Synergic control of the minimum toe clearance in young and older adults during foot swing on treadmill walking in different speeds.

BACKGROUND: The vertical toe position at minimum toe clearance (MTC) in the swing phase is critical for walking safety. Consequently, the joints involved should be strictly controlled and coordinated to stabilize the foot at MTC. The uncontrolled manifold (UCM) hypothesis framework has been used to determine the existence of synergies that stabilize relevant performance variables during walking. However, no study investigated the presence of a multi-joint synergy stabilizing the foot position at MTC and the effects of age and walking speed on this synergy. RESEARCH QUESTIONS: Is there a multi-joint synergy stabilizing MTC during treadmill walking? Does it depend on the persons' age and walking speed? METHODS: Kinematic data from 23 young and 15 older adults were analyzed using the UCM approach. The participants walked on a treadmill at three speeds: slow, self-selected, and fast. The sagittal and frontal joint angles from the swing and stance legs and pelvis obliquity were used as motor elements and the vertical toe position at MTC was the performance variable. The variances in the joint space that affected (VORT, 'bad' variance) and did not affect (VUCM, 'good' variance) the toe position at MTC and the synergy index (ΔV) were computed. RESULTS: The ΔV>0 was revealed for all subjects. Walking speed did not affect ΔV in older adults, whereas ΔV reduced with speed in young adults. ΔV was higher for older than for young adults at self-selected and fast speeds, owing to a lower VORT in the older group. SIGNIFICANCE: The vertical toe position at MTC was stabilized by a strong multi-joint synergy. In older adults, this synergy was stronger, as they were better at limiting VORT than young adults. Reduced VORT in older adults could be caused by more constrained walking, which may be associated with anxiety due to walking on a treadmill.

Exploring the ability of strength and dexterity tests to detect hand function impairment in individuals with Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) can affect hand function since the beginning of the motor symptoms. OBJECTIVE: To compare the ability of different hand function tests to: 1) distinguish individuals with PD from healthy controls; 2) differentiate stages of the disease; and 3) indicate changes over time due to disease progression. METHODS: Twenty-four individuals with PD (Hoehn and Yahr: I-III) and 24 age- and sex-matched controls performed the Jebsen-Taylor Hand Function Test (JTHFT), the Nine-Hole Peg Test (9HPT), and the maximum grip and the maximum pinch strength tests using their right and left hands. Eight individuals with PD (six females and two males) were reassessed after 18 months. The ROC analyses and Mann-Whitney U tests (for disease progression) using the average performance of the hands were done. RESULTS: Individuals with PD presented worse test performances than controls, except for the writing subtest of the JTHFT and the grip strength test. The JTHFT without the writing subtest (JTHFTnoW) was the most accurate to discriminate PD from controls (AUC = 0.899; sensitivity 75% and specificity 95.8%). The 9HPT and the simulated feeding and moving large, light objects JTHFT subtests were sensitive to distinguish stages, while the 9HPT, the moving small, common objects JTHFT subtest, and the grip strength were sensitive to changes with disease progression. CONCLUSION: The JTHFTnoW was highly discriminative of the hand function impairments in PD. TwoJTHFT subtests were the most sensitives to distinguish PD stages (i.e. simulated feeding JTHFT subtest) and disease progression (i.e. moving small, common objects JTHFT subtest).

Synergic control in asymptomatic welders during multi-finger force exertion and load releasing while standing.

