Postural stability analysis in virtual reality using the HTC vive

Altered postural control has been observed in chronic ankle instability (CAI). Kinesiophobia (fear of re-injury) has been identified as a factor influencing postural stability. Therefore, postural control was assessed during jump landing among CAI athletes with and without kinesiophobia, as well as healthy controls. A total of 60 participants were recruited, including 40 individuals with CAI and 20 healthy controls. The CAI group was subdivided into two cohorts: 20 subjects with kinesiophobia (Tampa Scale of Kinesiophobia score > 37) and 20 without kinesiophobia. All participants performed a single-leg jump landing task on a force plate. The following postural stability metrics were calculated: time to stabilization (TTS), and the mean and standard deviation of center of pressure (COP) displacement and velocity in the anterior-posterior (AP), medial-lateral (ML), and total directions. CAI subjects with kinesiophobia exhibited longer TTSs in the AP (p = 0.019), vertical, and total directions (p < 0.001, p = 0.015, p = 0.002) than healthy subjects. Additionally, CAI subjects with kinesiophobia demonstrated a significant increase in the velocity of COP displacement in the AP and ML directions (p < 0.001, p = 0.004). These individuals showed greater variability in the velocity of COP displacement in the AP direction and in COP displacement in the ML direction than healthy subjects (p < 0.001). Also, CAI with kinesiophobia group presented less variability in the velocity of COP displacement in the ML direction than other groups (p < 0.001, p = 0.026). CAI with kinesiophobia group needed more time and more velocity in the AP direction than without kinesiophobia group (p = 0.003). Individuals with a high fear of re-injury may perceive the jump landing task as threatening, requiring more time to land and regain stability. This fear can restrict the variability of velocity in the ML direction, resulting in decreased control over the AP direction due to limitations on managing degrees of freedom.

Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty

Individuals with transtibial amputation exhibit altered movement strategy to sustain stability during quiet standing due to reduced proprioception on the amputated limb. The aim of this study is to determine the movement strategies in anterior–posterior and medial–lateral directions in predicting the overall postural stability. In this crossover study, postural stability of ten transtibial amputees was assessed using computed posturography while wearing different prosthetic foot types: solid ankle cushion heel (SACH), single axis (SA) and energy storage and return (ESAR). Three stability indices were measured during four conditions: standing with eyes opened and closed, standing on compliant surface and standing with tilted head. From the standard multiple regression analysis, 63% to 99% of the OSI score in all sensory conditions were explained from the MLSI score, while 11% to 56% from the APSI score. The Pearson’s [Formula: see text] indicated significant strong positive relationship between OSI and MLSI [Formula: see text]–[Formula: see text] during all sensory conditions. The APSI score was significantly lower than OSI during eyes-closed and head extended conditions for all prosthetic feet [Formula: see text]. Adjustments in postural stability strategies in transtibial amputees mostly occurred in medial–lateral direction regardless of prosthetic feet types and altered sensory conditions.

Controlled single-group pretest/posttest design. The purpose of this study was to determine if a 6-week neuromuscular training program designed to decrease the incidence of anterior cruciate ligament (ACL) injuries would improve single-limb postural stability in young female athletes. We hypothesized neuromuscular training would result in an improvement in postural stability, with the greatest improvement taking place in the medial-lateral direction. Balance training has become a common component of programs designed to prevent ACL injury. Rehabilitation programs can improve postural stability following ACL injury and reconstruction; however, there is limited information available which quantifies improvement of postural stability following neuromuscular training designed to prevent ACL injuries in a healthy population. Forty-one healthy female high school athletes (mean age, 15.3 years; age range, 13-17 years) participated in this study. Single-limb postural stability for both lower extremities was assessed with a Biodex Stability System. The neuromuscular training program consisted of three 90-minute training sessions per week for 6 weeks. Following the completion of the training program, each subject was re-evaluated to determine change in total, anterior-posterior, and medial-lateral single-limb stability. Two-way analysis of variance models were used to determine differences between pretraining and posttraining and between limbs. The subjects showed a significant improvement in single-limb total stability (P = .004) and anterior-posterior stability (P = .001), but not medial-lateral stability (P = .650) for both the right and left lower extremity following training. In addition, the subjects demonstrated significantly better total postural stability on the right side as compared to the left (P = .026). A 6-week neuromuscular training program designed to decrease the incidence of ACL injuries improves objective measures of total and anterior-posterior single-limb postural stability in high school female athletes.

