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Background Reactive balance recovery evokes a negative peak of cortical electroencephalography (EEG) activity (N1) that is simultaneous to brainstem-mediated automatic balance-correcting muscle activity. This study follows up on an observation from a previous study, in which N1 responses were larger in individuals who seemed to have greater difficulty responding to support-surface perturbations. Research Question We hypothesized that people engage more cortical activity when balance recovery is more challenging. We predicted that people with lower balance ability would exhibit larger cortical N1 responses during balance perturbations. Methods In 20 healthy young adults (11 female, ages 19–38) we measured the amplitude of the cortical N1 response evoked by 48 backward translational support-surface perturbations of unpredictable timing and amplitude. Perturbations included a Small (8 cm) perturbation that was identical across participants, as well as Medium (13−15 cm) and Large (18−22 cm) perturbations scaled to participant height to control for height-related differences in perturbation difficulty. To assess individual differences in balance ability, we measured the distance traversed on a narrow (0.5-inch wide) 12-foot beam across 6 trials. We tested whether the cortical N1 response amplitude was correlated to balance ability across participants. Results Cortical N1 amplitudes in response to standing balance perturbations (54 ± 18 μV) were inversely correlated to the distance traveled in the difficult beam-walking task (R2 = 0.20, p = 0.029). Further, there was a significant interaction between performance on the beam-walking task and the effect of perturbation magnitude on the cortical N1 response amplitude, whereby individuals who performed worse on the beam-walking task had greater increases in N1 amplitudes with increases in perturbation magnitude. Significance Cortical N1 response amplitudes may reflect greater cortical involvement in balance recovery when challenged. This increased cortical involvement may reflect cognitive processes such as greater perceived threat or attention to balance, which have the potential to influence subsequent motor control.

Background Walking balance in older adults is disproportionately susceptible to lateral instability provoked by optical flow perturbations. The prolonged exposure to these perturbations could promote reactive balance control and increased balance confidence in older adults, but this scientific premise has yet to be investigated. This proof of concept study was designed to investigate the propensity for time-dependent tuning of walking balance control and the presence of aftereffects in older adults following a single session of optical flow perturbation training. Methods Thirteen older adults participated in a randomized, crossover design performed on different days that included 10 min of treadmill walking with (experimental session) and without (control session) optical flow perturbations. We used electromyographic recordings of leg muscle activity and 3D motion capture to quantify foot placement kinematics, lateral margin of stability, and antagonist coactivation during normal walking (baseline), early (min 1) and late (min 10) responses to perturbations, and aftereffects immediately following perturbation cessation (post). Results At their onset, perturbations elicited 17% wider and 7% shorter steps, higher step width and length variability (+171% and +132%, respectively), larger and more variable margins of stability (MoS), and roughly twice the antagonist leg muscle coactivation (p-values

Background This study presents a new approach to measure and analyze the walking balance of humans by collecting motion sensor data in a smartphone. Objective We aimed to develop a mobile health (mHealth) app that can measure the walking movements of human individuals and analyze the differences in the walking movements of different individuals based on their health conditions. A smartphone’s motion sensors were used to measure the walking movements and analyze the rotation matrix data by calculating the variation of each xyz rotation, which shows the variables in walking-related movement data over time. Methods Data were collected from 3 participants, that is, 2 healthy individuals (1 female and 1 male) and 1 male with back pain. The participant with back pain injured his back during strenuous exercise but he did not have any issues in walking. The participants wore the smartphone in the middle of their waistline (as the center of gravity) while walking. They were instructed to walk straight at their own pace in an indoor hallway of a building. The walked a distance of approximately 400 feet. They walked for 2-3 minutes in a straight line and then returned to the starting location. A rotation vector in the smartphone, calculated by the rotation matrix, was used to measure the pitch, roll, and yaw angles of the human body while walking. Each xyz-rotation vector datum was recalculated to find the variation in each participant’s walking movement. Results The male participant with back pain showed a diminished level of walking balance with a wider range of xyz-axis variations in the rotations compared to those of the healthy participants. The standard deviation in the xyz-axis of the male participant with back pain was larger than that of the healthy male participant. Moreover, the participant with back pain had the widest combined range of right-to-left and forward-to-backward motions. The healthy male participant showed smaller standard deviation while walking than the male participant with back pain and the female healthy participant, indicating that the healthy male participant had a well-balanced walking movement. The walking movement of the female healthy participant showed symmetry in the left-to-right (x-axis) and up-to-down (y-axis) motions in the x-y variations of rotation vectors, indicating that she had lesser bias in gait than the others. Conclusions This study shows that our mHealth app based on smartphone sensors and rotation vectors can measure the variations in the walking movements of different individuals. Further studies are needed to measure and compare walking movements by age, gender, as well as types of health problems or disease. This app can help in finding differences in gait in people with diseases that affect gait.

