102
Impaired Mobility
Nancy L. Low Choy, Eamonn Eeles, Ruth E. Hubbard
INTRODUCTION
Impaired mobility and balance dysfunction each become more
common with aging. Acute changes in each (“off legs,” falls)
remain among the “geriatric giants” or now, as they increasingly
are called, acute geriatric syndromes. Whether slower changes in
mobility and balance are physiologic (and inevitable) or pathologic (and potentially mutable) remains unclear. The accumulation of deficits, including those that affect motor performance,
may be inevitable at an advanced age. However, factors such as
sedentary behavior, emergence of chronic diseases, and low levels
of physical activity, which all make significant negative contributions to mobility integrity, can be mitigated.
This chapter addresses impaired mobility and the integral
relationship with balance, but does not focus on the issue of falls,
the theme of Chapter 103. We briefly review some essential features of how mobility changes with age. This is approached from
a hierarchical perspective that includes higher order, executive
function through gait speed to gait initiation, transitions from
sitting to standing and, finally, from lying to sitting. Next, we
describe some common gait disorders and how a structured
approach to assessment can facilitate their classification. The clinical assessment of balance and mobility for older adults is reviewed
to highlight strengths of specific tools for management in community and hospital settings. Finally, we explore the relationship
between impaired mobility and frailty and appraise current interventions for impaired mobility across the frailty spectrum.
AGE-RELATED CHANGES IN MOBILITY
Mobility is the term used to refer to a number of fundamental daily
activities that range from walking to sitting and standing tasks to
in-bed mobility. In this section, we explore the age-related changes
that occur with each of these activities, providing a foundation for
the assessment and management of balance and mobility.
Executive Function
Walking was traditionally seen as an automatic task requiring
little input from higher mental functions. However, an intricate
interaction between gait and executive function is now recognized.1 Older healthy adults with the greatest declines in executive function, relative to cognition, exhibit impaired functional
mobility2 and experience more falls.3 As executive function
declines, an increase in the double support phase and step time
of the gait pattern occurs.4
Studies investigating dual tasks, which are dependent on intact
executive function, have demonstrated that older adults are less
able to maintain normal walking while performing an additional
task, particularly talking.5 Even in physically fit older adults, dual
tasks influence balance during walking through a direct effect on
body sway and stride variability and an indirect effect on gait
velocity.6 Task shifting when multitasking is also impaired with
aging, with inhibitory control, mental set shifting, and attentional
flexibility predictive of functional mobility in older adults.7
The pathophysiology of these changes may originate in the
prefrontal cortex, which plays a crucial role in executive functioning and is particularly vulnerable to microvascular damage.8
Hypoactivation of the medial frontal gyrus, a region involved in
motor planning, is linked with falls in older adults7 although,
intriguingly, frontal executive network disruption does not appear
to be predictive of fallers.9 Pilot studies have shown that targeted
executive function training is feasible and may improve gait
parameters, including balance.10
Gait Speed
Older adults tend to walk more slowly than young adults. In a
nationally representative sample of community dwellers in
Ireland, usual walking speed declined after the age of 50 years,
with the most pronounced drop after age 65.11 Although this
sample excluded patients with severe cognitive impairment,
dementia, and Parkinson disease (PD) and those living in residential care facilities, individuals with chronic disease were
included. This raises the question of whether declines in gait
speed are secondary to pathologic processes rather than being
age-related changes. Studies of the fittest older adults support
the latter hypothesis. Cross-sectional investigations of elite
athletes have shown reductions in speed and endurance of
approximately 3.4%/year between 50 and 74 years, with notable
acceleration after older adults 75 years.12 However, although
some slowing of gait speed is to be expected with increasing age,
there is a growing body of evidence to suggest that this may not
be benign.
Generally speaking, gait speed is reflective of overall health
status. The mean walking speed of older community dwellers is
significantly faster than their age-matched peers in the hospital13
or in residential care facilities.14 Slow gait speed is also associated
with adverse outcomes. A systematic review of 27 different studies
has concluded that slowness (measured by walking at a usual pace
over 4 m) identified autonomous older adults at risk of future
disability, cognitive impairment, and institutionalization.15 Similarly, in pooled data from 34,485 people older than 65 years
followed for between 6 and 21 years, survival increased across the
full range of gait speeds, with significant increments per 0.1 m/
sec.16 Gait speed has therefore been advocated as a marker of
frailty, either exclusively17 or in combination with other markers
of strength and vitality.18 Indeed, in a study of seven potential
frailty criteria, including weakness, weight loss, and exhaustion,
slow gait speed was the strongest predictor of chronic disability
and the only significant predictor of falls.19 The dynamic nature
of frailty has also been explored and supported by the measurement of mobility changes in older adults.20
The cause of slow gait speed has not yet been fully elucidated,
but cerebrovascular disease is likely to be the key pathophysiologic factor. Slow walking has been linked to white matter hyperdensities and with gray matter changes in the medial temporal
area.9,21 A smaller volume of the prefrontal area seems to contribute to slow gait through slower information processing and
motor planning.22 Similarly, the association between faster gait
speed and larger cerebellar gray matter volume is significantly
influenced by information-processing ability.23 Hypertension
may also be a critical contributor. In the Cardiovascular Health
Study, hypertension accelerated slowing of gait speed24 and mediated the association between the degree of white matter hyperintensities and mobility impairments.25
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PART III Problem-Based Geriatric Medicine
Gait Initiation
Gait initiation requires the integrated control of limb movement
and posture and is achieved with purposeful postural shifts at toe
off, including relaxation of the triceps surae for swing and synergistic contraction of ventral, hip abductor and quadriceps muscles
for support, modulated by controlled knee flexion mid stance.
