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Postural instability, in particular at gait initiation (GI), and resulting falls are a major determinant of poor quality of life in subjects with Parkinson’s disease (PD). Still, the contribution of the basal ganglia and dopamine on the feedforward postural control associated with this motor task is poorly known. In addition, the influence of anthropometric measures (AM) and initial stance condition on GI has never been consistently assessed. The biomechanical resultants of anticipatory postural adjustments contributing to GI [imbalance (IMB), unloading (UNL), and stepping phase) were studied in 26 unmedicated subjects with idiopathic PD and in 27 healthy subjects. A subset of 13 patients was analyzed under standardized medication conditions and the striatal dopaminergic innervation was studied in 22 patients using FP-CIT and SPECT. People with PD showed a significant reduction in center of pressure (CoP) displacement and velocity during the IMB phase, reduced first step length and velocity, and decreased velocity and acceleration of the center of mass (CoM) at toe off of the stance foot. All these measurements correlated with the dopaminergic innervation of the putamen and substantially improved with levodopa. These results were not influenced by anthropometric parameters or by the initial stance condition. In contrast, most of the measurements of the UNL phase were influenced by the foot placement and did not correlate with putaminal dopaminergic innervation. Our results suggest a significant role of dopamine and the putamen particularly in the elaboration of the IMB phase of anticipatory postural adjustments and in the execution of the first step. The basal ganglia circuitry may contribute to defining the optimal referent body configuration for a proper initiation of gait and possibly gait adaptation to the environment.

Este artigo tem por objetivo discutir a validade teórica e operacional dos conceitos de território e região na proposta da Política Nacional de Ordenamento Territorial (PNOT) e na sistematização da primeira Política Nacional de Desenvolvimento Regional (PNDR I). O fio condutor da análise considera que a excessiva quantidade de metodologias e o uso indiscriminado de ambos os conceitos colocaram em questão a fundamentação teórica e a operacionalização dessas políticas no contexto da tentativa de diminuir as desigualdades regionais e de elaborar políticas públicas com a articulação de múltiplas escalas espaciais. O trabalho conclui que a “cegueira geográfica” do território e da região no planejamento governamental e nas políticas públicas brasileiras é consequência do problema metodológico, que pensa o rebatimento das políticas públicas no território, e não o território como base de sustentação para a elaboração e a articulação das políticas públicas.

The 2013–2014 Revolution in Ukraine has spurred a boom in civic anti-corruption initiatives across Ukraine. There is as yet little consolidated understanding of how effective these initiatives are and what explains variation in effectiveness. Insights from academic and practitioner literature suggest that factors associated with success in anti-corruption activism fall under three broad categories: environmental factors, advocacy strategies of civil society organizations, and their organizational characteristics. Drawing on a comprehensive study of anti-corruption activism in the regions of Ukraine, this article asks how these insights relate to anti-corruption activism in the regions of Ukraine. We find that anti-corruption initiatives generally face two key dilemmas: insufficient capacity in terms and financial and human resources, and the absence of a credible base of support. Anti-Corruption organizations that are most effective tend to be those that convincingly solve either one of these two dilemmas. In addition, we find that political will among local authorities is an important conducive factor to the effectiveness of anti-corruption activism. The article also discusses the implications of our findings for practitioners of international assistance.

Recently, in developed countries, especially in Japan, the population of elderly people are increasing. Physical function of elderly people deteriorates due to age, it causes stumble accident. A stumble accident of an elderly people leads to a bone fracture. In elderly people, it is very dangerous to become bedridden by bone fractures and injuries. Thus, it is important for elderly people to prevent stumble accident. The "Base of support" (BoS) has been reported to be related to stumble accident. We have been executing experimental consideration regarding stumble accident and BoS. In this study, we executed measurement and analysis of walking movement for human and analyzed based on the dynamic change for BoS. This experiment, we measured and analyzed walking movement using optical and inertial sensor type motion analysis device. In addition, we measured the step length using the camera. The Subjects walked straight for approximately 10 m indoors. Moreover, they executed heel strike according to the timing when the metronome sounds. Also, we changed the rhythm of the metronome every 10 bpm from 90 bpm to 140 bpm. As for experimental results, the dynamic change of BoS increased as walking rhythm changes faster. This is considered to be increasing movement of gravity center of human body. In this study, we executed measurement and analysis of walking movement for human and analyzed the dynamic change for BoS. However, it is considered necessary to reconsider the contents of the experiment. In the future, we aim to establish an index of the dynamic stability evaluation of human walking movement.

