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6 > Gait cycle > Flashcards

Gait cycle Flashcards

1
Q

definition of the gait cycle

A

movement pattern beginning and ending with ground contact of the same foot (e.g., right heel strike to right heel strike)

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2
Q

2 phase of the gait cycle with their percentage

A

Stance (~60%) vs. swing (~40%) (swing = in the air)

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3
Q

step

A

movement of a limb (e.g., left) from ground contact of that limb to ground contact of the opposite side (e.g., right)

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4
Q

stride

A

movement of both limbs during 1 gait cycle (2 steps consecutives)

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5
Q

the percentage of double-limb support / single-limb support

A

Double-limb support (two periods for ~10% of gait cycle) vs. single-limb support (90%)

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6
Q

stance phase

A

limb in contact with the ground

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7
Q

basic tasks of stance phase in locomotion

A
  1. Provide adequate support.
  2. Absorb shock of impact between the limb and the ground
  3. Provide adequate forward and backward force for progression.
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8
Q

what is the overarching goal of gait?

A

is to progress forward.

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9
Q

Basic tasks of swing phase in locomotion:

A
  1. Safe limb clearance
  2. Appropriate limb placement
    for next contact
  3. Transfer of momentum
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10
Q

étape of the stance phase

A
  • Loading response
    Initial contact + Foot flat
  • Midstance: most of single-limb support
  • Heel off ~30-40% of gait cycle
  • Terminal stance : Ends at opposite foot initial contact
  • Pre-swing
  • Toe off
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11
Q

stance phase in term of support

A

1- double support (10%)
2- single support (40%)
3- double support (10%)

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12
Q

swing phase in term of support

A

1- single support (40%)

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13
Q

kinematics of locomotion include

A
  • Temporal parameters
  • Distance parameters
  • Angular joint displacement
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14
Q

Factors affecting kinematic gait characteristics.

A
  • Walking speed
  • Age
  • Height
  • Weight/BMI
  • Aerobic conditioning
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15
Q

most kinematic gait analyse examine what ?

A

displacement characteristics

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16
Q

2 ways to walk faster

A
  1. Increase cadence (steps/minute)
  2. Increase step length
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17
Q

walking vs running

A

Absence of double limb support in running

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18
Q

Speed & the gait cycle

A
  1. Increased speed = decreased cycle duration
  2. As stance (less) (with little change in swing), double-support (less) & single-support (increase)
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19
Q

what the walking speed affects

A

swing and stances times differently

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20
Q

tall person vs short person

A
  • Tall = cover more distance base on the step length
  • The shorter one need to increase the frequency
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21
Q

Inverted Pendulum Model + equation

A
  • Potential energy (PE)
  • Kinetic energy (KE)
  • Total energy (TE
  • TE = KE + PE = always at equilibrium
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22
Q

an ideal pendulum maintains:

A
  • oscillation with no additional energy input by transforming PE to KE
  • PE and KE related to distance of a body’s COM from the Earth, and to the body’s linear & angular velocity.
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23
Q

inverted pendulum model

A
  • Changes at one joint would likely produce changes in movement patterns throughout the body, reducing the efficiency of the movement.

Just enough kinetics energy to the continue of the movement.
And progress the motion.
- Locomotion with little energy

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24
Q
  • Pathway of the center of mass
A
  • A – lateral displacement
  • B – vertical displacement
  • C – combined displacements of A & B
25
Q

what is the goal of the COM displacement of the body / center of mass

A

to limit unnecessary displacement of COM when walking (up/down + side/side)

26
Q

is COM path changes with speed?