These culminate in a forward step, with steady-state velocity
being achieved in less than two steps.26 Gait initiation is well
preserved in healthy older adults.27 Abnormalities of gait initiation are a sensitive but not specific sign of disease processes in
older adults, such as those with PD, multiple cerebral infarcts,
normal-pressure hydrocephalus, progressive supranuclear palsy,
and cervical myelopathy.
Transitions Into Standing from Sitting
The ability to stand from a bed or chair is a critical aspect of
mobility, independently predicting mobility disability and activities of daily living disability in community-dwelling older adults.28
The activity of standing up involves a number of phases, including the following: (1) a preparatory phase that positions the feet
for weight acceptance, along with forward inclination of the trunk
to shift the center of mass forward over the feet; (2) a peak force
phase, enabling weight acceptance onto the feet to commence
standing up; (3) a phase of controlled extension enabling attainment of upright stance; and (4) a stabilization phase in stance that
enables the individual to remain steady.29 Inefficient preparatory
patterns may occur when people are obese30 or present with
chronic obstructive airway disease,31 along with PD or some
other neurologic gait disturbance.27 Reduced range of motion in
the hips, pelvis, knees, and spine is common with aging and
impedes the initial shift of the total body center of mass over the
feet. Weakness of the hip girdle muscles is also a frequent finding
in older adults and is a manifestation of general deconditioning,
and those affected may need to use their arms to help themselves
up. Chair stands are sensitive to changes in postural control,
strength, and coordination and thus are useful as a physical performance measure32 for frail and high-function older adults.
Transitions from Lying to Sitting Over the Bed Edge
One study of older adults has shown the importance of the start
position in bed and strength in the upper limbs when weak trunk
musculature makes it difficult for older adults to sit up over the
bed edge.33 Preparatory positioning of the person (rolling the
person onto his or her side or elevating the bed head), in conjunction with use of the upper limbs, can provide effective assistance
during sitting over the bed edge when trunk muscles are weak.34
In addition, the lower limbs can be used for added momentum if
well-timed with upper limb and trunk components. When trunk
muscles are weak, ongoing reliance on the upper limbs for
support during sitting up and sitting will be required.34 Thus, for
an older adult to be independent in getting out of bed, muscles
of the trunk and upper and lower limbs need to be targeted in
intervention programs.
COMMON DISORDERS OF GAIT
Gait disturbances associated with aging are often multifactorial,
a combination of sensory, neurodegenerative, and negative
mental-cognitive biofeedback.35 Pragmatically, disorders of gait
may be divided into those that are clinically obvious and others
that are less apparent. The following gait patterns would be
evident to experienced clinicians and are classified according to
level of impairment and interaction with the nervous system36:
Middle-level disorders include the following:
• The slow and shuffling gait of parkinsonism
• The stiff limb with clumsy circumduction and scuffing of footwear due to hemiparesis, usually observed in a stroke victim
• Sensory cerebellar ataxia and vestibular pathology—share
unsteadiness as a core feature but can be discriminated clinically by isolating and unmasking the affected organ
Lowest level disorders include the following:
• Antalgic gait pattern with a shortened phase on the injured
side to alleviate pain experienced when bearing weight on that
side, often secondary to disease in the ankle, hip, or knee
• A combination of problems (frequently secondary to arthritis
or arthrodesis of the ankle) that cause alterations in load
bearing and secondary stress in adjacent joints (antalgic gait),
muscle weakness of the tibialis anterior (foot slap or toe drag
gait), and compensatory gait patterns (steppage gait) involving
recruitment of the long toe extensors, with hammer toe deformity a consequence
Because these disorders are covered in other chapters, here we
shall concentrate on gait disorders that may present more of a
diagnostic challenge. The term gait apraxia has largely been
superseded by the term higher level gait disorder. This is based on
abnormalities of the highest sensorimotor systems and assumes
integrity in basic sensorimotor circuitry.36 Gait pattern in higher
level disorders is attributed to a motor programming failure comparable to the problems encountered in PD. These abnormalities
can be classified according to their functional or neuroanatomic
associations. Even so, their exact nature is still debated, and the
present uncertainty is reflected by the many classification systems
that have been proposed (Table 102-1).36-38
For locomotion, interrelated higher level structures (the corticobasal ganglia–thalamocortical loop) meet the demands of the
personal desire to move and the maintenance of posture within
the confines of environmental limitations.38 Pathology in any of
these regions or their connections therefore results in an array of
gait disorders, such as the following:
• Suppression of conversion of personal will into task execution
manifesting as hesitation or freezing and problems initiating
TABLE 102-1 Classification of Higher Gait Disorders*
Location Classification36
Parameter
Frontal Gait Disorder
Phenomenology classification36
Clinical findings
Liston classification37
Elble classification38
Frontal Dysequilibrium
Subcortical Dysequilibrium
Speculative
Isolated gait ignition failure
Loss of postural balance
Inability to initiate a
reflexes
continue movement
←-------------------Equilibrium apraxia------------------→
Ignition apraxia
←-------------------------------------Mixed gait apraxia------------------------------------→
←------Dysfunctional or absent postural righting-----→ Gait ignition failure
Extrapyramidal features,
some postural imbalance
Mixed gait apraxia
Bizarre ineffective gait
*Cautious gait, psychogenic gait, and extrapyramidal overactivity probably retain their separate identities and have been omitted from the table.
