as the magnitude of a force x the length of its moment arm

48
Q

SI unit for torque

A

Nm

49
Q

Torque (quantitatively)

A

force x moment arm

50
Q

muscle force (def)

A

force generated by biomechanical activity, or the stretching of noncontractile tissue, that tends to draw the opposite ends of muscle toward eachother

51
Q

resistive force (def)

A

force generated by a source external to the body that acts contrary to muscle force
ex. gravity, inertia, friction

52
Q

mechanical advantage (def)

A

ratio of moment arm through which applied force acts to that through which a resistive force acts

mech. adv. = Mm/Mr (M=moment arm)

53
Q

mech. adv. > 1

A

allows the applied (muscle force) to be less than the resistive force to produce an equal amount of torque

54
Q

mech. adv. < 1

A

disadvantage, applied force must be greater to be equal to resistive force

55
Q

patella in terms of mech. adv.

A

patella increases mech. adv. of quads by increasing moment arm
absence of patella allows tendon to fall closer to the knee’s center of rotation

56
Q

first class lever

A

a lever for which the muscle force and resistive force act on OPPOSITE sides of the fulcrum
ex. elbow extension/triceps extension

57
Q

EFR

A

first class lever

58
Q

mech adv first class lever

A

<1

59
Q

Lever that resembles a teeter totter

A 
1st class lever
EFR
60
Q

second class lever

A

a lever for which the muscle force and resistive force act on the SAME side of the fulcrum, with the muscle force acting through a moment arm LONGER than that of the resistive force
ex. calf muscles work to raise body onto balls of feet (plantatflexion)

61
Q

FRE

A

second class lever

62
Q

mech adv second class lever

A

> 1

63
Q

Lever that resembles a wheel barrow

A 
second class lever
FRE
64
Q

third class lever

A

a lever for which the muscle force and the resistive force act on the SAME side of the fulcrum, with the muscle force acting through a moment arm SHORTER than that of the resistive force
ex. elbow flexion

65
Q

FER

A

third class lever

F____^E_____vR

66
Q

mech adv of third class lever

A

< 1

67
Q

lever that resembles a shovel

A

third class lever

68
Q

most human muscles rotate the limbs about body joints that operate at …. mech adv

A

< 1 or mechanical disadvantage

69
Q

during sports/PA, forces in muscles and tendons are….

A

MUCH HIGHER than those exerted by the hands or feet on external objects or the ground

70
Q

a person whose tendons are inserted on the bone further from the joint center should be able to lift …. weights because ….

A

able to lift HEAVIER weights

because muscles force acts through a longer moment arm and thus can produce greater torque around the joint

71
Q

variation in tendon insertion – mech adv of insertion farther from joint center is accompanied by… because…

A

LOSS OF MAX SPEED
because as the tendon is inserted farther from the joint center, the muscle has to contract more to make the jiont move through a given ROM

72
Q

To produce a given joint rotational velocity, a muscle inserted farther from the joint center must contract at a … speed, at which it can generate … force due to the …. relationship of muscles

A

contract at a HIGHER SPEED
can generate LESS force
due to INVERSE FORCE-VELOCITY relationship

73
Q

tendon insertion farther from joint than normal is advantageous for?
disadvantageous for?

A

slow movements such as power lifting

disadvantageous for athletic activities at HIGH SPEEDS such as tennis

74
Q

anatomical planes of the human body

A

sagittal plane - L/R
frontal plane - front/back
transverse plane - upper/lower

75
Q

sagittal plane and ex

A

L/R

ex. standing barbell curl

76
Q

frontal plane and ex

A

front/back

ex. standing lateral dumbbell raise

77
Q

transverse plane and ex

A

upper/lower

ex. dumbbell fly

78
Q

as weight is lifted, the moment arm (MR) changes with the horiz distance from the weight to the elbow.
how does this relate?

A

think ideal angle of elbow to manage weight due to mech adv.

79
Q

strength (def)

A

ability to exert force.