Introduction: Motor changes are observed in people living with HIV/AIDS. These changes may be associated with the chronicity of infection, continued use of antiretroviral medication, and/or the presence of comorbidities. Objective: The objective of the present study was to evaluate postural sway in people living with asymptomatic HIV/AIDS under treatment with highly active antiretroviral therapy. Methods: Twenty-seven subjects, recruited at an HIV referral center, aged between 30 and 40 years, participated in the study, divided into two groups: HIV group (n=12) and non-HIV group (n=15). The participants performed an experimental task, remaining on a force platform in a static position, in bipedal support and semi-tandem positions, in conditions with and without vision. Results: The results demonstrated that visual occlusion, when the bipedal base was adopted, generated significant differences in the area of oscillation and mean velocity in both groups. Differences were also observed in the area and mean velocity of both groups when the semi-tandem position was adopted without vision. When comparing the groups, it was possible to identify significant differences in the semi-tandem base with vision. Conclusion: Considering these results, it was found that postural oscillation was higher in the visual occlusion condition for both groups. Concomitant to this, we conclude that in the challenging condition, where the base of support is reduced, the HIV group presents greater oscillation (medial-lateral) than the non-HIV group.

Background A common technique to regain stability following an unexpected perturbation is reactive stepping, aimed to control the accelerated center of mass (COM). Many older adults (OA) struggle to execute the fast, coordinated stepping strategy required to arrest COM movement within the base of support (BOS) during these unexpected events, likely due to age-related physiological declines. Recent ecological data also suggests that many falls in OA occur due to errors in transferring or shifting body weight during activities of daily living. The present study utilized gait initiation, which requires a coordinated transition from quiet stance to dynamic gait, as an example of one of these difficult transitional movements. Research Question Our goal was to combine this inherently unstable task, gait initiation, with an unexpected mediolateral (ML) perturbation of the support surface to examine age-related changes in reactive stepping patterns during a novel transitional gait task. Methods A total of 18 young adults (YA) and 16 OA (>65 years) performed 35 trials containing 10 unexpected ML perturbations of the support surface. To quantify age-related differences, we calculated step width, length, time and COM velocity in the first two steps following the perturbation. Results We observed that, in general, OA walked slower and took shorter, faster steps (reducing time in single support) compared to YA. Following the perturbation, OA altered their stepping patterns by reducing their BOS (more narrow step width compared to YA), and required more than the two steps used by YA to complete the goal-directed task. Significance These age-related changes are concerning as a multi-step recovery strategy has been previously associated with an elevated risk of falls in OA.

Candidates frequently engage in partisan trespassing strategies where a candidate will highlight issues and traits associated with stereotypes of the opposing political party. Successful trespassing messages should lead voters to associate candidates with qualities that fit into stereotypes about both Democrats and Republicans, increase electoral support for a candidate, and expand a candidate’s base of support. Few studies, however, investigate whether there are differences in the effects of trespassing strategies across candidate sex. Through three survey experiments, I show that trespassing strategies have both positive and negative effects for female candidates. Voters associate female candidates who trespass with more issues and traits associated with the opposing political party, but voters also associate female candidates with fewer partisan qualities. This trade-off is one that both female and male candidates experience. Male candidates, unlike female candidates, can successfully attract more electoral support from out-partisan voters with trespassing strategies. These findings have broad implications for the viability of female candidates in national and state elections where candidates must secure support across a broad coalition of partisan and out-partisan voters.