Motor synergies, i.e., neural mechanisms that organize multiple motor elements to ensure stability of actions, are affected by several neurological condition. Asymptomatic welders showed impaired synergy controlling the stability of multi-finger action compared to non-welders and this impairment was associated with microstructural damage in the globus pallidus. We further explored the effect of welding-related metal exposure on multi-finger synergy and extended our investigation to posture-stabilizing synergy during a standing task. Occupational, MRI, and performance-stabilizing synergies during multi-finger accurate force production and load releasing while standing were obtained from 29 welders and 19 age- and sex-matched controls. R2* and R1 relaxation rate values were used to estimate brain iron and manganese content, respectively, and diffusion tensor imaging was used to reflect brain microstructural integrity. Associations of brain MRI (caudate, putamen, globus pallidus, and red nucleus), and motor synergy were explored by group status. The results revealed that welders had higher R2* values in the caudate (p = 0.03), putamen (p = 0.01), and red nucleus (p = 0.08, trend) than controls. No group effect was revealed on multi-finger synergy index during steady-state phase of action (ΔVZss). Compared to controls, welders exhibited lower ΔVZss (-0.106 ± 0.084 vs. 0.160 ± 0.092, p = 0.04) and variance that did not affect the performance variable (VUCM, 0.022 ± 0.003 vs. 0.038 ± 0.007, p = 0.03) in the load releasing, postural task. The postural synergy index, ΔVZss, was associated negatively with higher R2* in the red nucleus in welders (r = -0.44, p = 0.03), but not in controls. These results suggest that the synergy index in the load releasing during a standing task may reflect welding-related neurotoxicity in workers with chronic metals exposure. This finding may have important clinical and occupational health implications.

Developing an Upper Limb Kinematics Database of Activities of Daily Living.

Open-access databases can facilitate data sharing among researchers and provide normative data for objective clinical assessment development, robotic design, and biomechanical modeling. However, most existing databases focus on gait, balance, and hand gestures without providing elbow and shoulder kinematics that are required in activities of daily living. Furthermore, the few existing upper limb datasets include small sample sizes without consistent data collection protocols, which hinder robotic engineers' ability to design robotic devices that accommodate the general population. To address the literature gap, an open-access upper limb kinematic database was proposed. Due to the impact of COVID-19 on human research, only data from 16 participants were collected. Clinical Relevance-This provides baseline kinematics for developing objective clinical assessments and rehabilitation robots.

Planning and Executing Aiming Movements in Middle Childhood.

Harmonious voluntary movements require efficiency in their planning and execution. Throughout middle childhood structural changes in the central nervous and musculoskeletal systems influence these processes and resultant motor behavior. In this study, we evaluated the characteristics of the motor planning and executing of aiming movements directed at targets located in different positions in space in children aged 7, 9, and 11 years. We divided 43 right-handed children, into three age groups and instructed them to perform aiming movements directed at targets using a stylus on a digital tablet. The children performed the movement with their dominant upper limbs from a starting point towards targets positioned ipsilaterally or contralaterally to this dominant limb. We analyzed temporal and spatial variables of motor performance. Younger (7-year-old) children made more errors in the initial movement direction and more frequently corrected their movements during task execution when compared to 9- and 11-year-old children who did not differ from each other. All age groups were similar in movement accuracy and precision. Movements toward contralateral targets were slower and more accurate than movements toward ipsilateral targets for all groups. These results show that performing aiming movements develop with the onset of middle childhood.

Smell tests can discriminate Parkinson's disease patients from healthy individuals: A meta-analysis.

BACKGROUND: Olfactory impairment is common in Parkinson's disease (PD). The authors aimed to identify the clinical tests used to assess olfactory function and examine their ability to distinguish PD with different disease duration from healthy individuals with physiological aging. METHODS: Cross-sectional studies published until May 2020 that assessed the olfaction of individuals with PD using search terms related to PD, olfactory function, and assessment were searched on PubMed, PsycInfo, Cinahl, and Web of Science databases. RESULTS: Twelve smell tests were identified from the reviewed studies (n = 125) that assessed 8776 individuals with PD. Data of 6593 individuals with PD and 8731 healthy individuals were included in the meta-analyses. Individuals with PD presented worse performance than healthy individuals, regardless of the smell test used. The University of Pennsylvania Smell Identification Test (UPSIT) was used by most studies (n = 2310 individuals with PD) and presented smaller heterogeneity. When the studies were subclassified according to the years of PD duration, there were no significant differences. CONCLUSION: All smell tests were able to discriminate the olfactory function of PD from that of healthy individuals, although the UPSIT was widely used. The abnormal olfaction was not related to the disease duration. Systematic review protocol registration (PROSPERO/2020-CRD42020160878).

