Movement Science Module 4

Define mobility.

ability to move independently and safely from one surface to another

• in bed

• STS

• walking or running

• navigating complex environments

What are the essential requirements of locomotion?

1. progression

2. stability

3. adaption

What could happen if one’s Progression in regards to locomotion is impaired?

• shuffling

• freezing

• inability to walk

What areas of posture control are related to Stability in regards to locomotion?

• steady-state

• anticipatory

• reactive

What are the 2 phases of Normal Gait?

Stand and Swing

Describe Stance phase.

generation of horizontal forces against support surfaces to move in a desired direction (progression)

generation of vertical forces to support body against gravity

takes up 60% of gait cycle

Describe Swing phase.

advancement of swinging limb

preparation of weight acceptance (postural control)

foot clearance — used to clear obstacles

takes up 40% of gait cycle

What is steady-state gait?

walking without stopping or turning

long bouts

How much of the gait cycle is spent with Double-Limb support?

the first and last 10% of stance phase

Define Stride-Cycle.

time between two ipsilateral foot strikes

Define Stride length.

distance covered from one initial contact to the next by the same foot

How does the Motor System contribute to gait?

Stance phase:

• postural control and progression

• hip extensors control forward progression of body

Swing phase:

• beginning and end of swing phase

• hip flexors influence rhythm neurons for stance to swing transition

• hip flexors also help bring knee into flexion

What is the Active Push-off Theory?

energy created by plantar flexor group is transferred to the trunk to provide support and forward progression

What is the goal of the Motor System during stance phase?

stabilize limb for weight acceptance

What is the goal of the Motor System during swing phase?

reposition limb and toe clearance

What structure is responsible for gait adjustments necessary for obstacle clearance, negotiating new terrain, or changing walking speed and direction?

the cerebellum

What 2 ways is gait modified and adapted?

1. predictive

2. visually activated

How is gait predictively controlled?

minimizng destabilizing forces from your own movements

• ex trunk stability

Where does mobility fit in the ICF?

Under activities and participation

Define stability as it relates to locomotion.

orientation and stability

controlling COM

body segment alignment for task achievement and to meet environmental conditions

Define adaption as it relates to locomotion.

strategies to accomplish progression and stability

switching between reactive and anticipatory

adaption of gait to meet task and environmental demands

Define progression as it relates to locomotion.

Basic locomotor pattern that produces and coordinates rhythmic patterns of muscle activation in legs, trunk, and arms that successfully move body in desired direction

What is normal gait velocity in young adults?

1.46 m/s (3.26 mph)

What is another name for step frequency?

Cadence

What is average cadence in young adults?

1.9 steps per second

What is average step length in young adults?

76.3cm; increases with velocity

What is net extensor moment?

keeping the stance limb from collapsing during weight-bearing; helps stabilization

What is another brain structure used to negotiate obstacles during locomotion?

parietal cortex

What is “elevating strategy?”

active control of knee joint passively helps with flexion at hip and ankle joints following a trip in early swing

What is “lowering strategy?”

Foot placement quickly on support following late swing trip is associated with knee extension

How is gait modified via visually-activated strategies?

modify gait in response to potential stability threats

• usually within one step-cycle

• changing direction requires one step-cycle prior for planning

Which muscles relax at the initiation of gait from quiet stance?

postural muscles

• gastroc and soleus

How many steps does it take to reach steady-state gait from initiation?

1-3

Are higher brain centers required for alternating limb movements?

No; shown by animal studies

• CPGs

How do descending pathways aid gait?

• adaption to environment

• variation in patterns

• adaptions to task

What structures play a role in descending control of gait?

• cerebellum

• basal ganglia

• brainstem

• spinal cord

• cortex - for more challenging tasks, like uneven terrain

What are some examples of how secondary effects from primary neuropathologies can affect gait especially in older populations?

1. spasticity at ankle can affect push-off and foot strike

2. high hip extensor torque must be counteracted by high hip flexor torque

Define gait ataxia.

loss of proprioceptive information from lower extremities

How is stepping frequency modulated?

• sensory input

• onset of swing phase triggers by joint receptors

• muscle afferents in hip flexors

How is the head oriented during gait?

visual and vestibular systems

What do visual flow cues determine?

speed of gait

alignment of body and environment

What are the effects of increasing cognitive demands during gait?

• increased weaving → leads to hitting more obstacles

• slowing down

• slowed reaction times

Do higher centers use feedforward or feedback control to modulate gait patterns in response to goals and environmental demands?

feedforward

Are sensory inputs used for feedforward or feedback control of gait?

both

Where do the majority of falls take place?

in public

walking down stairs

What occurs during the stance and swing phases of stair ascent?

Stance:

• weight acceptance

• pull-up

• forward continuance

Swing:

• foot clearance and placement

What occurs during the stance and swing phases of stair descent?

Stance:

• weight acceptance

• forward continuance

• controlled lowering

Swing:

• leg pull-through

• prep for foot placement

How do the 3 components of locomotion apply to STS?

Progression: joint torque generation to rise

Stability: COM from chair to over feet

Adaption: adapt to task andenvironment

What joint is essential in rolling in bed?

shoulder girdle

What are the 3 key gait changes in older adults?

1. decreased velocity

2. decreased stride length

3. decreased power generation at push-off

What are the temporal or distance factors in regards to gait changes in older adults?

• decreased velocity

• decreased step length

• decreased stride length

• decreased step rate

• increased stride width

• increased stance phase

• increased time in double limb support

• decreased swing phase

What are the kinematic changes in gait in older adults?

• decreased vertical movement of COG

• decreased arm swing

• decreased flexion at all points of LE

• flat foot on heel strike

• decreased ability to covary hip or knee movements

• decreased dynamic stability during stance

What are changes in muscle activation during gait in older adults?

increased coactivation/stiffness

What are the kinetic changes during gait in older adults?

