Mobility (Lecture) Flashcards
what is the aim of postural control in walking?
Goal of walking: move CoG ahead of the BoS to advance
Continuum of strategies depending on phase of gait cycle to minimize loss of balance and continue forward progression
describe the response to perturbations (positive and negative tilt) in walking compared to in stance
It’s harder to maintain your balance with a perturbation while standing. As you’re walking your com is being projected out of your bos so it’s easier to respond to a perturbation that is displacing your com
- During quiet standing: the trunk and pelvis remained aligned with respect to earth’s vertical at any surface inclination.
- During walking: backward tilt of trunk and pelvis and an increase in pelvic lateral drop toward the swinging limb as downhill slope became steeper. Changes in trunk and pelvic postural alignment in the sagittal plane might be used to facilitate power generation or absorption in adapting to slope changes during walking
- These results showed that postural adaptations are task-specific and the control requirements are different between standing and walking on an inclined surface
what are the essetial requirements for successful locomotion?
Progression
Postural control
Adaptation
what are the 2 periods of the gait cycle and the tasks/phases for each?
what is the stride length, what is the step length, and what is step width?
stride length: from heel contact of one foot to heel contact of same foot
step length: from heel contact of one foot to heel contact of contralateral foot (mean = 76.3 cm)
step width: horizontal distance between the center of heel of the right and left foot
*note in class it was mentioned that it is impossible to have a step length of 0!
describe the entire stride cycle for the right foot
what is velocity and what is step frequency? - what is a normal value for healthy adults?
velocity: expressed in m/s, normal = 1.46 m/sec
cadence: number of steps per minute, normal = Mean cadence (step rate) of 1.9 steps/second
*note it is STEP length not STRIDE length for measuring cadence
what factors are velocity step length, width frequency, and stride length?
they are temporal distal factors used for gait analysis
describe the muscles involved in walking - joint kinematics!
p 316
*note it is not normal to have both knee flexors and extensors activated at the same time for walking!
what are the main goals of the swing phase?
1) reposition the limb
2) ensure toe clearance
*note this phase is less variable between people in terms of joint movement patterns than the stance phase!
what are the main goals of the stance phase?
1) stabilize the limbs for weight acceptance and shock absorption
2) generate propulsive forces for continued motion
describe the kinematics of a steady gait in terms of energy transfer
what are the main muscles responsible for 1) impact absorption for postural stability and 2) propulsive force to keep the body in motion?
describe joint kinetics for walking compared to kinemetics
* note joint kinetics deal with the forces generated and they do ont necessarily mirror the movements of the joint!
*note also that the line disappears during the swing phase and can be above 100% for impact forces such as running
describe joint KINETICS during walk and swing phase - which is the largest of all moments in the swing phase?
Stance phase: hat = head arm and trunk segment, faster walking speed = more stable (all ages)
swing phase: hip flexion initiates movement, swing phase sustained by momentum, joint knee torque constrains motion of knee, ankle plantar flexion moment increases to max just after knee flexion (largest of all moments) and is main contributer of limb acceleration into swing phase
describe the neural mechanisms for locomotion
note we use the precurser 5HTP so it can cross the blood brain barrier
what is the control mechanism for gait?
- descending influences from higher brain centres are important in the control of locomotor activity
- much research in this area is done on animals by transecting the brain along the neuraxis
- for cat transected at spinal cord, Brain not communicating with back but still moving hind legs
how does the somatosensory system contribute to gait?
how does vision contribute to gait?
Visual flow cues (optic flow) helps in gait speed determination
Vision influences alignment of the body with reference to the environment (visual vertical)
Used extensively in anticipatory gait modifications
how does the vestibular system contribute to gait?
Head stabilization along with vision
Top-down control (head movements independant from movements of the trunk)
what are some sensorymotor integration aspects for gait?
Steering mechanisms
Speed control
Obstacle avoidance
Anticipatory control
Dual Task
what happend to the COP when initiating gait? when is steady velocity acheived?
describe the walk-run transition
what are the 3 requirements for successful stair walking?