Immediate Effects of Arm Reaching Training in Standing on Postural Control Differ between Right and Left Stroke Individuals.

BACKGROUND: Arm reaching training in standing for several weeks affects the postural control of individuals recovering from cerebrovascular accident (CVA). Whether these effects differ with the side of the brain lesion are unknown. OBJECTIVES: To examine the immediate effects of a training session of arm reaching movements on the balance and trunk motion of individuals who suffered a right or left CVA. MATERIALS AND METHODS: Thirty-six adults divided into four groups (i.e., right CVA, left CVA, right control, and left control) performed 120 reaches in a standing position toward one of three target heights. Before and after the reaching trials, participants stood as quiet as possible on two force plates and had their postural sway, trunk motion, and body weight distribution assessed. RESULTS: CVA groups showed greater postural sway regardless of the brain lesion's side compared to the control groups. After the session of reaching movements, the left stroke group reduced the postural sway and trunk displacements. Larger ranges of weight-bearing asymmetry were more frequent after the training session, mainly for the right stroke group. CONCLUSIONS: A single session training of reaching movements affects mostly the postural control of left stroke survivors. More training sessions may be needed for individuals after right stroke to show balance improvements. The current findings support the hemispheric specialization for postural control and suggest that the training involving arm movements in standing can benefit the motor rehabilitation of stroke individuals.

Smell tests to distinguish Parkinson's disease from other neurological disorders: a systematic review and meta-analysis.

Introduction: Olfactory impairment has been considered for differential diagnosis in Parkinson's disease (PD) patients. The authors aimed to identify the tests used to assess the olfactory function in PD patients and examine these tests' ability to distinguish them from other neurological disorders.Areas covered: Cross-sectional studies published until May 2020 comparing the olfactory function of PD patients to other neurological disorders were searched on PubMed, PsycInfo, Cinahl, and Web of Science databases using search terms related to PD, olfactory function, and assessment. Five thousand three hundred and four studies were screened, and 35 were included in the systematic review. Six smell tests that evaluated a total of 1,544 PD patients were identified. Data of 1,144 patients included in the meta-analyses revealed worse smell performance than individuals with other neurological disorders, such as progressive supranuclear palsy and essential tremor, but not with idiopathic rapid eye movement sleep behavior disorder.Expert opinion: The University of Pennsylvania Smell Identification Test was the most used test to assess the olfactory function of PD. Smell loss was worse in PD than in some neurological disorders. The smell tests' ability in differentiating PD from other neurological disorders still deserves more attention in future studies. Protocol register (PROSPERO/2018-CRD42018107009).

Synergic control of action in levodopa-naïve Parkinson's disease patients: II. Multi-muscle synergies stabilizing vertical posture.

Postural instability is a major disabling feature in Parkinson's disease (PD). We quantified the organization of leg and trunk muscles into synergies stabilizing the center of pressure (COP) coordinate within the uncontrolled manifold hypothesis in levodopa-naïve patients with PD and age-matched control subjects. The main hypothesis was that changes in the synergic control of posture are present early in the PD process even before levodopa exposure. Eleven levodopa-naïve patients with PD and 11 healthy controls performed whole-body cyclical voluntary sway tasks and a self-initiated load-release task during standing on a force plate. Surface electromyographic activity in 13 muscles on the right side of the body was analyzed to identify muscle groups with parallel scaling of activation levels (M-modes). Data were collected both before ("off-drug") and approximately 60 min after the first dose of 25/100 carbidopa/levodopa ("on-drug"). COP-stabilizing synergies were quantified for the load-release task. Levodopa-naïve patients with PD showed no COP-stabilizing synergy "off-drug", whereas controls showed posture-stabilizing multi-M-mode synergy. "On-drug", patients with PD demonstrated a significant increase in the synergy index. There were no significant drug effects on the M-mode composition, anticipatory postural adjustments, indices of motor equivalence, or indices of COP variability. The results suggest that levodopa-naïve patients with PD already show impaired posture-stabilizing multi-muscle synergies that may be used as promising behavioral biomarkers for emerging postural disorders in PD. Moreover, levodopa modified synergy metrics differently in these levodopa-naïve patients compared to a previous study of patients on chronic antiparkinsonian medications (Falaki et al. in J Electromyogr Kinesiol 33:20-26, 2017a), suggesting different neurocircuitry involvement.

