Sway Parameters Research Articles

The effect of internal and external visualization of rotation on postural stability

IntroductionDuring mental rotation tasks, it is assumed that participants visualize a rotation of objects in their minds (internal visualization), but mental rotation has also been linked to the visible rotation of objects on a screen (external visualization). The angular disparity in mental rotation also influences postural sway, the movements of the body center. Postural sway is thus suspected as one type of indirect measurement of the rotation process. We compare the external visualization of rotation with the suspected internal visualization during mental rotation tasks. We suspect both are similar and thus produce a comparable effect on postural sway.MethodsOne hundred and fifty participants completed three rotation tasks with cube figures, two of which were aided by external visualization. Their center of pressure was measured throughout. The effects of external visualization, angular disparity, and their interaction on postural sway were compared using Bayesian statistics and a decision boundary of 3 or 1/3.Results and discussionThe results indicate no differences between conditions for all postural sway parameters. We observe differences between conditions in cognitive load and reaction time. However, as these partially also differ between the two external visualization conditions and do not transfer to differences between the postural sway parameters, the underlying processes in the three conditions are likely similar. Our results support the notion that the visualization of rotation is central to postural sway during mental rotation. This further supports that the rotation process of the external visualization and mental rotation are similar and thus that stimuli are indeed rotated mentally during mental rotation tasks. Our results further support that the common process between mental and manual rotation lies in the visualization instead of mental rotation being an imagined motor action. Because visual control and feedback play an essential role in many motor tasks, the results could also be of further interest for a more general link between motor and cognitive tasks and bidirectional benefits through the construction of visual similarities.

Assessment of postural sway with accelerometers: A comparison with force plate measures

Introduction & Purpose Postural control is essential for maintaining balance during static and dynamic tasks. It is typically measured by centre of pressure (CoP) deviations using a ground reaction force plate (FP). Alternatively, more affordable and accessible accelerometer-based measures have been proposed. However, no consensus on the best protocol exists (Pinho et al., 2019). This study investigates the feasibility of assessing postural sway using linear acceleration data, considering sensor placement, task difficulty and analysed parameters. Methods The University of Vienna Ethics Committee approved this study (Ref. Nr. 01108). Ten healthy adults (6 M/4 F; 37.9 ± 14.8 years; BMI = 23.3 ± 2.3) performed eleven balance tasks, seven easy tasks from the Berg Balance Scale and four harder tasks with eyes closed, each lasting 20 seconds. Postural sway was assessed using a FP and five inertial measurement units (IMUs) attached to the upper spine (C7), lower spine (L1), sacrum and both thighs. Data were synchronously collected at 1500 Hz, zeroed, band pass filtered (3rd order Butterworth, 0.3-10 Hz; Martinez-Mendez et al., 2012), and cropped to 19 s. Outcomes included CoP path length, root mean square of sway amplitude in the anteroposterior (AP) and mediolateral (ML) directions for the FP, and RMS of the linear acceleration in AP and ML directions, along with their sum, for the ACC. Combinations of the two AP, two ML and two overall parameters were analysed by winsorised Pearson correlations and Bland Altman limits of agreement of z-scores for each task and for each sensor site. Fisher's Z-transformed correlation coefficients and limits of agreement were compared across task difficulty, parameter combinations, and sensor placement sites using a 3-way ANOVA. Results Pearson coefficients correlating the ACC parameters with the FP parameters averaged 0.60 (95% CI [0.54, 0.66]) for the easy tasks and 0.78 (95% CI [0.726, 0.84]) for the hard tasks, with no significant differences between sensor sites. A significant interaction (p < 0.001) was found between task difficulty and parameter combination. Simple main effect analysis showed no difference between correlations of AP, ML and overall parameters for hard tasks but for easy tasks, where overall parameters showed the highest correlation, followed by ML and then AP parameters, all differing significantly from each other. The Bland Altman mean difference of z-scores between FP and ACC parameters was on average -0.002 (95% CI [-0.027, 0.024]). The lower and upper limits of agreement were on average -0.72 (95% CI [-0.84, -0.62]) and 0.73 (95% CI [0.62, 0.83]) respectively. Discussion The correlations between FP and ACC were higher during more challenging tasks, while the limits of agreement were broader and less precise in these tasks (data not shown). No optimal sensor placement site was identified as correlation and agreement between the two methods did not differ significantly between sites. The broad limits of agreement suggest relatively low precision of ACC measures compared to FP. Overall parameters often outperformed ML and AP parameters in terms of correlation and precision. Conclusion Accelerometer-based measures of postural sway showed high correlations with force plate measures but low precision when tasks where difficult enough to challenge participants’ balance. Sensor placement site did not influence correlation and precision. References Pinho, A. S., Salazar, A. P., Hennig, E. M., Spessato, B. C., Domingo, A., & Pagnussat, A. S. (2019). Can we rely on mobile devices and other gadgets to assess the postural balance of healthy individuals? A systematic review. Sensors, 19(13), Article 13. https://doi.org/10.3390/s19132972 Martinez-Mendez, R., Sekine, M., & Tamura, T. (2012). Postural sway parameters using a triaxial accelerometer: Comparing elderly and young healthy adults. Computer Methods in Biomechanics and Biomedical Engineering, 15(9), 899–910. https://doi.org/10.1080/10255842.2011.565753

