Wearable inertial sensors to measure gait and posture characteristic differences in older adult fallers and non-fallers: A scoping review

BackgroundWearable inertial sensors have grown in popularity as a means of objectively assessing fall risk. This review aimed to identify gait and posture differences among older adult fallers and non-fallers which can be measured with the use of wearable inertial sensors. In addition to describing the number of sensors used to obtain measures, the concurrent anatomical locations, how these measures compare to current forms of clinical fall risk assessment tests and the setting of tests.MethodsFollowing the development of a rigorous search strategy, MEDLINE, Web of Science, Cochrane, EMBASE, PEDro, and CINAHL were systematically searched for studies involving the use of wearable inertial sensors, to determine gait and postural based differences among fallers or those at high fall risk compared with non-fallers and low fall risk adults aged 60 years and older.ResultsThirty five papers met the inclusion criteria. One hundred and forty nine gait and posture characteristic differences were identified using wearable inertial sensors. There were sensor derived measures which significantly and strongly correlated with traditional clinical tests. The use of a single wearable inertial sensor located at the lower posterior trunk, was most the most effective location and enough to ascertain multiple pertinent fall risk factors.ConclusionThis review identified the capabilities of identifying fall risk factors among older adults with the use of wearable inertial sensors. The lightweight portable nature makes inertial sensors an effective tool to be implemented into clinical fall risk assessment and continuous unsupervised home monitoring, in addition to, outdoor testing.     

A mobile app to transparently distinguish single- from dual-task walking for the ecological monitoring of age-related changes in daily-life gait

BackgroundEarly detection of gait impairments in older adults allows the early uncovering of fall risk and/or cognitive deficits, resulting in timely interventions. Dual-task paradigms have been shown to be more sensitive than single-task conditions for the detection of subtle yet relevant gait impairments.Research questionCan a system - encompassing a pair of instrumented insoles and a customized mobile app - transparently and accurately study ecological walking activities in single- and dual-task conditions, with the aim of detecting early and subtle age-related alterations of gait?MethodsThe system was tested on 19 older adults during outdoor walking (two identical single-task trials and two motor-cognitive dual-task trials with the user engaged in a simple phone call and in a cognitive-demanding phone call). A single-task cognitive trial was included. Relative reliability of the gait parameters provided by the insoles during single-task walking was investigated (Intraclass Correlation Coefficient). The effect of dual tasking on both motor (Friedman test) and cognitive (Wilcoxon signed-rank test) domains was studied.To study usability, the system was tested on 5 older adults in real-life environment over 3 months.ResultsMost of the parameters showed excellent reliability. Independently from the cognitive demand, walking while talking resulted in increased gait cycle and step time, with a prolonged stance phase due to an augmented double-support. Variability of gait cycle and stance phase increased only during the most demanding dual-task. Dual tasking resulted in a reduced cognitive score.Usability feedback were excellent, with users reporting to understand the usefulness of the devised system and to feel at ease when using the system and the insoles.SignificanceThis work paves the way toward fruitful applications of the devised system to achieve accurate and ecological monitoring of daily-life walking activities, with the final aim of detecting early and subtle alterations of gait.     

Reducing the risk of falls among older adults: the Fallproof Balance and Mobility Program

Fall-related deaths among the older adult segment of the population constitute a growing public health concern that is largely preventable. A growing body of research has identified a number of effective intervention strategies that can lower the incidence of falls and/or risk factors that contribute to heightened fall risk. One particularly effective intervention strategy that has been identified is exercise, whether individually prescribed or conducted in group-based settings. The Fallproof Balance and Mobility Program was developed in response to the need for effective community-based programs that target the important intrinsic risk factors (e.g., impaired balance and gait, muscle weakness) associated with increased fall risk. This theory-driven program adopts a multidimensional approach to balance and mobility that has proven to be effective in reducing fall risk among older adults identified as moderate-to-high risk for falls. The fidelity of the program also has been maintained by implementing an instructor certification program and standardizing program content and delivery.     