This study aimed to examine whether the triceps surae (TS) muscle-tendon unit (MTU) mechanical properties affect gait stability and its reactive adaptation potential to repeated perturbation exposure in older adults. Thirty-four older adults each experienced eight separate unexpected perturbations during treadmill walking, while a motion capture system was used to determine the margin of stability (MoS) and base of support (BoS). Ankle plantar flexor muscle strength and Achilles tendon (AT) stiffness were analyzed using ultrasonography and dynamometry. A median split and separation boundaries classified the subjects into two groups with GroupStrong ( n = 10) showing higher ankle plantar flexor muscle strength (2.26 ± 0.17 vs. 1.47 ± 0.20 N·m/kg, means ± SD; P < 0.001) and AT stiffness (544 ± 75 vs. 429 ± 86 N/mm; P = 0.004) than GroupWeak ( n = 12). The first perturbation caused a negative ΔMoS (MoS in relation to unperturbed baseline walking) at touchdown of perturbed step (PertR), indicating an unstable position. GroupStrong required four recovery steps to return to ΔMoS zero level, whereas GroupWeak was unable to return to baseline within the analyzed steps. However, after repeated perturbations, both groups increased ΔMoS at touchdown of PertR with a similar magnitude. Significant correlations between ΔBoS and ΔMoS at touchdown of the first recovery step and TS MTU capacities (0.41 < r < 0.57; 0.006 < P < 0.048) were found. We conclude that older adults with TS muscle weakness have a diminished ability to control gait stability during unexpected perturbations, increasing their fall risk, but that degeneration in muscle strength and tendon stiffness may not inhibit the ability of the locomotor system to adapt the reactive motor response to repeated perturbations. NEW & NOTEWORTHY Triceps surae muscle weakness and a more compliant Achilles tendon partly limit older adults’ ability to effectively enlarge the base of support and recover dynamic stability after an unexpected perturbation during walking, increasing their fall risk. However, the degeneration in muscle strength and tendon stiffness may not inhibit the ability of the locomotor system to adapt the reactive motor response to repeated perturbations.

Although often framed as an emerging anthropocenic socio-ecological imaginary, the Latin American paradigm of Buen Vivir has provided a broad base of support for tourism development in the region. ...

Purpose: Cerebral Palsy (CP) can negatively affect dynamic stability in children with spastic diplegic Cerebral Palsy during walking. This condition results in a high risk of falling. There is limited evidence regarding the dynamic stability of children with Cerebral Palsy. Thus, this study aimed to investigate the dynamic stability of children with spastic diplegic Cerebral Palsy, compared to typically developed children during walking. Methods: Sixteen children including 8 with spastic diplegic Cerebral Palsy and 8 normal ones with an age range of 5 to 8 years participated in this quasi-experimental study. A Qualysis motion analysis system capturing at a frequency of 100 Hz was used to record data. Qualysis software and Visual3D software were utilized for data extraction. Data analysis was conducted using the Independent t-test with P

The ability to control the body's center of mass (CoM) is critical for preventing falls, which are a major health concern in aging populations. Control of the CoM has been assessed by characterizing dynamic margins of stability (MoS) which capture the dynamic relationship between the CoM and the base of support. Accurate estimation of CoM dynamics is best accomplished using a full-body marker set. However, a number of simplified estimates have been used throughout literature. Here, we determined the biases and sources of bias when computing MoS using four simplified CoM models, and we characterized how these biases varied in straight walking versus turning. CoM kinematics were characterized using a full-body marker set, the lower extremities and trunk, lower extremities only, an average of four pelvic markers, and one pelvic marker alone. Significant bias was demonstrated for most methods and was larger during turning tasks compared to straight walking. In the fore-aft direction, only overestimates in the MoS were observed, and these ranged from 15 to 110% larger than the true MoS value. In the mediolateral direction, both under- and over-estimates were observed and ranged from -175 to 225%. Across tasks, bias was smallest when using the lower extremity plus trunk (-23 to 62%) and pelvis average methods (-71 to 43%). Sources of bias were attributed to misestimates of CoM height, velocity, and position. Together, our findings suggest that the 1) lower extremity and trunk model and 2) pelvis average model should be considered in future studies to minimize bias when simplified models of CoM dynamics are desired.