Identifying the Problem Side with Single-Leg Squat and Hamstrings Flexibility for Non-Specific Chronic Low Back Pain.

Background and Objectives: In patients with non-specific chronic low back pain (LBP), their pain and problem sides can differ. Clinical Pilates assessment provides an approach to identify the problem side, but this approach requires experience and can be subjective. This study aimed to investigate if objective measures of single-leg squat postural control and hamstrings flexibility could identify the problem side in adults with non-specific chronic LBP. Materials and Methods: Forty adults with non-specific chronic LBP were tested on single-leg squat postural control and hamstrings flexibility. The problem side of participants was assessed with the Clinical Pilates method. Paired t-tests were used to compare the postural sway parameters of the single-leg squat and hamstrings flexibility between the problem and non-problem sides. Cohen's kappa was then used to assess the agreement of postural sway and flexibility measures with the Clinical Pilates method. Results: The problem side showed smaller vertical force variance, larger sway path distances, lower peak vertical force, smaller terminal knee flexion angle, longer time to complete the five single-leg squats, and tighter hamstrings as compared to the non-problem side. However, only the overall and anteroposterior sway path distances, terminal knee flexion angle, total squat duration, and hamstrings flexibility yielded moderate to strong agreement with the Clinical Pilates method. Conclusions: Single-leg squat postural sway parameters and hamstrings flexibility can objectively identify the problem side in adults with non-specific chronic LBP.

An anti-swing control method combining deep learning prediction models with a multistate fractional-order terminal sliding mode controller for wave motion compensation devices

Shipborne multidimensional wave motion compensation devices eliminate the relative motion of cargo between supply and supplied ships. However, the random sway of ships and complicated disturbances still cause various cargo swings. Therefore, an anti-swing control method is proposed that combines deep learning prediction models with a multistate fractional-order terminal sliding mode controller for wave motion compensation devices. First, the constrained workspaces and anti-swing trajectories of cargo based on deep learning prediction models are constructed to decrease the swings of cargo originating from ship sway and inaccurate control parameters. Second, a multistate fractional-order terminal sliding mode controller is presented to eliminate the disturbance-caused cargo swings. Third, the stability of the multistate sliding mode controller is proven. Finally, the effectiveness of the anti-swing control method is verified through simulations and experiments, and the experimental results demonstrate that the maximum amplitude of cargo swings is only a few millimetres and that the maximum mean absolute error of the payload swings is less than four millimetres.

Assessing fall risk in osteoporosis patients: a comparative study of age-matched fallers and nonfallers.

This study aimed to investigate sway parameters and physical activity level of the age/gender-matched older adults with osteoporosis faller and nonfaller patients. By examining these factors, our objective was to understand how these faller and nonfaller groups with osteoporosis differed particularly in terms of balance capabilities and their impact on physical activity levels. We recruited 24 patients with osteoporosis: 12 who reported a fall within a year before recruitment (fallers) and 12 without falls (nonfallers). Given the close association between biochemical markers of musculoskeletal health such as serum calcium, parathyroid hormone (PTH), Vitamin D, and renal function, we compared these markers in both groups. As a result, elderly individuals with osteoporosis and with a history of falls within the preceding year indicated significantly higher sway velocity (P = 0.012*), sway area (P < 0.001*), and sway path length (P = 0.012*). Furthermore, fallers had significantly lower calcium (P = 0.02*) and Parathyroid hormone (PTH) (P = 0.02*), as well as higher Alkaline Phosphatase (ALP) (P = 0.02*) as compared to nonfallers despite similar vitamin D and creatinine levels. In conclusion, diminished biochemical factors in the osteoporosis faller group could possibly cause postural instability resulting in lower physical activity levels in the osteoporosis fall group and increasing the risk of falls.

