Intro to gait Flashcards
How does walking and gait change through the life span
-as a kid it is hard too balance because the head is a large percentage of our weight
-as an adult you have a better walking pattern and balance
-in the elderly, posture changes to a forward and flexed posture and they take smaller strides.
What are requirements for gait
-to balance HAT in erect posture
-transfer HAT from one LE to the other
-lift each LE and move it forward
-coordination
-balance
-kinesthetic and proprioceptive senses
-integrity of joints and muscles
What are the tasks involved in walking
-weight acceptance: the leg has two hold the body
-single limb support: this way the other limb can advance
-swing limb advancement
Tasks for ambulation (what is required to happen for normal gait)
-maintenance of support of HAT against gravity
-maintenance of upright posture and balance (spine, head and hip position)
-control of foot trajectory: straight in front
Ways to analyze gait
-cinematography: videos and pictures
electrogoniometry: track ROM
force plate: look at ground contact
EMG: what muscles are active
observations
What is 1 gait cycle
right heel contact to the next right heel contact
OR
left heel contact to the next left heel contact
What is right step length
right heel to left heel (1/2 the stride)
what is left step length
left heel to right heel (1/2 the stride)
stride
distance from right heel to right heel
foot angle
how much toe out there is
-measured from the line of progression to the 2nd toe (the angle)
what is step width
distance between heel contracts o left and right (BOS)
What happens to the gait generally where one limb is in pain
decrease time in stance on that LE which affects how far the opposite LE can step
-decrease step length for opposite side
What happens generally to gait for a hemiparesis patient
cannot advance involved side or stand on involved side
-decrease step length on both sides
What happens generally to gait in Parkinson’s patients
not a lot of single leg stance
-shuffle feet
What are the time or temporal variables of gait
-stance time
-single support time
-double support time
-stride time
-cadence
-walking speed
-acceleration
Stance time
amount of time the LE is in the stance phase
-in total about 60%
single support time
total amount of time reference leg is in stance with the other LE in the swing phase
-COM is at its highest
-about 40% of the time
Double support time
Total amount of time reference leg is in stance phase with the other LE not in the swing phase
-COM is lowest
-about 20% of the time
Stride time
0-88-1.2 seconds ~ 1 second for a normal gait cycle
(time of one gait cycle)
Step time
0-44-0.6 seconds
-should be about half the time of the stride time
cadence
1.87 steps/sec (100 steps/min)
-how many contacts per second
-females tend to be quicker and males tend to take longer steps.
walking speed
1.37 m/sec (3mph)
acceleration
change in speed/direction
How can you get more speed with your gait
more speed can be achieved by bringing the weight closer to the joint axis
-the body does this by increasing hip, knee and dorsiflexion
What are the 2 general main phases of gait
swing phase 40% and stance phase 60%
What are the phases of stance relative to the support and how long are you in those phases
double limb support -20%
single limb support - 80 %
What are the steps of gait from older gait textbooks
heel contact
-foot flat
-mid stance
-heel off
-toe off
(heel off and toe off make up the push off phase)
-early swing
-mid swing
-late swing
Loading response
accepting the weight onto the limb
pre swing
getting ready to advance
initial swing
toe off ground
mid swing
limb is bring brought forward to about even with the other foot
-need to be able to clear the floor
terminal swing
the LE is being swung out in front of body
-reaching forward to put the foot down
What are the stance periods in order
-initial contact: normally the heel
-loading response: accepting the weight
-midstance: from opposite LE toe off to when it is level with the stance leg
-terminal stance: from mid stance to opposite initial contact
-pre swing: getting ready to advance
-toe off: normally 1st or 2nd toe is most of push up
Determinants of Gait
COM- they minimize the movement of COM to make it more effective
-pelvic rotation
-lateral pelvic tilt
-knee flexion at mid stance
-ankle mechanisms
-foot mechanism
-physiologic valgus at the knee
How is pelvic rotation a determinant of gait
occurs in the transverse plane and is necessary for limb advancement
How is lateral pelvic tilt a determinant of gait
occurs in the frontal plane
-as one foot steps, the pelvis drops slightly to keep the COM from going up too much
How is knee flexion at mid stance a determinant of gait
drops the COM a little
How is ankle and foot mechanisms a determinant of gait
related to limb length
How is valgus of the knee a determinant of gait
keeps COM closer to the center of the BOS
Energy requirements
-need energy to accelerate and decelerate segments of the body
-therefore speed of gait is based on energy - changing the speed will cost more energy for the body because they either have to speed up and accelerate or they have to the hold the limb in a decelerated sate
-metabolic energy to mechanical energy
-energy costs is the O2 consumption
Mechanical energy of walking (where is potential and kinetic highest and lowest)
the minimum potential energy is when COM is at its lowest
the Maximum potential energy is when COM Is at its highest
the minimum kinetic energy is when COM is at its highest
The maximum kinetic energy is when COM is at its lowest
Inertia and its relation to gait
-arises from internal properties of segments (the closer to the axis the distal end is the faster you move)
-directly proportional to mass of segment
-energy require to alter the velocity of the body
Describe the path of the center of pressure on the plantar surface of the foot
-COM goes through the foot
-heel then goes more laterally and then goes back medially through the big toe and some of the second toe
where do you get the ground reaction force
during the heel strike and then toe off phase
Describe the toques generated by ground reaction forces at the heel contact
-plantar flexion torque: external plantar flexion moment
-eversion torque goes medial towards the knee from the posterior view causing a varus torque at the knee
what do moments do
cause a rotation at a joint in a particular direction