Hearing loss and increased gait variability among older adults

BackgroundThe influence of age-related hearing loss on slow gait has been suggested; however, whether it is associated with increased gait variability, an important predictor of fall risk, remains unclear.Research questionIs poor auditory acuity associated with increased gait variability, and does this gait change relate to accidental falls among older adults with hearing loss?MethodsWe studied 107 older adults (mean age, 76.5 years; 80.5 % women). Auditory acuity was measured using a pure tone average (PTA) of hearing thresholds for 0.5–4 kHz tones in the better-hearing ear. Hearing loss was defined as a PTA of >25 dB. Gait speed and spatiotemporal variability (i.e., stride length and time variabilities) were assessed using a 5-m electronic walkway. We also assessed the occurrence of multiple falls within the previous year.ResultsFifty-two participants (48.6 %) experienced hearing loss. Multiple regression analysis adjusted for potential covariates showed that poor PTA was associated with slower gait speed and stride length variability, but not stride time variability. Among older adults with hearing loss, fall occurrence was associated with an increased stride length variability and not a slow gait or increased stride time variability.SignificanceThe association between hearing loss and increased gait variability observed in the present study suggests that age-related hearing loss can jeopardize gait control during daily activities. This leads to increased gait variability and increased risk of accidental falls. Our results provide additional information on how age-related hearing loss increases the risk of falls.     

Gait assessment in mild cognitive impairment and Alzheimer's disease: the effect of dual-task challenges across the cognitive spectrum

Gait impairment is a prominent falls risk factor and a prevalent feature among older adults with cognitive impairment. However, there is a lack of comparative studies on gait performance and fall risk covering the continuum from normal cognition through mild cognitive impairment (MCI) to Alzheimer's disease (AD). We evaluated gait performance and the response to dual-task challenges in older adults with AD, MCI and normal cognition without a history of falls. We hypothesized that, in older people without history of falls, gait performance will deteriorate across the cognitive spectrum with changes being more evident under dual-tasking. Gait was assessed using an electronic walkway under single and three dual-tasks conditions. Gait velocity and stride time variability were not significantly different between the three groups under the single-task condition. By contrast, significant differences of decreasing velocity (p<0.0001), increasing stride time (p=0.0057) and increasing stride time variability (p=0.0037) were found under dual-task testing for people with MCI and AD. Less automatic and more complex dual-task tests, such as naming animals and serial subtraction by sevens from 100, created the greatest deterioration of gait performance. Gait changes under dual-tasking for the MCI and AD groups were statistically different from the cognitively normal controls. Dual-task assessment exposed gait impairments not obvious under a single-task test condition and may facilitate falls risk identification in cognitively impaired persons without a history of falls.     

The Dynamic Gait Index in healthy older adults: the role of stair climbing, fear of falling and gender

The Dynamic Gait Index (DGI) was developed as a clinical tool to assess gait, balance and fall risk. Because the DGI evaluates not only usual steady-state walking, but also walking during more challenging tasks, it may be an especially sensitive test. The present investigation evaluated the DGI and its association with falls, fear of falling, depression, anxiety and other measures of balance and mobility in 278 healthy elderly individuals. Measures included the DGI, the Berg Balance Test (BBT), the Timed Up and Go (TUAG), the Mini-Mental State Exam (MMSE), the Unified Parkinson's Disease Rating Scale (UPDRS) motor part, the Activities-specific Balance Confidence (ABC) scale and the number of annual falls. The DGI was moderately correlated with the BBT (r=0.53; p<0.001), the TUAG (r=-0.42; p<0.001) and the ABC (r=0.49; p<0.001). Fallers performed worse on the DGI compared to non-fallers (p=0.029). Scores on the DGI were near perfect in men (23.3+/-1.2), but among women, there was a small, but significant (p<0.001) decrease (22.5+/-1.6). The reduction in the DGI score in women was due to stair climbing performance, with many women (65%) choosing to walk while holding a handrail, compared to only 39% of men. Scores on the BBT, the TUAG, the UPDRS and the MMSE were similar in men and women. Conversely, ABC scores and fall history were different. These findings suggest that the DGI, although susceptible to ceiling effects, appears to be an appropriate tool for assessing function in healthy older adults.     

