Gait and Posture Analysis Flashcards
What are the 2 main functions of the lower kinetic chain?
- To provide a stable BOS in standing
- To propel the body through space with gait
What can be defined as controlled instability?
gait
What are the 3 essential requirements of gait?
- Progression
- Postural control
- Adaptation
What can be defined as the interval of time between any of the repetitive events of walking?
the gait cycle
What are the 2 phases of gait?
Stance and swing
What percentage of the gait cycle consists of the stance phase? Swing phase?
stance: 60-65%
swing: 35-40%
What are the 3 tasks of the gait cycle?
- weight acceptance
- single limb support
- limb advancement
What does weight acceptance include?
the intervals of initial contact and loading response
Initial contact interval accounts for the first __% of the gait cycle
10%
What does single-leg support include?
midstance, terminal stance, and preswing
Describe midstance
It is the time in which one foot is being lifted until the body weight is aligned over the forefoot
*the first half of the single-limb support task
When does the terminal stance begin and end?
Begins when the heel of the weight-bearing foot lifts off the ground and continues until the contralateral foot strikes the ground
When does preswing begin and end?
Begins with initial contact of the contralateral limb and ends with the ipsilateral toe-off
What does the swing phase involve?
the forward motion of the NWB foot
What are the 3 intervals during the swing phase?
- Initial swing
- Midswing
- Terminal swing
When does initial swing begin and end?
Begins with the lifting of the foot from the floor and ends when the swinging foot is opposite the stance foot
When does midswing begin and end?
Begins as the swinging limb is opposite the stance limb and ends when the swinging limb is forward and the tibia is vertical
When does terminal swing begin and end?
Begins with a vertical tibia of the swing leg with respect to the floor and ends the moment the foot strikes the floor
What is normal step width and what does it form?
Normal is 5-10cm (2-4”) and it forms the BOS
What can be defined as the distance between the point of initial contact of one foot and the point of initial contact of the opposite foot?
Step Length
What is average step length?
About 28”
What can be defined as the distance between successive points of foot to floor contact of the same foot?
stride length
What makes up a stride length?
2 step lengths added together (56”)
What is the normal cadence of gait?
90-120 steps per minute
During gait, the vertical ground reaction force is created by what?
a combination of gravity, body weight, and the firmness of the ground
When do the 2 peaks during the gait cycle occur?
- 1st at maximum limb loading during the loading response
- 2nd during terminal stance
Do men or women tend to experience greater cumulative ground reaction forces? Explain why…
Women, because their legs account for a smaller percentage of total body height which means they must strike the ground more often to cover the same distance
What does gait involve?
The displacement of body weight in a desired direction
What are the 5 priorities of normal gait?
- Stability of the weight bearing foot throughout the stance phase
- Clearance of the NWB foot during the swing phase
- Appropriate prepositioning of the foot during terminal swing for the next gait cycle
- Adequate step length
- Energy conservation
In order for gait to be efficient and to conserve energy what must/must not occur?
the COG must undergo minimal displacement
What are the 6 determinants have the potential to reduce the energetic cost of human gait?
- Lateral displacement of the pelvis
- Pelvic rotation
- Vertical displacement of the pelvis
- Knee flexion in stance
- Ankle mechanism
- Foot mechanism
What is normal lateral displacement of the hips?
1-2” in order to center body weight over the stance leg
What does the forward rotation of the pelvis on the swing side prevent?
an excessive drop in the body’s COG
What does the vertical displacement of the pelvis do?
Keeps the COG from moving superiorly and inferiorly more than 2” during normal gait
If there is a disruption in the vertical displacement of the pelvis, what occurs?
Trendelenburg sign
What does knee flexion during midstance prevent?
an excessive rise in the body’s COG during that period of the gait cycle
Normal gait requires __ degrees of DF & __ degrees of PF
10
20
Describe the ankle mechanism present during gait
The co-action of dorsiflexion and plantarflexion muscles produces a relative lengthening of the leg, which results in a smoothing of the COG during stance phase
Describe the foot mechanism present during gait
The controlled lever arm of the forefoot at preswing is helpful as it rounds out the sharp downward reversal of the COG
As the upper body moves forward, the trunk twists about a ____ axis
vertical
As the upper body moves forward, the thoracic spine and pelvis rotate in ____ directions
opposite