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Frailty assessment based on wavelet analysis during quiet standing balance test

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Abstract

A standard phenotype of frailty was independently associated with an increased risk of adverse outcomes including comorbidity, disability and with increased risks of subsequent falls and fractures. Postural control deficit measurement during quiet standing has been often used to assess balance and fall risk in elderly frail population. Real time human motion tracking is an accurate, inexpensive and portable system to obtain kinematic and kinetic measurements. The aim of this study was to examine orientation and acceleration signals from a tri-axial inertial magnetic sensor during quiet standing balance tests using the wavelet transform in a frail, a prefail and a healthy population. Fourteen subjects from a frail population (79±4 years), eighteen subjects from a prefrail population (80±3 years) and twenty four subjects from a healthy population (40±3 years) volunteered to participate in this study. All signals were analyzed using time-frequency information based on wavelet decomposition and principal component analysis. The absolute sum of the coefficients of the wavelet details corresponding to the high frequencies component of orientation and acceleration signals were associated with frail syndrome. These parameters could be of great interest in clinical settings and improved rehabilitation therapies and in methods for identifying elderly population with frail syndrome.

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... Studies have suggested that compromised human balance is also an indicator of frailty [5][6][7], which is subsequently associated with the outcomes of falling and increased morbidity [8]. Accordingly, a few studies have aimed to determine differences in postural balance behaviors in categories of frailty [9][10][11]. ...
... To this end, significant differences in balance parameters have been obtained from multiscale entropy [10] and wavelet [11] approaches between non-frail and pre-frail/frail groups, but not between non-frail and pre-frail or between pre-frail and frail categories [10,11]. Further, traditional balance parameters were found to be different only between non-frail and frail samples [9]. ...
... To this end, significant differences in balance parameters have been obtained from multiscale entropy [10] and wavelet [11] approaches between non-frail and pre-frail/frail groups, but not between non-frail and pre-frail or between pre-frail and frail categories [10,11]. Further, traditional balance parameters were found to be different only between non-frail and frail samples [9]. ...
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Background: As the population of older adults quickly increases, the incidence of frailty syndrome, a reduction in physiological reserve across multiple physiological systems, likewise increases. To date, impaired balance has been associated with frailty; however, the underlying frailty-related postural balance mechanisms remain unclear. Objective: The aim of the current study was to use open-loop (OL; postural muscles) and closed-loop (CL; postural muscles plus sensory feedback) mechanisms to explore differences in postural balance mechanisms between nonfrail (n = 44), prefrail (n = 59) and frail individuals (n = 19). Methods: One hundred and twenty-two older adults (age ≥65 years) without major mobility disorders were recruited, and frailty was measured using Fried's criteria. Each participant performed two 15-second trials of Romberg balance assessment, once with their eyes open and once with their eyes closed. Body-worn sensors were used to estimate center of gravity (COG) plots. Body-sway (traditional stabilogram analysis) and OLCL (stabilogram diffusion analysis) parameters were derived using COG plots and compared between groups using ANOVA. Frailty and prefrailty were estimated using a multiple variable logistic regression while controlling for age, body mass index, body-sway and OLCL parameters. Results: Between-group differences in the parameters of interest were more pronounced during the eyes-closed condition, for which OL duration was approximately 33 and 22% shorter, respectively, in the frail and prefrail groups when compared to nonfrail controls (mean = 1.9 ± 1.1 s, p = 0.01). The average rate of sway during the OL was 164 and 66% higher, respectively, in frail and prefrail when compared to nonfrail subjects (0.03 ± 0.02 cm(2)/s, p < 0.001). RESULTS also suggest that OLCL parameters can predict frail and prefrail categories when compared to nonfrail controls. Using this method, frailty was identified with a sensitivity and specificity of 97 and 88% (as compared to nonfrail), and prefrailty with 82 and 92%, respectively. Conclusions: This study suggested an innovative method to differentiate between frailty status using sensory dependency characteristics of postural control. RESULTS suggest that postural muscle deconditioning may compromise balance in frail elders, leading to dependency on somatosensory feedback to compensate for errors and stabilize the system.
... One study [17] was a mixed methods design but only the objective quantitative results were included in the report. The studies were carried out in varying settings; home: n = 14 [11,17,24,[34][35][36][37][38][39][40][41][42][43][44], laboratory: n = 8 [42,[45][46][47][48][49][50][51], hospital: in-patient n = 2 [52,53], outpatient n = 2 [34,54], community centre n = 1 [55] and not specified: n = 4 [33,[56][57][58]. Participant numbers ranged from n = 30 to n = 718. ...
... Participants ranging in age 63-90 years were recruited from community, assisted-living or hospital environments. Four studies [45,46,48,54] included a healthy young cohort (age range 18-54 years) for comparison. For those studies that reported sex there was an overall predominance of females. ...
... Balance is measured in different ways throughout the literature varying in the nature of the assessment, the conditions under which the assessment took place and duration of each task. Those that assessed balance during a period of quiet standing did so over different time periods ranging from 10 -40-s [38,45,49,57]. Conditions varied between participants standing with feet together, feet semi-tandem, eyes open and/or eyes closed while another measured balance during a 30-s chair-stand exercise [46]. ...
Article
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Background Globally the population of older adults is increasing. It is estimated that by 2050 the number of adults over the age of 60 will represent over 21% of the world’s population. Frailty is a clinical condition associated with ageing resulting in an increase in adverse outcomes. It is considered the greatest challenge facing an ageing population affecting an estimated 16% of community-dwelling populations worldwide. Aim The aim of this systematic review is to explore how wearable sensors have been used to assess frailty in older adults. Method Electronic databases Medline, Science Direct, Scopus, and CINAHL were systematically searched March 2020 and November 2020. A search constraint of articles published in English, between January 2010 and November 2020 was applied. Papers included were primary observational studies involving; older adults aged > 60 years, used a wearable sensor to provide quantitative measurements of physical activity (PA) or mobility and a measure of frailty. Studies were excluded if they used non-wearable sensors for outcome measurement or outlined an algorithm or application development exclusively. The methodological quality of the selected studies was assessed using the Appraisal Tool for Cross-sectional Studies (AXIS). Results Twenty-nine studies examining the use of wearable sensors to assess and discriminate between stages of frailty in older adults were included. Thirteen different body-worn sensors were used in eight different body-locations. Participants were community-dwelling older adults. Studies were performed in home, laboratory or hospital settings. Postural transitions, number of steps, percentage of time in PA and intensity of PA together were the most frequently measured parameters followed closely by gait speed. All but one study demonstrated an association between PA and level of frailty. All reports of gait speed indicate correlation with frailty. Conclusions Wearable sensors have been successfully used to evaluate frailty in older adults. Further research is needed to identify a feasible, user-friendly device and body-location that can be used to identify signs of pre-frailty in community-dwelling older adults. This would facilitate early identification and targeted intervention to reduce the burden of frailty in an ageing population.
... A total of 28 studies were included in the review, but only 16 observational cross-sectional studies, following our inclusion criteria, were evaluated. Nine studies were done in the European area (six in Spain [18][19][20][21][22][23] and the other three in Ireland [24], Germany [25] and Switzerland [26]), three in the USA [27][28][29] while the other three were carried out in Japan [30], Taiwan [31] and Canada [32]. The papers were published between 2011 and 2016. ...
... Eight studies [20,21,23,24,27,28,30,32] stratified participants into three levels of frailty (non-frail, pre-frail and frail), six studies considered two levels of frailty, that is, non-frail and frail [18,19,25,26] or pre-frail [29,31]. Two studies considered only frail participants without any stratification [22,33]. ...
... sensors present in iPhone4 smartphones were used to register kinematics and accelerometry values of the Romberg Test for ataxia [18,38] and of the Extended Timed Get-Upand-Go Test for balance problems [19,[39][40][41][42]. Other three studies used MEMS inertial sensors to quantify drift-free 3D orientation [23] or kinematic capabilities [20,21]. ...
Article
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Objectives Frailty is a major health issue as it encompasses functional decline, physical dependence, and increased mortality risk. Recent studies explored Information and Communication Technology (ICT) interventions as alternatives to manage frailty in older persons. The aim of the present systematic review was to synthesize current evidence on ICT application within the complex models of frailty care in older people.Methods Data sources included PubMed, PsycINFO, EMBASE and Web of Science, considering eligible those reviews on ICT application in samples of older persons formally assessed as frail. Records were screened by two independent researchers, who extracted data and appraised methodological quality of reviews and studies.ResultsAmong the 764 retrieved papers, two systematic reviews were included. Most of the studies analyzed defined frailty considering only few components of the phenotype and used ICT to stratify different levels of frailty or to support traditional screening strategies. Assessment of frailty was the context in which ICT has been mostly tested as compared to intervention. Cost effectiveness evaluations of the ICT technologies were not reported.Conclusions The research investigating the use of ICT in the context of frailty is still at the very beginning. Few studies strictly focused on the assessment of frailty, while intervention on frailty using ICT was rarely reported. The lack of a proper characterization of the frail condition along with the methodological limitations prevented the investigation of ICT within complex care models. Future studies are needed to effectively integrate ICT in the care of frailty in orders.
... This questionnaire consists of a self-reporting survey of 25 yes/no questions that cover 7 dimensions of frailty, i.e., instrumental and social activities of daily living, physical functions, nutritional status, oral function, cognitive function, and depressive mood (Supplementary Material 1). To complement the existing methods, researchers have been interested in using technological tools to analyze postural balance and gait stability and find early markers of frailty [7,[9][10][11][12][13][14][15]. Greene et al. [15] achieved 84 and 94% accuracy in classifying pre-frail and healthy women and men, respectively. ...
... The use of technology allows for more objective evaluations and is therefore attractive to clinicians. To date, several studies have successfully combined the use of inertial sensors with statistical classification techniques [11,12,15]. Only one study has tried to use plantar pressure to distinguish frail people from healthy individuals [12]. ...
Article
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Background Frailty and falls are two adverse characteristics of aging that impair the quality of life of senior people and increase the burden on the healthcare system. Various methods exist to evaluate frailty, but none of them are considered the gold standard. Technological methods have also been proposed to assess the risk of falling in seniors. This study aims to propose an objective method for complementing existing methods used to identify the frail state and risk of falling in older adults. Method A total of 712 subjects (age: 71.3 ± 8.2 years, including 505 women and 207 men) were recruited from two Japanese cities. Two hundred and three people were classified as frail according to the Kihon Checklist. One hundred and forty-two people presented with a history of falling during the previous 12 months. The subjects performed a 45 s standing balance test and a 20 m round walking trial. The plantar pressure data were collected using a 7-sensor insole. One hundred and eighty-four data features were extracted. Automatic learning random forest algorithms were used to build the frailty and faller classifiers. The discrimination capabilities of the features in the classification models were explored. Results The overall balanced accuracy for the recognition of frail subjects was 0.75 ± 0.04 (F1-score: 0.77 ± 0.03). One sub-analysis using data collected for men aged > 65 years only revealed accuracies as high as 0.78 ± 0.07 (F1-score: 0.79 ± 0.05). The overall balanced accuracy for classifying subjects with a recent history of falling was 0.57 ± 0.05 (F1-score: 0.62 ± 0.04). The classification of subjects relative to their frailty state primarily relied on features extracted from the plantar pressure series collected during the walking test. Conclusion In the future, plantar pressures measured with smart insoles inserted in the shoes of senior people may be used to evaluate aspects of frailty related to the physical dimension (e.g., gait and balance alterations), thus allowing assisting clinicians in the early identification of frail individuals.
... The conditio sine qua non is that gravity, spread on the axes of the sensor according to the time-varying orientation in space of the sensor case, is subtracted from the accelerometer's readings so that RMS can be computed solely taking into account acceleration due to horizontal body sway. Finally, an alternative approach to time-domain signal analysis is that of using wavelet analysis (i.e., multi-level analysis of the frequency content of a signal) applied to the accelerometer readings [95]. This approach was proved to be even more sensitive than the inverted pendulum in distinguishing between healthy subjects and elderly subjects with frailty syndrome. ...
... Inertial sensing of human balance has been largely used in patients with Parkinson's Disease for detecting their postural abnormalities [96], assessing their postural strategies [97] and even for successfully training their static balance control with audio biofeedback [98]. Accelerometers have been used as well for detecting postural abnormalities in subjects with early-staged multiple sclerosis [99], in frail elderly population [95], subjects with a mild traumatic brain injury [100] and bilateral vestibular loss [101]. These researchers suggested an interesting application of IMUs not only for the postural assessment but also for the postural training of patients providing them biofeedback about their performances. ...
Article
Introduction: The present review aims to provide an overview of the most common uses of wearable inertial sensors in the field of clinical human movement analysis. Areas covered: Six main areas of application are analysed: gait analysis, stabilometry, instrumented clinical tests, upper body mobility assessment, daily-life activity monitoring and tremor assessment. Each area is analyzed both from a methodological and applicative point of view. The focus on the methodological approaches is meant to provide an idea of the computational complexity behind a variable/parameter/index of interest so that the reader is aware of the reliability of the approach. The focus on the application is meant to provide a practical guide for advising clinicians on how inertial sensors can help them in their clinical practice. Expert Commentary: Less expensive and more easy to use than other systems used in human movement analysis, wearable sensors have evolved to the point that they can be considered ready for being part of routine clinical routine.