Performance of discrete, reciprocal, and cyclic movements of the ipsilesional upper limb in individuals after stroke.

Aiming movements of the upper limbs can be classified either as discrete, or reciprocal, or cyclic. The control of these movements after a stroke can be affected. The aim of this experimental, cross-sectional study was to characterize the performance of these movements after the right and left hemisphere chronic stroke. Thirty-six individuals aged between 40 and 70 years, right-handed, were allocated into three groups (control, right stroke, and left stroke). Participants were asked to perform aiming movements on a tablet. Individuals after stroke performed the tasks only with their ipsilesional limb, while the control group performed movements with both limbs. The reaction and movement times, peak velocity, and the variability and error of the endpoint were analyzed. Individuals after stroke presented a worse performance in all movement classes as expected, but differently depending on the damaged hemisphere. Participants with right hemisphere damage showed larger endpoint errors, while those with left hemisphere damage had longer reaction and movement times. Both differences were seen consistently in discrete and reciprocal, but not in cyclic movements. Cyclic movements presented shorter latencies, were faster, and showed greater endpoint errors when compared to discrete and reciprocal movements. These results suggest that stroke affects differently the performance of discrete and reciprocal movements according to the hemisphere lesion side, but not in cyclic movements. Different levels of motor control among the three classes of movements by the nervous system may justify these results.

Synergic control of action in levodopa-naïve Parkinson's disease patients: I. Multi-finger interaction and coordination.

We explored the origin of the impaired control of action stability in Parkinson's disease (PD) by testing levodopa-naïve PD patients to disambiguate effects of PD from possible effects of long-term exposure to levodopa. Thirteen levodopa-naïve PD patients and 13 controls performed single- and multi-finger force production tasks, including producing a self-paced quick force pulse into a target. A subgroup of patients (n = 10) was re-tested about 1 h after the first dose of levodopa. Compared to controls, PD patients showed lower maximal forces and synergy indices stabilizing total force (reflecting the higher inter-trial variance component affecting total force). In addition, PD patients showed a trend toward shorter anticipatory synergy adjustments (a drop in the synergy index in preparation to a quick action) and larger non-motor equivalent finger force deviations. Lower maximal force, higher unintentional force production (enslaving) and higher inter-trial variance indices occurred in PD patients after one dosage of levodopa. We conclude that impairment in synergies is present in levodopa-naïve patients, mainly in indices reflecting stability (synergy index), but not agility (anticipatory synergy adjustments). A single dose of levodopa, however, did not improve synergy indices, as it did in PD patients on chronic anti-PD medication, suggesting a different mechanism of action. The results suggest that indices of force-stabilizing synergies may be used as an early behavioral sign of PD, although it may not be sensitive to acute drug effects in drug-naïve patients.

Preparation to a quick whole-body action: control with referent body orientation and multi-muscle synergies.

We examined the control of postural stability in preparation to a discrete, quick whole-body sway toward a target and back to the initial position. Several predictions were tested based on the theory of control with referent body orientation and the notion of multi-muscle synergies stabilizing center of pressure (COP) coordinate. Healthy, young adults performed fast, discrete whole-body motion forward-and-back and backward-and-back under visual feedback on the COP. We used two methods to assess COP stability, analysis of inter-trial variance and analysis of motor equivalence in the muscle activation space. Actions were always preceded by COP counter-movements. Backward COP shifts were faster, and the indices of multi-muscle synergies stabilizing COP were higher prior to those actions. Patterns of muscle activation at the motion onset supported the idea of a gradual shift in the referent body orientation. Prior to the backward movements, there was a trend toward higher muscle co-activation, compared to reciprocal activation. We found strong correlations between the sets of indices of motor equivalence and those of inter-trial variance. Overall, the results support the theory of control with referent coordinates and the idea of multi-muscle synergies stabilizing posture by confirming a number of non-trivial predictions based on these concepts. The findings favor using indices of motor equivalence in clinical studies to minimize the number of trials performed by each subject.

