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CSCS > Chapter 2 P20 biomechanics > Flashcards

Chapter 2 P20 biomechanics Flashcards

1
Q

biomechanics def

A

the mechanisms through which the musculoskeletal components interact to create movement.

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2
Q

origin and insertion

A

origin= proximal attachment, insertion= distal attachment

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3
Q

fleshy attachments

A

muscle fibers directly attached to bone; usually at proximal end of a muscle over a wide area

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4
Q

fibrous attachments

A

ie tendons, continuous with muscle and CT around bone and have fibers extending into the bone.

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5
Q

prime mover/ agonist

A

the muscle most directly involved in bringing about a movement.

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6
Q

antagonist

A

a muscle that can slow down or stop the movement of the agonist.

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7
Q

antagonist role

A

to assist in joint mobilization, slow down movement toward end range for protection

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8
Q

synergist muscles

A

muscles that assist the prime mover or agonist INDIRECTLY

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9
Q

first class lever

A

a lever where the muscle force and resistance act on opposite sides of the fulcrum. (teeter totter, triceps)

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10
Q

mechanical advantage def

A

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

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11
Q

mechanical advantage >1

A

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

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12
Q

mechanical advantage <1

A

on must apply greater muscle force than the amount of resistive force present, creating a disadvantage

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13
Q

moment arm, force arm, lever arm, torque arm

A

the perpendicular distance from the line of action of the force to the fulcrum (p 21)

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14
Q

mechanical advantage ratio calculation

A

moment arm of muscle force/ moment arm of resistive force

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15
Q

muscle force

A

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

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16
Q

resistive force

A

force generated by a source external to the body (eg gravity, inertia, friction) that acts contrary to muscle force

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17
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 through which the resistive force acts (calf, wheelbarrow). High mechanical advantage requiring smaller muscle force.

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18
Q

third-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 shorter than that through which the resistive force acts. Mechanical advantage is less than 1. (biceps)

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19
Q

torque, moment

A

the degree to which a force tends to rotate an object about a specified fulcrum. The magnitude of a force times the length of its moment arm.

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20
Q

Mechanical advantage of limbs

A

most operate at a mechanical advantage of < 1

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21
Q

moment arm variation

A

during resistance exercise, the moment arm through which the weight acts = the horizontal distance from a line through the center of mass of the barbell or DB to the body joint where rotation occurs, so the RESISTIVE MOMENT ARM varies through the movement

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22
Q

Variation in anatomy and moment arm/ strength

A

variation in human anatomical structure exists, including the points at which tendons are attached to bone. a person whose tendons are inserted on the bone farther from the joint center should be able to lift heavier weights because the muscle force acts through a longer moment arm, producing greater torque.

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23
Q

variation in anatomy and moment arm/ speed

A

a person whose tendons are inserted on the bone farther from the joint center should be able to lift more weight, but at the cost of a loss in maximum speed because, with the tendon inserted farther from the joint, center, the muscle has to contract more to make the joint move through a given ROM. This results in less rotation of a body segment around a joint, which translates in to a loss in movement speed.

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24
Q

anatomical position

A

body erect, arms at sides with palms forward

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25
Q

Sagittal plane

A

divides body in to L and R halves

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26
Q

frontal plane

A

divides body in to front and back halves

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27
Q

transverse plane

A

divides body in to inferior and superior planes

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28
Q

strength def

A

the ability to exert force

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29
Q

acceleration

A

change in velocity per unit of time

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30
Q

Newton’s second law

A

F= Mass x acceleration

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31
Q

power def

A

“explosive strength”, time rate of doing work…where work is the product of the force exerted on an object and the distance the object moves in the direction in which the force is exerted.

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32
Q

work formula

A

work = force x displacement

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33
Q

power formula

A

power= work / time

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34
Q

International system of units (SI)

A

worldwide standard

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35
Q

force is measured in

A

newtons (N)

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36
Q

distance is measured in

A

meters (m)

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37
Q

work is measured in

A

joules ( J) or neton meters (work= F x D

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38
Q

time is measured in

A

seconds (s)

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39
Q

power is measured in

A

watts (W) or joules per second J/S

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40
Q

work involved with lifting 100kg bar 2 meters per rep for 10 reps

A

P28, 29 revisit

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41
Q

Negative work and power

A

because power equals the product of force and velocity, when force is exerted on a weight in the direction opposite to the one in which the weight is moving (eccentrically), calculated power has a negative sign

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42
Q

angular displacement

A

the angle through which an object rotates

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43
Q

SI unit for angular displacement

A

radian (rad), 1 rad = 180 degrees/ pie = 57.3 degrees

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44
Q

angular velocity

A

the objects rotational speed

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45
Q

angular velocity measured

A

radians per second ( rad/s)

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46
Q

torque measurement

A

newton-meters (Nm) (not to be confused with work which is also measured in Nm)