A comparison of turn and straight walking phases as predictors of incident falls

BackgroundWhile gait assessments are recommended to evaluate fall risk in older adults, these often involve walking in a straight line, even though one-third of steps taken throughout the day involve turning. Falls that occur during a turn tend to be more serious than falls that occur during a straight walk, but little is known about how gait variables collected during a turn can predict falls.Research questionHow do gait characteristics collected from straight and turning walking phases predict falls in older adults?MethodsWe prospectively examined the association between six quantitative gait variables measured during normal walking turn and straight walking phases as predictors of incident falls in a community-based sample of older adults (N = 253; mean age 78.5; 51% women). Cox regressions adjusted for multiple potential confounders were used to examine the associations.ResultsParticipants had significantly slower stride velocity (57.81 vs 83.26 cm/s), shorter stride length (74.76 vs 101.81 cm,), lower swing (30.1 vs 32.41%), higher double support (39.79 vs 35.19%), and more swing (30.09 vs 32.41%) and stride length variability (31.86 vs 6.35 %) during turns compared with straights. Higher swing percent in both turns (adjusted hazard ratio; HR 0.92, 95% CI 0.87, 0.97) and straights (HR 0.89, 95% CI 0.84, 0.96) was associated with reduced risk of falls. Higher double support percent during both turns (HR 1.04, 95% CI 1.01, 1.07) and straights (HR 1.06, 95% CI 1.02, 1.09) was associated with increased risk of falls. More swing variability during turns (HR 1.03, 95% CI 1.00, 1.06), but not straights, was associated with increased risk of falls.SignificanceGait variables collected during turning and walking straight were similar in their predictions of future falls. In the future, clinical research that builds on these findings could improve identification and prevention of falls.     

Quantifying stair gait stability in young and older adults,with modifications to insole hardness

Stair gait falls are prevalent in older adults aged 65 years and older. Extrinsic variables such as changes to insole hardness are important factors that can compromise the balance control system and increase the incidence of falls, especially since age-related decline in the cutaneous sensation is common. Balance measurements such as the minimum center of mass/base of support (COM–BOS, termed ‘stability margin') and COM–BOS medial/lateral range provide information about stability during stair gait. This study was conducted to investigate stair gait stability of young and older adults, with modifications to insole hardness. Twenty healthy adults (10 young adults, 10 older adults) were recruited (mean age = 23.1, SD 2.1; mean age = 73.2, SD 5.5) and instructed to descend a 4 step staircase, for a total of 40 trials. All participants wore similar canvas shoes of varying sizes, and corresponding insole hardnesses (barefoot, soft, medium, hard). Kinematic equipment utilized 12 infrared markers anteriorly placed on the individual to record COM motion and BOS location. The findings from the study demonstrated that older adults were less stable during stair descent. Consequently, insole conditions revealed that the barefoot condition may increase the likelihood of falls, as opposed to the other insole hardnesses (soft, medium and hard). These results suggest that older adults while barefoot are putting themselves at a great risk of falling during stair descent. Since age-related changes are inevitable and the preferred footwear of choice inside the home is bare feet, this is a crucial issue that should be addressed.     

Exercise in the prevention of falls in older people: a systematic literature review examining the rationale and the evidence

Falls are a major source of death and injury in elderly people. For example, they cause 90% of hip fractures and the current cost of hip fractures in the US is estimated to be about 10 billion dollars. Age-related changes in the physiological systems (somatosensory, vestibular and visual) which contribute to the maintenance of balance are well documented in older adults. These changes coupled with age-related changes in muscle and bone are likely to contribute to an increased risk of falls in this population. The integrated rehabilitation-based model of fall risk factors reveals multiple sites for interventions that may reverse fall risk factors. Regular exercise may be one way of preventing falls and fall-related fractures. The evidence for this contention comes from a variety of sources. On the basis of 9 randomised controlled studies conducted since 1996, exercise appears to be a useful tool in fall prevention in older adults, significantly reducing the incidence of falls compared with control groups. However, current limitations such as inconsistencies in the measurement of key dependent and independent variables do not, at present, permit a meta-analysis of intervention trials. Further investigation, using trials designed with the current limitations in mind, is necessary to establish the optimum exercise programme to maximise fall prevention in older adults.     

