Midterm #3 Flashcards
(126 cards)
1
Q
sensory receptors in the muscle
A
muscle spindle
golgi tendon organs
2
Q
charcteristics of muscle spindle
A
located parallel to muscle fibers
monitor muscle lenght
limits stretch in muscle
3
Q
which muscle fibers/at what state do muscles need to be to be excited or inhibited by the muscle spindle
A
excitation of stretched muscle fibers and synergist muscle
inhibition of antagonist muscles
4
Q
location of golgi tendon organ
A
muscolotendinous junction
5
Q
charactersitics of golgi tendon organ
A
stimulated with stretch of tendon
inhibits muscle contraction
threshold can be changed with practive
protective mechanism
6
Q
mechanism of stretch shortening cycle
A
storage of enery in PEC and SEC
stimulation of muscle spindle reflex
algnment of cross bridges in slack muscle fibers
eccentric activation give more time for slow twitch fibers to develop tension
7
Q
what is a motor unit
A
a nerve and all the muscle fibers it innervates
8
Q
two main strategies of motor nuron activation
A
recruitment
rate coding
9
Q
what do the main strategies of motor neuron activation allow
A
large range of force
gradual change in force
10
Q
recruitment
A
activation via action potential of specific motor neurons
cause excitation and activation of muscle fibers
11
Q
result of recruitment
A
a muscle twitch - contraction
12
Q
muscle fibers within a motor unit
A
share similar characteristics
distirbuted randomly across muscle
1 muscle fiber controls 5-2000 muscle fibers
13
Q
lower innervation ratio
A
small # of motor units recruited
accurate movement
14
Q
high innervation ratio
A
large # of motor units recruited
15
Q
henneman size principle
A
small motor units recruited first then larger and large motor units
allows smooth and controlled increase in force
16
Q
rate coding
A
the force produced by motor unit is strongly regulated by rate of production of action potentials
17
Q
discharge rate of rate coding
A
from 10hz, 100ms intervals, up to 50hz
18
Q
twitch related to rate coding
A
messgae send as an interval
19
Q
unfused tetanus
A
no breaktime in incomeing APs
20
Q
fused retnus
A
maximal contraction
21
Q
how does a motor unit create greater overall force
A
when its activated at a higher rate
22
Q
eccentric activation
A
less motor units recruited compared to concentric
23
Q
what does it require to initiate a fast strong isometric contraction
A
use of rate coding
24
Q
component of muscle force
A
rotary component
stabilizing component/destabilizing component
25
rotary component
causes rotation
| perpendicular to the bone of insertion
26
stabilizing/destabilizing component
stabilizes or destabilizes joints
parallel to bone of insertion
causes compression or distraction
27
muscle adaptations to training
hypertrophy
| hyperplasia
28
hypertrophy
muscle growth -> increase in muscle force
increase in size of each muscle fiber
no change in # of fibers
29
hyperplasia
increase in # of muscle fibers
30
neural adaptation to training
```
increased strength without changes in cross sectional area
increased recruitment and rate coding
motor unit synchronization
increased coordination
inhibition of golgi tendon organ
```
31
increase in force production but no increase in EMG
strength gain due to neural factors
32
increase in EMG in direct correlation to the increase in force
strength gain due to hypertrophy
33
increase in force greater than increase in EMG, and increase in both
stregth gain due to neural factors and hypertrophy
34
what can strength training be largely attributed to
motor unit activation of the trained agonist muscle
35
when does chronic load lead to lengthened muscle adaptation
increase in sarcomere # by 20%
36
when does chronic load lead to shortened muscle adaptation
decreased sarcomere # by 40%
37
where are sarcomeres added
at the musculotendinous junction
38
which muscles are most adaptable
antigravity muscles
39
what will chronic use of high heels lead to
increased risk for lateral ankle sprain (increased plantarflexion)
increased risk for achilles tendon injury
40
categories of muscle architecture
longitudinal (fusiform)
| pennate
41
longitudinal muscle arrangements
anatomical and physiological cross sectional areas are equal
42
subsection of longitudinal muscle arrangements
fusiform
strap
radiate