CHAPTER 102 Impaired Mobility
gait or making turns (particularly affected by abnormalities of
the supplementary motor area and its connections)38
• Dysfunctional processing with gait adversely influenced by
emotional and environmental information
• Dysfunctional or absent postural righting reflexes, resulting in
injurious falls
• In contrast to hypokinesis implicit in basal ganglia underactivity, disturbance in basal ganglia function may also lead to
excessive, involuntary and uncontrolled limb movements.39
Classifications of gait have been criticized for their lack of
consistency.37 The Nutt classification, for example, includes
frontal gait disorder, cautious gait, frontal disequilibrium, and
cortical disequilibrium as distinct entities.36 The older adult, with
accumulation and overlap of pathology, may exhibit problems of
higher gait that are not reducible to such discrete categories.
Distinct gait parameters have been identified by Liston and colleagues according to their own clinically proposed subtypes.37
This allows for the theoretical inclusion of mixed pathology and
gait subtypes. The amalgamation of disordered balance in conjunction with ineffective gait by Elble38 seems a sensible if not
altogether precise way to overcome the lack of connection
between the site of pathology and physical characteristics of the
gait disturbance.
The phenomenologic entanglement of cautious gait is worthy
of consideration.40 Frequently multifactorial, a cautious gait may
be more classically considered as a sensory disorder across locomotor afferent axes—vestibular, visual, or peripheral nervous
system.41,42 The slower gait speed associated with loss of balance
confidence and fear of falling implicates a compensatory consolidation of remaining locomotor sensorimotor processing. Cautious gait may be entirely appropriate in the setting of a recent
fall, with loss of confidence or a perceived fear of falling.40 Crosssectional studies have suggested that a cautious gait is common
and is associated with poor standing balance, depression, anxiety,
fear of falling, and reduced strength.41,43 It is these features that
indicate a cautious gait as a marker of high risk but one potentially amenable to targeted interventions. The distinction between
dysfunctional and excessive compensatory mechanisms and a
primary disturbance of gait is important.44 Identification and
attempted correction of underlying factors contributing to the
syndrome of cautious gait should precede attribution of a primary
gait disorder.43
In direct contrast to cautious gait, those with careless gait15-17
exhibit disinhibition of movement, with an inability to match
their judgment to their physical limitations or the hazards posed
by the external environment. Although many studies have
reported that older adults with dementia walk slowly,45 if their
overall degree of physical impairment is taken into account (e.g.,
use of walking aids, functional impairment), they may actually
walk too quickly.46 Such recklessness implicates frontal lobe disturbance, as noted, and may account for the high incidence of
injurious falls observed in those with dementia. Similarly, in hospitalized older adults, those with delirium are at increased risk of
falls because of excessive ambulation and lack of insight into
mobility problems.47 Conceivably a motor expression of dysexecutive syndrome, and therefore measurable, the development of
tools to test ambulatory impulsivity would have clinical utility
and the potential to predict risk.