During human walking, step width is predicted by mediolateral motion of the pelvis, a relationship that can be attributed to a combination of passive body dynamics and active sensorimotor control. The purpose of the present study was to investigate whether humans modulate the active control of step width in response to a novel mechanical environment. Participants were repeatedly exposed to a force-field that either assisted or perturbed the normal relationship between pelvis motion and step width, separated by washout periods to detect the presence of potential after-effects. As intended, force-field assistance directly strengthened the relationship between pelvis displacement and step width. This relationship remained strengthened with repeated exposure to assistance, and returned to baseline afterward, providing minimal evidence for assistance-driven changes in active control. In contrast, force-field perturbations directly weakened the relationship between pelvis motion and step width. Repeated exposure to perturbations diminished this negative direct effect, and produced larger positive after-effects once the perturbations ceased. Both of these results provide evidence of gradual changes in active control in response to perturbations. In the longer term, these methods may be useful for improving deficits in the active control of step width often observed among clinical populations with poor walking balance.

Background Altered standing balance during pregnancy has been previously reported. To date, body center of mass (bCOM) motion has not been used to track balance changes in this population. We recently compared three methods to determine the torso center of mass (tCOM) location (via force plate acquired center of pressure calculation, using Pavol surface anthropometry measurements, and a combination of the two) to use in calculating the bCOM during pregnancy. Research question This current research explored two questions: (1) does walking balance change during pregnancy, and (2) do the methods for identifying tCOM location affect the resulting balance measures? Methods Fifteen pregnant women were recruited to perform 60-second trial of treadmill walking at 4-week intervals from 12 weeks gestation until delivery. Walking balance was measured as bCOM motion within the base of support. Gestation time and anthropometric model (force plate, Pavol, and combination) were repeated-measures independent variables in a general linear mixed model analysis. Results There was a significant decrease in walking balance during pregnancy. As gestation progressed, we observed non-linear changes in the bCOM motion within the base of support over time, with some changes starting early in pregnancy and others not starting until late 2nd trimester. The anthropometric model used to locate the bCOM significantly influences balance measures. The results of this study indicate that the force plate method is more appropriate for locating the tCOM in the anterior and lateral directions. Significance The results of this study will inform clinicians and patients about the gestational stage-associated changes in balance during pregnancy that increase the risk of falling and injury. Researchers should also carefully consider the method for locating the bCOM.

BACKGROUND: Dancesport is a popular activity among older adults who look for fun and fitness in Korea. Studies reported positive sociological and psychological effects of dancesport. But, little studies were performed to evaluate the effects of dancesport on balance performances. OBJECTIVE: The objective of the present study was to evaluate the effects of dancesport for 15 weeks on walking balance and standing balance of older adults. METHODS: Older adults regularly participated in the dancesport program 3 times a week for 15 weeks. The program included Rumba, Cha-cha-cha, and Jive. They exercised the prescribed dancesport at intermediate level for 50–60 mins for each time. A total 22 reflective markers were placed on the anatomical landmarks and 8 cameras were used to measure 3-D positions of participants. Also, center of pressure (COP) data were measured to analyze standing balance using a ground reaction board at 1200 Hz for 30 seconds. One-way analysis of variance (ANOVA) was performed to test the effects of 15 weeks of dancesport on walking balance and standing balance. RESULTS: The results suggested that, after 15 weeks of dancesport participation, older adults’ walking balance (48.3 ± 20.3 cm2 vs 38.2 ± 18.2 cm2) and standing balance (COP area: 189.4 ± 85.4 mm2 vs 103.5 ± 55.4mm2, COP distance: 84.2 ± 34.4 cm vs 76.5 ± 21.4 cm) were significantly improved. CONCLUSION: Performing dancesport would require moving center of mass rapidly and frequently while maintaining posture. This may result in improving walking balance and standing balance in the present study. The study concluded that dancesport would be an effective exercise method in enhancing postural stability of older adults.

People with chronic stroke (PwCS) are susceptible to mediolateral losses of balance while walking, possibly due in part to inaccurate control of mediolateral paretic foot placement. We hypothesized that mediolateral foot placement errors when stepping to stationary or shifting visual targets would be larger for paretic steps than for steps taken by neurologically-intact individuals, hereby referred to as controls. Secondarily, we hypothesized that paretic foot placement errors would be correlated with previously identified deficits in isolated paretic hip abduction accuracy. 34 PwCS and 12 controls walked overground on an instrumented mat used to quantify foot placement location relative to parallel lines separated by various widths (10, 20, 30 cm). With stationary step width targets, foot placement errors were larger for paretic steps than for either non-paretic or control steps, most notably for the narrowest prescribed step width (mean absolute errors of 3.9, 2.3, and 1.9 cm, respectively). However, no differences in foot placement accuracy were observed immediately following visual target shifts, as all groups required multiple steps to achieve the new prescribed step width. Paretic hip abduction accuracy was moderately correlated with mediolateral foot placement accuracy when stepping to stationary targets (r = 0.49), but not shifting targets (r = 0.16). The present results suggest that a reduced ability to accurately abduct the paretic leg contributes to inaccurate paretic foot placement. However, the need to ensure mediolateral walking balance through mechanically-appropriate foot placement may often override the prescribed goal of stepping to visual targets, a concern of particular importance for narrow steps.