Hand Grip and Load Force Coordination of the Ipsilesional Hand of Chronic Stroke Individuals.

Object manipulation depends on a refined control of grip force (GF) and load force (LF). After a brain injury, the GF control is altered in the paretic hand but what happens with the non-paretic hand is still unclear. In this study, we compared the GF control and GF-LF coordination of the non-paretic hand of 10 stroke individuals who suffered right brain damage (RBD) and 10 who suffered left brain damage (LBD), with 20 healthy individuals during lifting and oscillation task, using an instrumented object. GF was recorded with a force transducer, and LF was estimated from the object weight and acceleration. Overall, the ipsilesional hand of stroke individuals, independent of the lesion side, presented similar GF control and GF-LF coordination. However, LBD individuals took longer to start lifting the object, which may be due to the need of more time to obtain somatosensory information from the contact with the object. The findings indicate that stroke individuals preserve their ability to control and coordinate GF and LF when using their ipsilesional hand for object manipulation and the left hemisphere may play an essential role in the processing of somatosensory information needed for the GF control.

Quantitative analysis of multi-element synergy stabilizing performance: comparison of three methods with respect to their use in clinical studies.

A number of analyses associated with the uncontrolled manifold (UCM) hypothesis have been used recently to investigate stability of actions across populations. We explored whether some of those methods have an advantage for clinical studies because they require fewer trials to achieve consistent findings. We compared the number of trials needed for the analysis of inter-trial variance, analysis of motor equivalence, and analysis in the space of referent coordinates. Young healthy adults performed four-finger accurate force production tasks under visual feedback with the right (dominant) and left hand over three days. Three methods [analytical (M1), experimental (M2), and cumulative mean (M3) methods] were used to define the minimal number of trials required to reach certain statistical criteria. Two of these methods, M1 and M2, showed qualitatively similar results. Fewer trials (M1: 5-13, M2: 4-10) were needed for analysis of motor equivalence compared to inter-trial variance analysis (M1: 14-24, M2: 10-14). The third method (M3) showed no major differences among the outcome variables. The index of synergy in the inter-trial variance analysis required a very small number of trials (M1, M2: 2-4). Variables related to referent coordinates required only a few trials (under 3), whereas the synergy index in this analysis required the largest number of trials (M1: 24-34, M2: 12-16). This is the first study to quantify the number of trials needed for UCM-based methods of assessing motor coordination broadly used in clinical studies. Clinical studies can take advantage of specific recommendations based on the current data regarding the number of trials needed for each analysis thus allowing minimizing the test session duration without compromising data reliability.

Individual preferences in motor coordination seen across the two hands: relations to movement stability and optimality.

The framework of the uncontrolled manifold (UCM) hypothesis was used to explore variables related to stability of task performance in the two hands of young healthy individuals. Fourteen young adults performed four-finger accurate constant force production tasks interrupted by a voluntary quick force pulse production and by an externally imposed displacement of all fingers. Three groups of variables were used to quantify stability of steady force production: (1) indices of the inter-trial variance were computed within the UCM and orthogonal to the UCM; (2) indices of motor equivalence were computed between steady-state intervals separated by the force pulse and by the finger-lifting episode; and (3) referent coordinate and apparent stiffness were computed using the data during the ascending phase of the finger-lifting episode. In another task, the subjects performed accurate constant force production with visual feedback removal after the 8th second, and the drop in the total force after the removal was computed. There were differences between the right and left hand in some outcome variables such as variance within the UCM, and the timing of anticipatory synergy adjustments prior to the force pulse, consistent with the dynamic dominance hypothesis. There were significant correlations between the two hands for indices that were unrelated to accuracy of performance: variance within the UCM, index of motor equivalence, referent coordinate, apparent stiffness, and the drop of total force after visual feedback removal. We interpret these findings within the concept of stability-optimality trade-off. In particular, we conclude that individual subjects select particular, person-specific solutions within the spectrum allowed by the explicit task constraints, and this choice is consistent between the two hands. We conclude with a hypothesis that selecting specific solutions within the stability-optimality trade-off may represent an individual's personal preference consistent between the two hands.