The authoritarian regimes that expanded throughout Latin America in the 1960s were designed by their inspirations not only to solve the dilemmas that came from political conflict but also from the economic bottlenecks that hindered national and regional development. This article investigates how planning was specifically implemented by the regime of the “Argentine Revolution,” since its inception in 1966, as part of its model of authoritarian modernization. The Cordobazo showed that the authoritarian project had weaker bases than those assumed by its leaders. This determined that the planning bias was accentuated. The development plans were then conceived as a public action mechanism with a strong techno-bureaucratic content with the expectation that a national capitalism could be established. But they were also planned as a mechanism for expanding the social base of support, vis a vis the transition that was approaching.

Falls happen when the center of mass of body is outside of its base of support and the recovery of the center of mass back to the base of support failed. Balance ability is an essential ability needed for humans’ daily routine activities. Improving balance ability should result in a better and more convenient way of living. There are various factors influence on balance ability. The focus of this paper is to investigate which factors have the greatest effect on balance. Balance ability is measured by deviations of center of pressure in both $x$ -direction (side-to-side) and $y$ -direction (front-to-back) with the age, height, body mass index, and location of body center of mass. Coordinates of subject’s joints were tracked and recorded by a motion capture system with three cameras and then were used to calculate the coordinates of segment’s mass center. The coordinates of whole body mass center were determined using the weighted segmental method. The trajectories of the center of pressure were tracked and recorded by a Wii balance board under five standing postures and slow sway movement along $x$ -direction (side-to-side) situations. The information obtained from the center of mass and the center of pressure data analysis may assist with fall prediction and prevention. With a basic training on system operation, laypersons may use this affordable low cost system at home as an exercise tool to improve balance capability and reduce fall risk factors.

A teknofibra material walker which protects heat sensitive parts mounted in close proximity to high temperatures with balanced detector provides a smart solution for the elderly who are unable to walk without an assistive device. The walker provides a balance detection system which continuously calculates the dynamic state of walking of the elderly person with respect to the walker system and assist the elderly by generating an alarm if the system tends to become unstable. The sensor mounted at different places in the walker system continuously monitors the position of the elderly person through proximity and alert the user when he tries to cross the base of support area of the walker so that one can come back or slow down the walking speed and protect himself from falling. The walker with a compact design with three wheel foldable systems and sitting capability extended support for sitting is provided in the base of walker structure so as to male system stable. The three wheeled, foldable, made of light weighted and heat resisting material with sitting arrangements makes the overall structure very useful for elderly.

Gait and balance disorders are major problems that contribute to falls among subjects with Parkinson’s disease (PD). Strengthening the compensatory responses through the use of balance perturbations may improve balance in PD. To date, it is unclear how PD affects the ability to react and adapt to perturbations delivered while walking. This study aims to investigate how PD affects the ability to walk, respond to balance perturbations, and produce acute short-term effects to improve compensatory reactions and gait stability. A cable-driven robot was used to train nine patients with PD and nine age-matched controls with multidirectional waist-pull perturbations while walking on a treadmill. Margin of stability and base of support were evaluated while walking without cables and reacting to the perturbations. PD was associated with a reduced stability in the forward direction and the inability to produce proactive anticipatory adjustments. Both groups were able to improve the response to the disturbances and produce short-term aftereffects of increased gait stability once the cables were removed. A single session of perturbation-based balance training produced acute effects that ameliorated gait instability in PD. This result is encouraging for designing new therapeutic interventions that remediate falls risk.

Balance is key to independent mobility, and poor balance leads to a risk of falling and subsequent injury that can cause self-restriction of activity for older adults. Balance and mobility can be improved through training programs, but many programs are not intensive or engaging enough to sufficiently improve balance while maintaining adherence. As an alternative to traditional balance training, harnessed gardening sessions were conducted in an urban greenhouse as an example of a community activity through which balance and mobility can be trained and/or maintained. An inexpensive multidirectional harness system was developed that can be used as an assistive or rehabilitative device in community, private, and senior center gardens to allow balance or mobility-impaired adults to participate in programming. Two wearable sensor systems were used to measure responses to the system: the Polhemus G4 system measured gardeners’ positions and center of mass relative to the base of support, and ActiGraph activity monitors measured the frequency and intensity of arm movements in garden as compared to home environments. The harnessed gardening system provides a safe environment for intense movement activity and can be used as a rehabilitation device along with wearable sensor systems to monitor ongoing changes.