To assess measures of postural stability in a large population of persons aged over 60 years in order to compare performance between fallers and non-fallers and relate postural stability to fracture prevalence. The sensorimotor, visual and balance functions were measured in 1762 ambulatory, community-dwelling patients aged between 60 and 100 years (mean age, 70.1 years) living in a large semi-urban Australian city. A history of recent falls and fractures was recorded at the time of assessment. The prevalence of impairment in all tests increased with age. Men performed significantly better than women in tests of muscle strength, visual field dependence, sway on the floor with eyes open and dynamic balance. In the 12 months before testing, 72.3% of the patients experienced no falls, 18.4% fell only once and 9.3% fell on two or more occasions. Multiple fallers had weaker quadriceps, poorer tactile sensitivity, greater visual field dependence and greater body sway than other patients. Test scores for once-only fallers were mostly between those for non-fallers and multiple fallers. Those who suffered recent fall-related fractures had significantly reduced tactile sensitivity and quadriceps strength and increased body sway. Postural stability was also impaired in patients taking psychoactive and/or anti-hypertensive medications. Tests of postural stability can identify, independently of age, individuals living in the community who are at risk of falls and fall-related fractures.

Introduction: Flat feet or flatfeet are the postures that have a low medial longitudinal arch. The prevalence ofFlat feet was 10-25% of adults population. The lower feet arch might have an impact on body sway have duringstanding posture. Furthermore, increasing of the postural sway could have the higher risk of fall in elderly, thathas a prevalence of 30-50%. The aim study to find the correlation between the Flat feet posture with posturalstability, to prevent the risk of fall in the elderly.Method: This design was observational cross-sectional study. The study conducted in the elderly nursing home.The posture was examined by ink feet print on white paper. The Tinetti Balance Assessment assessed the posturalstability.Result: The subjects were 84 elderly, mostly were 60-74 years old, and 46 (54,8%) were female. The mostprevalence of the postural stability was the low risk of fall (59,5%). The frequency of Flat feet was 26 (31%).There was a relationship between Flat feet with postural stability in elderly (p = 0,020).Conclusion: There was a correlation between the Flat feet and the postural stability on elderly in the nursinghome.Keywords: Flat feet, postural stability, elderly

In 1983, the board of the Japan Society for Equilibrium Research presented a standard of stabilometry, but some problems remain.In order to determine the test conditions, we performed the following examination with a standard stabilometer.1 . For visual target testing, the distance from the subject to the target and the illumination of the peripheral visual field were studied.2. For the standing posture, body sway in the military standing posture was compared with that in natural standing.3. For foot position, body sway while standing with both feet together was compared with that feet in the fan-shaped position and with feet apart but parallel.4. For recording time, body sway while standing for 30 seconds was compared with that while standing for 60 seconds.5. To elimilinate transitional sway after standing erect with eyes closed, the time when the recording should start was studied.The parameters for stabilometry are as follows ; unit locus lengh, forward-backward and right-left diameters, area, rejection ellipse, center of sway, standard deviation, skewness and kurtosis of amplitude probability density distribution, velocity, vector of velocity, power spectrum.1. When the visual target was placed one meter from the subject and the peripheral field of vision was lighted, the mean and standard deviation of all parameters in stabilometry were the smallest.2. Standard deviations of the unit locus length, area and velocity during military posture standing were lower than during natural standing. However, maintenance of military standing for 60 seconds was difficult. Therefore, stabilometry with natural standing was considered more suitable for clinical examinations.3. Body sway while standing with feet 10 cm apart was less than when standing with the feet close together or in the fan-shaped position. However, standing with the feet close together was suitable for detecting slight equilibrium disturbances.4. Body sway observation for 60 seconds clarified the pattern of the body sway more definitely than did observation for 30 seconds.5.Irregular sway was recorded after the subject stood erect with eyes closed for 10 seconds. To eliminate transitional sway, the recording should be started when the body movements of the standing subject are stabilized.