Purpose The aims of this study were to describe participants' demographic characteristics by adherence levels and to examine the association between participants' baseline physical function and their adherence to an evidence-based group exercise program. Design A prospective exploratory study (N = 36,373). Methods Participants' physical function was assessed using 30-second chair-stand, arm-curl, and 8-foot up-and-go tests. Adherence was calculated as the proportion of attended sessions over offered sessions. Findings Participants' mean adherence was 52%. Older male, Asian/Pacific Islander race, and Washington State residents with fewer chronic conditions showed higher adherence. Multinomial logistic regression showed the baseline 30-second chair-stand, arm-curl, and 8-foot up-and-go tests significantly predict adherence levels after controlling for demographics. Conclusions Stronger upper- and lower-extremity strength and better walking balance and mobility are associated with higher adherence to exercise programs in older adults. Clinical relevance The results underscored the importance of offering classes at various physical function levels while considering participants' individual needs.

Objective: To evaluate construct validity and reproducibility of the Functional Gait Assessment (FGA) for measuring walking balance capacity in persons after stroke. Design: Cross-sectional study. Setting: Inpatient and outpatient rehabilitation center. Subjects: Fifty-two persons post-stroke (median (25% and 75% percentiles)) time post-stroke 6 (5–10) weeks) with independent walking ability (mean gait speed 1.1 ± .4 m/s). Methods: Subjects completed a standardized FGA twice within one to eight days by the same investigator. Validity was evaluated by testing hypotheses on the association with two timed walking tests, Berg Balance Scale, and the mobility domain of the Stroke Impact Scale using correlation coefficients ( r), and with Functional Ambulation Categories using the Kruskal–Wallis test. Reproducibility of FGA scores was assessed with intraclass correlation coefficient and standard error of measurement. Results: Subjects scored a median of 22 out of 30 points at the first FGA. Moderate to high significant correlations ( r .61–.83) and significant differences in FGA median scores between the Functional Ambulation Categories were found. Eight hypotheses (80%) could be confirmed. Inter-rater, intra-rater, and test–retest reliability of the total scores were excellent. The standard error of measurement and minimal detectable change were 2 and 6 points, respectively. No relevant ceiling effect was observed. Conclusion: The FGA demonstrated good measurement properties in persons after stroke and yielded no ceiling effect in contrast to other capacity measures. In clinical practice, a measurement error of 6 points should be taken into account in interpreting changes in walking balance.

Rapid motor learning may occur in situations where individuals perceive a threat if they do not perform a task well. This rapid motor learning may be facilitated by improved motor performance and, consequently, more errorless practice. As a first step towards understanding the role of perceived threat on rapid motor learning, the purpose of this study was to determine how performance of a motor task is affected in situations where perceived threat is high. We hypothesized that perceived threat in a virtual environment would result in improved performance of a walking task (i.e., walking on a narrow beam). Results demonstrated that increased perceived threat did not yield statistically significantly greater balance performance in the high-threat virtual environment (median percentage of successful steps: 78.8%, 48.3%, and 55.2% in the real low-threat, virtual low-threat, and virtual high-threat environments, respectively). These results may be partially attributed to habituation to threat over time and practice. If implemented carefully, virtual reality technology can be an effective tool for investigating walking balance in environments that are perceived as threatening.

Objectives Remote assessment of gait in patients' homes has become a valuable tool for monitoring the progression of Parkinson's disease (PD). However, these measurements are often not as accurate or reliable as clinical evaluations because it is challenging to objectively distinguish the unique gait characteristics of PD. We explore the inference of patients' stage of PD from their gait using machine learning analyses of data gathered from their smartphone sensors. Specifically, we investigate supervised machine learning (ML) models to classify the severity of the motor part of the UPDRS (MDS-UPDRS 2.10-2.13). Our goals are to facilitate remote monitoring of PD patients and to answer the following questions: (1) What is the patient PD stage based on their gait? (2) Which features are best for understanding and classifying PD gait severities? (3) Which ML classifier types best discriminate PD patients from healthy controls (HC)? and (4) Which ML classifier types can discriminate the severity of PD gait anomalies? Methodology Our work uses smartphone sensor data gathered from 9520 patients in the mPower study, of whom 3101 participants uploaded gait recordings and 344 subjects and 471 controls uploaded at least 3 walking activities. We selected 152 PD patients who performed at least 3 recordings before and 3 recordings after taking medications and 304 HC who performed at least 3 walking recordings. From the accelerometer and gyroscope sensor data, we extracted statistical, time, wavelet and frequency domain features, and other lifestyle features were derived directly from participants' survey data. We conducted supervised classification experiments using 10-fold cross-validation and measured the model precision, accuracy, and area under the curve (AUC). Results The best classification model, best feature, highest classification accuracy, and AUC were (1) random forest and entropy rate, 93% and 0.97, respectively, for walking balance (MDS-UPDRS-2.12); (2) bagged trees and MinMaxDiff, 95% and 0.92, respectively, for shaking/tremor (MDS-UPDRS-2.10); (3) bagged trees and entropy rate, 98% and 0.98, respectively, for freeze of gait; and (4) random forest and MinMaxDiff, 95% and 0.99, respectively, for distinguishing PD patients from HC. Conclusion Machine learning classification was challenging due to the use of data that were subjectively labeled based on patients' answers to the MDS-UPDRS survey questions. However, with use of a significantly larger number of subjects than in prior work and clinically validated gait features, we were able to demonstrate that automatic patient classification based on smartphone sensor data can be used to objectively infer the severity of PD and the extent of specific gait anomalies.