Relationship between hamstring activation rate and heel contact velocity: factors influencing age-related slip-induced falls

The purpose of this research was to determine whether a decreased hamstring activation rate among the elderly is responsible for a higher horizontal heel contact velocity and increased likelihood of slip-induced falls compared to their younger counterparts. Twenty-eight subjects from two age groups (14 young and 14 old) walked across a linear walking track with embedded force platforms while wearing a fall arresting harness attached to an overhead arresting rig for safety. In order to obtain realistic unexpected slip-induced fall data, a soapy vinyl floor surface was hidden from the subjects and unexpectedly introduced. Synchronized kinematics, kinetic and electromyography (EMG) analyses during the heel contact phase of the gait cycle while walking over slippery and non-slippery floor surfaces were examined in the study. Normalized EMG data were examined in terms of hamstring activation rate and evaluated with heel contact velocity and friction demand characteristic (as measured by peak required coefficient of friction (RCOF)) on the dry vinyl floor surface. Furthermore, slip parameters (i.e. slip distances and slipping velocity) were assessed on the soapy vinyl floor surface. The results indicated that younger adults' hamstring activation rate was higher than older adults, whereas younger adults' heel contact velocity was not different from older adults. These results suggested that heel contact velocity in younger adults was sufficiently reduced before the heel contact phase of the gait cycle. This could be due to the outcome of higher hamstring activation rate in younger adults in comparison to older adults. However, lower friction demand (peak RCOF), shorter slip distances, slower peak sliding heel velocity and more falls among older adults suggested that the slip initiation characteristics were not the only factors contributing to slip-induced falls among the elderly.     

Increased gait variability may not imply impaired stride-to-stride control of walking in healthy older adults: Winner: 2013 Gait and Clinical Movement Analysis Society Best Paper Award

Older adults exhibit increased gait variability that is associated with fall history and predicts future falls. It is not known to what extent this increased variability results from increased physiological noise versus a decreased ability to regulate walking movements. To “walk”, a person must move a finite distance in finite time, making stride length (L_n) and time (T_n) the fundamental stride variables to define forward walking. Multiple age-related physiological changes increase neuromotor noise, increasing gait variability. If older adults also alter how they regulate their stride variables, this could further exacerbate that variability. We previously developed a Goal Equivalent Manifold (GEM) computational framework specifically to separate these causes of variability. Here, we apply this framework to identify how both young and high-functioning healthy older adults regulate stepping from each stride to the next. Healthy older adults exhibited increased gait variability, independent of walking speed. However, despite this, these healthy older adults also concurrently exhibited no differences (all p > 0.50) from young adults either in how their stride variability was distributed relative to the GEM or in how they regulated, from stride to stride, either their basic stepping variables or deviations relative to the GEM. Using a validated computational model, we found these experimental findings were consistent with increased gait variability arising solely from increased neuromotor noise, and not from changes in stride-to-stride control. Thus, age-related increased gait variability likely precedes impaired stepping control. This suggests these changes may in turn precede increased fall risk.     

Effect of Tai Chi on gait and obstacle crossing behaviors in middle-aged adults

This study investigated whether long-term, habitual practice of Tai Chi (or Taiji) results in behavioral modifications during gait. Specifically, we examined whether Tai Chi (TC) experience alters gait behavior during normal and obstructed walking. Fifteen experienced TC practitioners and fifteen control subjects (average age 45 years, 23-66 year range) completed level walking trials with or without a stationary obstacle placed in their path. TC practitioners in this study had an average of 6.5 years (1.5-15 year range) of Chen-style Tai Chi experience. Kinematic analyses performed on their step-to-step gait characteristics over multiple steps revealed that TC practitioners used a more cautious strategy by using slower gait speeds and shorter and slower steps than controls (p 相似文献   

Reliability of inertial sensor based spatiotemporal gait parameters for short walking bouts in community dwelling older adults