International validation of meaningfulness of postural sway and gait to assess myeloneuropathy in adults with adrenoleukodystrophy.

The most common manifestation of X-linked adrenoleukodystrophy (ALD) is a slowly progressive myeloneuropathy, which leads to imbalance and gait disturbances. The variable progression of the disease complicates evaluation of its progression rate. Wearable sensors allow for easy and frequent balance and gait collection. This study reports baseline data from a longitudinal study on the quantitative assessment of balance and gait with wearable sensors and their clinical relevance. Data were collected from adult patients in two institutions. Postural body sway and gait parameters were measured using accelerometers. Disease severity was measured by the Expanded Disability Severity Scale (EDSS). Falling frequency and quality of life (QOL) were collected in men. The relationship between sway and gait variables and EDSS score, participants' use of a walking aid, and falling frequency was evaluated. One hundred twenty individuals with ALD were included. Sway variables significantly differentiate participants' assistive device use. Sway and gait variables were correlated to the EDSS in both sexes. Both gait speed and sway were correlated with falling frequency in men from one institution. Select QOL subscores were correlated with the EDSS in males from one institution. Accelerometry generated comparable results across sites. This study confirms the clinical correlation between spinal cord disease and imbalance and gait in ALD. For the first time, this study shows clinically meaningful relationships for sway and gait with use of an assistive device, falling frequency and QOL. Wearable accelerometers are a valid means to measure sway and gait in ALD. These measures are promising outcomes for clinical trial designs to assess myeloneuropathy in ALD and to monitor disease progression in individuals.

Impact of professional dance training on characteristics of postural sway.

The stability of human upright posture determines the range and dynamics of movements performed. Consequently, the repertoire and quality of the movements performed by a dancer are mainly determined by the efficiency of postural control. This is of particular importance in professional dance training that should focus on shaping optimal movement‑posture interaction. To get a deeper insight into this problem, the impact of the training on postural sway characteristics during quiet stance was analyzed in 16 female students in the seventh grade of a ballet school and compared with the size‑ and age‑matched group of secondary school students. Center of pressure trajectories were recorded for 25.6 s while standing quiet with eyes open (EO) and then with eyes closed (EC). The assessment of postural control was based on novel normalized sway parameters including sway vector (SV), sway anteroposterior (AP) and mediolateral (ML) directional indices (DIAP and DIML), and sway ratios (SRAP and SRML). The results document a significant contribution of vision to postural stability control in ballet students, which seems to compensate for training‑related changes in joint mobility and altered activity ranges of the legs' muscles. In the control group standing with EC, SV amplitude increased only by 18% whereas in the ballet students tested in the same conditions, the increase exceeded 72%. Under full control of standing posture (EO test), the training‑related increase of leg muscle forces allows dancers to maintain balance with lesser effort as documented here by 21% reduced SRAP. Additionally, the dancers while tested with their EC exhibited a 12% increase in the anteroposterior sway with a concomitant reduction of the mediolateral sway. The resulting changes in the postural control asymmetry were documented by both DIAP/DIML and SV azimuth. In conclusion, our novel analysis of postural sway seems a useful tool in monitoring the effects of training as well as the proper course of postural control development in children and adolescents.

Mediolateral Postural Sway Velocity as a Possible Indicator of Ground Reaction Force-Derived 180⁰ Turn Performance in Male Soccer Players: A Cross-Sectional Study

The main aim of the study was to investigate the relationship between ground reaction force (GRF) derived postural sway and 180° turn performance in soccer players on the axis of dominant and non-dominant legs. Twenty-seven male soccer players (mean age 22.45 ± 2.7 years) from the same league level agreed to participate in the study. The participants underwent GRF-derived postural sway and 180⁰ turn tests using a force plate in separate sessions, with at least 24-hour intervals between sessions. Postural sway was assessed in anteroposterior and mediolateral directions during a single-leg stance, while the 180° turn performance was evaluated through GRF-derived turn time and turn sway. The correlation, multiple regression, and group differences were computed to test study hypotheses. Positive correlations were observed between postural sway measures and 180⁰ turn time for dominant and non-dominant legs (r-range from 0.384 to 0.550). No measure of postural sway was significantly related to the 180⁰ turn sway (p&amp;gt; 0.05). Multiple stepwise regression analysis indicated that mediolateral sway velocity explained 30% and 17% of the variance of 180⁰ turn time for dominant and non-dominant legs, respectively. No statistical inter-limb differences were noted for 180⁰ turn and postural sway parameters. The results suggest that improving single-leg postural performance may enhance male soccer players' 180° turn performance. Therefore, unilateral stability in the mediolateral direction should be considered a potential indicator of change of direction-based performances.