... Recently, several studies have examined the functional tasks which make up the TUG test and the instruments used, together with improvements to the instruments, specifically attaching inertial sensors to the body (Najafi et al 2002, Moe-Nilssen and Helbostad 2004, 2005, Bidargaddi et al 2007, Ganea et al 2007, Botolfsen et al 2008, Higashi et al 2008, Janssen et al 2008, Marschollek et al 2009, Salarian et al 2009, 2010, Weiss et al 2010, Martínez-Ramírez et al 2011, Galán-Mercant and Cuesta-Vargas 2013a, 2013b, Greene et al 2014. A previous study concluded that inertial sensors can offer an accurate and reliable method for studying human motion, but the degree of accuracy and reliability is site-and task-specific (Cuesta-Vargas et al 2010). ...
... Our study calculates the ability of the expanded version of TUG to identify frail members of the population using the phenotypic definition of frailty as the gold standard and assumes that this was measured without error. Other recent studies (Ganea et al 2007, Martínez-Ramírez et al 2011, Greene et al 2014, as is the case in our study, have suggested that the readings derived from accelerometry are more sensitive in discriminating the characteristics associated with frailty. In particular, Greene et al (2014) investigated a fast method for the automatic, quantitative assessment of the frailty state of a patient based on a simple protocol employing a body-worn inertial sensor. ...
Article
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The aim of this study was to identify the series of kinematic variables demonstrating the greatest precision in discriminating between the function of two groups of elderly persons (frail and non-frail) in the 10 m expanded timed up and go (ETUG) test using inertial sensors embedded in the iPhone 4®. A cross-sectional study was conducted to identify the kinematic variables with the highest degree of precision in discriminating between the two groups. The predicted capability of the kinematic variables was evaluated using receiver operating characteristic curves. The sample comprised 30 participants over 65 years old, 14 frail and 16 non-frail, assessed for frailty syndrome using the Fried criteria. Acceleration variables discriminated between the participant groups in the study; specifically these were the peak negative acceleration variables for motion axes x, y and z. In terms of sensitivity, the values were greater than or equal to those for the variable traditionally used to discriminate in the ETUG test, namely time. The kinematic parameters obtained from the internal inertial sensors in the iPhone 4® are promising additions to the ETUG analysis. There are encouraging signs that the analyses of these parameters in the separate phases of the ETUG procedure offer the potential for improved discrimination between frail and non-frail individuals. However, further in-depth study is required to verify the findings.
... 5-24 15.4% [26,29,32,47,63,68,73,74] 25- 49 19.2% [27,28,34,35,51,55,58,59,67,72] 50-99 32.7% [30,31,33,36,37,39,50,52,53,56,57,60,61,62,65,71,77] 100-149 13.5% [38,45,48,49,69,70,78] 150-199 3.8% [64,75] 200-299 9.6% [25,40,43,46,76] ...
... 5.8% [42,44,54] Older Adult Balance Decline/None 1.9% [72] Older Adults Frail/Nonfrail 3.8% [44,60] Older Adults Assisted/Unassisted 1.9% [26] PD Fallers/Non-fallers 9.6% [47,55,57,74,78] PD with FOG/without FOG 3.8% [61,68] Demented Fallers/Nonfallers 1.9% [71] Stroke Fallers/Non-fallers 1.9% [27,28] ...
Article
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Falls represent a major burden on elderly individuals and society as a whole. Technologies that are able to detect individuals at risk of fall before occurrence could help reduce this burden by targeting those individuals for rehabilitation to reduce risk of falls. Wearable technologies especially, which can continuously monitor aspects of gait, balance, vital signs, and other aspects of health known to be related to falls, may be useful and are in need of study. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematics Reviews and Meta-Analysis (PRISMA) 2009 guidelines to identify articles related to the use of wearable sensors to predict fall risk. Fifty four studies were analyzed. The majority of studies (98.0%) utilized inertial measurement units (IMUs) located at the lower back (58.0%), sternum (28.0%), and shins (28.0%). Most assessments were conducted in a structured setting (67.3%) instead of with free-living data. Fall risk was calculated based on retrospective falls history (48.9%), prospective falls reporting (36.2%), or clinical scales (19.1%). Measures of the duration spent walking and standing during free-living monitoring, linear measures such as gait speed and step length, and nonlinear measures such as entropy correlate with fall risk, and machine learning methods can distinguish between falls. However, because many studies generating machine learning models did not list the exact factors being considered, it is difficult to compare these models directly. Few studies to date have utilized results to give feedback about fall risk to the patient or to supply treatment or lifestyle suggestions to prevent fall, though these are considered important by end users. Wearable technology demonstrates considerable promise in detecting subtle changes in biomarkers of gait and balance related to an increase in fall risk. However, more large-scale studies measuring increasing fall risk before first fall are needed, and exact biomarkers and machine learning methods used need to be shared to compare results and pursue the most promising fall risk measurements. There is a great need for devices measuring fall risk also to supply patients with information about their fall risk and strategies and treatments for prevention.
... The present findings suggest that a balance deficit is a specific marker of prefrailty. These results are in accordance with previous studies, which found significant differences in postural balance between the nonfrail and prefrail/frail groups, but not between the prefrail and frail ones [44,45] . Our results show that hip sway is a more sensitive marker of prefrailty compared to ankle sway. ...
Article
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Background: Frailty is a geriatric syndrome resulting from age-related cumulative decline across multiple physiologic systems, impaired homeostatic reserve, and reduced capacity to resist stress. Based on recent estimates, 10% of community-dwelling older individuals are frail and another 41.6% are prefrail. Frail elders account for the highest health care costs in industrialized nations. Impaired physical function is a major indicator of frailty, and functional performance tests are useful for the identification of frailty. Objective instrumented assessments of physical functioning that are feasible for home frailty screening have not been adequately developed. Objective: To examine the ability of wearable sensor-based in-home assessment of gait, balance, and physical activity (PA) to discriminate between frailty levels (nonfrail, prefrail, and frail). Methods: In an observational cross-sectional study, in-home visits were completed in 125 older adults (nonfrail: n=44, prefrail: n=60, frail: n=21) living in Tucson, Ariz., USA, between September 2012 and November 2013. Temporal-spatial gait parameters (speed, stride length, stride time, double support, and variability of stride velocity), postural balance (sway of hip, ankle, and center of mass), and PA (percentage of walking, standing, sitting, and lying; mean duration and variability of single walking, standing, sitting, and lying bouts) were measured in the participant's home using validated wearable sensor technology. Logistic regression was used to assess the most sensitive gait, balance, and PA variables for identifying prefrail participants (vs. nonfrail). Multinomial logistic regression was used to identify variables sensitive to discriminate between three frailty levels. Results: Gait speed (area under the curve, AUC=0.802), hip sway (AUC=0.734), and steps/day (AUC=0.736) were the most sensitive parameters for the identification of prefrailty. Multinomial regression revealed that stride length (AUC=0.857) and double support (AUC=0.841) were the most sensitive gait parameters for discriminating between three frailty levels. Interestingly, walking bout duration variability was the most sensitive PA parameter for discriminating between three frailty levels (AUC=0.818). No balance parameter discriminated between three frailty levels. Conclusion: Our results indicate that unique parameters derived from objective assessment of gait, balance, and PA are sensitive for the identification of prefrailty and the classification of a subject's frailty level. The present findings highlight the potential of wearable sensor technology for in-home assessment of frailty status.
... However, their methods were weakened by the postprocessing synchronization of the data, which aligned data from the 2 devices according to optimized correlation values rather than via real-time synchronization. Other researchers 26,[33][34][35][36][37] have explored the efficacy of accelerometry-based balance measures; however, no approach has combined the use of an accelerometer and a gyroscope in a commercially available, nondedicated device package and then evaluated its effectiveness in assessing postural stability relative to an accepted clinical system, such as the NeuroCom. The recent inclusion of relatively sophisticated inertial-measurement technologies in consumer electronics devices, such as smartphones and tablet-based computing devices, provides an opportunity to use these devices to objectively assess postural stability in athletes during healthy baseline testing, at diagnosis of concussion, during the return-to-play process, and when determining resolution of concussion symptoms. ...
Article
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Context: Force platforms and 3-dimensional motion-capture systems provide an accurate method of quantifying postural stability. Substantial cost, space, time to administer, and need for trained personnel limit widespread use of biomechanical techniques in the assessment of postural stability in clinical or field environments. Objective: To determine whether accelerometer and gyroscope data sampled from a consumer electronics device (iPad2) provide sufficient resolution of center-of-gravity (COG) movements to accurately quantify postural stability in healthy young people. Design: Controlled laboratory study. Setting: Research laboratory in an academic medical center. Patients or other participants: A total of 49 healthy individuals (age = 19.5 ± 3.1 years, height = 167.7 ± 13.2 cm, mass = 68.5 ± 17.5 kg). Intervention(s): Participants completed the NeuroCom Sensory Organization Test (SOT) with an iPad2 affixed at the sacral level. Main outcome measure(s): Primary outcomes were equilibrium scores from both systems and the time series of the angular displacement of the anteroposterior COG sway during each trial. A Bland-Altman assessment for agreement was used to compare equilibrium scores produced by the NeuroCom and iPad2 devices. Limits of agreement was defined as the mean bias (NeuroCom - iPad) ± 2 standard deviations. Mean absolute percentage error and median difference between the NeuroCom and iPad2 measurements were used to evaluate how closely the real-time COG sway measured by the 2 systems tracked each other. Results: The limits between the 2 devices ranged from -0.5° to 0.5° in SOT condition 1 to -2.9° to 1.3° in SOT condition 5. The largest absolute value of the measurement error within the 95% confidence intervals for all conditions was 2.9°. The mean absolute percentage error analysis indicated that the iPad2 tracked NeuroCom COG with an average error ranging from 5.87% to 10.42% of the NeuroCom measurement across SOT conditions. Conclusions: The iPad2 hardware provided data of sufficient precision and accuracy to quantify postural stability. Accuracy, portability, and affordability make using the iPad2 a reasonable approach for assessing postural stability in clinical and field environments.
... More recently, the use of inertial sensors has emerged as a promising alternative for analyzing human movements. Recent studies have demonstrated that the parameters obtained with these sensors during walking are significantly related to different motor deficiencies, frailty, Parkinson's disorder or other diseases, such as diabetes and mild cognitive impairment [20][21][22]. ...
Article
Physical frailty has become the center of attention of basic, clinical and demographic research due to its incidence level and gravity of adverse outcomes with age. Frailty syndrome is estimated to affect 20 % of the population older than 75 years. Thus, one of the greatest current challenges in this field is to identify parameters that can discriminate between vulnerable and robust subjects. Gait analysis has been widely used to predict frailty. The aim of the present study was to investigate whether a collection of parameters extracted from the trunk acceleration signals could provide additional accurate information about frailty syndrome. A total of 718 subjects from an elderly population (319 males, 399 females; age: 75.4 ± 6.1 years, mass: 71.8 ± 12.4 kg, height: 158 ± 6 cm) volunteered to participate in this study. The subjects completed a 3-m walk test at their own gait velocity. Kinematic data were acquired from a tri-axial inertial orientation tracker. The spatio-temporal and frequency parameters measured in this study with an inertial sensor are related to gait disorders and showed significant differences among groups (frail, pre-frail and robust). A selection of those parameters improves frailty classification obtained to gait velocity, compared to classification model based on gait velocity solely. Gait parameters simultaneously used with gait velocity are able to provide useful information for a more accurate frailty classification. Moreover, this technique could improve the early detection of pre-frail status, allowing clinicians to perform measurements outside of a laboratory environment with the potential to prescribe a treatment for reversing their physical decline.
... Statistical variability such as range and SD reflect overall magnitude of COP displacement, without considering the temporal structure of the COP time series. This fundamental difference may explain that nonlinear measures of postural signals reveal subtle temporal properties of signals which are not detected through traditional linear approach [48][49][50][51]. Traditionally, higher COP displacements have been linked with less stability and consequently, pathology. ...
Article
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Cardiovascular disease (CVD) patients with intrinsic cardiac cause for falling have been found to be frail and submissive to morbidity and mortality as post-operative outcomes. In these older CVD patients, gait speed is conjectured by the Society of Thoracic Surgeons (STS) as an independent predictor of post-operative morbidity and mortality. However, this guideline by STS has not been studied adequately with a large sample size; rather it is based largely on expert opinions of cardiac surgeons and researchers. Although one's gait speed is not completely associated with one's risk of falls, gait speed is a quick robust measure to classify frail/non-frail CVD patients and undoubtedly frail individuals are more prone to falls. Thus, this study examines the effects of inertial sensor-based quick movement variability characteristics in identifying CVD patients likely to have an adverse post-operative outcome. This study establishes a relationship with gait and postural predictor variables with patient's post-operative adverse outcomes. Accordingly, inertial sensors embedded inside smartphones are indispensable for the assessment of elderly patients in clinical environments and may be necessary for quick objective assessment. Sixteen elderly CVD patients (Age 76.1 ± 3.6 years) who were scheduled for cardiac surgery the next day were recruited for this study. Based on STS recommendation guidelines, eight of the CVD patients were classified as frail (prone to adverse outcomes with gait speed ≤ 0.833 m/s) and the other eight patients as non-frail (gait speed > 0.833 m/s). Smartphone-derived walking velocity was found to be significantly lower in frail patients than that in non-frail patients (p < 0.01). Mean Center of Pressure (COP) radius (p < 0.01), COP Area (p < 0.01), COP path length (p < 0.05) and mean COP velocity (p < 0.05) were found to be significantly higher in frail patients than that in the non-frail patient group. Nonlinear variability measures such as sample entropy were significantly lower in frail participants in anterior-posterior (p < 0.01) and resultant sway direction (p < 0.01) than in the non-frail group. This study identified numerous postural and movement variability parameters that offer insights into predictive inertial sensor-based variables and post-operative adverse outcomes among CVD patients. In future, smartphone-based clinical measurement systems could serve as a clinical decision support system for assessing patients quickly in the perioperative period.