A

YES

27
Q

joint angles

A
  • Variability in magnitudes of joint displacement exist for healthy gait, but the joint sequencing patterns tend to be very consistent across trials and subjects.
28
Q

ground reaction force

A
  • if something on the graph = the person is standing on the ground
    nothing = no contact with the ground
29
Q
  • COM acceleration
A

Upward accleration

30
Q

upward COM

A

acceleration over 100% BW

31
Q

negative acceleration (acceleration towards the ground)

A

less than 100% BW – occurs during single limb support

32
Q

inverse dynamics

A

Calculate net joint forces and moments of force (torque) from kinematic information (e.g., acceleration), inertial (e.g., mass) properties, and external forces (e.g., GRF)

33
Q

forward dynamics

A

Know force in muscles, joints, etc. and predict movement

34
Q
  • Link segment
A

break body into segments
(e.g., foot, shank, thigh)

35
Q

Newton’s 2nd law:

A

unbalanced force produces an acceleration
* ΣF = ma; ΣM = Iα
* α = angular acceleration

36
Q

Newton’s 3rd law:

A

for every force, there is an equal (magnitude) and opposite (direction) force

37
Q

Net external moments

A

moments applied to the joint due to external forces (e.g., GRF, gravity)

38
Q

Net internal moments

A

moments applied to the joint by muscles and soft tissue

39
Q

the joint moments (torque) represent what

A

the net moments (summation) from all muscles, ligaments, and other soft tissues

40
Q

what the internal moments allow us

A

to create rotations in the body

41
Q

where are the external moments

A

outside forces acting on the body

42
Q

you can see how the relationship between GRF and knee moments changes throughout the gait cycle

A
  • The way the limbs are spaced and the way the force vectors with respect to the limb joints occur with respect to the hip and/or knee, we have different types of extension and flexion moments being produced
43
Q

Power =

A

= rate of doing work (in watts)
= joint moment x angular velocity = M x ω

44
Q

Concentric =

A

generate power (+ive)

45
Q

Eccentric =

A

absorbs power (-ive)

46
Q

Power contributions vary by what

A

joint and phase of the gait cycle

47
Q

Muscle activation is measured using what

A

electromyography (EMG)

48
Q

contractions

A
  • Eccentric: lengthen
  • Concentric: shorten
  • Isometric: no change
49
Q

tibialis anterior

A
  • Most active during the early phase of stance and active during the swing phase
  • Swing phase: activated to keep the toes off of the ground to prevent tripping
  • Stance phase:
    When we think of the foot, the tibia attaches ankle, which is slightly in front of the heel
  • When we strike the floor at heel strike, the GRF will act at the back of the heel, which will want to cause “foot slap”
50
Q

what prevents foot slap during heel strike

A

contraction of the tibias anterior

51
Q

triceps surae

A
  • Gastrocnemius and soleus muscles
  • Most active during the single support phase of stance phase
  • Loading up eccentrically (during early phases of stance, they are loading up and stretching), then they begin to shorten/concentrically contract during the late phases of stance to propel us forward
52
Q

Quadriceps

A
  • Active preceding initial contact through opposite toe off as well as during the late phases of stance
  • Turn on in synchrony with hamstrings before initial contact to provide stability and balance to the knee joint (equal tension on both sides to keep the joint stiff)
  • As we are extending our foot during the late phases of the swing phase, we need control about multiple joints to fine tune where our foot is going to go
  • Acting to help the knee joint to get to extension before initial contact
  • Activity during the late stance phase is the rectus femoris acting as a hip extensor
53
Q

Hamstrings

A
  • In walking, the hamstrings slow down the “whip” of the knee before initial contact during swing phase
  • As leg gets brought through, in order to slow it down, the hamstrings engage in the late swing phase and early stance phase
  • ## They also work in harmony with the quadriceps to keep the knee joint stiff
54
Q

Iliopsoas

A
  • Exclusively a hip flexor
  • Activate during early swing phase to bring the leg forward
55
Q

Gluteus maximus

A
  • Major hip extensor
  • Active preceding initial through the early stages of stance
  • Engage this muscle in order to keep the hip extended, prevent us from collapsing to the ground
56
Q

Stretch-shortening cycle

A
  • Muscle activity starts eccentric contraction (stretch) then switches to concentric contraction (shortening)
  • Efficient way to generate muscle force
    and store energy
57
Q

where the energy is stored

A

in stretch muscle

58
Q

how the SSC is used by most muscles during gait

A

as an efficient means of generating muscle force and storing energy

59
Q

Most muscles decelerate limb movements then accelerate the limb in the opposite direction?

A

yes

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