Lower limb lymphedema disrupts both static and dynamic balance

BackgroundThe impact of lower-limb-lymphedema on quality of life of patients regarding balance is unclear due to the scarcity of literature. The aim of this study was to determine the static and dynamic balance of patients with lower-limb-lymphedema in comparison with healthy subjects. MethodsThis case-control designed study included 30 lymphedema patients and 30 healthy individuals, of whom were 52 female and 8 male with a mean age of 50.63 ± 9.72 years. Static balance stability and anterior-posterior with lateral sway parameters on four conditions (eyes-opened-stable-ground, eyes-closed-stable-ground, eyes-opened-unstable-ground, eyes-closed-unstable-ground) and dynamic stability of all participants were evaluated. FindingsThe demographic variables were similar between the groups. Majority of the patients had lymphedema due to cancer surgery with a stage of 2. Dynamic stability was significantly disrupted in lymphedema group in comparison with controls (P = 0.049). Static balance parameters were impaired on all conditions except the eyes opened-stable ground in lymphedema patients (P = 0.048,P = 0.043,P = 0.017). The dynamic with static balance and lateral sway parameters were correlated with the duration of lymphedema(P = 0.046,P = 0.002,P = 0.005). Anterior-posterior sway on eyes-closed-unstable-ground condition was correlated with functional status (P = 0.02). Static balance on eyes-opened-unstable-ground condition and anterior-posterior sway parameters were correlated with physical activity level (P = 0.015,P = 0.016,P < 0.05). InterpretationClosing eyes and the deterioration of ground caused significant alteration of the static and dynamic balance both separately and together in patients with lower-limb-lymphedema compared to healthy subjects. Regarding the static and dynamic imbalance, we suggest the evaluation of balance and inclusion of balance exercises in routine lymphedema rehabilitation program, especially in the early period of disease.

Impact of Differing Instability Devices on Postural Sway Parameters

Single-limb balance training is integral to preventing and rehabilitating lower extremity injuries. Previous investigations have shown that when using instability devices, differences may or may not exist in the postural sway parameters during use, depending on the specific devices being assessed. Thus, this investigation sought to examine the differences between a commonly used foam pad and a novel instability device (block) in postural sway measures. Twenty-two healthy individuals with no history of lower extremity injury or neurological disorders participated in this investigation. The participants performed three single-limb static balance exercises on a force platform sampling at 120 Hz. Each condition contained three 10-s trials separated by thirty seconds. The mean CoP values of the three trials in each condition were then compared using a within-subjects repeated-measures analysis of variance. Statistically significant differences were seen in the sway area between conditions (p = 0.009), the CoP path length (p = 0.007), the peak medial–lateral CoP displacement (p = 0.004), and the average sway velocity (p = 0.007). All variables displayed similar trends whereby the control condition showed significantly lower values than both instability devices, with no differences between devices. This investigation provides supporting evidence that different instability devices may deliver similar changes to postural sway parameters compared to control conditions. The novel block instability device used in this investigation may be used similarly to the traditional foam pad in prevention and rehabilitation settings based on the absence of differences between the two devices.

Relationship between functional movement screen scores and postural stability in football players: An asymmetrical approach

Introduction: Unilateral preference is dominant due to the intensive use of sport-specific movements in football. However, little is known about the possible correlation between unilateral functional movement and the center of pressure-based postural performance. The main aim of this study is to examine the correlation between functional movement screen (FMS) and postural stability in football players from an asymmetrical perspective. Materials and Methods: Fifty professional football players (male n = 25; age 21.40 ± 1.94 years; female n = 25; age 21.04 ± 1.24 years) volunteered for this study. All subjects completed a FMS test consisting of seven items and postural sway measures for dominant and non-dominant sides. Spearman’s correlation and the Mann-Whitney U-test were used for statistical processing. Results: A negative correlation was found between dominant and non-dominant sides FMS in scores and postural sway parameters in both male and female groups (p &lt; .05). Hurdle step (HS) and rotary stability (RS) proved to be strong predictors of postural stability for both groups (p &lt; .001). No significant differences were observed between dominant and nondominant sides in FMS items and postural sway parameters in both groups (p &gt; .05). Conclusions: The correlation of the FMS and postural sway measures may be useful to identify possible postural problems in football players. Therefore, the FMS test may be preferred by practitioners and physiotherapists.