... Frailty occurs in people older than 65 years (ranging from 7 to 16.3%), and its prevalence increases with age [1;2]. Moreover, this geriatric syndrome embodies an elevated risk of catastrophic declines in health and function among older adults [2][3][4][5][6]. However, it is not easy to identify those patients who are more prone to suffer this disability. ...
Chapter
Frailty syndrome is regarded as a major predictor of co-morbidities and mortality in older populations. Performance test such as the 30-s chair stand one (30-s CST) are a cornerstone for detecting early decline. However, predictions are normally more qualitative than quantitative. Latest advances in body-fixed sensors lead us to a new dimension of measurements, kinematic parameters that can furnish clinicians by objective information to outperform their diagnostics. In the case of the 30-s CST, it has been demonstrated that an instrumented version of the test is able not only to directly provide the actual outcome, the number of performed cycles, but also other kinematic parameters that can explain the movement performance. This instrumented version involves including an inertial unit which provides acceleration and angular velocity data. However, different steps are necessary to extract meaningful information from those rough data. Here, it is explained the full process to obtain kinematic parameters from the 30-s CST and the ones able to differentiate different frailty levels (i.e. Z-acceleration and Z-velocity peaks and positive and/or negative impulses). The main contribution is that this new quantitative information could be of special help in clinical diagnostics, home care services and/or in a fall risk prevention program.
... aA P ( m s adjusted for human movements, as recommended by the manufacturer [24]. The choice of the sampling frequency of 100 Hz was made also by following previous studies which used the same system for motion tracking (see [25][26][27][28][29]). The novel method for identification of pathological balance control is based on mathematical tools for static posturography [20,30]. ...
Article
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Techniques to quantify postural stability usually rely on the evaluation of only two variables, that is, two coordinates of COP. However, by using three variables, that is, three components of acceleration vector, it is possible to describe human movement more precisely. For this purpose, a single three-axis accelerometer was used, making it possible to evaluate 3D movement by use of a novel method, convex polyhedron (CP), together with a traditional method, based on area of the confidence ellipse (ACE). Ten patients (Pts) with cerebellar ataxia and eleven healthy individuals of control group (CG) participated in the study. The results show a significant increase of volume of the CP (CPV) in Pts or CG standing on foam surface with eyes open (EO) and eyes closed (EC) after the EC phase. Significant difference between Pts and CG was found in all cases as well. Correlation coefficient indicates strong correlation between the CPV and ACE in most cases of patient examinations, thus confirming the possibility of quantification of postural instability by the introduced method of CPV.
... The human movement evaluation is considered to be a cornerstone of both the generation of knowledge and the assessment of the effect of clinical treatments [1]. The most commonly technique of human movement evaluation used in physical therapy clinical practice has been the one-dimensional movable-arm goniometry [1][2][3]. The devices used in this clinical practice, however, provide information on motion in just a single plane [3]. ...
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Background The capacity to diagnosys, quantify and evaluate movement beyond the general confines of a clinical environment under effectiveness conditions may alleviate rampant strain on limited, expensive and highly specialized medical resources. An iPhone 4® mounted a three dimensional accelerometer subsystem with highly robust software applications. The present study aimed to evaluate the reliability and concurrent criterion-related validity of the accelerations with an iPhone 4® in an Extended Timed Get Up and Go test. Extended Timed Get Up and Go is a clinical test with that the patient get up from the chair and walking ten meters, turn and coming back to the chair. Methods A repeated measure, cross-sectional, analytical study. Test-retest reliability of the kinematic measurements of the iPhone 4® compared with a standard validated laboratory device. We calculated the Coefficient of Multiple Correlation between the two sensors acceleration signal of each subject, in each sub-stage, in each of the three Extended Timed Get Up and Go test trials. To investigate statistical agreement between the two sensors we used the Bland-Altman method. Results With respect to the analysis of the correlation data in the present work, the Coefficient of Multiple Correlation of the five subjects in their triplicated trials were as follows: in sub-phase Sit to Stand the ranged between r = 0.991 to 0.842; in Gait Go, r = 0.967 to 0.852; in Turn, 0.979 to 0.798; in Gait Come, 0.964 to 0.887; and in Turn to Stand to Sit, 0.992 to 0.877. All the correlations between the sensors were significant (p < 0.001). The Bland-Altman plots obtained showed a solid tendency to stay at close to zero, especially on the y and x-axes, during the five phases of the Extended Timed Get Up and Go test. Conclusions The inertial sensor mounted in the iPhone 4® is sufficiently reliable and accurate to evaluate and identify the kinematic patterns in an Extended Timed Get and Go test. While analysis and interpretation of 3D kinematics data continue to be dauntingly complex, the iPhone 4® makes the task of acquiring the data relatively inexpensive and easy to use.
... Consequently, dual task walking has become the standard measure of the relationship between cognitive ability and gait [19,20] . Current studies have used inertial sensors during walking and various functional tasks to record several parameters that are significantly associated with frail populations [21,22] . However, no studies have investigated the differences in the gait pattern between frail populations with and without MCI [8] . ...
Article
Background: Several studies have stated that frailty is associated with cognitive impairment. Based on various studies, cognition impairment has been considered as a component of frailty. Other authors have shown that physical frailty is associated with low cognitive performance. Dual task gait tests are used as a strong predictor of falls in either dementia or frailty. Consequently, it is important to investigate dual-task walking tests in elderly populations including control robust oldest old, frail oldest old with MCI and frail oldest old without MCI. Methods: Dual-task walking tests were carried out to examine the association between frailty and cognitive impairment in a population of advanced age. Forty one elderly men and women participated in this study. The subjects from control, frail with mild cognitive impairment (MCI) and frail without MCI groups, completed the 5-m walk test at their own gait velocity. Arithmetic and verbal dual-task walking performance was also assessed. Kinematic data were acquired from a unique tri-axial inertial sensor. Results: The spatiotemporal and frequency parameters related to gait disorders did not show any significant differences between frail with and without MCI groups. Conclusions: The evaluation of these parameters extracted from the acceleration signals lead us to conclude that these results expand the knowledge regarding the common conditions in these two diseases frailty and MCI and may highlight the idea that the impairment in walking performance does not depend of frailty and cognitive status.
... Mobility and balance impairment contribute to frailty, (Davis, Rockwood, Mitnitski, & Rockwood, 2011) and frailty is cited as one of the causes of falls (Coimbra et al., 2010). This may be related to the decrease in power generation capacity of muscles that occurs in frailty, which can somehow affect required postural adjustments (Martinez-Ramirez et al., 2011). Approximately 65% of individuals older than 60 years present daily episodes of dizziness or imbalance (Garcia, 2009). ...
Article
The aim of this study was to describe the association between frailty and geriatric syndromes (GS) [cognitive impairment (CI); postural instability (PI); urinary/fecal incontinence (UFI); polypharmacy (PP); and immobility (IM)] and the frequency of these conditions in elderly people assisted in primary health care. Five hundred twenty-one elderly participants of The Multidimensional Study of the Elderly in the Family Health Strategy (EMI-SUS) were evaluated. Sociodemographic data, identification of frailty (Fried phenotype) and GS were collected. Multinomial logistic regression analysis was performed. The frequency of frailty was 21.5%, prefrailty 51.1% and robustness 27.4%. The frequency of CI was 54.7%, PP 41.2%, PI 36.5%, UFI 14% and IM 5.8%. The odds of frailty when compared to robustness and adjusted for gender, age, depression, self-perception of health, nutritional status, falls, vision and hearing, was significantly higher in elderly with CI, PI and PP. The adjusted odds of prefrail when compared to robustness was significantly higher only in elderly with CI. The most frequently presented number of GS (0-5) was two geriatric syndromes (26.87%). The frequency of frailty was high among elderly in primary health care and was associated with three of five GS (CI - PI - PP).
... Finally, using chair stands as a surrogate for grip strength may additionally introduce an estimation of balance and proprioception into what should be strictly a sarcopenia measure. Since loss of balance and proprioception have also been shown to correlate with frailty measures, substituting chair stands for grip strength is reasonable (Deshpande, Metter, & Ferrucci, 2010;Martínez-Ramírez et al., 2011). ...
Article
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Introduction. The geriatric functional measures and syndromes collected 5 years apart in Waves 1 and 2 of the National Social Life, Health, and Aging Project (NSHAP) data set included: difficulty with activities of daily living and instrumental activities of daily living, the timed up and go, a 3-m timed walk, repeated chair stands, self-reported physical activity, accelerometry-assessed (in)activity, falls, fractures, and frailty. The purpose of this paper was to describe the data collection methods and report preliminary population estimates for each measures.
... In addition, taking into account the average age of the sample (64-65 years old), regardless of the gait (there is no correlation between the age and the maximum accelerations and imbalances in this trial), it can be observed how this also affects the postural control, as previous studies that link the loss of postural control with age made by Martínez-Ramirez et al. 23 or Chen et al. 24 indicated. ...
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To compare the behavior of the spinal levels for the accelerometric analysis and thus to define a proper placement point.
... For instance, people with vestibular dysfunction or peripheral neuropathy may have increased sway, without being classified as frail [32]. Nonetheless, our results are in general agreement with previous studies in terms of differences in postural balance in older adults with varying degrees of frailty [33][34][35]. In addition, postural sway in the ML direction during semitandem stance was significantly increased in subjects with a history of falling compared with those who did not fall in the previous year. ...
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Research on balance and mobility in older adults has been conducted primarily in lab-based settings in individuals who live in the community. Although they are at greater risk of falls, residents of long-term care facilities, specifically residential care communities (RCCs), have been investigated much less frequently. We sought to determine the feasibility of using portable technology-based measures of balance and muscle strength (i.e., an accelerometer and a load cell) that can be used in any RCC facility. Twenty-nine subjects (age 87 ± 6 years) living in RCCs participated. An accelerometer placed on the back of the subjects measured body sway during different standing conditions. Sway in antero-posterior and mediolateral directions was calculated. Lower extremity strength was measured with a portable load cell and the within-visit reliability was determined. Assessments of grip strength, gait speed, frailty, and comorbidity were also examined. A significant increase in postural sway in both the AP and ML directions occurred as the balance conditions became more difficult due to alteration of sensory feedback (p < 0.001) or reducing the base of support (p < 0.001). There was an association between increased sway and increased frailty, more comorbidities and slower gait speed. All strength measurements were highly reliable (ICC = 0.93-0.99). An increase in lower extremity strength was associated with increased grip strength and gait speed. The portable instruments provide inexpensive ways for measuring balance and strength in the understudied RCC population, but additional studies are needed to examine their relationship with functional outcomes.
... While this study explored a large number of features (up to 146 features), other possible features could be included in future research. Additional accelerometerbased features from the literature, that were relevant to older adult fall risk, could be generated from phasedependent local dynamic stability [30,31], discrete wavelet transform [32,33], sample entropy [5,34], and power spectral density [35,36]. Furthermore, this study examined features derived from a 7.62 m (25 ft) walking trial. ...
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Background Wearable sensors can be used to derive numerous gait pattern features for elderly fall risk and faller classification; however, an appropriate feature set is required to avoid high computational costs and the inclusion of irrelevant features. The objectives of this study were to identify and evaluate smaller feature sets for faller classification from large feature sets derived from wearable accelerometer and pressure-sensing insole gait data. Methods A convenience sample of 100 older adults (75.5 ± 6.7 years; 76 non-fallers, 24 fallers based on 6 month retrospective fall occurrence) walked 7.62 m while wearing pressure-sensing insoles and tri-axial accelerometers at the head, pelvis, left and right shanks. Feature selection was performed using correlation-based feature selection (CFS), fast correlation based filter (FCBF), and Relief-F algorithms. Faller classification was performed using multi-layer perceptron neural network, naïve Bayesian, and support vector machine classifiers, with 75:25 single stratified holdout and repeated random sampling. Results The best performing model was a support vector machine with 78% accuracy, 26% sensitivity, 95% specificity, 0.36 F1 score, and 0.31 MCC and one posterior pelvis accelerometer input feature (left acceleration standard deviation). The second best model achieved better sensitivity (44%) and used a support vector machine with 74% accuracy, 83% specificity, 0.44 F1 score, and 0.29 MCC. This model had ten input features: maximum, mean and standard deviation posterior acceleration; maximum, mean and standard deviation anterior acceleration; mean superior acceleration; and three impulse features. The best multi-sensor model sensitivity (56%) was achieved using posterior pelvis and both shank accelerometers and a naïve Bayesian classifier. The best single-sensor model sensitivity (41%) was achieved using the posterior pelvis accelerometer and a naïve Bayesian classifier. Conclusions Feature selection provided models with smaller feature sets and improved faller classification compared to faller classification without feature selection. CFS and FCBF provided the best feature subset (one posterior pelvis accelerometer feature) for faller classification. However, better sensitivity was achieved by the second best model based on a Relief-F feature subset with three pressure-sensing insole features and seven head accelerometer features. Feature selection should be considered as an important step in faller classification using wearable sensors.
