Locomotion Flashcards
Define locomotion
Variety of movements or methods that animals use to move from one place to another.
Define activity
Task you perform in your daily routine or in the context of your social activity. It requires multiple structures and functions.
Do you need big samples to assess gait cycle in the context of treadmill walking ?
No. In this conditions the gait cycle is a rhythmic pattern performed without consciousness (automatically). Its structure is repeated over and over.
Define human gait
It’s a type of locomotion, that uses movements sequences of several body segments in order to propel the body forward with the least energy expenditure.
What are the different perspectives when studying gait ?
- kinetics : study of forces acting in muscles
- kinematics : study of the movements taking place when walking
- dynamic and static posture analysis
- motor control : study of the motor planning and execution
- research : focused on properties and alteration of the gait
- clinical/ functional assessment : the use of references to identify the abnormal
What are the characteristics of human gait ?
- spatial : considering the stride length and the step length
- temporal : considering the speed and the cadence
Define stride length and stride width
Stride length : the distance you cover when you do 2 steps. It equals to a gait cycle.
Stride width : how distant the feet are from the center line from a frontal plane perspective. It can be negative. The reference is the width of the pelvis.
Define the angle of progression ?
The angle of rotation present in the lower limp when walking.
Define speed and cadence
- speed : is the distance covered in an hour. The average is 4,5 km/h but it depends on the person’s preference and not only their morphology.
- cadence : is the number of steps per minute. The average is from 60 to 120 steps/ minute.
How can you modulate the gait speed ?
By modifying the cadence or the stride length.
What are the requirements for normal gait
- upright position with the body weight equally supported by the lower limbs
- proper weight transfer
- center of mass projection within the base of support
- constant sensorial information (ex: visual, proprioceptive)
Define gait cycle and describe its two main phases
It is the time from when the foot touches the ground to the time it touches it again. It is composed by stance phase which represents 60% in normal gait cycle and swing phase which represents 40% of normal gait cycle.
What are the different interphases of the stance phase ?
All the different moments when your foot is in contact with the ground :
- heel strike
- foot flat
- mid stance
- heel-off
- toe-off
What are the interphases of the swing phase ?
- acceleration
- mid-swing
- deceleration
What are all the interphases of the gait cycle ?
- STANCE PHASE :
Heel strike Foot flat Mid-stance Heel off Toe off
- SWING PHASE :
Acceleration
Midswing
Deceleration
What happens to the duration of stance phase when you accelerate the speed ?
The foot spends less time on the ground and the stance phase proportion is reduced.
What are the requirements to achieve stability in the gait cycle ?
- motor control
- proper plantar function / structure
- proper strength levels
Name two structures that can influence the limb progression
- opposite plantar flexors
- hip extensors
Describe what happens during the first foot rocker
- loading response
- OKC
- fulcrum = ankle
- plantar flexion
- eccentric contraction of the dorsi flexors
Describe the second foot rocker
- CKC
- fulcrum = ankle
- tibial motion over the foot
- ankle dorsiflexion
- foot is not moving
Describe the third foot rocker
- CKC
- forefoot rocker during heel-off
- fulcrum = metatarso-phalangial
- passive extension of the toes
- shift of body weight
What happens to foot positioning when one walk fast ?
The forefoot contacts the ground instead of the heel.
At normal seep what happens if the foot is not properly positioned ?
- the knee is slightly flexed
- it causes injuries lie ankle sprain
Explain the foot clearance mechanism and describe the muscles activating to make it happen
It happens to make sure one has enough space between the foot and the floor to make the swing happens.
It takes place during toe-off, swing phase and heel-strike.
It implies
- hip flexors
- knee flexors
- dorsiflexors
What is affected in the syndrome of “drop foot”
- the nerve controlling ankle dorsiflexion is affected.
- the limb progression becomes difficult.
- the patient compensate by flexing the hip and knee more.
What are the requirements for proper heel strike
- proper foot positioning to allow optimal shock absorption caused by ground reaction forces.
- calcaneus hits the ground
- dorsiflexors (to keep the foot in neutral position)
- knee flexors/ extensors (knee has to be nearly in full extension)
- coordination
What causes ankle sprain when foot contacts the ground ?
- ankle plantar flexion
- foot inversion
During which phases of the gait cycle is there a double support ?
Double support I :
- initial contact
- loading response
Double support II :
- pre swing
During which phases of the gait cycle is there a single support (of the considered leg) ?
