apply a systematic method for observational task analysis
- general observations: timing, spatial aspects (gait speed, step length)
- specific deviations: using task-related determinants as a guide, a necessary element
hypothesized causes for movement deviations: foot drop -> ankle df weakness or uncontrolled ankle pf - testing hypothesis
describe the general timing of movements in a sequence
- initial position
- initiation
- execution (can break into phases)
- termination
describe the personal, environmental, and task-related determinants for a given performance of a functional task
- personal: strength, cognition
- environmental: support, distractions
- task: height of chair
systematically observe walking gait
- general gait observations: overall view of walking pattern, looking for obvious problems
- areas of focus: symmetry between R and L UEs and LEs, arm swing opposite of legs, head and trunk posture, impression of gait speed
what is normal adult gait speed
1.4 m/s
what are the phases of gait/functional tasks of gait analysis
weight acceptance
single limb support
swing limb advancement
parts of weight acceptance
- heel-first initial contact
- controlled ankle plantar flexion (heel rocker)
- controlled knee flexion
- hip/pelvic stability
parts of single limb support
- hip/pelvic stability
- controlled tibial progression (ankle rocker)
- controlled heel rise (forefoot rocker)
- hip extension (trailing limb posture)
parts of swing limb advancement
- rapid ankle plantar flexion
- passive knee flexion (60 degrees)
- hip flexion (30 degrees)
- ankle dorsiflexion (approximately neutral)
- knee extension
generate hypotheses for problems, based on gait observations
- use critical events as a guide for specific deviations
- look at hypothesis in light of entire gait cycle: compare deviations -> one deviation could be just a response to another (forward trunk lean due to weak knee extensors)
- compare to patient history information
- plan further tests/measures to confirm
task-related determinants
- an element or aspect of the task that is critical to successful task performance
- start with overall goal of the task
- “mini” goals to achieve overall goal (TRD)
a task cannot be completed without TRD
sit-to-stand task determinants
generate forward trunk momentum (initiation)
- forward movement of head/trunk
- flexion lumbar spine and hips
position center of mass over feet (execution phase 3)
- flexion of lumbar spine and hips
- foot positioning (heel posterior to knee)
generate force to raise center of mass (execution phase 2)
- extension motion of hip, knee, and ankle during ascent
- general symmetry of trunk motion
arresting momentum of center of mass (termination)
- stability of center of mass position over feet base of support
age-related personal factors linked to changes in gait patterns
- people >/ 65: 1/3 experience a fall per year
- leading cause of injury deaths, disability, loss of independence
- 20-30% have an injury that reduces mobility
- due to age-related changes
fall (functional limitation) threshold
decreases due to
- genetics (primary aging)
- environment (secondary aging)
- disease
skeletal function changes in older adults
bone
- shape/density altered with balance of resorption and formation of bone
- decline in bone mass with age
- decreased tolerance for stress
- altered joint motion on altered surfaces
joint: ROM and flexibility
- decreased motion with age at most joints (elbow more protected)
- active decreased more than passive: muscle tendon unit function indicated
joint: increased stiffness
- due to viscoelastic change in cartilage, tendon, ligament, muscles
- greater demand moments for movement at joints
motor function changes in older adults
muscular changes
- sarcopenia: age-associated decline in muscle mass related to total number of fibers decreasing
- begins at age 30, gradual 30-50, 30% loss from 50-80
- beyond sarcopenia: when torque (moment) production normalized to cross-sectional area or mass, still weakness with old age that is not explained
neuromuscular changes in older adults
recruitment
- initially numbers of fibers recruited
- more variable over time
- can achieve same levels with practice
proximal > distal
- distal muscles lose strength and power, proximal compensate
- ankle work is lower and hip work is higher in elderly
fast-twitch reduced
- decreased CSA of Type II > Type I
- possibly more of T1 and T2 blend, not definite
co-activation: increased co-activation leads to decreased effective moment production
- in extension demand moment, flexors and extensors are active in older adults
- co-activation of HS and quads increase in older adults at all gait speed -> inefficient gait pattern
sensory changes in older adults
- somatosensory: decreased proprioception, tactile sensitivity, vibration sense (peripheral neuropathy)
- vision: decreased acuity, visual threshold (light needed), and contrast sensitivity
- vestibular: decreased hair and nerve cells
strength, power, and endurance in older adults
- strength: maximal moment/torque production, declines 10-15% per decade after 5th decade
- power: moment x angular velocity, declines very similar to that of strength, more closely correlated with functional ability, loss appears earlier and rate of decline more rapid than strength
general changes in older adult gait
- decreased gait speed
- decreased stride length
- decreased SLS time (increased DLS time)
- altered joint kinematics (joint/hip)
- increased step width variability
- increased energy expenditure
older adult slower gait speed is due to
step length
- gait speed = step speed (cadence) x step length
- it’s not the frequency of steps that affects speed but the length
- step length changes with age, step frequency (cadence) is similar
- changes in kinematics are expected with change in speed - what is important is kinematic change at same speed
changes in gait kinematics in oldies
- hip extension motion decreased in elderly
- pelvic motion (transverse, sagittal) - more anterior pelvic tilt in adults
- ankle plantar flexion motion decreased in older adults
increased energy expenditure in oldies is due to
coactivation
reasons for gait changes in older adults
- desire for increased stability: fear of falling, increased DLS
- impaired body structure and function: changes in tendon/ligament, especially in ankle
- desire to limit force absorption at joints
- maximally walking economy: increased energy expenditure demands requires decreased gait speed
- change in motor pattern: distal lose function, proximal compensate (proximal recruited preferentially)