43
subsections of pennate muscle arrangements
unipennate
bipennate
multipennate
44
unipennate muscle arrangements
one group of muscle fibers parallel to each other but oblique to the tendon
45
bipennate muscle arrangements
two groups of muscle fibers
oblique to each other an to tendon
within the group fibers parallel to each other
46
multipennate muscle arrangements
more than 2 groups of fibers
| fibers are parallel to each other within the group but oblique to other groups and tendon
47
physiological cross sectional area
perpendicular to muscle fibers
48
anatomical cross sectional area
perpendicular to midline of muscle
49
what does a greater pennation lead to
greater physiological cross sectional area -> larger force
50
different sarcomere arrangements within a muscle
parallel
| in series
51
which sarcomere arrangement has larger physiologicalcross section area (greater force)
parallel sarcomere
52
what advantage have sarcomeres in series
fast control of range of motion
53
what does the length of a muscle influence
the speed and distance a muscle can shorten
54
what is one gait cycle
step with left leg followed by step with right leg
| same as 1 stride
55
1 stride length (gait cycle length)
144 cm
56
walking speed
step length x step rate
| stride length x stride rate
57
phases of a gait
```
reference limb
stance phase
swing phase
single limb support
double limb support
```
58
what are the 3 tasks performed during 1 stride
accept weight on foot once it is on the ground
support weight on single leg
advance swing limb in front of body
59
critical elements for each phase of gait
weight acceptance
single limb support
swing limb advancement
60
weight acceptance
```
intial contact, loading response
contact floor with heel
stabilize hip
restrain knee flexion
restrain ankle, plantar flexion
```
61
single limb support
midstance -> stabilize hip in frontal plane, extend knee, restrain ankle dorsiflexion
terminal stance -> forward free fall, raise heel
62
swing limb advancement
preswing, initial swing, midswing -> flex knee and hip, dorsiflex ankle
terminal swing -> decelerate ankle and knee extension, neutral position of ankle
63
external forces during gait cycle
Ground Reaction Force
weight of body
intersegmental torque
64
internal forces acting during gait cycle
active - muscles
| passive - connective tissue
65
what dictates the type of external torque created at a joint at a specific time of the gait cycle
location of ground reaction force
66
what torques are generated by ground reaction force at heel contact
plantar flexion torque
| eversion torque
67
where oes most of the torque for propelling the body forward come from
ankle plantar flexion 53%
| hip flexion 30%
68
peak ground reaction forces during gait cycle
certical -> 120% BW
anterior-posterior -> 20% BW
medial-lateral -> 5% BW
69
running phases by Dr. Jackuelin Perry
stance
early float
middle swing
late float
70
stance
right heel strike to right toe off
35% of gait cycle
single limb stance
71
early float
right toe off to left heel strike
15% of gait cycle
both limbs are in the air
72
middle swing
left heel strike to left toe
35% of gait cycle
contralateral limb is in single leg stance
73
late float
left toe off to right heel strike
15% of gait cycle
both limbs in the air
74
ratio of stance to float in running
35% stance
| 65% float
75
phases within stance
loading response
mid stance
terminal stance
76
hip knee and ankle at lowest point of stance
hip 25F
knee 40F
ankle 20DF
77
ankle knee and hip motion during swing
ankle from 30 PF to 5 DF
knee from 10F to 100F
hip 10 Ext to 30F
78
what does float in running replace from walking
double limb support
| approxx. 2.1 m/sec
79
stance in walking and running
drops from 60% to 35%
80
angular displacement
is larger during running at the hip and the knee
81
foot position during running and walking
running -> rearfoot striker/midfoot and frontfoot
| walking -> rearfoot
82
ankle position in running vs. walking
running -> neutral position at initial contact, followed by dorsiflexion
walking -> neutral to plantar flexion
83
magnitude relation in walking vs. running
forces magnitude 2-4 times larger in running
84
highest/lowest potential energy during walking
highest: midstance
lowest: double limb support
85