Drug burden exponentially challenges the vertical and multiple pathways involved. This may be less of a direct effect on the
locomotor system, except in the case of extrapyramidal consequences of neuroleptics, and more an impact on the executivecognitive hierarchy. Any drug or combination that impinges on
sentient capability can affect mobility adversely and will make a
preexisting mobility impairment even more precarious.48 Conversely, treating cognitive impairment may improve gait characteristics, showing that assessment and thoughtful pharmacologic
857
management of cognition is the prerequisite of a holistic approach
to the optimization of mobility.49,50
CLINICAL ASSESSMENT OF BALANCE
AND MOBILITY
Community ambulation imposes challenges to mobility and
balance through the demands of speed, distance, surface (e.g.,
cement, gravel, sand), terrain (e.g., slope, curb, and road challenges) and stairs that is further challenged by dual tasks (e.g.,
talking, carrying objects), objects in the environment (e.g., people,
animals, physical structures), different lighting (e.g., dark, dim,
shade, sunlight), and weather conditions.51 Balance is integral to
mobility and may be associated with stabilizing activities (e.g.,
preserving upright posture while standing), more dynamic and
adaptive responses to internal perturbations, or reactive responses
to external perturbations.52
Balance and gait impairments can be quantified using different
tests. These measure varying balance parameters, gait speed,
and impact of other graded challenges, including secondary tasks
that require attention and higher order executive function. A
range of balance and mobility tools32,53-76 is summarized in
Table 102-2 in relation to reliability, validity, performance norms
for older adults, sensitivity to change across short (e.g., acute
hospital stay) or longer time periods (e.g., subacute rehabilitation,
community-based care), and ability to predict adverse health or
fall outcomes. The functional gait assessment,72-77 BEST test and
mini–BEST test,69-72 and timed up-and-go (TUG) test, with or
without dual task components,60-64 have emerged as the stronger
tools to consider in relation to outcomes and for predicting risk
of falls in rehabilitation and community contexts. Evidence has
also suggested that monitoring backward walking78 and stair
climbing in conjunction with gender and fear of falling79 are
critical elements indicating the risk of falls in home and community settings.
A broader functional approach to balance and mobility assessments, with the inclusion of bed mobility, sitting and standing
balance, transfers, and walking, appears to be better suited to the
acute ward setting when frail older adults are hospitalized. Some
tools (Table 102-3) have been mainly investigated in subacute
rehabilitation settings (e.g., Clinical Outcome Variables Scale
[COVS],80 modified elderly mobility scale [MEMS]81) and residential care settings (PMS),82-84 whereas the de Morton mobility
index (DEMMI)85-89 and hierarchical assessment of balance and
mobility (HABAM)90-93 have been more thoroughly examined in
the acute ward setting. The assessment of balance and mobility
across a range of motor tasks offers several clinical benefits, such
as the following:
• Risk stratification of health—using mobility and balance as a
noninvasive tool to identify physiologic decline before conventional means of evaluation register such concerns
• Exploration of relationships between mobility and balance
and specific diagnoses and/or geriatric syndromes
• Identification of objective thresholds of improvement to
determine suitability and timing of more intensive rehabilitation programs
• Visual demonstration of progress to inform patients and caregivers, facilitate teaching and learning opportunities, and
enable multidisciplinary understanding
• Assessment of mobility and balance to provide a culture of
clinically meaningful patient contact without redress to expensive technologies
Given the importance of mobility and balance as an overall
correlate of an individual’s state of health, selection of a mobility
tool with the capacity to track daily changes in a patient’s health,
such as the HABAM (Figure 102-1),93 is an important criterion
to consider when managing an acutely unwell patient. This has
102
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PART III Problem-Based Geriatric Medicine
TABLE 102-2 Measures of Balance and Gait for the Hospital, Rehabilitation, or Community Settings
Clinical Balance
and Gait Measures
Items Rated or Measured
by Scale or Test
Clinical Test for
Sensory Integration
of Balance
(CTSIB)53,54
Five times sit to stand
(5×STS)32,55,56
Feet apart—firm EO/EC,
foam EO/EC
Feet together—firm EO/EC,
foam EO/EC
Time to complete standing
up and sitting down five
times
Berg Balance Scale
(BBS): 0-56
points57-59
14 items rated 0-4—sitting,
standing, transfers,
stepping, 360-degree
turn, pick up object on
floor
Time to stand, walk, turn at
3 m, return to chair and
sit down60,61
Timed up-and-go
(TUG) test—TUG
manual; TUG
cognitive60-64
Reliability and
Validity for Older
Adults
Normative Data for
Older Adults
Well established53
Pass-fail; 30-sec trials53
Well-established
acute and
rehabilitation
settings32,55
Well established
across settings
60-69 yr = 11.4 sec;
70-79 yr = 12.6 sec;
80-89 yr = 14.8 sec55
Well established
across acute,
rehabilitation,
and community
settings
60-69 yr < 8.5 sec;
70-79 yr < 9.5 sec63
Age-matched healthy
adults = 1.36 m/sec
Older men > 550 m
Older women > 450 m
>56
MDC= 4-7 points58
10-m walk test
(10MWT)65
6-m walk test
(6MWT)66
10-m timed (sec) over 14-m
walkway
Distance walked over 30-m
walkway
Well established
Dynamic Gait Index
(DGI)—score 0-24;
eight walking items
rated 0-367,68
Standard—change walk
speed; walk + head
movements, pivot turn,