To quantify how postural stability is modified during experimental pain while performing different cognitively demanding tasks. Sixteen healthy young adults participated in the experiment. Pain was induced by intramuscular injection of hypertonic saline solution (1mL, 6%) in both vastus medialis and vastus lateralis muscles (0.9% isotonic saline was used as control). The participants stood barefoot in tandem position for 1min on a force plate. Center of pressure (CoP) was recorded before and immediately after injections, while performing two cognitive tasks: (i) counting forwards by adding one; (ii) counting backwards by subtracting three. CoP variables-total area of displacement, velocity in anterior-posterior (AP-velocity) and medial-lateral (ML-velocity) directions, and CoP sample entropy in anterior-posterior and medial-lateral directions were displayed as the difference between the values obtained after and before each injection and compared between tasks and injections. CoP total area ( - 84.5 ± 145.5 vs. 28.9 ± 78.5cm2) and ML-velocity ( - 1.71 ± 2.61 vs. 0.98 ± 1.93cm/s) decreased after the painful injection vs. Control injection while counting forward (P < 0.05). CoP total area (12.8 ± 53.9 vs. - 84.5 ± 145.5cm2), ML-velocity ( - 0.34 ± 1.92 vs. - 1.71 ± 2.61cm/s) and AP-velocity (1.07 ± 2.35 vs. - 0.39 ± 1.82cm/s) increased while counting backwards vs. forwards after the painful injection (P < 0.05). Pain interfered with postural stability according to the type of cognitive task performed, suggesting that pain may occupy cognitive resources, potentially resulting in poorer balance performance.

To investigate the utility of risk factors such as bone mineral density, lifestyle, and postural stability in the prediction of osteoporotic fractures. Longitudinal, epidemiological, and population based survey. City of Dubbo, New South Wales. All residents of Dubbo aged > or = 60 on 1 January 1989. Incidence of fracture for individual subjects. The overall incidence of atraumatic fractures in men and women was 1.9% and 3.1% per annum respectively. The predominant sites of fracture were hip (18.9%), distal radius (18.5%), ribs and humerus (11.9% in each case), and ankle and foot (9.1% and 6.6% respectively). Major predictors of fractures in men and women were femoral neck bone mineral density, body sway, and quadriceps strength. Age, years since menopause, height, weight, and lifestyle factors were also correlated with bone mineral density and body sway and hence were indirect risk factors for fracture. Discriminant function analysis correctly identified 96% and 93% (sensitivities 88% and 81%) of men and women, respectively, who subsequently developed atraumatic fractures. Predictions based on this model indicated that a woman with a bone mineral density in the lowest quartile in the hip together with high body sway had a 8.4% probability of fracture per annum. This represented an almost 14-fold increase in risk of fracture compared with a woman in the highest bone mineral density quartile with low postural sway. An individual with all three predictors in the "highest risk" quartile had a 13.1% risk of fracture per annum. Bone mineral density, body sway, and muscle strength are independent and powerful synergistic predictors of fracture incidence.

: Purpose: The aim of this investigation was to evaluate the effects on neurocognitive performance and postural stability of inspired CO2 and breathing resistance during endurance exercise. Methods: Subjects (N=16) completed five dives. Each dive involved a different combination of inspired CO2 (0%, 1%, and 2% SEV CO2) and breathing resistance (work of breathing per tidal volume of 1.0 kPa and 1.8 kPa at a minute ventilation of 62.5 L/min. Neurocognitive functioning was assessed pre/post each dive using a subset of Automated Neuropsychological Assessment Metrics (ANAM). Postural stability was assessed post each dive through the use of a Wii Balance Board. Amplitude and sample entropy (SampEn) were calculated for the center of pressure (COP) in both the anterior-posterior (X) and medial-lateral (Y) directions. A general linear model multivariate analysis of variance (GLM MANOVA) with repeated measures was conducted to evaluate the effect of exercise and breathing conditions on ANAM performance. Four GLM MANOVAs with repeated measures were conducted to evaluate the effect of breathing conditions on postural stability. Alpha was set at p = 05. Results: There were no significant differences found. Conclusions: The results of this study can be interpreted as the various combinations of high CO2 levels and high breathing resistance did not impair neurocognitive performance and postural stability. Future studies should focus on other neurocognitive and neurophysiological tests to verify these results. However, it should be noted that the individuals who were most likely to have shown neurocognitive effects from the CO2 exposures did not complete post-exercise neurocognitive assessments.

This paper presents an experimental study to investigate how humans interact with a robotic arm simulating primarily unstable, damping-defined, mechanical environments, and to quantify lower bounds of robotic damping that humans can stably interact with. Human subjects performed posture maintenance tasks while a robotic arm simulated a range of negative damping-defined environments and transiently perturbed the human arm to challenge postural stability. Analysis of 2-dimensional kinematic responses in both the time domain and phase space allowed us to evaluate stability of the coupled human-robot system in both anterior-posterior (AP) and medial-lateral (ML) directions, and to determine the lower bounds of robotic damping for stable physical human-robot interaction (pHRI). All subjects demonstrated higher capacity to stabilize their arm against negative damping-defined environments in the AP direction than the ML direction, evidenced by all 3 stability measures used in this study. Further, the lower bound of robotic damping for stable pHRI was more than 3.5 times lower in the AP direction than the ML direction: -30.0 Ns/m and -8.2 Ns/m in the AP and ML directions, respectively. Sensitivity analysis confirmed that the results in this study were relatively insensitive to varying experimental conditions. Outcomes of this study would allow us to design a less conservative robotic impedance controller that utilizes a wide range of robotic damping, including negative damping, and achieves more transparent and agile operations without compromising coupled stability and safety of the human-robot system, and thus improves the overall performance of pHRI.