... Given that the goal of postural control is to maintain the center of mass (COM) within the limits of stability, direct measurement of COM may provide better insights into the mechanisms of balance control [11]. Numerous studies have reported using acceleration-based and gyroscope-based sway metrics for assessing balance deficits in older adults at risk of falling [12], in patients with Parkinson disease [13], MS [14,15], and Alzheimer disease [16]. However, conventional inertial sensor(s) often still need to be synced with a host computer through additional hardware, and the sensor needs to be secured using straps or other means. ...
Article
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Balance impairment is common in individuals with multiple sclerosis (MS). However, objective assessment of balance usually requires clinical expertise and/or the use of expensive and obtrusive measuring equipment. These barriers to the objective assessment of balance may be overcome with the development of a lightweight inertial sensor system. In this study, we examined the concurrent validity of a novel wireless, skin-mounted inertial sensor system (BioStamp®, MC10 Inc.) to measure postural sway in individuals with MS by comparing measurement agreement between this novel sensor and gold standard measurement tools (force plate and externally validated inertial sensor). A total of 39 individuals with MS and 15 healthy controls participated in the study. Participants with MS were divided into groups based on the amount of impairment (MSMild: EDSS 2–4, n = 19; MSSevere: EDSS ≥6, n = 20). The balance assessment consisted of two 30-s quiet standing trials in each of three conditions: eyes open/firm surface, eyes closed/firm surface, and eyes open/foam surface. For each trial, postural sway was recorded with a force plate (Bertec) and simultaneously using two accelerometers (BioStamp and Xsens) mounted on the participant’s posterior trunk at L5. Sway metrics (sway area, sway path length, root mean square amplitude, mean velocity, JERK, and total power) were derived to compare the measurement agreement among the measurement devices. Excellent agreement (intraclass correlation coefficients >0.9) between sway metrics derived from the BioStamp and the MTx sensors were observed across all conditions and groups. Good to excellent correlations (r >0.7) between devices were observed in all sway metrics and conditions. Additionally, the acceleration sway metrics were nearly as effective as the force plate sway metrics in differentiating individuals with poor balance from healthy controls. Overall, the BioStamp sensor is a valid and objective measurement tool for postural sway assessment. This novel, lightweight and portable sensor may offer unique advantages in tracking patient’s postural performance.
... 9 Recovery of balance in patients with stroke is very important because this gives them greater independence in carrying out their daily activities and reduces the risk of falling. 10 Inertial sensors are tools that help us to measure the kinematic parameters of a gesture, 11,12 and these instruments have been used in balance tests on healthy people 13,14 and in patients with stroke 15,16 with a range validity of .66-.99 17 and a reliability of .84-.97, 18 which has led to their wider use in research and in clinical practice. ...
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Objective: The study aimed to analyze the differences between kinematic parameters in the single-leg stance (SLS) in patients with stroke and in healthy elderly people measured with 2 inertial sensors-1 in the trunk and 1 in the lumbar region. Methods: Two groups of participants were measured: the first group consisted of 5 healthy elderly people over 65 years of age; the second group consisted of 5 patients with stroke over 65 years of age, recovering for more than 6 months after suffering a stroke, and who had been undergoing rehabilitation treatment for at least 6 months. Two inertial sensors were located in the participants: in the trunk region (T7-T8) and in the lumbar region (L5-S1). The SLS test was performed in 4 conditions: right-dominant leg, open eyes; right-dominant leg, closed eyes; left-nondominant leg, open eyes; and left-nondominant leg, closed eyes. Results: Significant differences in displacement in the lumbar and trunk sensors are highlighted in 6 of 36 variables. In the velocity variables, significant differences were only found in 1 variable. Differences during SLS between the affected and the nonaffected legs in patients with stroke were found in 5 of the 36 analyzed variables and in 1 variable in velocity. The intraclass correlation coefficients were higher than .866 (95% confidence interval: .828-.857) for all variables. Conclusions: Only significant differences were found in 7 of the 128 kinematic variables analyzed in both groups, so that it could be confirmed that there are no significant differences in the static balance between healthy elderly people and people with stroke who undergo the rehabilitative treatment.
... Several researches have provided evidence that spectral analysis of the CoP signal is more sensitive than traditional measures in detecting changes in postural control as the result of dual-tasking or different standing conditions or differentiating between groups [80,90,92,93,114,117]. Within spectral analysis methods, wavelet analysis has been suggested to be particularly well suited for the analysis of standing CoP signals [48,114,115,118,119]. Wavelet analysis uses variable-sized, time-scale specific windows to deconstruct the signal into time-scale bands; the time-scales can then be transformed to frequencies. ...
Thesis
Lower-limb prosthesis users have commonly-recognized deficits in gait and posture control. However, existing methods in balance and mobility analysis fail to provide sufficient sensitivity to detect changes in prosthesis users' postural control and mobility in response to clinical intervention or experimental manipulations and often fail to detect differences between prosthesis users and non-amputee control subjects. This lack of sensitivity limits the ability of clinicians to make informed clinical decisions and presents challenges with insurance reimbursement for comprehensive clinical care and advanced prosthetic devices. These issues have directly impacted clinical care by restricting device options, increasing financial burden on clinics, and limiting support for research and development. This work aims to establish experimental methods and outcome measures that are more sensitive than traditional methods to balance and mobility changes in prosthesis users. Methods and analysis techniques were developed to probe aspects of balance and mobility control that may be specifically impacted by use of a prosthesis and present challenges similar to those experienced in daily life that could improve the detection of balance and mobility changes. Using the framework of cognitive resource allocation and dual-tasking, this work identified unique characteristics of prosthesis users’ postural control and developed sensitive measures of gait variability. The results also provide broader insight into dual-task analysis and the motor-cognitive response to demanding conditions. Specifically, this work identified altered motor behavior in prosthesis users and high cognitive demand of using a prosthesis. The residual standard deviation method was developed and demonstrated to be more effective than traditional gait variability measures at detecting the impact of dual-tasking. Additionally, spectral analysis of the center of pressure while standing identified altered somatosensory control in prosthesis users. These findings provide a new understanding of prosthetic use and new, highly sensitive techniques to assess balance and mobility in prosthesis users.
... Balance involves the reception and integration of sensory stimuli, and the planning and execution of movements to control the centre of gravity on the base support, carried out by the postural control system that integrates information from the vestibular and somatosensory system and visual receptors [126,127]. Evidence shows that postural instability is related to frailty [128][129][130][131] and pre-frailty [132]. Accordingly, the presence of postural instability determines a greater chance of the elderly being frail or pre-frail [133]. ...
Chapter
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Frailty is one of the leading causes of morbidity and premature mortality in older people. It is a multidimensional syndrome characterized by a reduced ability to deal with acute, physical, mental, socio-economic and spiritual stressors, and/or to perform daily living activities. Physical frailty is a complex condition deriving from multiple causes and contributors. It is characterized by the decline of physiological systems, leading to a loss of strength and endurance, and reduced physical ability. Frailty presents an increased risk of vulnerability to disease, dependency and/or death. Frail individuals are also prone to falls and are at greater risk of hospitalization and admission to long-term care. Consequently, there is a need for an effective tool or tools that can easily identify frail community-living individuals at an early stage of physical decline. Screening tools can be performance-based tests, questionnaires or a combination of both. The aim of the present narrative literature review is to describe the existing simple performance-based frailty screening tools.
... In [36] Ramirez and colleagues conducted a study to assess posture control by conducting an standing balance test amongst three different age groups: frail, pre-frail and healthy individuals. The associated data was extracted from inertial sensors and temporal and frequency compo- nents were obtained by using wavelet decomposition. ...
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Background: Frailty assessment is a critical approach in assessing the health status of older people. The clinical tools deployed by geriatricians to assess frailty can be grouped into two categories; using a questionnaire-based method or analyzing the physical performance of the subject. In performance analysis, the time taken by a subject to complete a physical task such as walking over a specific distance, typically three meters, is measured. The questionnaire-based method is subjective, and the time-based performance analysis does not necessarily identify the kinematic characteristics of motion and their root causes. However, kinematic characteristics are crucial in measuring the degree of frailty. Results: The studies reviewed in this paper indicate that the quantitative analysis of activity of daily living, balance and gait are significant methods for assessing frailty in older people. Kinematic parameters (such as gait speed) and sensor-derived parameters are also strong markers of frailty. Seventeen gait parameters are found to be sensitive for discriminating various frailty levels. Gait velocity is the most significant parameter. Short term monitoring of daily activities is a more significant method for frailty assessment than is long term monitoring and can be implemented easily using clinical tests such as sit to stand or stand to sit. The risk of fall can be considered an outcome of frailty. Conclusion: Frailty is a multi-dimensional phenomenon that is defined by various domains; physical, social, psychological and environmental. The physical domain has proven to be essential in the objective determination of the degree of frailty in older people. The deployment of inertial sensor in clinical tests is an effective method for the objective assessment of frailty.
... Also Thiede et al. (Glaviano et al. 2016) did not identify any significant difference in balance parameters. On the contrary, Martínez-Ramírez et al. (2011) have examined orientation and acceleration signals of a tri-axial inertial magnetic sensor during the quiet standing balance tests in a frail, a pre-frail and a healthy population. The frail group showed, during the closed eyes postural test, greater values in the sway area of the center of mass (COM) than the healthy group. ...
Article
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The rapid ageing of society makes necessary the development of advanced technologies for the identification of frailty. In this paper, we present a system for mobility evaluation in frailty phenotype assessment. The system is equipped with wireless, small and non-invasive wearable sensors for an objective evaluation of mobility. The paper proposes an optimization of gait analysis algorithm using a dynamic threshold. The results obtained from a comparison with the gold standard show errors of 3.7% for double support, 5.1% for stride length, and 5.8% for stride speed. Moreover, a simple and automatic tool, which estimates postural and walking parameters to assist medical staff in assessing frailty, is developed.
... Specifically, we focus on potential predictors offered by the Continuous Wavelet Transform (CWT), which allows us to observe the evolution of frequency-related parameters over time. In recent years, other researchers investigated the use of CWT, in combination with sensor-derived data, extracted during different activities [8]- [10]. We believe that a deeper investigation on the CWT frequency content, aimed at identifying the most relevant frequency bands, may be beneficial to the field of automated frailty assessment based on wearable sensors. ...
... Evidências mostram que a instabilidade postural está relacionada à fragilidade (15)(16)(17)(18) e pré-fragilidade (19) . (3) . ...
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Objective: to analyze the relationship between postural instability and the condition and markers of physical frailty of the elderly people in outpatient geriatric and gerontology care. Method: a cross-sectional study with a sample of 381 elderly subjects. Physical frailty was evaluated by the frailty phenotype and postural instability through the Berg Balance Scale. Univariate analyses consisted in Chi-square tests, and multivariate analyses used the Forward Stepwise method, which resulted in a model of physical frailty associated with postural instability. Results: among the participants, 56 (14.7%) were frail, 217 (57%) pre-frail, and 68 (28.3%) non-frail. Pre-frailty (p < 0.001), frailty (p = 0.000), and the markers hand grip strength (p = 0.0008), unintentional weight loss (p = 0.0094), level of physical activity (p = 0.0001), fatigue/exhaustion (p = 0.0001), and gait speed (p = 0.0001) were associated with postural instability. Conclusion: the presence of postural instability determines a greater chance of the elderly being frail or pre-frail. This result favors the planning of gerontological nursing care and strengthens the treatment plan under a specific approach.
... Their study validated the high correlation between the EMG signal and balance condition of the human body. The acceleration signals were processed by using the wavelet analysis as well as the principal component analysis (PCA) for evaluating the balancing ability of human bodies among the frail, pre-frail and healthy groups [5]. The sample entropy values were utilized to quantify the regularity of COP fluctuations [6]. ...
Article
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The purpose of this research is to investigate the feasibility of evaluating the human’s balancing ability by means of the human body’s swaying acceleration measurements instead of the traditional center-of-pressure (COP) measurement. The COP measurement has been used broadly for assessing the balance ability of patients in hospitals. However, the force plate system which is employed to measure the COP signals of the human body is generally restrictive due to the very high cost as well as the bulky portability. In this study, the balancing ability of the human body was evaluated through the measurements of a capacitive accelerometer. The segmentalized principal components analysis (sPCA) was employed to reduce the influence of the gravity component in acceleration measurement projected onto the horizontal components while the accelerometer inevitably tilts. The signal relationship between the COP and the acceleration was derived, so that the swaying acceleration measurements of human body can be utilized to evaluate the human body’s balancing ability.
... In order to characterize differing health and frailty states, some studies examined measurements obtained with an inertial sensor and portable data recorder fitted to the waist [17] or analyzed signals from a triaxial inertial magnetic sensor during balancing trials [18], while others introduced multimedia interactive games with several measuring devices (grip strength meter, pressure pad, functional reach measuring instrument) [19], or used a hand-grip electronic dynamometer to test the association between handgrip strength and mortality [20]. Video games enabling muscle strength measurement were introduced in [21] to study age-related loss of muscle strength. ...