step over and around
obstacles, walk up and
down stairs
Biomechanical, stability,
transitions anticipatory
control, reactive control,
sensory orientation,
walking tasks and gait
Well established
Healthy older adults
score = 21 ± 367,68
Well established
Healthy older adults
score >69%71
Standard—change walk
speed, walk + head
movements, pivot turn,
step over obstacles,
heel-toe walk, walk with
EC, backward walking,
walk up and down stairs
Well established86,88
Healthy older adults
score > 22
MDC = 577
BEST test—score
0-108; 36 items
rated 0-3 (six
categories of
balance and gait
tested)69-73
Functional gait
assessment—
score 0-30; 10
items rated 0-373-77
Well established
Predictive of
Adverse Health or
Falls and Fall Risk
Floor and
Ceiling Effects
Failed trials on foam
EO/EC linked to
adverse health and
fallers54
>13.6 sec (older adults
with disability)
>15 sec linked to
recurrent fallers
41-56: low fall risk
21-40: moderate fall
risk
0-20: high fall risk59
Ceiling effect
with higher
functioning
older adults
No ceiling effect;
real change =
2.5 sec56
>13.5 sec moderate
predictor of falls
Faller-nonfaller
3.69 sec difference
>13.5 sec
Predictive of 83% of
prospective fallers
in 6-mo60,64
Not established
No ceiling effect
MDC = 2.5 sec60
Fallers walk < 250 m
MDC varies between
clinical groups by
≈90 m
Moderate risk for fall
< 1968
Fallers = 11 ± 4
Predictive of 67% of
prospective fallers
across 6 mo
Predictive of fallers73
No ceiling effect
defined
<22/30—high fall risk
up to 80 yr of age
<20—high fall risk if
>80 yr
Predictive of 100% of
fallers across
6 mo73,76,77
No ceiling effect
established in
older adults
Ceiling effect
with higher
functioning
older adults
No ceiling effect
Ceiling effect
with higher
functioning
older adults
No ceiling effect
established in
older adults
EC, Eyes closed; EO, eyes open; MDC, minimal detectable change.
particular utility in frail older adult patients, in whom traditional
signs of illness may not be present.
IMPAIRED MOBILITY AND FRAILTY
Falls are frequently pivotal events in the life of a frail individual.
Trauma aside, the loss of confidence, mobility decline, deconditioning, social withdrawal, and fear of falling can become overwhelming. The most consistent independent predictors of future
falls in older adults are gait or balance deficits.94 This is consistent
with the paradigm of frailty in older adults as the failure of a
complex system.95
Normal ambulation requires the coordination of many different muscles acting on multiple joints; it is accomplished by the
integration of activity in spinal neuronal circuitries with sensory
feedback signals and descending commands from the motor
cortex.96 The central nervous system coordinates this activity,
adjusts it to fit environmental conditions, and refines it when
required, all while maintaining a remarkable degree of precision.
This is evident when foot position is considered during normal
walking, in which multiple joints and muscles act to ensure that
the foot is elevated by 1 to 2 cm above the ground and the position varies by less than 4 mm.97,98 The computational task solved
by the human brain to accomplish this feat is extraordinary, given
the infinite number of combinations of joint and muscle positions
that have to be attained relative to each other to arrive at the
desired outcome. Bipedalism is a higher order function that
requires a significant degree of connectivity and coordination
among several interdependent components (muscular, skeletal,
and nervous) of the complex system that is the human body.
Consequently, it is not surprising that frail individuals who have
gait and balance deficits and who have lost the ability to integrate
multiple inputs in the face of stress often present with impaired
mobility and falls.99
There is a direct relationship between frailty and mobility;
impairment in balance and mobility is universal at a high frailty
CHAPTER 102 Impaired Mobility
859
TABLE 102-3 Functional Mobility Measures for Acute Wards, Residential Care, and Rehabilitation Units*
102
Reliability and
Validity for Older
Frail Adults
Predictive for
Falls and Fall
Risk
Minimal
Detectable
Change
Bed mobility, horizontal and
vertical transfers, wheelchair
mobility; upper limb function;
walking ability—speed,
distance, external challenges
Lying down and sitting up, sit to
stand, standing balance, gait
speed, gait independence,
stairs, functional reach
Bed mobility, sitting, transfers,
walking82,83
Established in
subacute
rehabilitation
settings
Not established
7 points7
Ceiling effect with
higher functioning
adults
Established in
subacute
rehabilitation
settings
Established in
residential care
settings
Not established81
Not defined
Ceiling effect with
higher functioning
adults
5 points82,83
None reported in
aged care
context
De Morton mobility
index (DEMMI)—
converted score,
0%-100%85-89
15 items of graded challenge—
bed mobility, sitting, standing,
gait, advanced gait activities
9 points89
None reported with
older adults
Hierarchal assessment
balance and mobility
(HABAM)—0-6590-93
Three broad categories of
graded challenge mobility
(bed, sitting, standing)—
walking, 0-26; transfers,
0-18; balance, 0-21 (no aid)
Established in
acute ward,
rehabilitation,
and community
settings86-88
Established for
acute hospital
settings90-93
Inverse relationship
between level of
mobility and risk
of falls94
Not established
Not established
Sensitivity to
change in health
status reported
in acute setting93
None reported with
older adults
Functional Mobility
Measures
Items Rated or Measured by
Scale or Tool
Clinical Outcome
Variables Scale
(COVS)—0-91
points; 13 items
rated 1-780
Modified elderly
mobility scale—0-23
items rated 0-381
Physical mobility scale
(PMS)—0-4682-84
Floor and Ceiling
Effects
*Functional mobility includes a range of motor tasks from bed mobility to walking.