Aim of the study Independent sitting requires the control of the involved body segments over the base of support using information obtained from the three sensory systems (visual, vestibular, and somatosensory). The contribution of somatosensory information in infant sitting has not been explored. To address this gap, we altered the context of the sitting support surface and examined the infants' immediate postural responses. Materials and methods Ten 7-month-old typically developing infants sat on compliant and firm surfaces in one session. Spatial, frequency, and temporal measures of postural control were obtained using center of pressure data. Results Our results suggest that infants' postural sway is not immediately affected by the different types of foam surface while sitting. Conclusions It seems that mature sitter infants are able to adapt to different environmental constraints by disregarding the distorted somatosensory information from the support surface and relying more on their remaining senses (visual and vestibular) to control their sitting posture.

To determine and compare gait speed during head-forward and side-to-side head-turn walking in individuals with lower versus greater lateral balance.Cross-sectional study.University research laboratory.Older adults (N=93; 42 men, 51 women; mean age ± SD, 73 ± 6.08y) who could walk independently.(1) Balance tolerance limit (BTL), defined as the lowest perturbation intensity where a multistep balance recovery pattern was first evoked in response to randomized lateral waist-pull perturbations of standing balance to the left and right sides, at 6 different intensities (range from level 2: 4.5-cm displacement at 180cm/sIndividuals with low versus high BTL had a slower self-selected head-forward gait speed and head-turn gait speed (P=.002 and P.001, respectively); the magnitude of difference was greater in head-turn gait speed than head-forward gait speed (Cohen's d=1.0 vs 0.6). Head-turn gait speed best predicted BTL. BTL was moderately and positively related (P=.003) to the ABC Scale and negatively related (P=.017) to TUG.Head-turn gait speed is affected to a greater extent than head-forward gait speed in older individuals with poorer lateral balance and at greater risk of falls. Moreover, head-turn gait speed can be used to assess the interactions of limitations in lateral balance function and gait speed in relation to fall risk in older adults.

Introdução: O ballet clássico é uma das atividades físicas mais procuradas com o objetivo de obter boa postura. Entretanto, a exigência da organização das contrações musculares e adaptações articulares durante os movimentos do ballet, podem gerar alterações biomecânicas relacionadas à postura desse indivíduo. Objetivo: Realizar uma revisão de literatura do tipo integrativa sobre os principais fatores biomecânicos relacionados à postura em praticantes do ballet clássico. Materiais e métodos: Foi realizada, no período entre janeiro a agosto de 2016, uma busca nas bases de dados eletrônicas Pubmed, Scientific Eletronic Library Online (SciELO), Biblioteca Virtual em Saúde (BVS), Physiotherapy Evidence Database (PEDro), Periódicos Capes e Google Scholar. Resultados: Foram encontrados um total de 673 artigos científicos, sendo selecionados 27 publicações após avaliação dos critérios de inclusão e exclusão. Os artigos pesquisados encontraram associação da postura de bailarinos com o centro de oscilação do corpo, cinestesia, controle do equilíbrio postural; sendo que as mudanças biomecânicas foram justificadas pelo longo período da prática dessa modalidade. Conclusão: Os bailarinos apresentaram menor oscilação do corpo em menor base de apoio, boa correspondência cinestésica para membros superiores, controle do equilíbrio postural por melhor resposta neuromuscular especialmente de olhos abertos e alterações posturais na coluna vertebral e membros inferiores.