Exploring the interplay between ankle muscle strength, postural control, and pain intensity in chronic ankle instability: A comprehensive analysis

BackgroundChronic Ankle Instability (CAI) is a common musculoskeletal condition characterized by recurring ankle sprains and impaired postural control (PC). Understanding the relationship between ankle muscle strength, PC, and the role of pain is essential for effective management. ObjectivesThis prospective cross sectional study aimed to 1. Compare ankle isometric muscle strength (IMS) and PC between CAI and asymptomatic sides. 2. Assess the correlations between ankle IMS and PC and explore the potential mediating effect of pain in individuals with CAI. MethodsA total of 44 individuals with CAI, were enrolled in the study. Ankle IMS (dorsiflexors, plantar flexors, invertors, and evertors) was measured using a dynamometer, while PC was evaluated using sway parameters (anterior-posterior and medial-lateral sway, ellipse area). Pain levels were reported using a Visual Analog Scale. ResultsThe CAI ankles exhibited significantly lower ankle IMS in all muscle groups compared to the asymptomatic ankles (p < 0.001). Additionally, the CAI side showed increased postural sway and a larger ellipse area (p < 0.001), indicating reduced PC. Negative correlations were observed between ankle IMS and PC parameters on the CAI side, with dorsiflexor strength showing correlations ranging from −0.423 to −0.387, plantar flexor strength ranging from −0.423 to −0.371, invertor strength ranging from −0.412 to −0.238, and evertor strength ranging from −0.451 to −0.365 (p < 0.001). Mediation analysis revealed that pain played a significant mediating role in connecting ankle IMS and PC parameters among individuals with CAI, with statistical significance (p < 0.05). ConclusionsIndividuals with CAI exhibit weaker ankle IMS and diminished PC in comparison to their healthy side. Moreover, pain was identified as a mediator in the relationship between ankle IMS and PC in CAI. These findings underscore the importance of addressing both ankle IMS and pain in the rehabilitation and management of CAI.

Postural control and trunk stability on sway parameters in adults with and without chronic low back pain

BackgroundPostural sway changes often reflect functional impairments in adults with chronic low back pain (LBP). However, there is a gap in understanding how these individuals adapt their postural strategies to maintain stability.PurposeThis study investigated postural sway distance and velocity, utilizing the center of pressure (COP) and center of gravity (COG), between adults with and without LBP during repeated unilateral standing trials.MethodsTwenty-six subjects with LBP and 39 control subjects participated in the study. Postural sway ranges, COP/COG sways, and sway velocities (computed by dividing path length by time in anteroposterior (AP) and mediolateral (ML) directions over 10 s) were analyzed across three unilateral standing trials.ResultsA significant group interaction in sway range difference was observed following repeated trials (F = 5.90, p = 0.02). For COG sway range, significant group interactions were demonstrated in both directions (F = 4.28, p = 0.04) and repeated trials (F = 5.79, p = 0.02). The LBP group demonstrated reduced ML sway velocities in the first (5.21 ± 2.43 for the control group, 4.16 ± 2.33 for the LBP group; t = 1.72, p = 0.04) and second (4.87 ± 2.62 for the control group, 3.79 ± 2.22 for the LBP group; t = 1.73, p = 0.04) trials.ConclusionThe LBP group demonstrated decreased ML sway velocities to enhance trunk stability in the initial two trials. The COG results emphasized the potential use of trunk strategies in augmenting postural stability and optimizing neuromuscular control during unilateral standing.

Stepping into emotions: investigating the effect of angry and fearful faces on forward stepping and quiet stance.

Facial expressions conveying an emotion may affect social interactions, such as approach- or avoidance-related behaviors. A specific facial feature is the gaze direction. An emotional facial expression such as anger will elicit distinct behavioral tendencies, depending on whether the angry gaze is directed toward the onlooker, or in a different direction. We tested whether facial expressions of anger and fear, combined with direct or averted gaze, elicit approach- or avoidance tendencies, using a go/no-go variant of the whole-body stepping task. Healthy adults stood on a force plate, recording the center of pressure (COP). Participants were presented with angry or fearful faces; either with direct or averted gaze. Participants had to identify the emotion, and "depending on instructions- either make a single step forward, or remain in a quiet stance. From the COP of the forward steps, we derived parameters such as reaction time and step size. From the quiet standing trials we derived parameters of postural sway, indicative of postural "freeze." We used analysis of variance to analyze the outcomes. First, we found that steps were initiated faster with angry faces than with fearful faces, in line with existing literature. Second, we did not observe a significant effect of gaze direction. Forward steps with direct and averted gaze had similar COP characteristics. Finally, we had expected to find freeze (postural immobility) with fearful faces, but this was also not observed. We discuss various explanations for the finding, and implications for research into the motoric grounding of social interactions.