Article
The implications of frailty in older adults' health status and autonomy necessitates the understanding and effective management of this widespread condition as a priority for modern societies. Despite its importance, we still stand far from early detection, effective management and prevention of frailty. One of the most important reasons for this is the lack of sensitive instruments able to early identify frailty and pre-frailty conditions. The FrailSafe system provides a novel approach to this complex, medical, social and public health problem. It aspires to identify the most important components of frailty, construct cumulative metrics serving as biomarkers, and apply this knowledge and expertise for self-management and prevention. This paper presents a high-level overview of the FrailSafe system architecture providing details on the monitoring sensors and devices, the software front-ends for the interaction of the users with the system, as well as the back-end part including the data analysis and decision support modules. Data storage, remote processing and security issues are also discussed. The evaluation of the system by older individuals from 3 different countries highlighted the potential of frailty prediction strategies based on information and communication technology (ICT).
... It consists of four balance assessments based on: (i) eyes open standing on a firm surface, (ii) eyes closed standing on a firm surface, (iii) eyes open standing on a flexible surface (such as a foam), and (iv) eyes closed standing on a flexible surface [16]. In postural control, the goal is to maintain COM within the limits of stability, thus direct measurement of COM may provide an understanding of the mechanisms responsible for balance control [17]. A number of studies reported the use of accelerometers and gyroscopes to quantify sway metrics for fall detection of balance deficit in the elderly at risk of falling and in patients with Parkinson disease, multiple sclerosis, or Alzheimer disease [18][19][20]. ...
Article
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The effect of center of mass (COM) height on stand-still postural sway analysis was studied. For this purpose, a measurement apparatus was set up that included an accelerometry unit attached to a rod: three plumb lines, positioned at 50 cm, 75 cm, and 100 cm to the end of the rod, each supported a plumb bob. Using a vice mechanism, the rod was inclined from vertical (0 degree inclination) in steps of 5 degrees to 90 degrees. For each inclination, the corresponding inclination angle was manually measured by a protractor, and the positions of the three plumb bobs on the ground surface were also manually measured using a tape measure. Algebraic operations were used to calculate the inclination angle and the associated displacements of the plumb bobs on the ground surface from the accelerometry data. For each inclination angle, the manual and accelerometry calculated ground displacement produced by each plumb bulb were close. It was demonstrated that the height of COM, where the measurement was taken, affected the projected displacement on the ground surface. A higher height produced a greater displacement. This effect has an implication in postural sway analysis where the accelerometry readings may need comparison amongst subjects with different COM heights. To overcome this, a method that normalized the accelerometry readings by considering the COM height was proposed, and the associated results were presented.
... Mittels integrierter Sensoren im Schuh können menschliche Bewegungen detektiert werden und deren Abweichungen von der Norm festgehalten werden. Es konnte gezeigt werden, dass motorische Defizite, Frailty, Morbus Parkinson oder andere Erkrankungen wie Mild Cognitive Impairment und Diabetes mellitus in Beziehung zu den Abweichungen in den normalen Bewegungsabläufen stehen (Martinez-Ramirez et al., 2011;Yang et al., 2011;Millor et al., 2013). ...
Thesis
Gleichzeitig mit der immer älter werdenden Weltbevölkerung tritt das Phänomen „Frailty“ immer häufiger auf und bringt einschneidende Konsequenzen für den Einzelnen, aber auch für die Gesellschaft mit sich. Häufig erfolgt im deutschen Sprachgebrauch die Verwendung des Begriffes Gebrechlichkeit, wobei dieser der Komplexizität nicht annähernd gerecht wird. Frailty muss als dynamischer Prozess angesehen werden, der sowohl in die positive als auch die negative Richtung aktiv beeinflusst werden kann. Zur Vorbeugung und auch Verhinderung des Fortschreitens dieses Phänomens ist die frühzeitige Erkennung besonders wichtig, um mittels aktiver Maßnahmen gegensteuern zu können. Bisher hat sich jedoch noch keine einheitliche Methode zur Erfassung von Frailty etabliert. Als Möglichkeit, diese zu detektieren, hat sich in den letzten Jahren die Ganganalyse etabliert, wobei hier bisher vor allem Veränderungen der Gehgeschwindigkeit mit Frailty assoziiert waren. Das Ziel der vorliegenden Studie war die Aufdeckung von Zusammenhängen zwischen Merkmalen im räumlich-zeitlichen und dreidimensionalen Gang und Frailty. In der vorliegenden Arbeit wurden verschiedene Gangparameter mittels elektronischer Ganganalyse gemessen. Die Erhebung erfolgte anhand zweier Ganganalysesysteme, dem GaitRite- und dem eGait-System. Mittels GaitRite-System wurden zehn räumlich-zeitliche Gangparameter erfasst: Velocity, Swing time, Stride length, Stride length variability, Stride time, Stride time variability, Double support time, Double support time variability, Stride width sowie Stride width variability. Zur Erfassung der dreidimensionalen Gangparameter wurden Maximum toe clearance, Toe off angle und Heel strike angle erhoben. Zur Einstufung der Frailty wurden in dieser Studie insgesamt vier verschiedene Erfassungsinstrumente (Fried Phänotyp (FP), Clinical Frailty Scale (CFS), Frailty Index (FI)-31 Variablen, Frailty Index auf einer geriatrischen Beurteilung basierend (FI-CGA) angewendet. Anhand der so erlangten Ergebnisse erfolgte die Einteilung in zwei Gruppen, die der Gebrechlichen und die der Nicht-Gebrechlichen. Die Gangparameter wurden zudem unter drei unterschiedlichen Bedingungen erhoben (Gang mit Rechenaufgabe, Gang mit erhöhter Aufmerksamkeit sowie Gang am Rollator). Die an 123 geriatrischen Patienten erhobenen Daten wurden auf statistisch signifikante Zusammenhänge mit Frailty überprüft. In Bezug auf das primäre Studienziel bestätigte die Analyse der Daten Veränderungen in der Gehgeschwindigkeit bei Patienten mit Frailty. Zudem zeigte sich als weiterer räumlich-zeitlicher Gangparameter die Stride length über alle vier Erfassungsinstrumente signifikant geeignet, gebrechliche von nicht-gebrechlichen Personen abzugrenzen. Im dreidimensionalen Gang konnten diese Unterscheidung die Gangparameter Maximum toe clearane und Toe off angle leisten. Hohe Werte in den Frailty Indices korrelierten mit niedriger Velocity, Stride length und Maximum toe clearance und einem höheren Toe off angle. Je nach verwendetem Erfassungsinstrument unterschieden sich auch weitere Gangparameter wie Heel strike angle oder Swing time und Double support time zwischen den Gruppen signifikant, jedoch nicht in dem Maße wie die oben genannten. Die vorliegende Arbeit konnte über verschiedene Erfassungsinstrumente zeigen, dass neben der Velocity weitere Veränderungen im Gang mit Frailty assoziiert sind.
... 81 This finding is supported by experimental studies reporting that the frail population could require more cognitive resources to maintain upright standing, and consequently increase the delay of postural control adjustment in comparison with healthy older adults. [82][83][84] While there is no clear evidence of specific system alteration between frail 85 recently reported significant higher risk of falls in people with sarcopenia than without. Further, in a systematic review and meta-analysis of 10 studies with 10,073 participants, Zhang et al 86 concluded that sarcopenia is a risk factor for falls among community-dwelling older people, but not in nursing home residents. ...
Article
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One of the most widely conserved hallmarks of aging is a decline in functional capabilities. Mobility loss is particularly burdensome due to its association with negative health outcomes, loss of independence and disability, and the heavy impact on quality of life. Recently, a new condition, physical frailty and sarcopenia, has been proposed to define a critical stage in the disabling cascade. Physical frailty and sarcopenia are characterized by weakness, slowness, and reduced muscle mass, yet with preserved ability to move independently. One of the strategies that have shown some benefits in combatting mobility loss and its consequences for older adults is physical activity. Here, we describe the opportunities and challenges for the development of physical activity interventions in people with physical frailty and sarcopenia. The aim of this article is to review age-related physio(patho)logical changes that impact mobility in old age and to provide recommendations and procedures in accordance with the available literature.
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Frailty is an important geriatric syndrome strongly linked to falls risk as well as increased mortality and morbidity. Taken alone, falls are the most common cause of injury and hospitalization and one of the principal causes of death and disability in older adults worldwide. Reliable determination of older adults' frailty state in concert with their falls risk could lead to targeted intervention and improved quality of care. We report a mobile assessment platform employing inertial and pressure sensors to quantify the balance and mobility of older adults using three physical assessments (timed up and go (TUG), five times sit to stand (FTSS) and quiet standing balance). This study examines the utility of each individual assessment, and the novel combination of assessments, to screen for frailty and falls risk in older adults. Data were acquired from inertial and pressure sensors during TUG, FTSS and balance assessments using a touchscreen mobile device, from 124 community dwelling older adults (mean age 75.9 ± 6.6 years, 91 female). Participants were given a comprehensive geriatric assessment which included questions on falls and frailty. Methods based on support vector machines (SVM) were developed using sensor-derived features from each physical assessment to classify patients at risk of falls risk and frailty. In classifying falls history, combining sensor data from the TUG, Balance and FTSS tests to a single classifier model per gender yielded mean cross-validated classification accuracy of 87.58% (95% CI: 84.47–91.03%) for the male model and 78.11% (95% CI: 75.38–81.10%) for the female model. These results compared well or exceeded those for classifier models for each test taken individually. Similarly, when classifying frailty status, combining sensor data from the TUG, balance and FTSS tests to a single classifier model per gender, yielded mean cross-validated classification accuracy of 93.94% (95% CI: 91.16–96.51%) for the male model and 84.14% (95% CI: 82.11–86.33%) for the female model (mean 89.04%) which compared well or exceeded results for physical tests taken individually. Results suggest that the combination of these three tests, quantified using body-worn inertial sensors, could lead to improved methods for assessing frailty and falls risk.
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Objectives: We present the novel urine collection method used during in-home interviews of a large population representative of older adults in the United States (aged 62-91, the National Social Life, Health and Aging Project). We also present a novel assay method for accurately measuring urinary peptides oxytocin (OT) and vasopressin (AVP), hormones that regulate social behaviors, stress, and kidney function. Method: Respondents in a randomized substudy (N = 1,882) used airtight containers to provide urine specimens that were aliquoted, stored under frozen refrigerant packs and mailed overnight for frozen storage (-80 °C). Assays for OT, AVP, and creatinine, including freeze-thaw cycles, were refined and validated. Weighted values estimated levels in the older U.S. population. Results: Older adults had lower OT, but higher AVP, without the marked gender differences seen in young adults. Mild dehydration, indicated by creatinine, specific gravity, acidity, and AVP, produced concentrated urine that interfered with the OT assay, yielding falsely high values (18% of OT). Creatinine levels (≥ 1.4 mg/ml) identified such specimens that were diluted to solve the problem. In contrast, the standard AVP assay was unaffected (97% interpretable) and urine acidity predicted specimens with low OT concentrations. OT and AVP assays tolerated 2 freeze-thaw cycles, making this protocol useful in a variety of field conditions. Discussion: These novel protocols yielded interpretable urinary OT and AVP values, with sufficient variation for analyzing their social and physiological associations. The problem of mild dehydration is also likely common in animal field studies, which may also benefit from these collection and assay protocols.
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Introduction: Low back pain (LBP) is widely prevalent in healthcare workers. It is associated with impaired postural and core stability. So far, centre of pressure (CoP) measures have been commonly recorded through the use of a force plate in order to assess postural stability. However, this approach provides limited information about the centre of mass (CoM) movement in the lumbar region in individuals with LBP. Recent developments in sensor technology enable measurement of the trunk motion which could provide additional information on postural sway. However, the question remains as to whether CoM measures would be more sensitive in discriminating individuals with mild and moderate back pain than traditional CoP analyses. This study aims to investigate the sensitivity of CoP and CoM measures under varied stable, metastable and unstable testing conditions in healthcare workers, and their relationship with the level of subjective reported back pain. Methods and analysis: This is a cross-sectional controlled laboratory study. A group of 90 healthcare professionals will be recruited from rehabilitation centres within local areas. Participants will complete the Oswestry Disability Questionnaire. The primary outcome will be the rate of their back pain on the 0-10 Low Back Pain Scale (1-3 mild pain and 4-6 moderate pain). Secondary outcomes will include variables of postural and core stability testing during bipedal and one-legged stance on a force plate, a foam mat placed on the force plate, and a spring-supported platform with either eyes open or eyes closed. Both CoP using the posturography system based on a force plate and CoM using the inertial sensor system placed on the trunk will be simultaneously measured. Ethics and dissemination: Projects were approved by the ethics committee of the Faculty of Physical Education and Sport, Comenius University in Bratislava (Nos. 4/2017, 1/2020). Findings will be published in peer-reviewed journals and presented at conferences.
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This work analyses different concepts for frailty diagnosis based on affordable standard technology such as smartphones or wearable devices. The goal is to provide ideas that go beyond classical diagnostic tools such as magnetic resonance imaging or tomography, thus changing the paradigm; enabling the detection of frailty without expensive facilities, in an ecological way for both patients and medical staff and even with continuous monitoring. Fried's five-point phenotype model of frailty along with a model based on trials and several classical physical tests were used for device classification. This work provides a starting point for future researchers who will have to try to bridge the gap separating elderly people from technology and medical tests in order to provide feasible, accurate and affordable tools for frailty monitoring for a wide range of users.