1) progression: generation of forces to propel the body up or eccentric forces for descent
2) stability: control COM within constantly changing BOS
3) adaptation: ability to accomodate changes in stair environment
describe the stance and swing phase for stair ascent
describe the stance and swing phase for stair descent
* note same muscle groups used as stair ascent but eccentrically
what is known about transfers?
much research has been done on the biomechanical perspective, but little on perceptual strategies and strategy modifications
describe the sit-to-stand process 4 steps and what is necessary for completion
describe the 3 supine to stand strategies - most common one for young healthy adults?
pattern a = most common
a: symmetric trunk, symmetric squat and UE
b: symmetric trunk, asymmetric squat (second most common)
c: asymmetric trunk, asymmetric US, half-kneel (third most common)
describe the movement pattern and what is required to rise from bed
note this is the most common method used for healthy young adults
describe the rolling pattern
this is most common pattern for young healthy adults
what are promary and secondary age-related changes?
describe age-related gait changes
Hip, knee & ankle flex decrease, less vertical head movement
Dynamic balance: Difficulty controlling HAT (head & trunk segment)
: Decreased joint torques and powers: Increased age results in use of hip extensors more and knee extension and PF less, decreased push-off
what are 4 main changes as we age in adaptive balance control?
describe proactive and reactive adaptation in older adults
describe the role of pathology and cognative factors in older adult mobility
describe older adults wrt COG changes and muscle strength changes
age-related changes with stair walking
age-related changes with sitting to standing
age-related changes with rising from a bed
describe a basic mobility evaluation
describe the functional ambulation scale
*note this is regardless of whether they use an assistive device or not
what is the framework and it’s divisions for classifying gait disorders?
3 primary divisions baed on:
Neurologic diagnosis: Parkinsonian gait, cerebellar ataxia, hemiplegic gait
Suspected level of CNS involvement: low, middle, high levels of gait disorders
Primary pathophysiologic mechanism producing disordered gait: four main impairments
- defective muscle activation (paresis)
- abnormal velocity-dependant muscle recruitment (spasticity)
- loss of selective & coordinated motor control (coactivation, abn synergies)
- abn mechanical properties of non-neural components (tendon system)
what are primary and secondary impairments for abmornal gait?
go over observational gait analysis slide - Winter’s framework for understanding atypical gait patterns
*note slide was not discussed in class, but prof said it’s important to know :/
text p 431
Review mobility in terms of the ICF framework
review the systems approach to mobility and gait rehab
in considering gait rehab, what 4 dimensions should you consider when selecting goals/activities?
ambient: can be things like lighting differences
what does current research sugest for effectiveness of gait training?
A need for intense task-related practice to promote the re-acquisition of locomotor skills
Motor-learning is promoted by :
- changing environmental contexts
- altering physical demands
- introducing problem solving
- randomising practice tasks
- empowering the patient (study: Neurological patients can increase their walking speed when motivated to do so)
what are the task requirements of gait?
describe the task-oriented approach to mobility training
- must be 1) challenging, 2) progressive, and 3) invoke active participation
- looks into 1) intervention at impairment level and 2) intervention at activity level
Therapeutic interventions that are task-specific:
- Minimize impairments
- Maximize gait strategies
- Gait skill practice
- Uses part and whole practice
- Emphasis on varied task and environmental contexts
what are some sensory cues that can be used for mobility training?
describe interventions at the impairment level for the task-oriented approach to gait training
target Neuromuscular & musculoskeletal impairments of:
1) propulsion
2) postural control
*Considering therapeutic strategies of: High-intensity resistance training, Resistance exercise, and Strength training, All strategies showed changes in strength but not always in functional gait!
describe interventions at the activity level for the task-oriented approach to gait training
consider: “Functional” strategies, The demands of the task, and Specific requirements of gait – type of muscle activity (concentric, isometric, eccentric), range where muscle is active… etc
1) stability/postural support: use of walking aids and/or Physical guidance to facilitate correct mvts & avoid unwanted or compensatory mvts (Control of the HAT segment, Extensor support moment, Foot placement at initial contact, Balance during double- and single-limb support)
2) progression: increase energy generation (push and pull), advancement of swing limb (increase gait speed)
3) adaption: adapt gait to changing tasks and environments