Background Adding haptic input by lightly touching a railing or using haptic anchors may improve walking balance control. Typical use of the railing(s) and haptic anchors requires the use of one and two arms in an extended position, respectively. It is unclear whether it is arm configuration and/or the number of arms used or the addition of sensory input that affects walking balance control. Research question This study examined whether using one arm or two arms to add haptic input through light touch on a railing or using the haptic anchors affects walking balance control. Methods In this study, young adults (n = 24) walked while using (actual use) or pretending to use (pretend use) the railing(s) and haptic anchors with one or two arms. Inertial-based sensors (Mobility Lab, APDM) were used to measure stride velocity, relative time spent in double support (%DS), and peak normalized medio-lateral trunk velocity (pnMLTV). Results Using two arms lead to a decrease in pnMLTV compared to using one arm and pnMLTV was lower in the actual use trials compared to the pretend use trials for the anchors only. Stride velocity and %DS did not change between trials when one or two arms were used or when participants actually or pretended to use the haptic tools. Participants walked slower when using the railing compared to the anchors. Significance The importance of considering the number of arms is highlighted in the improved balance control when using two arms with either tool. The augmented sensory input adds to the stabilizing effect of arm configuration for the anchors but not the railings. These results have implications for future research and rehabilitation efforts emphasizing sensorimotor integration to improve walking balance control.

Background Depletion of ovarian hormone in postmenopausal women has been associated with changes in the locomotor apparatus that may compromise walking function including muscle atrophy/weakness, weight gain, and bone demineralization. Therefore, handgrip strength (HGS), bone mineral density (BMD) and body composition [percentage body fat mass (%BFM), fat mass (FM), Fat-free mass (FFM) and body mass index (BMI)], may significantly vary and predict WB in postmenopausal women. Consequently, the study sought to 1. Explore body composition, BMD and muscle strength differences between premenopausal and postmenopausal women and 2. Explore how these variables [I.e., body composition, BMD and muscle strength] relate to WB in postmenopausal women. Method Fifty-one pre-menopausal (35.74 + 1.52) and 50 postmenopausal (53.32 + 2.28) women were selected by convenience sampling and studied. Six explanatory variables (HGS, BMD, %BFM, FFM, BMI and FM) were explored to predict WB in postmenopausal women: Data collected were analyzed using multiple linear regression, ANCOVA, independent t-test and Pearson correlation coefficient at p

This review aims to describe the factors that influence participation in physical activity (PA) in people with neuromusculoskeletal (NMS) conditions.A systematic search of six databases was conducted. Articles were included if the study qualitatively explored factors that influence participation in PA by individuals with a NMS condition. Fifteen peer-reviewed articles published between 2003 and 2013 were analysed for common themes and critically appraised.Results were categorised using the International Classification of Functioning, Disability and Health framework. The most common demotivators reported for the three areas of functioning, body function and structures, activities and participation were lack of walking balance, muscle weakness, pain, stiffness, bladder and blower problems, depression, thermoregulation and fear of injury. Fluctuating symptoms and fatigue were mentioned as demotivators in all of the progressive conditions. Maintaining independence, function and weight, and the prevention of secondary conditions were the leading motivators reported in this domain. Most common environmental barriers include accessibility, costs, transport and insufficient information and knowledge from health professionals. Social support is a consistent determinate of PA and is reported as a facilitator in every study. The most common personal demotivators include lack of motivation, feelings of self-consciousness and embarrassment in public, anxiety, frustration and anger. Personal motivators include goal setting and achieving, enjoyment, feeling good, feeling "normal", motivation and optimism, redefining self and escapism from everyday boundaries.Individuals with NMS conditions report complex common barriers, facilitators, demotivators and motivators to participation in PA. The way these factors influence participation in PA is unique to the individual; therefore, it is necessary to adopt an individually tailored approach when designing interventions.Individuals with neuromusculoskeletal conditions report common factors that influence participation in physical activity. It is the characteristics, attitude and beliefs of an individual that determine the way in which these factors influence participation in physical activity. Health professionals should be guided by the International Classification of Functioning, Disability and Health framework when assessing individuals, as the model will ensure all major factors of interest with regard to disability and physical activity behaviour are considered. Interventions to promote participation in physical activity in people with neuromusculoskeletal conditions require an individual approach that facilitates the assessment and management of an individual's barriers to physical activity. A multi-disciplinary approach may be required to address factors that influence participation in physical activity. Health professionals must be informed about other areas of expertise and draw on this when necessary.

Gait and balance disorders are among the most common causes of falls in older adults. Most falls occur as a result of unexpected hazards while walking. In order to improve the effectiveness of current fall-prevention programs, new balance training paradigms aim to strengthen the control of the compensatory responses required after external perturbations. The aim of this study was to analyze the adaptions of reactive and proactive strategies to control stability after repeated exposures to waist-pull perturbations delivered while walking. Eight healthy young subjects participated in a single training session with the Active Tethered Pelvic assisted Device (A-TPAD). Participants were exposed to repeated multi-directional perturbations of increasing intensity. The Antero-Posterior (AP) and Medio-Lateral (ML) Base of Support (BoS) and Margin of Stability (MoS) during the response to diagonal perturbations were compared before and after the training. Results showed that participants adapted both the reactive and proactive strategies to control walking balance by significantly increasing their pre- and post-perturbation stability. The changes were principally accounted for by an increment of the AP BoS and MoS and a reduction of ML BoS. This improved their ability to react to a diagonal perturbation. We envision that this system can be used to develop a perturbation-based gait training aimed at improving balance and control of stability during walking, thus reducing fall risk.