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47
Q

Rotational work equation

A

work= torque x angular displacement

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48
Q

strength

A

the capacity to produce force at any given velocity

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49
Q

power

A

the mathematical product of force and velocity at whatever speed

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50
Q

biomechanical factors in human strength

A

neural control, muscle cross section area, muscle fiber arrangement, muscle length, joint angle, muscle contraction velocity, joint angular velocity, body size

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51
Q

neural control affect on strength

A

affects the maximal force output of a muscle: determines how many motor units are involved in muscle contraction (recruitment) and the rate at which the motor units are fired (rate coding)

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52
Q

muscle cross section area affect on strength

A

force a muscle can exert is related to its cross-section area, not its volume. taller person has more muscle volume, but with everything else equal, strength should be the same

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53
Q

arrangement of muscle fibers affect on strength

A

variation of arrangement in sarcomeres in relation to the long axis of the muscle. PENNATE MUSCLE has fibers that align obliquely with the tendon, creating a feather-like arrangement. More pennation = greater strength, less pennation = greater velocity.

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54
Q

maximally contracting muscles can generate forces of

A

23-145 psi or 16-100 N/cm2

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55
Q

Angle of pennation is modifiable

A

through training

56
Q

muscle length affect on strength

A

When a muscle is at its resting length, the actin and myosin filaments lie next to each other, so that a maximum number of potential cross-bridges are available - so, greatest force is produced at resting length. Stretching muscle reduces the number of potential cross-bridge sites.

57
Q

joint angle affect on strength

A

movement about a joint is manifested as torque, changes through the movement

58
Q

muscle contraction velocity affect on strength

A

force capability of muscle decreases as velocity of contraction increases

59
Q

joint angular velocity affect on strength

A

concentric m action, eccentric muscle action, isometric muscle action

60
Q

muscle torque varies with

A

joint angular velocity according to the type of muscular action

61
Q

greatest force can be produced by muscle during which type of muscle action?

A

eccentric

62
Q

strength to mass ratio affect on strength

A

if mass and strength increase or decrease disproportionately, it lowers or increases ability to accelerate (for runners).

63
Q

a low strength to mass ratio is important in

A

sports with weight classes

64
Q

classic formula for strength to mass ratio

A

weight lifted/ body weight to the 2/3 power

65
Q

sources of resistance to muscle contraction -gravity

A

gravity = mass x local acceleration due to gravity

66
Q

weight of a barbell

A

in pounds measures force and changes with local gravity, in KG is measured in mass and stays the same

67
Q

Inertia and lifting weights

A

initial acceleration of weight provides inertia producing less resistance later in the movement (clean)

68
Q

sources of resistance to muscle contraction- friction

A

sled, airdyne - more force to begin movement, and constant force to keep motion. Friction coefficient does not change with speed.

69
Q

sources of resistance to muscle contraction-fluid resistance def

A

the resistive force encountered by an object moving through a fluid (liquid or gas) or by a fluid moving past or around an object or through an opening

70
Q

fluid resistance machines act

A

concentrically only

71
Q

sources of resistance to muscle contraction- elasticity

A

bands: force is proportional to length band is stretched, so force increases at end of motion where there is less potential for force production from muscle and is force is low at beginning of movement where force potential is greatest.

72
Q

resistance training and injuries- back

A

back muscles act with a severe mechanical disadvantage; deep squatting positions are not necessarily associated with back injury; a normal lordotic lumbar position is safest (moderately arched)

73
Q

85-90% of dsk herniations occur at

A

L4-5

74
Q

intra-abdominal pressure and lifting belts

A

fluid around abdominal muscles helps to stabilize torso during contraction. wight lifting belts have been shown to increase intra-abdominal pressure, should only be used for heavy sets or may weaken intra-abdominal musculature.

75
Q

the valsalva maneuver

A

is not necessary for increasing intra-abdominal pressure compressive force in thoracic cavity can place stress on hear during valsalva and make blood return to the heart difficult, valsalva can transiently slightly raise blood pressure

76
Q

shoulder injuries

A

shoulder joint is prone to injury, warm up well and exercise the shoulder in a balanced way

77
Q

knee inuries

A

patella is most prone with resistance training due to too much volume/intensity producing tendonitis, no evidence knee wraps help and may cause chondromalacia

78
Q

elbows and wrists injuries

A

lifting overhead is primary incident of injury, but it’s pretty small. Most injuries from sports.

