Week 8: gait Flashcards
What is gait
Walking
Cyclical
repetitious sequence of limb motions to move body forward
Two stages of gait
- Stance: foot in contact with ground
- Swing: no ground contact
Percentage of gait cycle
Stance 60%
Gait
The manner or style of walking
Gait cycle
A fundamental unit to describe the gait during ambulation. This occurs from the time when the heel of one foot strikes the ground to the time at which the heel of the same foot contacts the ground again.
Stride length
The interval between 2 sequential initial floor contacts from the same limb
Step length
The interval between an initial contact from one foot to the initial contact of the other foot
Heel strike
The onset of stance made by the contact of the heel onto the ground
Toe off
The lift off of the big foot from contact point on the ground
Ground reaction force
The force exerted by the ground of a body in contact with it
Stance phase
The entire period during which the foot is on the ground
Swing phase
The time the foot is in the air
Loading response
Body weight transfer from initial contact through until the opposite limb is lifted for swing
Mid stance
Initial phase of single leg support where momentum moves mass over forefoot.
Terminal stance
Completes single leg support. Body weight moves ahead of forefoot
Pre swing
Final phase of stance, represents functional commitment to initiating forward motion prior to swing phase
Initial swing
The lift off the foot from the floor
Mid swing
Middle area of swing when foot is opposite the stance foot
Terminal swing
Last phase of swing in preparation for initial contact
During gait lower limb muscles function to
- Produce appropriate movements required for locomotion
- Accelerate/decelerate body parts
- Stabilise body parts for efficient movement
Hip motion range
from 30° flexion to 20° extension (total range 50)°
Hip motion allows what
pelvis & trunk to remain erect whilst body weight moves over supporting foot
Knee motion range
ranges from approx. 60° flexion to 0° extension (total range 55° to 60°)
Knee motion allows what
- Key to stance stability
- Reduces the length of the swinging limb and hence facilitates foot clearance in swing phase
Ankle motion range
ranges from 20° plantarflexion to 5° dorsiflexion (total range 25°)
Ankle motion phase 1
Plantarflexion reduces impact of heel contact at loading response
Ankle motion phase 2
Dorsiflexion through mid-stance to terminal stance facilitates advancement of body weight over foot
Ankle motion phase 3
Plantarflexion prepares limb for swing phase by transforming extended knee into freely flexing joint
Ankle motion phase 4
Dorsiflexion during swing allows for foot clearance
Coronal pelvic motion is what
lift/drop around an AP axis
Coronal pelvis motion activates what
contralateral (supported limb) gluteus medius and minimus limit drop during stance phase
Failure of coronal pelvic motion causes what
Trendelenburg gait (weakness of hip abductors on stance leg)
Sagittal pelvis motion is what
tilt around a transverse axis
Trunk movements during gait
At thorax & shoulder
- Posterior (backward) over swinging limb
- Upper limb swings forward with contralateral lower limb
Centre of gravity
imaginary point that represents the concentration of the weight of the body
- Can be inside or outside the body, dependent on body position
- Static anatomical position: CoG falls just anterior to the vertebra S2
- Is at its highest level during mid-stance phase of gait.
Vertical movements of CoG
- Approx. 3-5 cm in amplitude
- Highest point: mid stance
- Lowest point: double support
Lateral movements of CoG
- Due to lateral transference of body weight from one leg to the other
- Approx. 4cm total (2cm each side)
- Largest displacement: mid stance
We need to limit the amount of movement of CoG to
- Minimise energy expenditure
- Limit wear and tear on musculoskeletal system
Factors limiting movements of CoG
(vertical)
- Inversion/eversion of foot during stance -> limits inferior and superior excursion of CoG
- Plantarflexion @late stance phase -> limits inferior excursion of CoG
- Anterior pelvic rotation during swing -> limits inferior excursion of CoG
- Knee flexion during support phase -> limits superior excursion of CoG
- Anterior pelvic tilt during swing phase (with knee flexion @early swing) -> limit superior excursion of CoG
Factors limiting movements of CoG
(lateral)
- Width of base of support