Walking dysfunctions persist following poststroke rehabilitation. A major limitation of current rehabilitation efforts is the inability to identify modifiable deficits that, when improved, will result in the recovery of walking function. Previous studies have relied on cross-sectional analyses to identify deficits to target during walking rehabilitation; however, these studies did not account for the influence of a key covariate - maximum walking speed.To determine the relationships between commonly studied poststroke variables and the long-distance walking function of individuals poststroke when controlling for maximum walking speed.Correlation analyses of cross-sectional data from 57 individuals more than 6 months poststroke measured the relationships between standing balance, walking balance, balance self-efficacy, lower extremity motor function, and maximum walking speed versus long-distance walking function. For a subgroup of subjects who completed training, the relationship between changes in maximum walking speed versus changes in long-distance walking function was assessed.Each measurement of interest strongly correlated with long-distance walking function (rs from 0.448 to 0.900, all Ps ≤ .001); however, when controlling for maximum walking speed, none of the other measurements remained related to long-distance walking function. In contrast, when controlling for each of the other measurements, maximum walking speed remained highly related. Moreover, changes in maximum walking speed resulting from training were highly related to changes in long-distance walking function (r = .737, P ≤ .001).For individuals in the chronic phase of stroke recovery, improving maximum walking speed may be necessary to improve long-distance walking function.

While assisting with balance is a primary reason for rollator use, few studies have examined how the upper limbs are used for balance. This study examines upper limb contributions to balance control during rollator-assisted walking. We hypothesized that there would be an increased upper limb contribution, measured by mean vertical loading (Fz) and variation in frontal plane center-of-pressure (COPhigh), when walking balance is challenged/impaired. Experiment 1 compared straight-line and beam-walking in young adults (n = 11). As hypothesized, Fz and COPhighincreased in beam-walking compared to baseline (mean Fz: 13.7 vs. 9.1% body weight (BW), p < 0.001, RMS COPhigh: 1.35 vs. 1.07 cm, p < 0.001). Experiment 2 compared older adults who regularly use rollators (RU, n = 10) to older adult controls (CTL, n = 10). The predicted higher upper limb contribution in the RU group was not supported. However, when individuals were grouped by balance impairment, those with the lowest Berg Balance scores (< 45) demonstrated greater speed-adjusted COPhigh than those with higher scores (p = 0.013). Furthermore, greater COPhigh and Fz were correlated to greater reduction in step width, supporting the role of upper limb contributions to frontal plane balance. This work will guide studies assessing reliance on rollators by providing a basis for measurement of upper limb balance contributions.

There are different ways to add haptic input during walking which may affect walking balance. This study compared the use of two different haptic tools (rigid railing and haptic anchors) and investigated whether any effects on walking were the result of the added sensory input and/or the posture generated when using those tools. Data from 28 young healthy adults were collected using the Mobility Lab inertial sensor system (APDM, Oregon, USA). Participants walked with and without both haptic tools and while pretending to use both haptic tools (placebo trials), with eyes opened and eyes closed. Using the tools or pretending to use both tools decreased normalized stride velocity (p .001-0.008) and peak medial-lateral (ML) trunk velocity (p .001-0.001). Normalized stride velocity was slower when actually using the railing compared to placebo railing trials (p = .006). Using the anchors resulted in lower peak ML trunk velocity than the railing (p = .002). The anchors had lower peak ML trunk velocity than placebo anchors (p .001), but there was no difference between railing and placebo railing (p .999). These findings highlight a difference in the type of tool used to add haptic input and suggest that changes in balance control strategy resulting from using the railing are based on arm placement, where it is the posture combined with added sensory input that affects balance control strategies with the haptic anchors. These findings provide a strong framework for additional research to be conducted on the effects of haptic input on walking in populations known to have decreased walking balance.

Visual (i.e., optical flow) perturbations can be used to study balance control and balance deficits. However, it remains unclear whether walking balance control adapts to such perturbations over time. Our purpose was to investigate the propensity for visuomotor adaptation in walking balance control using prolonged exposure to optical flow perturbations. Ten subjects (age: 25.4 ± 3.8 years) walked on a treadmill while watching a speed-matched virtual hallway with and without continuous mediolateral optical flow perturbations of three different amplitudes. Each of three perturbation trials consisted of 8 min of prolonged exposure followed by 1 min of unperturbed walking. Using 3D motion capture, we analyzed changes in foot placement kinematics and mediolateral sacrum motion. At their onset, perturbations elicited wider and shorter steps, alluding to a more cautious, general anticipatory balance control strategy. As perturbations continued, foot placement tended toward values seen during unperturbed walking while step width variability and mediolateral sacrum motion concurrently increased. Our findings suggest that subjects progressively shifted from a general anticipatory balance control strategy to a reactive, task-specific strategy using step-to-step adjustments. Prolonged exposure to optical flow perturbations may have clinical utility to reinforce reactive, task-specific balance control through training.