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previously, frailty indices were constructed using mostly subjective health measures. The reporting error in this type of measure can have implications on the robustness of frailty findings. to examine whether frailty assessment differs when we construct frailty indices using solely self-reported or test-based health measures. secondary analysis of data from The Irish LongituDinal study on Ageing (TILDA). 4,961 Irish residents (mean age: 61.9 ± 8.4; 54.2% women) over the age of 50 years who underwent a health assessment were included in this analysis. We constructed three frailty indices using 33 self-reported health measures (SRFI), 33 test-based health measures (TBFI) and all 66 measures combined (CFI). The 2-year follow-up outcomes examined were all-cause mortality, disability, hospitalisation and falls. all three indices had a right-skewed distribution, an upper limit to frailty, a non-linear increase with age, and had a dose-response relationship with adverse outcomes. Levels of frailty were lower when self-reported items were used (SRFI: 0.12 ± 0.09; TBFI: 0.17 ± 0.15; CFI: 0.14 ± 0.13). Men had slightly higher frailty index scores than women when test-based measures were used (men: 0.17 ± 0.09; women: 0.16 ± 0.10). CFI had the strongest prediction for risk of adverse outcomes (ROC: 0.64-0.81), and age was not a significant predictor when it was included in the regression model. except for sex differences, characteristics of frailty are similar regardless of whether self-reported or test-based measures are used exclusively to construct a frailty index. Where available, self-reported and test-based measures should be combined when trying to identify levels of frailty. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Loss of somatosensory feedback after amputation inflicts a serious challenge to achieve postural stability. Improving motor skills by incorporating sensory feedback in rehabilitation protocols for persons with lower limb amputation has been gaining traction over time. However, the control mechanisms involved in this regarding time–frequency analysis have not been investigated yet. The purpose of this study was to explore the frequencies/time-scales responsible for postural stability in trans-femoral amputees with vibrotactile feedback. Center of Pressure (COP) signals were collected from 5 trans-femoral amputees and 10 healthy subjects during weight shifting balance tasks. A customized foot insole was used to estimate the COP for actuation of vibratory feedback. The evaluation of postural sway fluctuations by means of COP excursions with vibrotactile feedback was computed by wavelet transform method. Vibrotactile feedback was found to be effective in controlling low frequency postural sway in amputees. We found significantly higher energy (p = 0.004, 0.0007) at shorter time-scales (j = 6,7, freq. = 0.6–1.25 Hz) and lower energy (p = 0.0006) at longer time-scale (j = 10, freq. = 0.078 Hz) in amputees with vibrotactile feedback in comparison to healthy subjects using Coif 1 wavelet. We also found significant increase in energy (p = 0.003) during forward weight shifting with vibrotactile feedback in the sound limb of amputees in comparison to no feedback session at frequency/time-scales corresponding to somatosensory acuity (j = 6–8, freq. = 0.3–1.5 Hz) using Haar wavelet. These findings reflect the higher contribution of somatosensory receptors in amputees with vibrotactile feedback and may provide a better understanding of the mechanisms associated with standing balance in terms of time–frequency analysis.
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Background: Frailty has become the center of attention of basic, clinical and demographic research because of its incidence level and the gravity of adverse outcomes with age. Moreover, with advanced age, motor variability increases, particularly in gait. Muscle quality and muscle power seem to be closely associated with performance on functional tests in frail populations. Insight into the relationships among muscle power, muscle quality and functional capacity could improve the quality of life in this population. In this study, it was examined the relationship between the quality of the muscle mass and muscle strength with gait performance in a frail population. Methods: Twenty-two institutionalized frail elderly subjects (93.1 ± 3.6) participated in this study. Muscle quality was measured by segmenting areas of high- and low-density fibers as observed in computed tomography images. The assessed functional outcomes were leg strength and power, velocity of gait and kinematic gait parameters obtained from a tri-axial inertial sensor. Findings: Our results showed that a greater amount of high-density fibers, specifically those of the quadriceps femoris muscle, were associated with better gait performance in terms of step time variability, regularity and symmetry. Additionally, gait variability was associated with muscle power. In contrast, no significant relationship was observed between gait velocity and either muscle quality or muscle power. Interpretation: Gait pattern disorders could be explained by a deterioration of the lower limb muscles. It is known that an impaired gait is an important predictor of falls in older populations; thus, the loss of muscle quality and power could underlie the impairments in motor control and balance that lead to falls and adverse outcomes.
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O objetivo do estudo foi realizar uma revisão integrativa em bases de dados para verificar a produção científica (inter) nacional sobre instabilidade postural e a condição de fragilidade física em idosos. Trata-se de uma revisão integrativa realizada nas bases de dados LILACS, MEDLINE, SciELO e PubMed, no período de 2001 a 2016.Incluíram-se artigos originais diretamente relacionados ao tema, disponíveis na íntegra, nos idiomas português e inglês. A busca inicial resultou em 483 artigos e, após critérios pré-estabelecidos de inclusão e exclusão, 24 artigos perfizeram o corpus da revisão. As publicações apresentaram crescimento recente com destaque para a literatura internacional. Emergiram três categorias temáticas: instabilidade postural associada ao envelhecimento: causas e consequências; reconhecimento da fragilidade física e instabilidade postural: relações e associações; e intervenções para a reabilitação do equilíbrio postural. A instabilidade postural associa-se ao processo de envelhecimento, como um marcador de fragilidade física e da saúde da pessoa idosa. Os resultados oferecem subsídios para fortalecer a gestão de cuidados preventivos da progressão da síndrome da fragilidade.
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Background and objective: Sensor technology, in particular wearable inertial sensors, has the potential to help researchers objectively assess the functionality of older adults. The following review provides an overview about the possible use of sensor technology to detect and prevent pre-frailty and frailty. Method: A systematic literature search in PubMed and the Cochrane Library was conducted. Articles were selected according to the following criteria: frail and/or pre-frail population, use of wearable and non-wearable sensor technology to measure or enhance human movements or activities of daily living and a focus on frailty assessment. Results: A total of 28 publications were found. Sensor-derived parameters obtained during assessment of gait, functional performances and physical activity were reported to be relevant for screening and monitoring pre-frailty and frailty; however, current findings are limited to cross-sectional studies, which do not allow establishment of a causal relationship between motor performance, physical activity and specific frailty states. No study monitored specific activities of daily living. Discussion: Outcome variables from technology-based assessment seem to provide valuable information for frailty assessment. Strenuous testing conditions as well as increased variability in gait, functional performance and physical activity may be useful in identifying frailty. Outcome variables derived from gait, motor assessment and physical activity must still be validated in large cohorts and under daily living conditions in order to develop robust screening tools for pre-frailty and frailty. Further research should focus on specific activities of daily living in pre-frail or frail older adults and technology-based approaches for intervention and prevention.
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Background: Short-term and mid-term comparison of the efficacy of a multimodal program that incorporates a therapeutic workout program, medication review, diet adjustment and health education, in comparison to the standard medical practice in the improvement of the neuromuscular and physiological condition. Furthermore, it is intended to analyse the maintenance of these effects in a long-term follow-up (12 months) from the onset of the intervention. Methods: A randomized clinical trial of elderly frail patients drawn from the Clinical Management Unit "Tiro de Pichón", Health District of Malaga, will be included in the study (after meeting the inclusion / exclusion criteria) will be randomized in two groups: a control group that will undergo an intervention consistent of medication review + diet adjustment + health education (regular workout recommendations within a complete advice on healthy lifestyles) and an experimental group whose intervention will consist of a multimodal treatment: therapeutic workout program+ medication review+ diet adjustment + health education. The sociodemographic, clinical and tracing variables will be reflected at the beginning of the study. In addition, the follow-up variables will be gathered at the second and sixth months after the beginning of the treatment and at the third and sixth months after the treatment (follow-up). The follow-up variables that will be measured are: body mass index, general health condition, fatigue, frailty, motor control, attention- concentration- memory, motor memory, spatial orientation, grip strength, balance (static, semi-dynamic), gait speed and metabolomics. A descriptive analysis of the sociodemographic variables of the participants will be conducted. One-Factor ANOVA will be used for the Within-Subject analysis and as for the Between-Subject analysis, the outcome variables between both the groups in each moment of the data collection will be compared. Discussion: A multimodal program that incorporates a therapeutic workout program, medication review, diet adjustment and health education may be effective treatment to reduce the functional decline in elderly. The results of the study will provide information on the possible strengths and benefits in multimodal program in elderly. Trial registration: ClinicalTrials.gov NCT02772952 registered May 2017.
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Background: Ankle sprain is the most common sports-related injury, and approximately 80% of patients studied suffered recurrent sprains. These repeated ankle injuries could cause chronic ankle instability, a decrease in sports performance, and a decrease in postural control ability. At the present time, smartphones have become very popular and powerful devices, and smartphone applications (apps) that have been shown to have good validity have been designed to measure human body motion. However, the app focusing on ankle function assessment and rehabilitation is still not widely used and has very limited functions. The purpose of this study is to evaluate the feasibility of smartphone-based systems in the assessment of postural control ability for patients with chronic ankle instability. Methods: Fifteen physically active adults (6 male, 9 female; aged = 23.4 ± 5.28 years; height = 167.13 ± 7.3 cm; weight = 62.06 ± 10.82 kg; BMI = 22.08 ± 2.57 kg/ m(2)) were recruited, and these participants had at least one leg that was evaluated as scoring lower than 27 points according to the Cumberland Ankle Instability Tool (CAIT). The smartphone used in the study was ASUS Zenfone 2, and an app developed using MIT App Inventor was used to record built-in accelerometer data during the assessment process. Subjects were asked to perform single leg stance for 20 s in eyes-open and eyes-closed conditions with each leg. The smartphone was fixed in an upright position on the middle of the shin, using an exercise armband, with the screen facing forward. The average of recorded acceleration data was used to represent the postural control performance, and higher values indicated more instability. Data were analyzed with a paired t-test with SPSS 17.0, and the statistical significance was set as alpha <0.05. Results: A significant difference was found between CAIT scores from the healthier leg and injured leg (healthier leg 23.07 ± 3.80 vs. injured leg 18.27 ± 3.92, p < 0.001). Significant differences were also found between the scores for the healthier leg and injured leg during both eyes-open and eyes-closed conditions (eyes-open: healthier leg 0.051 ± 0.018 vs. injured leg 0.072 ± 0.034, p = 0.027; eyes-closed: healthier leg 0.100 ± 0.031 vs. injured leg 0.123 ± 0.038, p = 0.001, unit: m/s(2)). Significant differences were also found between eyes-open and eyes-closed conditions during both single leg standing with healthier leg and injured leg (healthier leg: eyes-open 0.051 ± 0.018 vs. eyes-closed 0.100 ± 0.031, p < 0.001; injured leg: eyes-open 0.072 ± 0.034 vs. eyes-closed 0.123 ± 0.038, p = 0.001, unit: m/s(2)). The results demonstrate that the smartphone software can be used to discriminate between the different performances of the healthier leg and injured leg, and also between eyes-open and eyes-closed conditions. Conclusion: The smartphone may have the potential to be a convenient, easy-to-use, and feasible tool for the assessment of postural control ability on subjects with chronic ankle instability.
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This study analyzes the technologies used in dealing with frailty within the following areas: prevention, care, diagnosis and treatment. The aim of this paper is, on the one hand, to analyze the extent to which technology is present in terms of its relationship with frailty and what technological resources are used to treat it. Its other purpose is to define new challenges and contributions made by physiotherapy using technology. Eighty documents related to research, validation and/or the ascertaining of different types of hardware, software or both were reviewed in prominent areas. The authors used the following scales: in the area of diagnosis, Fried’s phenotype model of frailty and a model based on trials for the design of devices. The technologies developed that are based on these models accounted for 55% and 45% of cases respectively. In the area of prevention, the results proved similar regarding the use of wireless sensors with cameras (35.71%), and Kinect™ sensors (28.57%) to analyze movements and postures that indicate a risk of falling. In the area of care, results were found referring to the use of different motion, physiological and environmental wireless sensors (46,15%), i.e. so-called smart homes. In the area of treatment, the results show with a percentage of 37.5% that the Nintendo® Wii™ console is the most used tool for treating frailty in elderly persons. Further work needs to be carried out to reduce the gap existing between technology, frail elderly persons, healthcare professionals and carers to bring together the different views about technology. This need raises the challenge of developing and implementing technology in physiotherapy via serious games that may via play and connectivity help to improve the functional capacity, general health and quality of life of frail individuals.
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The frailty status can be improved by intervention. Both Exergaming and combined exercise have been proposed for improving physical performance in community-dwelling elderly. However whether frailty status can be improved by exergaming is unclear. Moreover, whether Kinect-based exergaming training can exert a stronger effect on improving frailty status than combined exercise needs to be established. This study was to investigate the effects of Kinect-based exergaming on improving frailty status and physical performance in the prefrail and frail elderly by comparing its effects with those of combined exercise. Fifty-two prefrail and frail elderly were recruited and randomized to Kinect-based exergaming group (EXER group) or combined exercise group (CE group) emphasizing resistance, aerobic, and balance training for 36 sessions over 12 weeks. Our results showed that both groups reversed the frailty status (EXER group: p=0.016, effect size=2.29 and CE group: p=0.031, effect size=2.67). Three out of 5 physical characteristics of the frailty phenotype, namely, weakness, slow walking speed, and low activity level, were significantly reversed by both exergaming and combined exercise. However, the exergaming training also significantly reversed the exhaustion. Furthermore, compared with the CE group, the EXER group showed greater improvement in dynamic balance control indicated by the forward reaching test (p=0.0013, effect size=0.40) and single leg stance test (p=0.049, effect size=0.42). It seems that Kinect-based exergaming exerted effects that were at least as beneficial as those of combined exercise in reversing frailty status and the frailty phenotype. We recommend the use of exergaming aided by Kinect in the prefrail and frail elderly.