The purpose of this study was to examine the effects of visual and somatosensory information on body sway in individuals with Down syndrome (DS). Nine adults with DS (19-29 years old) and nine control subjects (CS) (19-29 years old) stood in the upright stance in four experimental conditions: no vision and no touch; vision and no touch; no vision and touch; and vision and touch. In the vision condition, participants looked at a target placed in front of them; in the no vision condition, participants wore a black cotton mask. In the touch condition, participants touched a stationary surface with their right index finger; in the no touch condition, participants kept their arms hanging alongside their bodies. A force plate was used to estimate center of pressure excursion for both anterior-posterior and medial-lateral directions. MANOVA revealed that both the individuals with DS and the control subjects used vision and touch to reduce overall body sway, although individuals with DS still oscillated more than did the CS. These results indicate that adults with DS are able to use sensory information to reduce body sway, and they demonstrate that there is no difference in sensory integration between the individuals with DS and the CS.

Purpose The benefits of motor control-based therapeutic exercise and its combination with whole-body vibration in individuals with nonspecific Low Back Pain (NSLBP) are not well established. Methods Seventy-five females with NSLBP were randomly assigned to control, motor control, and combination groups. The experimental group received 3 therapeutic exercise sessions per-week for 8 weeks. The pre- and post-intervention measurements used in the current research included trunk muscle activation, the VAS, and postural stability assessments. Results The results indicated a decrease in the center of pressure path length in both the anterior-posterior and medial-lateral directions, a drop in pain, and an increase in all studied muscle activation following the intervention in the freestyle lifting task in the motor control and combination groups (p < 0.05). However, post-hoc analysis revealed no significant difference between the motor control and combination groups at post-test in any of the measured parameters (p > 0.05). Conclusion Both motor control exercises and their combination with whole-body vibration effectively improve pain, postural stability, and trunk muscle activation in individuals with NSLBP. Effects were generally comparable, with the combination offering only a slight additional pain reduction. Motor control exercises alone may be sufficient, while the combination can be an alternative.

Mobility-related problems in older people may be relieved by the use of walking canes. However, the influence of the cane length on the postural stability of cane users has not been explored. The objective of this study is to examine the influence of a single-point cane with different lengths on the postural sway of regular cane users, older women during two stance positions, with feet parallel and semi-tandem stance. Eighteen older women, who used a single-point walking cane for at least 6 months, stood on a force plate with feet parallel or in semitandem position for 40 s. They always used a cane that was adjusted to one of three different lengths resulting from the distance between the wrist crease and the floor, named WF, or this distance plus 7.5 or 10 cm. Amplitude and speed of the centre of pressure (COP) and its components (rambling and trembling) in the anterior-posterior and medial-lateral directions and mean vertical force applied to the cane were compared across cane lengths. The amplitude and velocity of COP, rambling and trembling increased with the cane length. This effect was observed for the anterior-posterior with the feet parallel and in the medial-lateral direction with the semi-tandem position. More force was applied on the shorter cane (WF) in semitandem position. Longer canes increased the postural sway in the older women and restricted the body weight loaded on the cane. Improper cane length influences the postural sway particularly in a semitandem stance of regular cane users. This may cause a negative impact on postural stability required in daily life activities. The current findings may contribute to the prescription of this assistive device for older adults.

To investigate the relations between the balance function and gross motor ability, we recruited 15 children with cerebral palsy from 5 to 12 years in age. Balance function was tested by the Smart Balance Master System and by clinical tests. The Motor Age test was used to test gross motor ability. Analysis showed that postural stability in eyes open, eyes closed, and swaying vision conditions (visual surrounding swaying with body sway), the duration of one leg standing, and the duration of maintaining a heel-to-toe position were significantly correlated with gross motor ability. Postural stability in the eyes-closed condition was the best predicting factor and could explain 64% of the variability of gross motor ability. Whether the training of postural stability in eyes-closed condition can improve the gross motor function needs further study.