Combination of intrinsic control and volitional control that recognizes the user's locomotion mode (LM) has been applied to powered prosthetic legs, which enables lower limb amputees to adapt to varying terrains seamlessly. However, errors in volitional control may disrupt the user's walking balance. This study aimed to determine whether the critical errors in volitional control could be detected before they disturbed the user's walking. The positive answer might lead to more robust volitional control for powered prosthetic legs. To achieve this goal, volitional control and intrinsic control were connected hierarchically to operate a powered transfemoral prosthesis. Critical errors for recognizing the user's LM were introduced artificially when transfemoral amputees walked with the powered prosthesis. Intrinsic measurements from the prosthesis were explored first in order to select effective data sources for error detection. Then a phase-dependent outlier detector was designed and offline evaluated. The results demonstrated that the designed detector can detect the tested critical errors with a high sensitivity and a low false alarm ratio before the errors disrupted the amputees' balance. Additional engineering efforts were still necessary to test the detector on more error types and design a control strategy that can make volitional control of powered lower limb prosthesis robust and safe to use.

Spinal cord injury affects walking balance control, which necessitates methods to quantify balance ability. The purposes of this study were to 1) examine walking balance through foot placement variability post-injury; 2) assess the relationship between measures of variability and clinical balance assessments; and 3) determine if spatial parameter variability might be used as a clinical correlate for more complex balance measurements.Ten persons with spinal cord injury walked without devices on a split-belt treadmill at self-selected speeds. Ten healthy controls walked at 0.3 and 0.6m/s for comparison. Variability of step width and length, anteroposterior and mediolateral foot placements relative to center-of-mass, and margin-of-stability were calculated. Clinical assessments included Berg Balance Scale and Dynamic Gait Index.Participants with spinal cord injury demonstrated significantly different variability in all biomechanical measures compared to controls (P ≤ 0.007). Berg Balance Scale scores were significantly inversely associated with step length as well as anteroposterior and mediolateral foot placement variability (P ≤ 0.05). Dynamic Gait Index scores were significantly inversely associated with mediolateral foot placement variability (P ≤ 0.05). Participants with spinal cord injury showed significant correlations between spatial parameter variability and all other measures (P ≤ 0.005), except between step length and margin-of-stability (P=0.068); controls revealed fewer correlations.Persons post-spinal cord injury exhibit an abnormal amount of stepping variability when challenged to walk without devices, yet preserve the ability to avoid falling. When complex laboratory measures of variability are unavailable clinically, spatial parameter variability or standardized balance assessments may be plausible indicators of walking balance control.

The study evaluated the effects of shoe style on workers' instability during walking at elevation. Twenty-four construction workers performed walking tasks on roof planks in a surround-screen virtual reality system, which simulated a residential roof environment. Three common athletic and three work shoe styles were tested on wide, narrow and tilted planks on a simulated roof and on an unrestricted surface at simulated ground. Dependent variables included lateral angular velocities of the trunk and the rear foot, as well as the workers' rated perceptions of instability. The results demonstrated that shoe style significantly affected workers walking instability at elevated work environments. The results highlighted two major shoe-design pathways for improving walking balance at elevation: enhancing rear foot motion control; and improving ankle proprioception. This study also outlined some of the challenges in optimal shoe selection and specific shoe-design needs for improved walking stability during roof work. The study adds to the knowledge in the area of balance control, by emphasising the role of footwear as a critical human-support surface interface during work on narrow surfaces at height. The results can be used for footwear selection and improvements to reduce risk of falls from elevation.

Maintaining balance while walking is challenging for lower limb amputees. The effect of prosthetic foot stiffness on recovery kinetics from an error in foot placement may inform prescription practice and lead to new interventions designed to improve balance. Ten unilateral transtibial amputees were fit with two prosthetic feet with different stiffness properties in random order. After a 3-week acclimation period, they returned to the lab for testing before switching feet. Twelve non-amputees also participated in a single data collection. While walking on an instrumented treadmill, we imposed a repeatable, unexpected medial or lateral disturbance in foot placement by releasing a burst of air at the ankle just before heel strike. Three-dimensional motion capture, ground reaction force and center of pressure (COP) data were collected for two steps prior, the disturbed step and three steps after the disturbance. During undisturbed walking, coronal ankle impulse was lower by 42% for amputees wearing a stiff compared to a compliant foot (p=0.017); however, across steps, both prosthetic recovery patterns were similar compared to the sound limb and non-amputees. Peak coronal hip moment was 15-20% lower for both foot types during undisturbed walking (p

Every year there are thousands of pedestrians in Sweden who are injured because of slippery pavements and roadways. Using an appropriate anti-skid device may reduce the risk of slips and falls on ice and snow. Methods to describe functional problems in walking on different slippery surfaces during winter have been developed as rating scales for evaluating walking safety and walking balance and an observation method to observe posture and movements during walking. Practical tests of all 25 anti-skid devices on the market in Sweden were carried out on different slippery surfaces; gravel, sand, salt, snow and ice. The anti-skid devices were described according to the subjects' perception of walking safety, walking balance and priority for own use. The postures and movements during walking were analysed by an expert physical therapist. The wholefoot device 'studs' was perceived as the best according to walking safety and walking balance and had the highest priority for own use.