Posturography is used to assess balance in clinical settings, but its relationship to gait stability is unclear. We assessed if dynamic gait stability is associated with standing balance in 12 patients with unilateral vestibulopathy. Participants were unexpectedly tripped during treadmill walking and the change in the margin of stability (MoSchange) and base of support (BoSchange) relative to nonperturbed walking was calculated for the perturbed and first recovery steps. The center of pressure (COP) path during 30-s stance with eyes open and closed, and the distance between the most anterior point of the COP and the anterior BoS boundary during forward leaning (ADist), were assessed using a force plate. Pearson correlations were conducted between the static and dynamic variables. The perturbation caused a large decrease in the BoS, leading to a decrease in MoS. One of 12 correlations was significant (MoSchange at the perturbed step and ADist; r = −.595, P = .041; nonsignificant correlations: .068 ≤ P ≤ .995). The results suggest that different control mechanisms may be involved in stance and gait stability, as a consistent relationship was not found. Therefore, posturography may be of limited use in predicting stability in dynamic situations.

How does challenging authority look? This article describes two steps taken to prepare for and engage in challenges to existing laws. The first step is use of the nursing process to help structure deliberations about when to pursue, justify, and target a challenge to existing law to create desired outcomes. The second step is the important process of building the case for change and the broad base of support needed to push against resistance to change. The article details two examples of specific legislative successes the author accomplished using these two steps.

Context:The push-up-plus (PP) exercise has been recommended for strengthening of the serratus anterior (SA). Previous studies have investigated the effect of different stability properties of the base of support to adjust the difficulty level of SA muscle-strengthening exercises in the PP position. However, the optimal humeral-elevation angle (HEA) for selective activation and maximum contraction of the SA during PP has not been investigated.Objectives:To assess the effects of HEA during PP on electromyographic (EMG) activity in the SA, upper trapezius (UT), and pectoralis major (PM) and on the UT:SA and PM:SA activity ratios.Design:Comparative, repeated-measures design.Setting:University research laboratory.Participants:29 healthy men.Main Outcome Measures:The subjects performed PP at 3 different HEAs (60°, 90°, and 120°); EMG activity in the SA, UT, and PM was measured, and the UT:SA and PM:SA activity ratios were calculated. Differences in muscle activity and ratios between the 60°, 90°, and 120° HEAs were assessed using 1-way repeated-measures analysis of variance; the Bonferroni correction was applied.Results:SA muscle activity was significantly increased, in order of magnitude, at the 120°, 90°, and 60° HEAs. UT:SA and PM:SA activity ratios were significantly greater during performance of the PP at an HEA of 60° than at HEAs of 120° and 90°.Conclusion:The results suggest that an HEA of 120° should be used during performance of the PP because it produces greater SA activation than HEAs of 60° and 90°.

Low back pain (LBP) can affect performance in the combined task (CT) of gait and prehension, since it increases muscle activity amplitude during voluntary movements, impairs the anticipatory postural adjustments and reduces gait speed. We analyzed and compared the effect of adding the prehension movement toward a dowel located at three different heights (80, 100 and 120% of the lower limb length) on gait of individuals with and without LBP. The CT caused anticipatory adjustments, showing that gait changes started during the approach phase and continued on the step corresponding to grasping, especially for the lowest dowel height. Furthermore, individuals with LBP reduced walking speed, increased the width of the base of support, increased electromyography activity of low back trunk muscles, and increased the margin of dynamic stability compared with control group. These results suggest that individuals with LBP used a strategy to reduce threat to body stability due to addition of the manual task.

This study aimed to estimate the error made by investigators when force-plate data are used to approximate base of support size during gait initiation. Step length and step width obtained with a method based on motion capture system (Kinematics method, considered the "gold standard") and with a method based on the centre of pressure traces obtained from a force-plate (Force-plate method) were purposely compared using descriptive statistics and the Bland and Altman (BA) method. Participants (N=19) performed series of gait initiation in Spontaneous and Maximal Velocity Conditions (SVC and MVC, respectively). BA analysis showed that 1) step length and width biases, corresponding to the difference between the two methods, were very small (2.1%) in both velocity conditions and 2) the 95% limits of agreement of the BA plots ranged between 10% and 15% in absolute value. Repeated measures ANOVA showed that step length was significantly larger in MVC than in SVC, with no velocity X method interaction. There was no significant effect of the method on both step parameters. The present results suggest that the Force-plate method is sufficiently accurate to compare step parameters across conditions. However, researchers should be aware that non-negligible errors might occur when considering individual data.