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Lower limb spasticity is a common sensorimotor consequence post-stroke, which further complicates stability control by altering the temporal relationship between individual-limb centre of pressure (COP) displacements. The present work employed the discrete wavelet transform to better understand the influence of lower limb spasticity on the control of standing balance, which occurs across multiple timescales. An 8-level decomposition of the individual-limb COP was performed, using retrospective data from 91 stroke survivors with (n=29) and without (n=56) lower limb spasticity. Inter-limb temporal synchrony and spatial symmetry at each timescale were evaluated by the cross correlation coefficient at zero phase-lag and the RMS ratio, respectively, using the reconstructed time series at each timescale. Reduced temporal synchrony was observed among individuals with lower limb spasticity at frequencies down to 0.20 Hz. The present results suggest that the additional balance control challenges associated with post-stroke lower limb spasticity may be linked to the ability to temporally co-modulate the more rapid COP displacements. This may be particularly problematic if individuals are faced with balance perturbations, which require rapid reactive balance corrections to regain stability.
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Over the last years, inertial sensing has proven to be a suitable ambulatory alternative to traditional human motion tracking based on optical position measurement systems, which are generally restricted to a laboratory environment. Besides many advantages, a major drawback is the inherent drift caused by integration of acceleration and angular velocity to obtain position and orientation. In addition, inertial sensing cannot be used to estimate relative positions and orientations of sensors with respect to each other. In order to overcome these drawbacks, this study presents an Extended Kalman Filter for fusion of inertial and magnetic sensing that is used to estimate relative positions and orientations. In between magnetic updates, change of position and orientation are estimated using inertial sensors. The system decides to perform a magnetic update only if the estimated uncertainty associated with the relative position and orientation exceeds a predefined threshold. The filter is able to provide a stable and accurate estimation of relative position and orientation for several types of movements, as indicated by the average rms error being 0.033 m for the position and 3.6 degrees for the orientation.
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Human movement has been the subject of investigation since the fifth century when early scientists and researchers attempted to model the human musculoskeletal system. The anatomical complexities of the human body have made it a constant source of research to this day with many anatomical, physiological, mechanical, environmental, sociological and psychological studies undertaken to define its key elements. These studies have utilised modern day techniques to assess human movement in many illnesses. One such modern technique has been direct measurement by accelerometry, which was first suggested in the 1970s but has only been refined and perfected during the last 10-15 years. Direct measurement by accelerometry has seen the introduction of the successful implementation of low power, low cost electronic sensors that have been employed in clinical and home environments for the constant monitoring of patients (and their controls). The qualitative and quantitative data provided by these sensors make it possible for engineers, clinicians and physicians to work together to be able to help their patients in overcoming their physical disability. This paper presents the underlying biomechanical elements necessary to understand and study human movement. It also reflects on the sociological elements of human movement and why it is important in patient life and well being. Finally the concept of direct measurement by accelerometry is presented with past studies and modern techniques used for data analysis.
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The factorial and discriminant validity of the Center for Epidemiological Studies Depression (CES-D) scale was examined for a sample of 116 parents who were participating in family support programs designed to prevent child abuse and neglect. Participants' self-reports of depressive symptoms as measured by the CES-D were analyzed in relation to their self-esteem (measured with the Rosenberg Self-Esteem scale) and state and trait anxiety (measured with Spielberger's State-Trait Anxiety Inventory). Factorial validity was adequate, and results indicated a moderate correlation between the CES-D and self-esteem and state anxiety. However, a high correlation was obtained between the CES-D and trait anxiety, which suggests that the CES-D measures in large part the related conceptual psychological domain of predisposition for anxiousness.
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This study investigated whether 184 volunteers from 20 to 79 years of age could perform eight timed balance tests and examined the relationship between test performance and age. All subjects were able to balance with their feet together and eyes closed for 30 seconds. The ability to balance on the right and left legs did not differ significantly. Subjects over 60 years of age were unable to balance on one leg, particularly when their eyes were closed, for as long a period as younger subjects. The Pearson product-moment and Spearman correlations of age and duration of one-legged balance were -.65 and -.71 (eyes opened) and -.79 and -.75 (eyes closed). The findings suggest that when timed balance tests are performed as a part of a patient's neurologic examination, the results should be interpreted in light of the patient's age. Information is provided to assist in this interpretation.
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A short battery of physical performance tests was used to assess lower extremity function in more than 5,000 persons age 71 years and older in three communities. Balance, gait, strength, and endurance were evaluated by examining ability to stand with the feet together in the side-by-side, semi-tandem, and tandem positions, time to walk 8 feet, and time to rise from a chair and return to the seated position 5 times. A wide distribution of performance was observed for each test. Each test and a summary performance scale, created by summing categorical rankings of performance on each test, were strongly associated with self-report of disability. Both self-report items and performance tests were independent predictors of short-term mortality and nursing home admission in multivariate analyses. However, evidence is presented that the performance tests provide information not available from self-report items. Of particular importance is the finding that in those at the high end of the functional spectrum, who reported almost no disability, the performance test scores distinguished a gradient of risk for mortality and nursing home admission. Additionally, within subgroups with identical self-report profiles, there were systematic differences in physical performance related to age and sex. This study provides evidence that performance measures can validly characterize older persons across a broad spectrum of lower extremity function. Performance and self-report measures may complement each other in providing useful information about functional status.
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Frailty is considered highly prevalent in old age and to confer high risk for falls, disability, hospitalization, and mortality. Frailty has been considered synonymous with disability, comorbidity, and other characteristics, but it is recognized that it may have a biologic basis and be a distinct clinical syndrome. A standardized definition has not yet been established. To develop and operationalize a phenotype of frailty in older adults and assess concurrent and predictive validity, the study used data from the Cardiovascular Health Study. Participants were 5,317 men and women 65 years and older (4,735 from an original cohort recruited in 1989-90 and 582 from an African American cohort recruited in 1992-93). Both cohorts received almost identical baseline evaluations and 7 and 4 years of follow-up, respectively, with annual examinations and surveillance for outcomes including incident disease, hospitalization, falls, disability, and mortality. Frailty was defined as a clinical syndrome in which three or more of the following criteria were present: unintentional weight loss (10 lbs in past year), self-reported exhaustion, weakness (grip strength), slow walking speed, and low physical activity. The overall prevalence of frailty in this community-dwelling population was 6.9%; it increased with age and was greater in women than men. Four-year incidence was 7.2%. Frailty was associated with being African American, having lower education and income, poorer health, and having higher rates of comorbid chronic diseases and disability. There was overlap, but not concordance, in the cooccurrence of frailty, comorbidity, and disability. This frailty phenotype was independently predictive (over 3 years) of incident falls, worsening mobility or ADL disability, hospitalization, and death, with hazard ratios ranging from 1.82 to 4.46, unadjusted, and 1.29-2.24, adjusted for a number of health, disease, and social characteristics predictive of 5-year mortality. Intermediate frailty status, as indicated by the presence of one or two criteria, showed intermediate risk of these outcomes as well as increased risk of becoming frail over 3-4 years of follow-up (odds ratios for incident frailty = 4.51 unadjusted and 2.63 adjusted for covariates, compared to those with no frailty criteria at baseline). This study provides a potential standardized definition for frailty in community-dwelling older adults and offers concurrent and predictive validity for the definition. It also finds that there is an intermediate stage identifying those at high risk of frailty. Finally, it provides evidence that frailty is not synonymous with either comorbidity or disability, but comorbidity is an etiologic risk factor for, and disability is an outcome of, frailty. This provides a potential basis for clinical assessment for those who are frail or at risk, and for future research to develop interventions for frailty based on a standardized ascertainment of frailty.
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A multiscale Canny edge detection is equivalent to finding the local maxima of a wavelet transform. The authors study the properties of multiscale edges through the wavelet theory. For pattern recognition, one often needs to discriminate different types of edges. They show that the evolution of wavelet local maxima across scales characterize the local shape of irregular structures. Numerical descriptors of edge types are derived. The completeness of a multiscale edge representation is also studied. The authors describe an algorithm that reconstructs a close approximation of 1-D and 2-D signals from their multiscale edges. For images, the reconstruction errors are below visual sensitivity. As an application, a compact image coding algorithm that selects important edges and compresses the image data by factors over 30 has been implemented
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It is generally accepted that human bipedal upright stance is achieved by feedback mechanisms that generate an appropriate corrective torque based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Because orientation information from the various senses is not always available (eyes closed) or accurate (compliant support surface), the postural control system must somehow adjust to maintain stance in a wide variety of environmental conditions. This is the sensorimotor integration problem that we investigated by evoking anterior-posterior (AP) body sway using pseudorandom rotation of the visual surround and/or support surface (amplitudes 0.5-8degrees) in both normal subjects and subjects with severe bilateral vestibular loss (VL). AP rotation of body center-of-mass (COM) was measured in response to six conditions offering different combinations of available sensory information. Stimulus-response data were analyzed using spectral analysis to compute transfer functions and coherence functions over a frequency range from 0.017 to 2.23 Hz. Stimulus-response data were quite linear for any given condition and amplitude. However, overall behavior in normal subjects was nonlinear because gain decreased and phase functions sometimes changed with increasing stimulus amplitude. "Sensory channel reweighting" could account for this nonlinear behavior with subjects showing increasing reliance on vestibular cues as stimulus amplitudes increased. VL subjects could not perform this reweighting, and their stimulus-response behavior remained quite linear. Transfer function curve fits based on a simple feedback control model provided estimates of postural stiffness, damping, and feedback time delay. There were only small changes in these parameters with increasing visual stimulus amplitude. However, stiffness increased as much as 60% with increasing support surface amplitude. To maintain postural stability and avoid resonant behavior, an increase in stiffness should be accompanied by a corresponding increase in damping. Increased damping was achieved primarily by decreasing the apparent time delay of feedback control rather than by changing the damping coefficient (i.e., corrective torque related to body-sway velocity). In normal subjects, stiffness and damping were highly correlated with body mass and moment of inertia, with stiffness always about 1/3 larger than necessary to resist the destabilizing torque due to gravity. The stiffness parameter in some VL subjects was larger compared with normal subjects, suggesting that they may use increased stiffness to help compensate for their loss. Overall results show that the simple act of standing quietly depends on a remarkably complex sensorimotor control system.
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The common denominator in the assessment of human balance and posture is the inverted pendulum model. If we focus on appropriate versions of the model we can use it to identify the gravitational and acceleration perturbations and pinpoint the motor mechanisms that can defend against any perturbation.We saw that in quiet standing an ankle strategy applies only in the AP direction and that a separate hip load/unload strategy by the hip abd/adductors is the totally dominant defence in the ML direction when standing with feet side by side. In other standing positions (tandem, or intermediate) the two mechanisms still work separately, but their roles reverse. In the tandem position ML balance is an ankle mechanism (invertors/evertors) while in the AP direction a hip load/unloading mechanism dominates.During initiation and termination of gait these two separate mechanisms control the trajectory of the COP to ensure the desired acceleration and deceleration of the COM. During initiation the initial acceleration of the COM forward towards the stance limb is achieved by a posterior and lateral movement of the COP towards the swing limb. After this release phase there is a sudden loading of the stance limb which shifts the COP to the stance limb. The COM is now accelerated forward and laterally towards the future position of the swinging foot. Also ML shifts of the COP were controlled by the hip abductors/adductors and all AP shifts were under the control of the ankle plantar/dorsiflexors. During termination the trajectory of both COM and COP reverse. As the final weight-bearing on the stance foot takes place the COM is passing forward along the medial border of that foot. Hyperactivity of that foot's plantarflexors takes the COP forward and when the final foot begins to bear weight the COP moves rapidly across and suddenly stops at a position ahead of the future position of the COM. Then the plantarflexors of both feet release and allow the COP to move posteriorly and approach the COM and meet it as quiet stance is achieved. The inverted pendulum model permitted us to understand the separate roles of the two mechanisms during these critical unbalancing and rebalancing periods.During walking the inverted pendulum model explained the dynamics of the balance of HAT in both the AP and ML directions. Here the model includes the couple due to the acceleration of the weight-bearing hip as well as gravitational perturbations. The exclusive control of AP balance and posture are the hip extensors and flexors, while in the ML direction the dominant control is with the hip abductors with very minor adductor involvement. At the ankle the inverted pendulum model sees the COM passing forward along the medial border to the weight-bearing foot. The model predicts that during single support the body is falling forward and being accelerated medially towards the future position of the swing foot. The model predicts an insignificant role of the ankle invertors/evertors in the ML control. Rather, the future position of the swing foot is the critical variable or more specifically the lateral displacement from the COM at the start of single support. The position is actually under the control of the hip abd/adductors during the previous early swing phase.The critical importance of the hip abductors/adductors in balance during all phases of standing and walking is now evident. This separate mechanism is important from a neural control perspective and clinically it focuses major attention on therapy and potential problems with some surgical procedures. On the other hand the minuscule role of the ankle invertors/evertors is important to note. Except for the tandem standing position these muscles have negligible involvement in balance control.