highest lowest kinestic energy during walking
highest: double limb support
lowest: midstance
86
energy during running
elastic energy
kinetic energy
potential energy
87
kinetic energy during running
highest in float phase
88
potential energy during running
highest during float phase
89
major clinical problems faced by runners
muscle pveruse
pressure of floor contact
mechanics of eccentric contraction
90
what bones are at greater risk for injury during running
the first 3 metatarsal heads and the big toe
91
what may prolonged running lead to
stress fructure
92
what can help muscles to reduce risk of injury during running
strength and flexibility training
93
muscles that contract eccentrically
```
RF
Vastii
BFSH
BFLH
semimembranosus
```
94
when and where does strain occur
in tnedon and aponeuroses while muscles are contracting isometrically
95
what does faster running require
rapid and severe lengthening of tendons and aponeuroses
96
what can be done to prevent running injuries
increased strength and endurance of muscles
progressive tissue adaptation to eccentric load
cushioning
97
what is classified as fluids
liquids and gases that flow and change shape
98
fluid mechanics
study of forces tha fluids exert on objects
99
two different forces
buoyant force
| dynamic force
100
characteristics of buoyant force
due to immersion in fluid
vertical force
always acts upwards
101
what causes buoyant force
increase in depth -> linear increase in pressure
102
equation of buoyant force
pressure = force / unit area
103
2 findings of archimedes related to buoyant force
buoyant force is difference between the force acting upward and downward on an object
also equlas the weight of the volume of fluid displaced by the object
104
what should the weight of an object be to float
needs to be equal to the weight of the fluid
105
weight of an object to accelerate up/down in water
accelerate up -> object needs to be lighter than the weight of the fluid
accelerate down -> object needs to be lighter to accelerate down
106
specific gravity
weight of an object / weight of an volume of water
107
what is another way to determine if an object sinks or floats
density = mass/volume
108
dynamic fluid force
force due to relative motion
109
what is dynamic fluid force proportional to
fluid density x surface area of the object x relative velocity
110
relative velocity
compares my velocity to the velocity of air
| difference between both the velocity of fluid and an object
111
in what is dynamic fluid force resolved into
drag force
| lift force
112
drag force
acts in opposite to relative motion of the object
will tend to slow down the relative velocity of the object
produced by surface drag and form drag
113
calculation of drag force
1/2 coefficient of drag(roughness of surface) x density of fluid x area of object x relative velocity (squared)
114
surface drag
sum of driction forces between fluid and suface of object
115
what increases surface drag
higher viscocity
116
form drag
sum of impact between object and fluid molecules
| increases as the amount of turbulent flow increases
117
turbulent flow
fluid molecules separate from the surface
118
laminar flow
molecules of the fluid stay close to the object and press against it
119
what reduces stream force
```
smoother body surface
streamline the shape of the body
lower air density - warmer air
reduce surface area exposed to flow
use wind
drafting
```
120
lift force
dynamic fluid component that acts perpendicular to relative motion of object
121
direction of lift force
determined by direction of flow of fluid
| perpendicular to the flow of fluid
122
what causes lift force
lateral deflection of fluid molecules as they pass an object
123
what kind of force is used at an airfoil
the net force generated is lift force
124
Bernoulli´s Principle
faster moving fluids exert less pressure than slower moving fluid
fluids on a curved surface move faster than on a straight surface
125
why did ski jumpers change the position to a V position
to increase the surface area -> increase the lift
126
magnus effect
curving of a ball in the air
if backspin, motion of the air molecules at the top of the ball is slower
motion of air molecules at the bottom of the ball move faster
down motion of ball due to Bernoulli´s Priniple