Falls are the leading cause of fatal and non-fatal injuries among the elderly in the United States and throughout the world. Many studies have been done over the last few decades in an attempt to better understand how to prevent falls among the elderly population. Unfortunately, most of these studies are conducted by simulating falls in a laboratory with healthy adults which has been shown to be quite different from a real world fall. This pilot study defines corrective behaviors implemented by the elderly to maintain balance and looks specifically at measures of stability when the hand touch corrective behavior is used. These measures include base of support area, proximity of center of mass to base of support perimeter, time for center of mass to contact base of support perimeter, and jerk of the center of mass of the torso. Initial findings indicate that the hand touch corrective behavior is used to both maintain and regain stability. It is anticipated that, with the evaluation of the remaining trials, a model of fall-initiation of the frail elderly will be developed to provide key biomechanical stability measures for use as a proxy for a fall in laboratory studies, as well as to provide new insights in fall interventions.

A description of the theory and the mathematical base of support vector machines with a survey on its applications is first presented in this chapter. Then, a method for obtaining nonlinear kernel of support vector machines is proposed. The proposed method uses the gray wolf optimizer for solving the corresponding nonlinear optimization problem. A sensitivity analysis is also performed on the parameter of the model to tune the resulting classifier. The method has been applied to a set of experimental data for diabetes mellitus diagnosis. Results show that the method leads to a classifier which distinguished healthy and patient cases with 87.5% of accuracy.

To determine the impact of body weight on quiet standing postural sway characteristics in young women, this research compared spontaneous oscillations of the center of foot pressure (COP) between 32 obese (BMI: 36.4 ± 5.2 kg/m2), and 26 normal-weight (BMI: 21.4 ± 1.5 kg/m2) women and assessed the influence of obesity treatment and body weight reduction on postural sway. Trajectories of the COP were assessed while the subjects were standing quietly with eyes open (EO) and closed (EC). Both in the sagittal (AP) and frontal (ML) planes the sway range, average velocity, and maximal velocity of COP were calculated. Moreover, the total average and maximal velocities were computed. In the obese group, the tests were performed twice-before and after the obesity treatment. A greater (18% in EC) AP sway range and a substantial reduction of ML sway (25% in EO, 22% in EC) were observed in the obese women. The total COP velocities (average and maximal) were decreased in obese women (20% and 20% in EO) as well as the velocities in the frontal plane (EO: 33%, 41%; EC: 34%, 40%). Body weight reduction resulted in significant changes in postural sway. The following parameters increased: ML sway range (28% in EO), average (20% in EO, 16% in EC) and maximal ML (20% in EO) velocities. The results indicate that young obese women in the habitual standing position are characterized by the destabilizing influence of mass in the sagittal plane only in the absence of a visual control. This effect is dominated by the stabilizing mass effect in the frontal plane, which affects overall postural stability when standing. The reduction of body mass enables a decrease in ML static stability, likely due to natural changes in the base of support while standing.

Made available in DSpace on 2019-10-06T17:09:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-13 Differences in the postural stabilization of older and young adults have been shown to be task-dependent on both visual and postural challenges; however, the gaze behavior during such tasks has rarely been examined. This study investigated the effects of horizontal and vertical saccades on gaze control, center of pressure (CoP) and head displacement of young and older adults on different bases of support. Ten young adults (20.7 ± 3.4 years) and ten older adults (71.6 ± 3.1 years) remained in an upright stance on a force platform wearing an eye-head tracker device. The participants performed 30-second trials according to two bases of support (feet apart and semi-tandem) and three gaze behavior (fixation, horizontal and vertical saccades) conditions. Older adults presented greater CoP amplitude (p < 0.002) and velocity (p < 0.001) (ML axis), and higher head amplitude (ML) (p < 0.002) than young adults during the semi tandem base. Head displacement of both groups presented higher velocity (ML axis) during horizontal (p < 0.001) and vertical saccades (p < 0.01) than the fixation task only on the semi tandem base. There was higher number of fixations (p < 0.001) and lower mean fixation duration (p < 0.001) on the semi-tandem base (p < 0.05). The results showed higher gaze latency variability in vertical saccades for older adults (p < 0.01). Challenging postural tasks may alter postural adjustments and gaze control during saccadic tasks. Particularly, the greater postural instability of older adults increased the gaze latency variability during saccadic tasks, suggesting some deterioration in the posture-gaze relation with aging. UNESP - Sao Paulo State University Department of Physical Education Faculty of Sciences Health Informatics Postgraduate Program Paulista School of Medicine Federal University of São Paulo Post-graduation Program in Movement Sciences São Paulo State University – UNESP UNESP - Sao Paulo State University Department of Physical Education Faculty of Sciences Post-graduation Program in Movement Sciences São Paulo State University – UNESP