burden100 and leads to functional decline, with physical activity a
critical element in the prevention of this deterioration. Although
mobility and balance impairment are sensitive if nonspecific indicators of acuity in frail patients, these elements may be insufficient to define frailty fully in keeping with the tenet that multiple
systems, not just mobility, are implicated. Thus, holistic management is required that is best informed through a comprehensive
geriatric assessment.101
Through a comprehensive assessment, targeted interventions
can be implemented. Several groups have emphasized the need
to understand osteoporosis and sarcopenia (the reduction of
muscle mass and function) in the pathogenesis of frailty,102-104 as
well as the negative impact of chronic diseases (e.g., degenerative
arthritis, obesity) on the progression to frailty.105 Because immobility and lack of exercise are major factors responsible for the
emergence of chronic diseases and development of sarcopenia,
objective evaluation of physical performance has been advocated
as an indicator of frailty in older adults.85,93 Poor performance on
selected tests characterize those who may benefit from targeted
and multifactorial interventions.106-108
Some components of frailty may be more predictive of adverse
outcomes. Women with lower limb osteoarthritis or rheumatoid
arthritis have a mild to moderate risk of falls and balance impairments in comparison to age-matched older women.105 Among
very frail older adults, those with mobility disability had a higher
risk of mortality and nursing home placement than those without
disability.109 The effects of osteoporosis and sarcopenia have been
implicated in more severe presentations of frailty in communitydwelling older women.103,104 In participants in the MacArthur
Study of Successful Aging, six frailty subdimensions were identified, involving different combinations of four or more of ten
criteria: weight loss, weak grip, exhaustion, slow gait, low physical
activity, cognitive impairment, high interleukin-6 level, high
C-reactive protein level, subjective weakness, and anorexia. Each
had a different predictive validity for disability and mortality,
suggesting “that pathways to frailty differ and that sub-dimensionadapted care might enhance care of frail seniors.”110
Although some researchers in the aging field have emphasized
the conceptualization of frailty as a risk state and others have
aimed to clarify components of the risk state, the importance of
mobility impairment is universally recognized. Both approaches
to frailty are motivated by the need to increase our understanding
of the pathways to poor health in older adults, and they are not
irreconcilable. Inouye and associates,111 for example, have identified impaired mobility as one of four shared risk factors—along
with older age, baseline cognitive impairment, and baseline functional impairment—for five common geriatric syndromes (delirium, pressure ulcers, incontinence, falls, and functional decline)
and for the overarching geriatric syndrome of frailty. It is certainly feasible to unite the two different approaches to frailty,
recognizing and investigating the importance of components of
frailty, yet managing it as a complex condition.
INTERVENTIONS FOR IMPAIRED MOBILITY
The prevalence of impaired mobility and frailty requires a continuing emphasis on interventions within the community, residential care, and hospital settings.
Community-Dwelling Older Adults
Exercise programs of varying design have diverse positive effects
in community-dwelling older adults, including improved muscle
strength and gait speed,112 reduction in falls,113 and improved
balance.114 In longitudinal cohort studies, physical activity is protective of impaired physical function.115 Participation in frequent
and intense training can result in even greater improvements in
reactive balance performance; for example, older athletes undertaking long-term, high-intensity training demonstrate better and
more rapid stabilization of posture following perturbation than
healthy older adults under challenging conditions.116 A systematic
review and meta-analyses of intervention programs involving
older adults117 has revealed stronger effects in programs that
included exercises that challenged balance, used a higher dose of
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PART III Problem-Based Geriatric Medicine
HIERARCHICAL ASSESSMENT OF BALANCE AND MOBILITY
Completed By: __________________________________ Date Completed: _____________________
Date Assessed
Instrument
Day
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BALANCE
21. Stable ambulation
21
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14. Stable dynamic standing
10
10. Stable static standing
7
7. Stable dynamic sitting
5. Stable static sitting
5
5
5
5
0. Impaired static sitting
TRANSFERS
18. Independent and vigorous
18
16. Independent
16
14 Independent but slow
14
12. One-person standby
12
11. One-person minimal assist
11
7. One-person assist
7
3. Two-person assist
7
7
3
0. Total lift
MOBILITY
28. Unlimited, vigorous
26. Unlimited
25. Limited >50 m, no aid
21. Unlimited, with aid
19. Unlimited with aid, slow
18. With aid >50 m
18
18
16. No aid, limited 8-50 m
15
15. With aid 8-50 m
14
14. With aid <8 m+
12. 1 person standby/+/-aid
12
9. 1 person hands-on/+/-aid
7. Lying-sitting independently
9
7
12
9
7
4. Positions self in bed
0. Needs positioning in bed
Notes for scoring the HABAM.