80
Q

how to measure strength? (controversy)

A

the weight that a person can lift is the oldest quantitative measure
isometric strength testing and isokinetic strength testing are more recent measurements

81
Q

acceleration (def)

A

change in velocity per unit time

82
Q

resistive force (Def)

A

force = (mass)x(acceleration)

83
Q

Strength (Knuttgen and Kraemer)

A

the maximal force that a muscle or muscle group can generate at a specified velocity
THIS DEF IS MORE MEANIGFULLY RELATED TO SPORT ABILITY THAN ARE STATIC MEASURES

84
Q

what def of strength is more meaningful for sport ability than static measures?

A

Knuttgen and kraemer: “the max force that a muscle or muscle group can generate at a specific velocity”

(must control for velocity during strength training)

85
Q

controlling and monitoring velocity during strength training requires… but

A

sophisticated equipment

but there are more meaningful strength scores than static strength measures or maximum loads lifted

86
Q

Power (def)

A

the time rate of doing work

Work = force x distance
POWER = WORK/TIME
87
Q

WORK =

A

FORCE x DISTANCE

88
Q

SI unit for forocoe

A

N

89
Q

SI unit for distance

A

meter

90
Q

SI unit for time

A

seconds

91
Q

SI unit for work

A

Joule or Nm

note: convert kg –> N

92
Q

volume of work =

A

(force)(distance)(reps)

93
Q

distance component of work refers to…

A

distance moved along the line of action of the force

94
Q

SI unit for power

A

watt (W)

J/s

95
Q

weight SI unit

A

includes acceleration by gravity (m/s^2)

if local g is not available, 9.8 m/s^2 is approximate

96
Q

weight=

A

(mass)(acceleration of gravity)

97
Q

angular displacement (def)

A

the angle through which an object rotates

98
Q

SI unit for angular displacement

A

radian (rad)

99
Q

1 radian =

A

180/pi = 57.3deg

100
Q

angular velocity (def)

A

object’s rotational speed

101
Q

SI unit for angular velocity

A

rad/s

102
Q

distance component of the torque unit refers to…

A

length of the moment arm (perpendicular to line of action of force)

103
Q

SI unit for torque

A

Nm or joules (J)

104
Q

work done in rotating an object is measured in…

A

J (joules)

105
Q

rotational work =

A

torque x angular displacement

106
Q

rotational power

A

work / time

107
Q

SI unit for rotational power

A

watts

108
Q

although strength is often associated with … speeds and the word power with …. speeds of movement, both variables reflect…

A

strength - slow speed of movement
power - high speed of movement

both variables reflect the ability to exert force at a given speed

109
Q

difference between strength and power

A

strength - capcity to exert force at any given speed

power is mathematical product of force and velocity at whatever speed

110
Q

CRITICAL: the ability to exert force at speeds characteristic of a given sport to overcome gravity and accelerate the body or an implement

ex…

A

O Line and D Line exert force/power at slow speed

badmitton/tennis player exerts force/power at high speed

111
Q

biomechanical factors in human strength include… (8)

A 
neural control
muscle cross-sectional area
muscle fiber arrangement
muscles length
joint angle
muscle contraction velocity
joint angular velocity
body size
112
Q

neural control affects maximal force output of a muscle by…

A

recruitment and rate coding

113
Q

recruitment

A

neural control

determining which and how many motor units are involved in a muscle contraction

114
Q

rate coding

A

neural control

the rate at which the motor units are fired

115
Q

force is greater when (regarding neural control)

A

more motor units are involved in contraction
motor units are greater in size
the rate of firing is faster

116
Q

much of improvement in strength in the first few wks of RT is attributable to…

A

neural adaptations, where brain learns how to generate more force from a given amount of contractile tissue

117
Q

improvements in strength after first few wks of is through (slower or faster) mechanisms than neural adaptations?

A

slower

118
Q

muscle cross-sectional area

A

force a muscle can exert is related to its cross-sectional area rather than its volume

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