• decreased power generation at push-off

• decreased power absorption at heel strike

How might an older person visually present different than a younger adult during gait?

• eyes pointed down more

• decreased step length

• decreased heel strike

• decreased arm swing

• kyphotic posture

Do older adults have more varied gait patterns than younger adults?

Yes; linked to higher rate of falls

What is the minimal walking speed to cross the street safely?

1.4 m/s

Do older adults have higher or lower amounts of muscle responses than younger adults?

higher

Trips vs Slips

Trips:

• 35-47% of falls

• depend on reactive

• lower muscle activation leads to or recovery

Slips:

• 27-32% of falls

• due to later onset of muscle reactions during slips

Both:

• need hip flexors from swing leg and plantar flexors of stance leg for recovery

What happens in an older adults upper body during gait/slips/trips?

upper body falls much father forward than a younger person’s when falling; whole body has to react to the trip/slip

How does the vestibular system in older adults change over time?

decreased saccule response

What are other factors that may affect gait in older adults?

• fear

• repeated falls

How does dual tasking affect performance?

• decreased ability to avoid obstacles

• decreased balance control

• detracts from executive attentional function

What percentage of fall-related deaths are related to stairs?

10%

Look at slide 41

Look at slide 41

What is the first sign of a neurological disorder?

impaired mobiilty

Disorders of gait can be classified into what 2 frameworks?

pathophysiological and diagnositc

What pathophysiological mechanisms produce disordered gait?

• spasticity

• paresis

• loss of selectivity in motor output

• coordination problems

• changes in tendons

• diminished adaption (from reactive and APAs)

What is the primary neuromuscular impairment of the CST and motor neurons?

paresis

What do weak plantar flexors and Tib Ant lead to?

• reduced knee flexion in swing

• knee hyperextension in stance

What do weak quads lead to?

knee hyperextension

What do weak hip flexors lead to?

• using PPT or abs to raise leg

• circumduction

• contralateral vaulting

• poor knee flexion in swing

What do weak hip extensors lead to?

• forward lean

• bad HAT stability

• compensatory backwards lean

• strongly correlated with reduced gait speed

What do weak hip abductors lead to?

• hip drop

• lateral lean towards stance leg

• frontal plane instability

What can plantar flexor spasticity cause?

• inversion and equinovarus foot position

• prevents heel strike

• limits DF

• hinders stability

• no push-off

• toe drag

• resists knee extension

• shortened stride length and reduced gait velocity as compensations

What does quad spasticity cause?

• excessive shock absorption response at knee

• knee hyperextension

• no effect on speed

What does hamstring spasticity lead to?

• excessive knee flexion (crouching gait - common in CP)

• excessive knee flexion in heel strike due to limited knee extension in swing

• shorter steps

What does hip adductor spasticity cause?

• contralateral hip drop

• '“scissors gait”

• medial displacement during swing

• smaller BoS

• can catch on opposite limb

What is impaired programming?

inability to modulate a muscle’s activity through the gait cycle

What is an example of an abnormal synergy/abnormal muscle coupling?

hip and ankle flexors activate together and prevent knee extension during gait

What are the 3 coordination problems?

1. increased muscle activation separate from spasticity-mediated stretch

2. abnormal phasing of multijoint movement leading to poor intersegmental control

3. coactivation of agonist and antagonist

What is the minimal amount of DF needed for smooth progression of the foot?

5 degrees

What is a predictor of adverse health outcomes in the geriatric population?

performance of complex walking tasks

How do somatosensory impairments affect gait?

ataxia

How do vision impairments affect gait?

poor adaption

How do vestibular defects affect gait?

• depend on age at time of loss

• ataxia

• can’t stabilize head

• VOR deficit

What is a body image deficit?

leaning towards ipsilateral side of stance leg and losing stability

What is unilateral space neglect?

inability to perceive and integrate one side of the body

What is impaired body image?

improper foot placement leading to difficulty controlling COM

What is the Rise-to-Walk test characterized by?

nonfluid strategy

What are the components of the Task-Oriented Approach to examination?

• Measure Participation

• Assess Functional task (mobility)

• Observe strategies used to accomplish requirements of mobility

• Identify underlying sensory, motor, and cognitive impairments that constrain mobility

What are some examples of self-report measures?

• Mobility and Self-Care (MOSES) Questionnaire

• Participation Survey/Mobility (PARTS/M)

• Craig Handicap Assessment and Reporting Technique (CHART)

• Assessment of Life Habits (LIFE-H)

• Life Space Questionnaire (LSQ)

What 2 tests measure walking endurance?

2 min walk test

6 min walk test

What is the single best measure of gait function?

gait velocity

What are examples of tests that measure complex walking capacity?

• Timed Up and Go (TUG) Test

• Dynamic Gait Index (DGI)

• Functional Gait Assessment (FGA)*

• Stops Walking When Talking (SWWT)

• Emory Functional Ambulation Profile (EFAP)

• High-Level Mobility Assessment (HiMAT)

What tests examine gait form?

• Observational Gait Analysis (OGA) ← the framework

• Rancho Los Amigos Gait Analysis Form

• Gait Assessment Rating Scale (GARS)

Look at slide 78

Look at slide 78

What are the objective targets for improving gait?

• MCID for DGI: 4 points

• MCID for gait speed between 20-60 days after stroke: 0.16 m/sec

• MCID for gait speed for older adults to improved mobility status: 0.10 m/sec

Considerable evidence supports the effectiveness of ________

task-specific, high intensity locomotor training

What are the 3 key principles of the task-oriented approach?

1. challenge

2. progressive and optimally adapted

3. active participation