Gait Cycle Flashcards
the fundamental component of human locomotion
the gait cycle
one complete gait cycle starts/ends
anatomical interactions occurring
start = moment foot first contacts the ground
end = moment same foot again makes ground contact with next step
any event can actually be chosen, but initial contact most convenient
2 phases of gait cycle
stance + swing
stance phase
lower extremity contacting the ground
AKA support phase or contact phase
initial contact to toe off
swing phase
lower extremity is swinging through the air preparing for the next impact
typical gait cycle duration and phase timing when walking
1 second duration
- 6s stance
- 4s swing
3 subdivisions of stance phase
contact, midstance, propulsive period
open-chain motions
swing phase
distal end of kinetic chain freely mobile
closed-chain motions
stance phase
distal end of kinetic chain is fixed by ground-reactive forces
walking % stance phase contact/midstance/propulsive period
contact = 27% (0-27%)
midstance = 40% (27-67%)
propulsive period = 33% (67-100%)
running % stance phase contact/midstance/propulsive period
contact = 20% (0-20%)
midstance = 25% (20-45%)
propulsive period = 55% (45-100%)
contact period
first part of stance phase
beginning at touchdown and ending when entire forefoot makes ground contact
midstance period
second part of stance phase
body’s center of mass is “vaulting” over the stance phase foot
propulsive period
final part of stance phase
beginning with heel leaving the ground and ending when tips of the phalanges no longer make ground contact
stance phase periods % of entire gait cycle
contact = 18% (0-18%)
midstance = 24% (18-42%)
propulsive period = 20% (42-62%)
keys (determinants) to metabolically efficient gait
pelvic rotation pelvic tilt knee flex/ext during stance hip-ankle-knee interactions lateral pelvic displacement
in terms of energy: metabolically efficient gait
translate center of mass through space along path requiring least expenditure of energy
flattening of the pathway of the center of mass through space
is having a flat pathway of the center of mass through space best
no; metabolically expensive (e.g. exaggerated knee flexion)
defining difference between walking and running
center of mass during midstance
walking = high point
running = low point
can airborne phase be used to distinguish walking from running
no; slow running has no airborne phase
Weber paradox
when a muscle is fully stretched or shortened, contact between the muscle filaments is diminished and the muscle is weakened
how does Weber paradox apply to gait
explaining walk-run transition preferences; walking slowly, running fast preferred over walking quickly and running slowly
2 requirements for initiation of gait cycle
1 postural adjustment (interactions between proprioceptive and motor systems)
2 motor commands for volitional movement
what makes initiation of gait cycle complex
motor circuits for postural adjustments and motor commands for volitional movement function independently
2 pitfalls of “normal” gait
1 needs to be chose for the individual (e.g. elderly female vs physically fit young man)
2 differing from normal does not necessarily mean undesirable or requiring correction
7 major events during gait cycle
1 initial contact 2 opposite toe off 3 heel rise 4 opposite initial contact 5 toe off 6 feet adjacent 7 tibia vertical
7 periods during gait cycle
1 loading response (stance) 2 mid-stance 3 terminal stance 4 pre-swing (stance) 5 initial swing 6 mid-swing 7 terminal swing
cycle time
duration of a complete gait cycle
double support
initial contact for one foot occurs while other foot is still on the ground
AKA double limb stance
single limb stance
during swing phase on the left side, only the right foot is on the ground
AKA right/left single support
leading leg in double support
leg in front
in loading response AKA braking double response, initial double support, weight acceptance
trailing leg in double support
leg behind
in pre-swing AKA weight release or second/terminal/thrusting double support
phase that occurs in some forms of running, differing from walking
flight phase AKA float, double-float, non-support phase
replaces double support phase; neither foot is on ground
stride length (meters)
distance between two successive placements of the SAME foot
consists of two step lengths (L/R)
step length (meters)
distance one foot moves in front of another; DIFFERENT feet
step length in pathological gait
typically different between R/L
e.g. one foot takes a step forward, the other is brought up beside it, step length = 0 or even a negative value
stride length step length in pathological gait
always the same L/R unless individual walking around a curve (inside leg shorter)
drawback to stride definition
non-pathological gait cycle = consists of one step by each foot
some pathological cycles = consists of HOPPING on same foot while other foot is in the air
walking base (millimeters)
side-to-side distance measured between the line of the two feet
usually measured at midpoint of back heel, but sometimes below center of ankle joint
AKA stride width or base of support
walking base = 0
tandem gait = one foot placed directly in front of the other while walking
toe out/in (degrees)
angle between the direction of progression and a reference line on the sole of the foot (typically midline of foot, judged by eye)
utilized coefficient of friction
ratio of horizontal to vertical forces acting on foot; determines if foot slips (utilized coefficient > actual coefficient between foot/ground)
0.35-0.40 generally sufficient to prevent slippage
cadence
number of steps taken in a given time
measure of half cycles (bc two steps in a cycle)
speed of walking (m/s)
distance covered by whole body in a given time
step factor
step factor = step length / leg length
account for differences in size; speed may be expressed in statures per second
walk ratio
walk ratio = step length / step rate
butterfly diagram
representation of ground reaction force vector at 10 ms intervals progressing from L to R
redundancy of muscular system
if a particular muscle cannot be used, its functions may be taken over by another muscle or group of muscles
5 main functions of walking gait
1 support head, arms, TRUNK via semirigid lower limb
2 maintain upright posture + BALANCE
3 control FOOT to clear obstacles and gently land (eccentric)
4 generate mechanical energy (concentric) to influence VELOCITY
5 SHOCK ABSORPTION and stability, reduce forward velocity of body (eccentric)
3 functional tasks required in gait, which is why patterns tend to be variable pre-7 yrs
1 forward progression in a range of speeds
2 body balanced alternately on each limb
3 support of upright body
3 ways to measure different aspects of gait analysis
1 force platforms (ground reaction forces)
2 electromyography (muscle activity)
3 high-speed video motion analysis system (movement)
spatial descriptor gait
Foot in space
stride length, step length, step width, foot angle
temporal descriptor gait
Foot in time
cadence, stride time, step time