• Baseline (-14) is taken as 2 weeks prior to the current assessment.
•
Each domain (balance, transfers, mobility) is scored at the highest level attained.
•
In balance, “dynamic” refers to withstanding a force, either administered externally (e.g., a sternal nudge) or internally (e.g., reaching
forward).
•
In transfers, standby assist refers to no hands-on assistance but presence of an aide for security; minimal assist refers to hands
on with little force, chiefly for guidance.
•
In mobility, <8 m corresponds to not being able to walk outside the room; 8-50 m mobility is being able to get to the nursing station
and back; >50 m is more than one trip around the ward.
•
The HABAM should be scored using the patient’s usual walking aid.
A
Figure 102-1. Hierarchical assessment of balance and mobility form. A, The patient’s mobility and balance had
deteriorated considerably from baseline. The patient could only move from side to side in bed and required the
assistance of two people to transfer and to walk. By the second hospital day, however, recovery had begun
and accelerated after day 5.
861
CHAPTER 102 Impaired Mobility
HIERARCHICAL ASSESSMENT OF BALANCE AND MOBILITY
102
Completed By: __________________________________ Date Completed: _____________________
Date Assessed
Instrument
Day
-14
01
02
03
05
06
0
0
0
0
0
0
0
0
0
0
07
08
09
10
11
12
13
14
15
16
17
18
BALANCE
21. Stable ambulation
21
14. Stable dynamic standing
10. Stable static standing
7. Stable dynamic sitting
5. Stable static sitting
5
0. Impaired static sitting
TRANSFERS
18. Independent and vigorous
18
16. Independent
14 Independent but slow
12. One-person standby
11. One-person minimal assist
7. One-person assist
3. Two-person assist
3
3
0. Total lift
MOBILITY
28. Unlimited, vigorous
26. Unlimited
25. Limited >50 m, no aid
21. Unlimited, with aid
19. Unlimited with aid, slow
18. With aid >50 m
18
16. No aid, limited 8-50 m
15. With aid 8-50 m
14. With aid <8 m+
12. One-person standby/+/-aid
9. One-person hands-on/+/-aid
7. Lying-sitting independently
4. Positions self in bed
0. Needs positioning in bed
7
4
Notes for scoring the HABAM.
• Baseline (-14) is taken as 2 weeks prior to the current assessment.
•
Each domain (balance, transfers, mobility) is scored at the highest level attained.
•
In balance, “dynamic” refers to withstanding a force, either administered externally (e.g., a sternal nudge) or internally (e.g., reaching
forward).
•
In transfers, standby assist refers to no hands-on assistance but presence of an aide for security; minimal assist refers to hands
on with little force, chiefly for guidance.
•
In mobility, <8 m corresponds to not being able to walk outside the room; 8-50 m mobility is being able to get to the nursing station
and back; >50 m is more than one trip around the ward.
•
The HABAM should be scored using the patient’s usual walking aid.
B
Figure 102-1, cont’d. B, Another patient with a similar level of decline continued worsening on the second and
third hospital days; this signaled a rapidly fatal course that ended in death by day 6. (Modified from MacKnight
C, Rockwood K: Rasch analysis of the hierarchical assessment of balance and mobility [HABAM]. J Clin Epidemiol
53:1242-1247, 2000; and Rockwood K, Rockwood MR, Andrew MK, et al: Reliability of the hierarchical assessment of balance and mobility in frail older adults. J Am Geriatr Soc 56:1213-1217, 2008.)
862
PART III Problem-Based Geriatric Medicine
exercise, and did not include a walking program. These elements
are integrated into the balance strategy training program,118
Otago Exercise Program,119 and tai chi120,121 to promote healthier
aging of sedentary and active older adults. Intervention programs
involving frail older adults may need to be modified to accommodate problems such as degenerative arthritis,105 osteoporosis
and sarcopenia,103,104 and the age-related decline in sensorimotor
systems.122
Because the benefits of exercise are rapidly lost when exercise
is ceased, the issue of adherence to interventions and exercise
continues to need attention.123 Although adherence to exercise is
a multifactorial issue, follow-up of older adults participating in
an exercise-based intervention after discharge to home has
revealed that being female, with a low self-efficacy124 for falls,
as well as concern regarding pain during exercise, are critical
factors to consider.125 Other studies have emphasized the need to
screen for cognitive impairment before commencing interventions.126 Limited but fairly consistent findings in trials of higher
methodologic quality have shown that home-based exercise and
fall-related multifactorial programs,106-108 along with communitybased tai chi programs delivered in a group format,120,121 have
been effective in reducing fear of falling in community-living
older adults. Of note, frail older females positively engaged in
a home-based intervention program when provided with supportive phone follow-up across the intervention period,125 supporting one strategy for future delivery of home-based programs
for frail older adults. It is thus important to monitor physical
capacity and balance, along with cognition and self-efficacy, when
individuals enroll in intervention programs in home or community contexts. Physical capacity along with self-efficacy will help
inform goal setting and the type of instruction and support
that individual participants may require to maximize community
ambulation.
