Normal and Pathological Gait

Question 1

how many steps does an adult take on average a day

Answer 1

5000 steps

- 4km per day

Question 2

what are features of human gait

Answer 2

bipedal
reciprocating
upright
terrestrial

Question 3

what are functional requirements of gait

Answer 3

shock absorption
stability
propulsion
energy conservation

Question 4

why do we need shock absorption during gait

Answer 4

prevent damage to joints

Question 5

what stability is required during gait

Answer 5

joint stability
- prevent bucking of joints against gravity

global stability
- keep centre of mass within base of support (speed, step length, foot position)

foot clearance
- prevent stumbling (knee flexion, ankle dorsal flexion)

Question 6

what are four gait factors that affect stability

Answer 6

step width
step length
cadence
speed

Question 7

what parts of gait require energy

Answer 7

(gait is inherently efficient)

step to step transition

swinging leg through

balance control

aberrant movement and muscle activation

Question 8

what is normal toe clearance in walking

Answer 8

around 1.2 +/- 0.4cm

Question 9

what is the stride length equal too

Answer 9

right step length + left step length

Question 10

can stride length be asymmetrical ?

Answer 10

no - always symmetrical

step lengths can be asymmetrical however

Question 11

how is stride time calculated

Answer 11

inverse of cadence

Question 12

what is a stride defined as

Answer 12

initial contact of one foot until the next initial contact of the same foot

Question 13

how long is the stance phase of the gait cycle and the swing phase

Answer 13

stance - 60%

swing - 40%

Question 14

what is double support during the gait cycle

Answer 14

period when both feet are in contact with the ground

Question 15

what is a stride composed of

Answer 15

2 x DS + 2 x SS

Question 16

what are the phases of the gait cycle

Answer 16

initial contact
loading response 
mid stance
terminal stance
pre swing 
initial swing 
mid swing 
terminal swing

Question 17

what is the most common model for clinical gait analysis

Answer 17

divide body into “rigid” segments connected by pin joints with 3 degrees of freedom

then need motion capture

then can calculate joint angles

Question 18

what is Newton’s 1st law

Answer 18

if the net force on an object is zero, then the objects remains in rest (i.e. velocity of the object is constant)

Question 19

what is Newton’s 2nd law

Answer 19

force = mass x acceleration

Question 20

what is Newton’s 3rd law

Answer 20

every action has an equal and opposite reaction

Question 21

what does the GRF related to

Answer 21

the acceleration of the COM

Question 22

what is the vertical force related to

Answer 22

vertical acceleration of the COM

Question 23

what is the anterior-posteror force related to

Answer 23

forward acceleration of the COM

Question 24

what is the medial-lateral force related to

Answer 24

medial acceleration of the COM

Question 25

what are the factors of kinetics

Answer 25

forces
moments
powers

Question 26

what is moments and the equation for it

Answer 26

turning effect about a point

M = F x d

Question 27

what is the equation for power

Answer 27

Power = moment x angular velocity

Question 28

what is power generation

Answer 28

internal moment and angular velocity in the same direction

Question 29

what is power absorption

Answer 29

internal moment and angular velocity in opposite directions

Question 30

how can net moments be estimated

Answer 30

from GRF magnitude and orientation relative to anatomical joint centres