This study aimed to determine the validity of the centre of mass position (COM) position and extrapolated COM (XCOM), relative to the base of support, for predicting stability during a walking task where the base of support is constrained. Nine young healthy participants walked on a narrow beam. Three-dimensional motion capture was used to calculate the COM and XCOM relative to the base of support. Steps were classified as having either the COM or XCOM inside or outside the base of support, and were classified as successful (stable – foot placed on the beam) or failed (unstable – foot stepped off the beam). If the COM or XCOM are valid measures of stability, they should be within the base of support for successful steps and outside the base of support for failed steps. Classifying the COM and XCOM inside or outside the base of support correctly predicted successful or failed steps in 69% and 58% of cases, respectively. When the COM or XCOM were outside the base of support, walking faster seemed to help participants to maintain stability. The further the COM or XCOM were outside the base of support during a successful step, the more likely participants were to fail on a subsequent step. The results of this study suggest that both COM and XCOM are valid measures of stability during a beam walking task, but that classifying COM and XCOM as inside or outside the base of support may be over-simplistic.

The biomechanical mechanisms of loss of balance have been studied before for slip condition but have not been investigated for arbitrary perturbation profiles under non-slip conditions in sagittal plane. This study aimed to determine the thresholds of center of mass (COM) velocity and position relative to the base of support (BOS) that predict forward and backward loss of balance during walking with a range of BOS perturbations. Perturbations were modeled as sinusoidal BOS motions in the vertical or anterior-posterior direction or as sagittal rotation. The human body was modeled using a seven-link model. Forward dynamics alongside with dynamic optimization were used to find the thresholds of initial COM velocity for each initial COM position that would predict forward or backward loss of balance. The effects of perturbation frequency and amplitude on these thresholds were modeled based on the simulation data. Experimental data were collected from 15 able-bodied individuals and three individuals with disability during perturbed walking. The simulation results showed similarity with the stability region reported for slip and non-slip conditions. The feasible stability region shrank when the perturbation frequency and amplitude increased, especially for larger initial COM velocities. 89.5% (70.9%) and 82.4% (68.2%) of the measured COM position and velocity combinations during low (high) perturbations were located inside the simulated limits of the stability region, for able-bodied and disabled individuals, respectively. The simulation results demonstrated the effects of different perturbation levels on the stability region. The obtained stability region can be used for developing rehabilitative programs in interactive environments.

Due to increased sedentary workstyles, active workstations have shown the ability to increase activity while only moderately affecting work ability. However, previous examinations have not examine fine motor mousing tasks on tripping descriptors.What affect do mousing tasks of varying target size have on tripping descriptors during walking workstation use?Three-dimensional kinematic data were collected while participants used a walking workstation completing one baseline and three mousing conditions of varying target sizes.Target size main effects (p 0.001) detected decreased stride length in all experimental conditions, which were supported by moderate effect sizes, and decreased stance width and time in double limb support (p 0.001 for both comparisons). Stance width differences resulted in large effect sizes between baseline and all conditions, while only moderate effect sizes were observed between time in double limb support in baseline compared to all conditions. No changes in knee flexion range of motion were observed in response to target size (p = 0.278).These results indicate that walking workstation users shorten their stride length and decrease their base of support while completing mousing tasks. The placement of the upper extremities on the workstation desk likely acted as the primary mechanism to increase stability. It is concluded that performing mousing tasks of varying target size using a walking workstation does not pose greater risk for adverse gait events.