BackgroundWhen performing quantitative analysis of gait in older adults we need to strike a balance between capturing sufficient data for reliable measurement and avoiding issues such as fatigue. The optimal bout duration is that which contains sufficient gait cycles to enable a reliable and representative estimate of gait performance.Research questionHow does the number of gait cycles in a walking bout influence reliability of spatiotemporal gait parameters measured using body-worn inertial sensors in a cohort of community dwelling older adults?MethodsOne hundred and fifteen (115) community dwelling older adults executed three 30-metre walk trials in a single measurement session. Bilateral gait data were collected using two inertial sensors attached to each participant’s right and left shank, and gait events detected from the medio-lateral angular velocity signal. The number of gait cycles selected from each walking trial was varied from 3 to 16. Intraclass correlation coefficients (ICC(2,k)) were calculated to evaluate the reliability of each spatiotemporal gait parameter according to the number of gait cycles included in the analysis.ResultsThe specified algorithm and the clipping procedure for extracting short bouts of gait data seem appropriate for assessing older adults, providing reliable spatiotemporal measures from three gait cycles (three strides per leg) and good reliability for most parameters describing gait variability and gait asymmetry after six gait cycles (six strides per leg).SignificanceA combination of using bilateral sensor data and adaptive thresholds for gait event detection enable reliable measures of spatiotemporal gait parameters over short walking bouts (minimum six gait cycles) in community dwelling older adults. This opens new possibilities in the use of wearable sensors in gait assessment based on short walking tasks. We recommend the number of gait cycles should be reported along with the calculated measures as reference values.     

Gait variability in older adults: a structured review of testing protocol and clinimetric properties

Gait variability (stride-to-stride fluctuations) is used increasingly as a marker for gait performance and future mobility status, cognitive status, and falls. This structured review explicitly examined literature that reported on the reliability, validity and responsiveness of gait variability in older adults. We searched Medline, Embase, Web of Science, Scopus, CINAHL, PEDRO, Biomechanics, SportDiscus and PsycInfo databases. Two independent reviewers undertook data extraction, with adjudication by a third reviewer in cases of disagreement. Twenty-two full papers were screened and 10 met the predefined inclusion criteria, involving 1036 participants who were mainly community dwelling older adults in their 8th decade. A wide range of gait variability parameters, testing protocols and calculations of gait variability were reported. Reliability estimates varied, but were mostly fair to moderate. Concurrent validity was established for stance time variability and change estimates were reported for stance time and swing time. Standard of reporting was generally poor, with insufficient detail provided for aspects of measurement and testing protocols. Further research is required to standardise testing procedures and establish reliability, responsiveness and validity for confident use of gait variability as a robust measure.     

A comparison of the efficacy of textured insoles on balance performance in older people with versus without plantar callosities

BackgroundTextured insoles have been suggested to enhance foot sensation, which contributes to controlling upright balance. However, the interaction between plantar callosity and the textured surface has not been studied.Research questionFirstly, to compare the efficacy of textured insoles on balance performance and foot position sense between two groups of older people: one group had plantar callosity, and the other did not. Secondly, to investigate the efficacy of textured insoles within each study group.MethodsThirty older people with a history of falls (15 with plantar callosity and 15 without callosity) participated in this study. All participants underwent assessments of postural sway on a force plate, joint position sensation of the ankle with a slope box, and mobility using the "Timed Up and Go" test under three insole surface conditions: 1) smooth (control), 2) placebo and 3) textured surface. Two-way analyses of variance were used to compare the outcomes of the two groups and three conditions.ResultsOlder people with plantar callosity had worse ankle joint position sense and slower antero-posterior and mediolateral postural sway velocity than their peers who did not have plantar callosity. The textured insoles improved ankle joint position sense and mobility regardless of callus status in the plantar surface of older peoples’ feet. The insole-callosity interaction was not significant for any study outcome.SignificanceTextured insoles could be beneficial to older people with and without callosity as they have shown immediate improvements in ankle joint position sense and mobility.     

Backward relative to forward walking speed and falls in older adults with dementia

BackgroundAdults with dementia have a high risk of falls and fall-related injuries. A greater slowing of backward walking speed (BWS) relative to forward (FWS) has been indicated with older age, and slower BWS has been related to an increased risk of falls. Similarly, slow BWS relative to FWS has been observed in people with dementia.Research questionIs slower BWS, and slower BWS relative to FWS associated with increased risk of prospective falls in older adults with dementia?MethodsIn total, 52 women and 12 men with dementia living in nursing homes, mean age 86 years, and mean Mini-Mental State Examination score of 14.2 points were included. BWS and FWS was measured over 2.4 m, and the directional difference (DD) calculated (100*((FWS-BWS)/FWS)). Falls were followed for 6 months by review of fall incident reports in electronic medical records at nursing homes and the regional healthcare provider.ResultsAltogether, 95 falls occurred with mean incidence rate 3.1 falls per person-years. Of included participants, 15 (23%) fell once, and 17 (27%) fell twice or more. In negative binomial regression analyses, greater DD was associated with lower prospective incidence fall rate ratio, IRR (IRR= 0.96, p < .001), while BWS was not (IRR= 0.04, p = .126).SignificanceIn this study of adults with dementia, slower BWS was not associated with prospective falls. However, slower BWS relative to forward (greater DD) was associated with fewer falls, and possibly a protective response. This is novel research, yet results are promising and indicate that assessing walking speed in multiple directions may inform fall risk in adults with dementia.     