From One to Two: Can Visual Feedback Improve the Light Touch Effects on Postural Sway?

The postural control is improved by implicit somatosensory information from lightly touching a rigid bar or explicit visual information about the postural sway. Whether these two additional sources provided at the same time further reduce the postural sway is still unknown. Participants stood on a force plate as quiet as possible lightly touching the bar while received or not visual feedback of the center of pressure position on a monitor screen. Postural sway reduced similarly with the light touch regardless of the additional visual feedback. The findings suggested that providing explicit visual feedback of the center of pressure does not increase the light touch effects on the postural sway. The importance of the implicit somatosensory information on postural control is discussed.

Stability of steady hand force production explored across spaces and methods of analysis.

We used the framework of the uncontrolled manifold (UCM) hypothesis and explored the reliability of several outcome variables across different spaces of analysis during a very simple four-finger accurate force production task. Fourteen healthy, young adults performed the accurate force production task with each hand on 3 days. Small spatial finger perturbations were generated by the "inverse piano" device three times per trial (lifting the fingers 1 cm/0.5 s and lowering them). The data were analyzed using the following main methods: (1) computation of indices of the structure of inter-trial variance and motor equivalence in the space of finger forces and finger modes, and (2) analysis of referent coordinates and apparent stiffness values for the hand. Maximal voluntary force and the index of enslaving (unintentional finger force production) showed good to excellent reliability. Strong synergies stabilizing total force were reflected in both structure of variance and motor equivalence indices. Variance within the UCM and the index of motor equivalent motion dropped over the trial duration and showed good to excellent reliability. Variance orthogonal to the UCM and the index of non-motor equivalent motion dropped over the 3 days and showed poor to moderate reliability. Referent coordinate and apparent stiffness indices co-varied strongly and both showed good reliability. In contrast, the computed index of force stabilization showed poor reliability. The findings are interpreted within the scheme of neural control with referent coordinates involving the hierarchy of two basic commands, the r-command and c-command. The data suggest natural drifts in the finger force space, particularly within the UCM. We interpret these drifts as reflections of a trade-off between stability and optimization of action. The implications of these findings for the UCM framework and future clinical applications are explored in the discussion. Indices of the structure of variance and motor equivalence show good reliability and can be recommended for applied studies.

Gait characteristics of younger-old and older-old adults walking overground and on a compliant surface / Características da marcha de idosas jovens e muito idosas em solo estável e sobre superfície complacente

BACKGROUND: Walking across unstable surfaces disturbs normal stability and efficient strategies must be used to avoid falls. This study identified age-related changes in gait during unstable surface walking. METHOD: Eight healthy younger-old adults (YOG, mean age, 68.6 years) and eight healthy older-old adults (OOG, mean age, 82.1 years) were assessed. Both groups performed the Timed Up and Go Test (TUG) and walked on a rigid and on a compliant surface while kinematic data were obtained. RESULTS: The OOG needed more time to complete the TUG test compared to YOG (F1,14=5.18; p=0.04). The gait speed, stride length and vertical displacement of the foot were similar for both groups, but they were slower (F1,14=5.64; p=0.03) when walking on the compliant surface. The knee and hip range of motion on the sagittal plane (F1,14=191.9; p<0.001 and F1,14=36.4, p<0,001, respectively) increased on the complaint surface but no group effect was found. The displacement of upper trunk on the frontal plane was similar between groups (F1,14=2.43; p=0.14) and conditions (F1,14=1.15; p=0.3). The OOG had greater displacement of the pelvic segment on the frontal plane than the YOG (F1,14=4.9; p=0.04) mainly for the complaint surface. CONCLUSIONS: Older-old individuals have slower TUG test and greater displacement of the pelvic segment on a compliant surface. More challenging tasks and/or environment should be used for gait assessment and intervention of older adults with risk of falls.