79
Q

muscle recruitment

A

recruitment of motor units for contraction

80
Q

rate coding

A

rate at which motor units fire

81
Q

muscle force is greater when

A

more motor units are involved
the motor units are larger in size
the rate coding is fast

82
Q

most of the improvement in the first few weeks of resistance training is

A

neural adaptation

83
Q

muscle cross section area vs volume

A

force a muscle can exert is related to muscle cross section area, not volume

84
Q

actin and myosin positioning at resting length

A

A and M lie next to each other so the max # of potential cross-bridge sites are available

85
Q

muscle can generate greatest force at

A

resting length

86
Q

joint angle and body movements

A

all body movements- even in a straight line- occur by means of rotation about a joint or joints

87
Q

forces that muscles produce must be manifested as

A

torques

88
Q

force capability of a muscle declines as

A

the velocity of contraction increases

89
Q

3 types of muscle action

A

concentric, eccentric, isometric

90
Q

greatest muscle force can happen with

A

eccentric muscle action

91
Q

most common sources of resistance for strength training are

A

gravity, inertia, friction, fluid resistance, elasticity

92
Q

gravity def

A

downward force on an object/weight

93
Q

weight formula

A

mass x local gravity : F=MA

94
Q

the pound is a unit of

A

force

95
Q

the mass of a weight stays

A

constant

96
Q

the moment arm is always____to the line of action of the force

A

perpendicular

97
Q

the torque due to an object’s weight is is the product of:

A

the weight and the horizontal distance from the weight to the pivot point

98
Q

advantages of weight machines

A

safety, design flexibility(hip rotation), ease of use

99
Q

advantages of free weights

A

whole body training, simulation of real life activities

100
Q

when weights are accelerated they have ____

A

inertia / inertial force which must be decelerated to stop

101
Q

an exercise involving higher acceleration (explosive) provides greater____

A

resistance to the muscle early in the lift and less resistance later in the lift

102
Q

because of inertia, heavier weights can be handled in

A

accelerative exercises than in slow exercises

103
Q

Bracketing Technique

A

an athlete performs the sport movement with less than normal and greater than normal resistance ( a form of acceleration training)

104
Q

friction def

A

the resistive force encountered when one attempts to move an object while it is pressed against another object

105
Q

exercise devices that use friction

A

belt or break pad cycles, weighted sled

106
Q

it takes more force to ____movement between two surfaces in contact than to _____

A

initiate than to maintain movement

107
Q

friction resistance ___ change as speed increases

A

does not

108
Q

fluid resistance def

A

the resistive force encountered by an object moving through a fluid (liquid or gas) or by a fluid moving past or around an object or through an opening

109
Q

fluid resistance is a significant factor in

A

swimming, rowing, golf, sprinting, discus throwing, rowing

110
Q

two sources of fluid resistance

A

surface drag, form drag

111
Q

surface drag def

A

friction of fluid passing along the surface of an object

112
Q

form drag

A

resistance resulting from the way in which a fluid passes against the front or rear of an object when passing through it

113
Q

cross sectional (frontal) area has a major effect on

A

form drag

114
Q

fluid resistance machines and muscle action

A

muscle action is concentric of agonist and concentric of antagonist

115
Q

elasticity in resistance training

A

devices that have elastic components such as springs, bands, bows, or rods often used at home

116
Q

the resistance provided by a standard elastic component is proportional to

A

the distance it is stretched

117
Q

the problem with elastic components for resistance training

A

every exercise movement begins with lower resistance and ends with high resistance which is contrary to the force capability pattern

118
Q

muscle groups show a drop off in force capability towards …

A

the end of the range of motion

119
Q

the problem with band training for vertical jumping

A

least resistance at start where force is applied, most resistance after muscle has contracted, risk for injury with being pulled to the floor

120
Q

activity with high injury risk

A

team sports

121
Q

activities with intermediate injury risk

A

running, aeroics

122
Q

activities with low injury risk

A

cycling, walking, resistance training

123
Q

resistance training injuries per 1,000

A

4/1,000

124
Q

the back muscles act at a great

A

mechanical disadvantage

125
Q

deep squatting positions are not necessarily associated with

A

back injury

126
Q

85-90% of all intervertebral disk herniations occur at

A

between L4-5 or L5-S1

127
Q

the valsalva maneuver is not necessary for generation of

A

intra-abdominal pressure

128
Q

an advantage of the valsalva maneuver is

A

it increases the rigidity of the entire torso, making it easier to support heavy loads

129
Q

a disadvantage of the valsalva maneuver is

A

it can put pressure on the heart, making it more difficult for blood to return to the heart

130
Q

valsalva maneuver can transiently, slightly raise

A

blood pressure

131
Q

the glottis and ab muscles can contract without the valsalva maneuver and this must be regarded as

A

safer than using the valsalva and used for most resistance training

132
Q

a weight belt is not needed for exercises that

A

do not directly affect the lower back

133
Q

lifting belts should not be worn while performing

A

lighter sets

134
Q

the shoulder joint is particularly prone to injury during resistance training because…

A

of its structure and the forces it is subjected to. It is not a true socket

135
Q

the shoulder joint has the greatest

A

ROM of any joint in the body

136
Q

the knee is prone to injury because

A

of its location between two long levers

137
Q

the patella’s main function is to

A

hold the quadiceps tendon away from the knee’s axis of rotation, thereby increasing the moment arm of the quadriceps

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