The currently approved objective clinical measure of standing balance in astronauts after space flight is the Sensory Organization Test battery of computerized dynamic posturography. No tests of walking balance are currently approved for standard clinical testing of astronauts. This study determined the sensitivity and specificity of standing and walking balance tests for astronauts before and after long-duration space flight. Astronauts were tested on an obstacle avoidance test known as the Functional Mobility Test (FMT) and on the Sensory Organization Test using sway-referenced support surface motion with eyes closed (SOT 5) before and six months after (n=15) space flight on the International Space Station. They were tested two to seven days after landing. Scores on SOT tests decreased and scores on FMT increased significantly from pre- to post-flight. In other words, post-flight scores were worse than pre-flight scores. SOT and FMT scores were not significantly related. ROC analyses indicated supra-clinical cut-points for SOT 5 and for FMT. The standard clinical cut-point for SOT 5 had low sensitivity to post-flight astronauts. Higher cut-points increased sensitivity to post-flight astronauts but decreased specificity to pre-flight astronauts. Using an FMT cut-point that was moderately highly sensitive and highly specific plus SOT 5 at the standard clinical cut-point was no more sensitive than SOT 5, alone. FMT plus SOT 5 at higher cut-points was more specific and more sensitive. The total correctly classified was highest for FMT, alone, and for FMT plus SOT 5 at the highest cut-point. These findings indicate that standard clinical comparisons are not useful for identifying problems. Testing both standing and walking balance will be more likely to identify balance deficits.

Error augmentation during training has been proposed as a means to facilitate motor learning due to the human nervous system’s reliance on performance errors to shape motor commands. We studied the effects of error augmentation on short-term learning of walking on a balance beam to determine whether it had beneficial effects on motor performance. Four groups of able-bodied subjects walked on a treadmill-mounted balance beam (2.5-cm wide) before and after 30 min of training. During training, two groups walked on the beam with a destabilization device that augmented error (Medium and High Destabilization groups). A third group walked on a narrower beam (1.27-cm) to augment error (Narrow). The fourth group practiced walking on the 2.5-cm balance beam (Wide). Subjects in the Wide group had significantly greater improvements after training than the error augmentation groups. The High Destabilization group had significantly less performance gains than the Narrow group in spite of similar failures per minute during training. In a follow-up experiment, a fifth group of subjects (Assisted) practiced with a device that greatly reduced catastrophic errors (i.e., stepping off the beam) but maintained similar pelvic movement variability. Performance gains were significantly greater in the Wide group than the Assisted group, indicating that catastrophic errors were important for short-term learning. We conclude that increasing errors during practice via destabilization and a narrower balance beam did not improve short-term learning of beam walking. In addition, the presence of qualitatively catastrophic errors seems to improve short-term learning of walking balance.

Aim To clarify the usefulness of the number of steps walked daily as a health promotion parameter in the elderly. Methods The study was performed at five welfare centers for the elderly in the suburban area of Takatsuki-city, Japan. Subjects comprised 339 community-dwelling persons (96 men and 243 women) aged 60-89 years. The number of steps walked daily, usual walking speed, "timed up and go" (TUG) time, handgrip strength, body muscle mass and bone density were measured. Psychological and physical status and lifestyle factors were determined vie questionnaire. Subjects were classified into one of two groups, a low- or high-level walking group, according to the Healthy Japan 21 criteria. Differences between the two groups were analyzed. Results Men walked 8,075 steps (mean number) daily, and women walked 7,902 steps daily. The number decreased with age in both men and women and correlated with usual walking speed and TUG time. Low-level walking was found in 41.7% of men and 28.8% of women. Intermittent claudication and fear of falling were the main contributors to low-level walking, whereas walking almost daily and engaging in physical activity with a view toward health promotion were the main contributors to high-level walking. Conclusion For the elderly population, the number of steps walked daily was related to their walking ability, such as walking speed and walking balance, and could be considered as a useful health promotion parameter. Taking a walk daily could be the main approach to increase the number of steps walked daily in the elderly.

Muscle weakness and sensory deficits in people with myelomeningocele (MMC) make their walking control a greater challenge. We know little about how people with MMC optimize their walking balance. Recently, researchers have argued that medial-lateral control of gait requires more active neural input than the anterior-posterior direction, which is more passive. Our goal was to investigate the effect of providing external lateral stabilization (ELS) on walking patterns in people with MMC. We examined 12 people with MMC who could perform at least 4-6 independent steps. We found that the normalized step width (SW) was decreased 20% from without stabilizer to with stabilizer, where as the normalized step length (SL) was increased 4.17% from without stabilizer to with stabilizer. The ELS resulted in 25.10% reduction in centre of mass (COM) ranges of motions in the medial-lateral direction and 13.43% reduction in pelvic range of motions in the frontal plane. Our results suggested that by decreasing the medial-lateral control demands in people with MMC, we could improve gait with smaller SW, longer SL as well as reduced COM and pelvic ranges of motion in the frontal plane. In addition, ELS decreased energy cost and muscle co-activation of soleus and vastus lateralis that may help in diminishing the chances of pain and fatigue in people with MMC. Exploring the effect of the ELS provided us information that might be used to increase mobility safety and to develop a superior rehabilitation intervention for people with MMC.