Instrumented shoes for activity classification in the elderly

Quantifying daily physical activity in older adults can provide relevant monitoring and diagnostic information about risk of fall and frailty. In this study, we introduce instrumented shoes capable of recording movement and foot loading data unobtrusively throughout the day. Recorded data were used to devise an activity classification algorithm. Ten elderly persons wore the instrumented shoe system consisting of insoles inside the shoes and inertial measurement units on the shoes, and performed a series of activities of daily life as part of a semi-structured protocol. We hypothesized that foot loading, orientation, and elevation can be used to classify postural transitions, locomotion, and walking type. Additional sensors worn at the right thigh and the trunk were used as reference, along with an event marker. An activity classification algorithm was built based on a decision tree that incorporates rules inspired from movement biomechanics. The algorithm revealed excellent performance with respect to the reference system with an overall accuracy of 97% across all activities. The algorithm was also capable of recognizing all postural transitions and locomotion periods with elevation changes. Furthermore, the algorithm proved to be robust against small changes of tuning parameters. This instrumented shoe system is suitable for daily activity monitoring in elderly persons and can additionally provide gait parameters, which, combined with activity parameters, can supply useful clinical information regarding the mobility of elderly persons.     

Impaired perceived timing of falls in the elderly

Falls are the leading cause of injury-related deaths and hospitalizations, with older adults at an increased risk. As humans age, physical changes and health conditions make falls more likely. While we know how the body reflexively responds to prevent injury during a fall, we know little about how people perceive the fall itself. We previously found that young adults required a fall to precede a comparison sound stimulus by approximately 44 ms to perceive the two events as simultaneous. This may relate to common anecdotal reports suggesting that humans often describe distortions in their perception of time − time seems to slow down during a fall – with very little recollection of how and when the fall began. Here we examine whether fall perception changes with age. Young (19–25y) and older (61–72y) healthy adults made temporal order judgments identifying whether the onset of their fall or the onset of a comparison sound came first to measure the point of subjective simultaneity. Results show that fall perception is nearly twice as slow for older adults, where perturbation onset has to precede sound onset by ∼88 ms to appear coincident, compared to younger adults (∼44 ms). We suggest that such age-related differences in fall perception may relate to increased fall rates in older adults. We conclude that a better understanding of how younger versus older adults perceive falls may identify important factors for innovative fall prevention strategies and rehabilitative training exercises to improve fall awareness.     

Aging effect on step adjustments and stability control in visually perturbed gait initiation

Gait adaptability is essential for fall avoidance during locomotion. It requires the ability to rapidly inhibit original motor planning, select and execute alternative motor commands, while also maintaining the stability of locomotion. This study investigated the aging effect on gait adaptability and dynamic stability control during a visually perturbed gait initiation task. A novel approach was used such that the anticipatory postural adjustment (APA) during gait initiation were used to trigger the unpredictable relocation of a foot-size stepping target. Participants (10 young adults and 10 older adults) completed visually perturbed gait initiation in three adjustment timing conditions (early, intermediate, late; all extracted from the stereotypical APA pattern) and two adjustment direction conditions (medial, lateral). Stepping accuracy, foot rotation at landing, and Margin of Dynamic Stability (MDS) were analyzed and compared across test conditions and groups using a linear mixed model. Stepping accuracy decreased as a function of adjustment timing as well as stepping direction, with older subjects exhibited a significantly greater undershoot in foot placement to late lateral stepping. Late adjustment also elicited a reaching-like movement (i.e. foot rotation prior to landing in order to step on the target), regardless of stepping direction. MDS measures in the medial-lateral and anterior-posterior direction revealed both young and older adults exhibited reduced stability in the adjustment step and subsequent steps. However, young adults returned to stable gait faster than older adults. These findings could be useful for future study of screening deficits in gait adaptability and preventing falls.