- mid-stance
- terminal-stance
Describe the joint kinematics at heel strike
It’s a moment not a movement ! Double support takes place
- hip is flexed (20/30°)
- knee nearly in full extension (0/5°)
- ankle is neutral
What allows the chock absorption during the loading response ?
- eccentric contraction of the ankle dorsiflexors
Describe the joint kinematics of the loading response
- it’s the first movement
- first foot rocker
- the last instant of double support
- hip is slightly flexed
- the knee is in eccentric flexion with the purpose of load absorption
- the ankle is in eccentric plantar flexion with the purpose of load absorption
What is the most challenging phase for the balance ?
Mid stance
Describe the joints kinematics during mid stance
- longest phase of the gait cycle
- momentum acquired by opposite limb
- second foot rocker
- hip extension
- knee extension
- ankle dorsiflexion
- gluteus med (hip abductor) stabilizes the pelvis (about 5° of pelvic tilt) on the side of support
- gastrocnemius stabilizes the tibia (“triceps surae”)
What is tredelenbourg sign?
- excessive pelvic tilt on the contra lateral side
= limping - sign of gluteus med weakness
- signe of inability to maintain the pelvis stable
Describe the joint kinematics of terminal stance
- Third foot rocker
- hip reaches its peak of extension (adductor longus works eccentric here)
- knee is kept close to full extension (gastrocnemius still stabilizing )
- ankle is still dorsi flexing (!) due to forward movement of the tibia
- heel rise
- begging of weight transfer to the other limb
How do we conventionally describe the general motion of the lower limps during mid stance ?
It’s trajectory follows the motion of an inverted pendulum.
Describe the joint kinematics in pre swing phase
- End of stance phase
- body weight has been transferred to the opposite limb
- hip and knee start to flex : rectus femoris provides an eccentric contraction allowing the flexion (it controls both knee and hip)
- maximal plantar flexion with toe-off propulsion
Describe the joint kinematics in initial swing phase
- OKC
- acceleration phase
- hip, knee and ankle concentric flexion ( the sartorius, gracilis and semitendinosus are working eccentrically because AB° and ADD° happens at the same time)
- foot clearance mechanisms
Describe the joint kinematics in mid-swing
- hip flexion
- knee starts extension : It’s a turning point because previously flexed articulation will start to extend again
- ankle is neutral : isometric contraction of foot extensors
Describe the joints kinematics of terminal swing
- deceleration phase
- hamstrings are working eccentrically to stabilize hip and knee this is the phase in which they work the most
- hip flexion motion decelerates
- knee is almost fully extended
- ankle stabilized in neutral position
What is the direction of plantar loading progression during stance phase ?
Posterior to anterior
Regarding plantar loading progression in stance phase, when does the maximum load happens ?
Between mid-stance and terminal stance
What is the purpose of adductor longus eccentric contraction in terminal stance ?
- controlling the movement of the hip articulation
- help reaching the pic value of hip extension
- it’s an eccentric contraction because the muscle is lengthening to control the hip extension
What is the purpose of gluteus medius concentric contraction during the stance phase ?
As it stabilize the hip during stance. There is 5° pelvic tilt so it’s not fully isometric.
Why does extensors digitorum work eccentrically in swing phase ?
To hold the ankle in a neutral position
Why does the rectus femoris contract eccentrically in pre swing phase ?
Because it controls the knee flexion
What are the purposes of each type of contraction in the gait cycle ?
Isometric = stability Concentric = propulsion Eccentric = control
Name the important bi articular muscles acting in gait cycle
- biceps femoris
- rectus femoris
- sartorius
- gastrocnemius
What is the role of biceps femoris in gait cycle ?
- bi articular nature
- active in the final stages of the gait cycle such as terminal swing
- decelerates the hip and knee flexion
What is the role of rectus femoris in gait cycle ?
- controls knee and hip range of motion in pre-swing
What is the role of sartorius in gait cycle ?
- in swing phase
- when acceleration takes place
- it is responsible for flexing the hip and the knee
What is the role of gastrocnemius in gait cycle ?
- active in mid-stance
- active in terminal stance
- it locks the knee in extension
- it controls the ankle in extension
Who is responsible for the hip motion in mid stance ?
Momentum and propulsion
Give examples of muslces shortening and lengthening at the same time and when in the gait cycle ?
- rectus femoris : stretches distally and contracts proximally in pre swing or initial swing
- gastrocnemius : stretches distally and contracts proximally in initial swing
- hamstrings : pre swing/ initial swing