Elderly people lose their rhythm of walking balance, because their body alignment and standing balance become less stable through aging. The fluctuations of both hips movement while walking were measured using a portable measurement system with two accelerometers. Before they have had physical exercise and when walking without shoe insoles, the fluctuations of the hip movement, having back and knee pain, was not rhythmic, and also not proportional to 1/f (f=frequency) fluctuation, their walking was unstable. After physical exercise and walking with insoles, their walking became rhythmic and was approximately close to proportional to 1/f fluctuation, and their walking improved. This study provides useful information for the improvement of walking. Index Terms—Walking balance, AR modeling, spectral analysis, 1/f fluctuation

Many different corrective reactions can be used to regain balance during walking. However, the nervous system does not hesitate to decide which reaction will be used. A rule-based finite state control system that preselects appropriate reactions is a practical way to simplify this task. The proposed model suggests that much of this is achieved by groups of spinal interneurons.

The interest for effective preventive strategies for slips and falls is growing. Much remains to be done, however, to prevent slips and falls in the traffic environment. Using an appropriate anti-slip device may reduce the risk of slips and falls on different surfaces outdoors during winter. The aim of this study was to evaluate the best anti-slip devices of different designs in the Swedish market on a larger group of healthy individuals in different ages on five different slippery surfaces as a way to develop a standard method to test anti-slip devices. Three different designs of anti-slip devices: heel device, foot-blade device and whole-foot device were evaluated on ice surfaces uncovered or covered with gravel, sand, salt or snow. The evaluations were done according to subject's perceived walking safety and balance, videorecordings of walking postures and movements, time to take on and off each anti-slip device, advantages/disadvantages with each anti-slip device and a list of priorities for own use according to three criteria: safety, balance and appearance. The heel device was perceived to be the most safe on all five surfaces, followed by the toe device and the whole-foot device. The heel device was also perceived to be the one with the best walking balance on uncovered ice and on snow covered ice. There were some significant differences due to gender and age. Most subjects walked with a normal muscle function in the hip and knee when walking with or without an anti-slip device on all surfaces. The heel device was perceived as the most rapid one to take on and the toe device as the most rapid one to take off. All three devices were perceived as having a good foothold. The heel device was perceived to fit the shoe and to be stable at heel-strike. The toe device was easily portable and stable on uncovered ice. The whole-foot device was comfortable to walk with and safe on snow covered ice. The heel device had the highest priority according to walking safety, walking balance and choice for own use.

There are few reports concerning the gait characteristics of sciatic nerve palsy. Four cases, one with complete palsy and three with incomplete palsy, are presented. Complete palsy (case 1) was due to sacrifice of the sciatic nerve in a wide excision for chondrosarcoma in the left ischium. Incomplete palsy (cases 2, 3, and 4) was due to contusion incurred in traffic accidents. It is noteworthy that all four patients could walk with or without a short-leg brace. But the patients with complete loss of proprioception distal to the ankle (cases 1 and 2) had to watch their steps while walking to maintain their walking balance. This clinical analysis revealed that proprioceptive impairment of the sciatic nerve caused a walking disability even though the palsy was incomplete.

A pair of autistic monozygotic twins were assessed on relevant portions of the Geddes Psychomotor Inventory. Over-all motor development of the 3-yr., 6-mo. old twins was similar and considered a partial consequence of the same genotype and comparable environmental experiences from birth. The twins exhibited poor or unsuccessful performance on tasks requiring abilities in language, communication, and appropriate relationships to objects; superior performance on specific fine manual motor skills, walking balance board, and climbing; at-age performance on tasks which were considered measures of patterned gross movement, balance, postural maintenance, and spatial orientation; and few typical autistic motor characteristics.

Background: For optimal guidance of walking rehabilitation therapy of stroke patients in an in-home setting, a small and easy to use wearable system is needed. In this paper we present a new shoe-integrated system that quantifies walking balance during activities of daily living and is not restricted to a lab environment. Quantitative parameters were related to clinically assessed level of balance in order to assess the additional information they provide. Methods: Data of 13 participants who suffered a stroke were recorded while walking 10 meter trials and wearing special instrumented shoes. The data from 3D force and torque sensors, 3D inertial sensors and ultrasound transducers were fused to estimate 3D (relative) position, velocity, orientation and ground reaction force of each foot. From these estimates, center of mass and base of support were derived together with a dynamic stability margin, which is the (velocity) extrapolated center of mass with respect to the front-line of the base of support in walking direction. Additionally, for each participant step lengths and stance times for both sides as well as asymmetries of these parameters were derived. Results: Using the proposed shoe-integrated system, a complete reconstruction of the kinematics and kinetics of both feet during walking can be made. Dynamic stability margin and step length symmetry were not significantly correlated with Berg Balance Scale (BBS) score, but participants with a BBS score below 45 showed a small-positive dynamic stability margin and more asymmetrical step lengths. More affected participants, having a lower BBS score, have a lower walking speed, make smaller steps, longer stance times and have more asymmetrical stance times. Conclusions: The proposed shoe-integrated system and data analysis methods can be used to quantify daily-life walking performance and walking balance, in an ambulatory setting without the use of a lab restricted system. The presented system provides additional insight about the balance mechanism, via parameters describing walking patterns of an individual subject. This information can be used for patient specific and objective evaluation of walking balance and a better guidance of therapies during the rehabilitation. Trial registration: The study protocol is a subset of a larger protocol and registered in the Netherlands Trial Registry, number NTR3636.