CONTEXTUALIZAÇÃO: Caminhar em superfícies instáveis perturba a estabilidade corporal, e estratégias eficientes devem ser utilizadas para evitar quedas. Objetivo: Identificar alterações da marcha relacionadas ao envelhecimento durante a caminhada em superfície instável. MÉTODO: Oito idosos jovens sadios (GIJ, idade média, 68,6 anos) e oito idosos muito idosos sadios (GMI, idade média, 82,1 anos) foram avaliados. Ambos os grupos realizaram o Teste Timed Up and Go (TUG) e andaram sobre uma superfície rígida e uma complacente, enquanto dados cinemáticos foram registrados. RESULTADOS: O GMI levou mais tempo para completar o TUG quando comparado ao GIJ (F1,14=5,18; p=0,04). A velocidade, o comprimento do passo e o deslocamento vertical do pé foram similares entre os grupos, e ambos foram mais lentos (F1,14=5,64; p=0.03) ao andar sobre a superfície complacente. A amplitude de movimento do joelho e do quadril no plano sagital (F1,14=191,9; p<0,001 e F1,14=36,4, p<0,001, respectivamente) aumentaram na superfície complacente, mas nenhuma diferença entre os grupos foi encontrada. O deslocamento do tronco superior no plano frontal foi similar entre os grupos (F1,14=2,43; p=0,14) e condições (F1,14=1,15; p=0,3). O GMI teve maior deslocamento do segmento da pelve no plano frontal do que o GIJ (F1,14=4,9; p=0,04), principalmente na superfície complacente. CONCLUSÃO: Indivíduos muito idosos são mais lentos no TUG e apresentam maior deslocamento do segmento pélvico na superfície complacente. Tarefas e/ou ambientes mais desafiadores deveriam ser usados para avaliação da marcha e intervenção em idosos com risco de quedas.

Gait characteristics of younger-old and older-old adults walking overground and on a compliant surface.

BACKGROUND: Walking across unstable surfaces disturbs normal stability and efficient strategies must be used to avoid falls. This study identified age-related changes in gait during unstable surface walking. METHOD: Eight healthy younger-old adults (YOG, mean age, 68.6 years) and eight healthy older-old adults (OOG, mean age, 82.1 years) were assessed. Both groups performed the Timed Up and Go Test (TUG) and walked on a rigid and on a compliant surface while kinematic data were obtained. RESULTS: The OOG needed more time to complete the TUG test compared to YOG (F1,14=5.18; p=0.04). The gait speed, stride length and vertical displacement of the foot were similar for both groups, but they were slower (F1,14=5.64; p=0.03) when walking on the compliant surface. The knee and hip range of motion on the sagittal plane (F1,14=191.9; p<0.001 and F1,14=36.4, p<0,001, respectively) increased on the complaint surface but no group effect was found. The displacement of upper trunk on the frontal plane was similar between groups (F1,14=2.43; p=0.14) and conditions (F1,14=1.15; p=0.3). The OOG had greater displacement of the pelvic segment on the frontal plane than the YOG (F1,14=4.9; p=0.04) mainly for the complaint surface. CONCLUSIONS: Older-old individuals have slower TUG test and greater displacement of the pelvic segment on a compliant surface. More challenging tasks and/or environment should be used for gait assessment and intervention of older adults with risk of falls.

Revision of posturography based on force plate for balance evaluation.

BACKGROUND: The maintenance of balance and body orientation in humans is guaranteed by the adequate functioning of the postural control system. The investigation of this control has awakened the interest of professionals from several fields such as Physical Therapy, Physical Education, Engineering, Physics, Medicine, Psychology, and others. OBJECTIVES: The purposes of this study are to revise the methods of data analysis used to investigate the postural control in human beings and to demonstrate the computational algorithms of the main measures used in the postural control evaluation. CONCLUSION: The experimental procedures and measures used in postural control evaluation presented in this review can help in the standardization of postural control investigation.