Normal and Pathological Gait Flashcards
how many steps does an adult take on average a day
5000 steps
- 4km per day
what are features of human gait
bipedal
reciprocating
upright
terrestrial
what are functional requirements of gait
shock absorption
stability
propulsion
energy conservation
why do we need shock absorption during gait
prevent damage to joints
what stability is required during gait
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)
what are four gait factors that affect stability
step width
step length
cadence
speed
what parts of gait require energy
(gait is inherently efficient)
step to step transition
swinging leg through
balance control
aberrant movement and muscle activation
what is normal toe clearance in walking
around 1.2 +/- 0.4cm
what is the stride length equal too
right step length + left step length
can stride length be asymmetrical ?
no - always symmetrical
step lengths can be asymmetrical however
how is stride time calculated
inverse of cadence
what is a stride defined as
initial contact of one foot until the next initial contact of the same foot
how long is the stance phase of the gait cycle and the swing phase
stance - 60%
swing - 40%
what is double support during the gait cycle
period when both feet are in contact with the ground
what is a stride composed of
2 x DS + 2 x SS
what are the phases of the gait cycle
initial contact loading response mid stance terminal stance pre swing initial swing mid swing terminal swing
what is the most common model for clinical gait analysis
divide body into “rigid” segments connected by pin joints with 3 degrees of freedom
then need motion capture
then can calculate joint angles
what is Newton’s 1st law
if the net force on an object is zero, then the objects remains in rest (i.e. velocity of the object is constant)
what is Newton’s 2nd law
force = mass x acceleration
what is Newton’s 3rd law
every action has an equal and opposite reaction
what does the GRF related to
the acceleration of the COM
what is the vertical force related to
vertical acceleration of the COM
what is the anterior-posteror force related to
forward acceleration of the COM
what is the medial-lateral force related to
medial acceleration of the COM
what are the factors of kinetics
forces
moments
powers
what is moments and the equation for it
turning effect about a point
M = F x d
what is the equation for power
Power = moment x angular velocity
what is power generation
internal moment and angular velocity in the same direction
what is power absorption
internal moment and angular velocity in opposite directions
how can net moments be estimated
from GRF magnitude and orientation relative to anatomical joint centres