Conference Paper
The skill of balance is essential for activities of daily living. Through the use of a triaxial accelerometer and a portable data logger the skill of balance can be assessed during: quiet standing, walking, ascending steps, descending steps, sitting-down in a chair, and standing-up from a chair. Results are reported as performance parameters. Comparing the results obtained by the same control subject before and after a time comparable to that of a therapeutic intervention, paired Student t tests show consistency over time but significant changes under different test conditions in the same session
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The study investigates the validity of the Physical Activity Scale for the Elderly (PASE) in 21 Dutch elderly men and women. The PASE is an easily scored, brief questionnaire for elderly, suitable for large epidemiologic studies. The PASE score was compared with physical activity measured with the doubly labeled water method. The correlation coefficient of the PASE score with the residuals from the regression analysis using total energy expenditure as dependent and resting metabolic rate as independent variate was 0.58 (95% CI = 0.50–0.81). Women had greater engagement in extremely high scoring activities as housework and taking care of others, resulting in higher PASE scores than men (97.9 and 71.9). The higher scores in women were not linked to higher activity levels, which suggests that the mentioned activities may be overvalued. Sex specific correlation coefficients were 0.79 (CI = 0.32–0.95) and 0.68 (CI = 0.15–0.90) for men and women, respectively. In conclusion, the PASE proved to be a reasonable valid method to classify healthy elderly men and women into categories of physical activity. Some possible refinements were suggested, which may improve the accuracy of the PASE questionnaire.
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Ankle sprains are one of the most common lower extremity injuries. Real time human motion tracking is an accurate, inexpensive and portable system to obtain kinematic and kinetic measurements. The purpose of this study was to discriminate between subjects with chronic ankle instability and subjects with stable ankles through inertial tracking technology and force plates. Twelve subjects (mean (SD) 23.16 (5.32) years, 174.83 (8.78) cm, 73.58 (17.10) kg) with stable ankles and 13 (mean (SD) 24.69 (5.91) years, 173.31 (9.07) cm, 69.61 (15.32) kg) with chronic ankle instability performed the Star Excursion Balance Test. Time-frequency information based on wavelet decomposition was used for analysing all signals. Dynamic balance impairment associated with chronic ankle instability was observed in the peak amplitude in the wavelet approximation as well as the absolute sum of the coefficients of the wavelet details of the acceleration, orientation and force signals. These results were found despite Star Excursion Balance Test performance during anterior, posteromedial and posterolateral excursions lead to similar specific reach distances in both limbs in either the chronic ankle instability or stable ankle groups. These parameters could be of great interest in detecting dynamic balance impairment in individuals at risk of sprains that might otherwise go undetected by only reach distance assessment.
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Two hundred and forty-three elderly people aged 60 to 96 years were questioned about their falls, and their sway was measured. For comparison sway was also measured in 63 younger subjects. Sway increased with age and was higher in women at all ages. There was no difference in sway between those with no history of falls and those who fell only because of tripping. In both sexes sway was significantly increases in people who fell because of loss of balance and in women whose falls were due to giddiness, drop attacks, turning the head, and rising from bed or a chair. This suggests that there is a physiological decline in postural control with advancing age and also a decline due to disease of the central nervous system.
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Two different balance testing methods were compared: (1) measurement of spontaneous postural sway during quiet standing, and (2) measurement of induced postural sway in response to an applied postural perturbation. Eyes-open tests were performed in 64 healthy young and elderly adults and in five elderly subjects with a history of falling. In both balance tests, the sway was defined in terms of the displacement of the center of pressure on the feet. Spontaneous sway was quantified using a number of different amplitude- and frequency-based parameters. Induced sway was measured in response to anterior-posterior acceleration of a platform on which the subject stood. The induced-sway test was specially designed to be safe and nonthreatening for elderly subjects; thus, the platform perturbation was confined to small accelerations and a gentle pseudorandom motion was used. To derive a measure of postural stability, the data from this test were fitted with a model that was then used to predict the response to sudden (transient) perturbations, thereby simulating the response in actual falls. Although both induced- and spontaneous-sway measures demonstrated significant aging-related decreases in stability, the differences were more pronounced for the induced-sway data. Conversely, some of the spontaneous-sway measures were much more successful in distinguishing the fallers from the nonfallers. There was a significant correlation between induced-sway and certain spontaneous-sway measures in the normal young adults; however, in the elderly normals and fallers, the data from the two types of balance tests either showed no correlation or, for certain spontaneous-sway measures, tended to show an inverse relationship.
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We investigated factors associated with falls in a community-based prospective study of 761 subjects 70 years and older. The group experienced 507 falls during the year of monitoring. On entry to the study a number of variables had been assessed in each subject. Variables associated with an increased risk of falling differed in men and women. In men, decreased levels of physical activity, stroke, arthritis of the knees, impairment of gait, and increased body sway were associated with an increased risk of falls. In women, the total number of drugs, psychotropic drugs and drugs liable to cause postural hypotension, standing systolic blood pressure of less than 110 mmHg, and evidence of muscle weakness were also associated with an increased risk of falling. Most falls in elderly people are associated with multiple risk factors, many of which are potentially remediable. The possible implications of this in diagnosis and prevention are discussed.
Article
To study risk factors for falling, we conducted a one-year prospective investigation, using a sample of 336 persons at least 75 years of age who were living in the community. All subjects underwent detailed clinical evaluation, including standardized measures of mental status, strength, reflexes, balance, and gait; in addition, we inspected their homes for environmental hazards. Falls and their circumstances were identified during bimonthly telephone calls. During one year of follow-up, 108 subjects (32 percent) fell at least once; 24 percent of those who fell had serious injuries and 6 percent had fractures. Predisposing factors for falls were identified in linear-logistic models. The adjusted odds ratio for sedative use was 28.3; for cognitive impairment, 5.0; for disability of the lower extremities, 3.8; for palmomental reflex, 3.0; for abnormalities of balance and gait, 1.9; and for foot problems, 1.8; the lower bounds of the 95 percent confidence intervals were 1 or more for all variables. The risk of falling increased linearly with the number of risk factors, from 8 percent with none to 78 percent with four or more risk factors (P less than 0.0001). About 10 percent of the falls occurred during acute illness, 5 percent during hazardous activity, and 44 percent in the presence of environmental hazards. We conclude that falls among older persons living in the community are common and that a simple clinical assessment can identify the elderly persons who are at the greatest risk of falling.
Article
Postural sway behavior while standing and during and after an unexpected disturbance of balance was examined in men aged 31 to 35, 51 to 55, and 71 to 75 years. The groups studied were random samples of men living in the town of Jyväskylä in 1981. Postural sway while standing was more pronounced in the older age groups, whereas after a disturbance of balance postural sway was nearly the same in all age groups. The functioning of the postural control system was correlated with the vibratory threshold on the ankles, grip strength, as well as with aerobic and anaerobic capacity within the age groups. Further, in the youngest age group the functioning of the postural control system was poorer among those who had been subject to noise at their work. The correlation between health status and postural sway was negligible. The results may indicate the partly parallel and similar effects of aging, poor physical fitness, and harmful environmental factors on the functioning of the postural control system.
Article
Postural sway increases with age. The decreased stability associated with postural sway often has been related to the reduced peripheral sensibility in the visual, vestibular, and proprioceptive systems. We examined whether the micropostural adjustments necessary for maintaining balance also require some cognitive processing. Young and older subjects were submitted to an auditory reaction time task while maintaining an upright posture on a force platform. The auditory stimuli were presented randomly when subjects were in a central or in an eccentric less stable postural position in four conditions of vision/surface. If the postural adjustments require some cognitive processing, a more eccentric position of the center of foot pressure (COP) would require more attention than a stable position of the COP because when an eccentric position is identified, a corrective response subsequently needs to be selected, programmed, and executed. The visual and surface conditions were altered to determine if additional attentional resources need to be allocated to the postural task when there is a reduction of the sensory information available. Results showed that as the sensory information decreased, the postural task became increasingly difficult for the elderly and required more of their attentional capacity (as indexed by increases in reaction time).
Article
Aging is associated with a decline in the maximal in vitro specific force in the rat costal diaphragm. The purpose of this study was to determine if this force deficit is associated with a decrease in the concentration of myofibrillar protein in diaphragm fibers of senescent rats. Isometric twitch and tetanic contractile properties were measured on diaphragm strips from young adult (9-month-old: n = 12) and senescent (26-month-old: n = 13) male specific pathogen free-barrier protected Fischer 344 rats. Maximal tetanic force (Po) normalized to the cross-sectional area (CSA) of the in vitro diaphragm strips was 16.4% lower in the senescent diaphragms (21.03 +/- 0.4 N/cm2) compared to the young adult (25.16 +/- 0.5 N/cm2) (p < 0.001). Diaphragm water content was significantly higher in the senescent group (75.9% of total wet mass) compared to the young adult (72.1% of total wet mass, p < 0.05). Subtracting the contribution of water from the CSA of the diaphragm strips significantly reduced (p < 0.05) the senescent specific Po deficit (from -16.4 to -6.4%). Further, correcting Po for the contribution of myofibrillar protein to CSA resulted in no age group differences in specific force. These data indicate that the age-related decline in diaphragm in vitro maximal specific Po can be explained by an age-related increase in the water content of the diaphragm muscle. Future experiments are necessary to determine the mechanism(s) responsible for this observation.
Article
The aim of this investigation was to develop an inexpensive, efficient system for the clinical assessment of static and dynamic balance and postural sway using accelerometry-based measurements. Subjects consisted of 10 young (range 18-32 years) and 10 older (range 69-86 years) individuals screened for polypharmacy and history of cardiovascular, neurological or orthopedic health conditions. A lightweight uniaxial accelerometer and general-purpose microcomputer were used to obtain measurements of postural sway. Customized software was written to acquire the data and provide a real-time display consisting of amplitude and frequency characteristics of the sway profile. Intraclass reliability coefficients greater than R = 0.75 were obtained in both eyes-open and challenging-standing balance tasks. Preliminary results demonstrate that the instrumentation can be used to discriminate among balance tasks and to differentiate healthy older adults from those with a tendency toward frequent falls. Moreover, the technique described yields a simple-to-administer, inexpensive procedure that can be conducted in the home or another natural environment. Accelerometry also allows for balance training and re-learning, using tasks that might ordinarily pose a balance challenge for the older or frail adult.
Article
This investigation sought to determine whether older idiopathic frequent fallers could be distinguished from healthy older adults on the basis of balance and movement coordination tests. A secondary objective was to determine the relationships among clinical balance test scores, balance performance data obtained by accelerometry, and quantitative motor coordination tests. Two group comparison designs. A motor control research laboratory in a university setting. The 16 subjects recruited for this study included eight healthy older subjects and eight age-matched idiopathic fallers. Each participant's balance performance was assessed by accelerometry, as well as by coordination and clinical tests. Accelerometry scores, obtained by 1g accelerometers placed at the hip and on the head, were made with eyes open or closed, either standing on the floor or on a wedge of compliant foam. Clinical balance scores were obtained using variants of Romberg's test and the functional reach test. Motor coordination tests obtained included the heel-to-toe transition and rapid stepping tests. Statistically significant differences were obtained between groups for all accelerometry variables except root mean square. All accelerometry variables were successful in discriminating between head and hip sites. Moreover, the amplitude of sway obtained from accelerometry data identified significant differences among the four test conditions. The Romberg test, using right leg alone with eyes open, showed a significant difference between fallers and healthy older subjects. Walking velocity was significantly faster for normal older subjects than for fallers (1.10 m/sec vs 0.80 m/sec). No significant between-group differences were obtained using the functional reach test. Coordination skills yielded significant between-group differences using the rapid stepping test but no significant differences between groups with the heel-toe transition test. Accelerometry is an inexpensive and clinically useful technique that can distinguish between healthy older people and idiopathic frequent fallers. In conjunction with clinical procedures and commercially available tests to assess motor coordination, these techniques can identify older individuals susceptible to frequent falls.
A group of 32 healthy men (M) divided into three different age groups, i.e. M20 years [mean 21 (SD 1); n = 12], M40 [mean 40 (SD 2); n = 10] and M70 [mean 71 (SD 5); n = 10] volunteered as subjects for examination of maximal and explosive force production of leg extensor muscles in both isometric and dynamic actions (squat jump, SJ and counter movement jump, CMJ, and standing long-jump, SLJ). The balance test was performed on a force platform in both isometric and dynamic actions. Maximal bilateral isometric force value in M70 was lower (P < 0.001) than in M40 and as much as 46% lower (P < 0.001) than that recorded in M20 (P < 0.001). The maximal rate of force development (RFD) on the force-time curve was in M70 lower (P < 0.001) than in M40 and as much as 64% lower than in M20. The heights in SJ and CMJ and the distance in SLJ in M70 were lower (P < 0.001) than in M40 and M20 (P < 0.001). In response to modifications of the visual surroundings the older subjects were 24%-47% (P < 0.05 and P < 0.001) slower in their response time in reaching the lit centre (TT) and remained 20%-34% (P < 0.001) less time inside the centre (TC) from the overall time of lighting than M40 and M20, respectively. In both older groups the individual values of isometric RFD correlated significantly (P < 0.05) with the individual balance values of TT and TC. The present results would suggest that the capacity for explosive force production declines drastically with increasing age, even more than maximal muscle strength. Aging may also lead to impaired balance with a decrease in event detection and speed of postural adjustments. The decreased ability to develop force rapidly in older people seems to be associated with a lower capacity for neuromuscular response in controlling postural sway.