Older Adults in Residential Care Facilities
Exercise programs for frail older adults in long-term care have
yielded conflicting results. A systematic review of physical training in institutionalized older adults has indicated positive effects
on muscle strength, but effects on gait, disability, balance, and
endurance were inconclusive.109 In some studies, exercise programs involving very frail older people resulted in no improvements in physical health or function,127 with an increase in
musculoskeletal injury and falls128 reported. In contrast, other
studies have concluded that exercise improves physical performance scores,129 slows further functional decline, and reduces
falls.100,130 Given these discrepancies in reported adverse events,
it is likely that the status of an individual needs to be understood
so that the benefits of exercise can be attained while the potential
for adverse outcomes, such as falls, can be reduced through
appropriate selection of the delivery mode. Tools with predictive
capacity for falls in the residential care setting, such as the Physical Mobility Scale,84 could be instructive in this context, enabling
clinicians to meet the needs of residents to participate safely in
exercise programs for improved health.
Older Adults in Hospital
Impaired mobility in the hospital should be considered a negative
prognostic sign. Mobility decline in hospital is an important
determinant of poor functional recovery,131 as well as a predictor
of mortality.132 Measured through accelerometry, lower mean
daily step count is associated with readmission to hospital,133 and
an inability to engage with performance-related tasks is linked to
failure to achieve premorbid mobility.132 Note also that many
acutely ill people cannot walk, decline in bed mobility which can
be tracked by the HABAM, is also a herald of death.93 Hence, if
physicians only think about walking before they concern themselves with mobility, they will miss informative clinical signs.
What can be done to mitigate these adverse outcomes? Even
in ambulatory hospitalized patients, the time spent standing
or walking is only of the order of 1 hour/day.132 Interestingly,
the risk-averse culture within health profession may contribute
to the restriction of mobility activities in an effort to provide
“care and keep them safe.”134
Avoidance of nosocomial disability requires identification of
frail inpatients with interventions to address the multifactorial
nature of mobility disturbance. Again, interventions to improve
outcomes in hospitalized older adults have centered on exercise.
A Cochrane systematic review135 has determined the effect of
exercise interventions for acutely hospitalized older medical
patients on functional status, adverse events, and hospital outcomes. Of 3138 potentially relevant articles screened, seven randomized controlled trials and two controlled clinical trials were
included. Although the effects of exercise on functional outcome
measures were unclear, there was level 2 evidence that multidisciplinary intervention that includes exercise may increase the
proportion of patients discharged to home, and reduce the length
and cost of the hospital stay for acutely hospitalized older medical
patients.
Nutritional support also improves outcomes of hospitalized
older adults.136 Although mobility outcomes were not explicitly
reported, attention to nutrition significantly reduced patients’
risk of dying after hip fracture.137 Anabolic agents are theoretically attractive as therapeutic agents in hospitalized older adults,
reducing the negative nitrogen balance and improving body composition, but small randomized controlled trials have shown no
effects on mobility or function, and further studies with longer
follow-up periods are needed.138
Embedding nutritional support, early mobilization and cognitive stimulation in an Eat, Walk, Engage model has shown promising effects on outcomes such as length of hospital stay.139 This
holistic approach is congruent with informing interventions
through a comprehensive geriatric assessment (CGA),101,140 with
subsequent optimal outcomes for older adults.
CONCLUSION
Mobility impairment is integral to frailty, however it is defined.
The need to quantify mobility performance during the acute care
period is compelling, with selection of tools that are sensitive to
changes in health status. Measures of balance and gait that include
a graded challenge are more instructive for rehabilitation and
community contexts. Assessment tools deliver a number of
functions—for inpatients, they can provide clinicians with valuable information on which to make decisions regarding readiness
for discharge from the acute hospital environment; for community dwellers, they provide predictive indicators for falls so that
preemptive prevention interventions can be implemented.
Multifactorial and multidisciplinary interventions are essential
to manage impaired mobility in older adults at the frailer end of
the health spectrum. Exercise modes that include balance training, functional strength, and endurance training seem to be most
effective to manage the demands of community ambulation and
promote healthier aging. Knowledge of the factors limiting
engagement and adherence to exercise modes is another challenge that requires the attention of health professionals with
physical capacity, cognition, and self-efficacy emerging as issues
to be considered when planning intervention programs for older
adults.