Acute and chronic effects of stretching on balance: a systematic review with multilevel meta-analysis.

Balance is a multifactorial construct with high relevance in, e.g., everyday life activities. Apart from sensorimotor control, muscle strength and size are positively linked with balance performance. While commonly trained for via resistance training, stretch training has emerged as a potential substitution in specific conditions. However, no review has investigated potential effects of stretching on balance, yet. PubMed, Web of Science and Scopus were searched with inception to February, 2024. Studies were included if they examined acute and/or chronic effects of any stretching type against passive and/or active controls on balance parameters - without any population-related restrictions concerning sex/gender, age, health status, activity level. Methodological quality was assessed using PEDro scale. Meta-analyses were performed if two or more studies reported on the same outcome. Certainty of evidence was determined based on GRADE criteria. Eighteen acute and eleven chronic effect studies were included. Stretching studies exhibited significant improvements for sway parameters with eyes open against passive controls of moderate magnitude for chronic (ES: 0.63, p = 0.047) and of small magnitude for acute studies (ES: 0.21, p = 0.032). Most other subgroups against passive controls as well as actively-controlled comparisons resulted in trivial and/or non-significant effects. Even though some pooled effects slightly reached the level of significance, the overall results are biased by (very) low certainty of evidence (GRADE criteria downgrading for risk of bias, imprecision, publication bias). Moderators suggested by literature (strength, muscle size, flexibility, proprioception) were rarely assessed, which prevents conclusive final statements and calls for further, high quality evidence to clarify potential mechanisms-if any exist.

Effect of sit-stand workstation position and computer task on head and trunk postural sway and discomfort

Adjustable-height desks may provide musculoskeletal health benefits to offset the effects of prolonged sitting. One mechanism may be increased postural variability, here characterized by head and trunk postural sway. Linear acceleration of the head and trunk were measured while participants used computer workstations in seated and standing positions during keyboard and mouse tasks; secondary measures were discomfort and proprioception (head and neck repositioning error). Median accelerations of the head and trunk were 20–26% lower in mouse tasks compared to keyboard tasks (p < 0.01). There were no significant differences in sway parameters between seated and standing positions. Discomfort and proprioception were correlated; subjects who experienced increased neck discomfort after 1.5 h of computer work had almost twice the head and neck repositioning error. The results suggest that postural sway is more affected by different tasks (keyboard vs. mouse) than by different workstation configurations and that low proprioception acuity may relate to the development of discomfort.

Facilitating or disturbing? An investigation about the effects of auditory frequencies on prefrontal cortex activation and postural sway.

Auditory stimulation activates brain areas associated with higher cognitive processes, like the prefrontal cortex (PFC), and plays a role in postural control regulation. However, the effects of specific frequency stimuli on upright posture maintenance and PFC activation patterns remain unknown. Therefore, the study aims at filling this gap. Twenty healthy adults performed static double- and single-leg stance tasks of 60s each under four auditory conditions: 500, 1000, 1500, and 2000 Hz, binaurally delivered through headphones, and in quiet condition. Functional near-infrared spectroscopy was used to measure PFC activation through changes in oxygenated hemoglobin concentration, while an inertial sensor (sealed at the L5 vertebra level) quantified postural sway parameters. Perceived discomfort and pleasantness were rated through a 0-100 visual analogue scale (VAS). Results showed that in both motor tasks, different PFC activation patterns were displayed at the different auditory frequencies and the postural performance worsened with auditory stimuli, compared to quiet conditions. VAS results showed that higher frequencies were considered more discomfortable than lower ones. Present data prove that specific sound frequencies play a significant role in cognitive resources recruitment and in the regulation of postural control. Furthermore, it supports the importance of exploring the relationship among tones, cortical activity, and posture, also considering possible applications with neurological populations and people with hearing dysfunctions.

Feasibility of at-home motor assessments using wireless technology in patients with myelopathy: year 1 follow up of CYGNET, an observational study of patients with adrenomyeloneuropathy (P6-6.006)

Feasibility of at-home motor assessments using wireless technology in patients with myelopathy: year 1 follow up of CYGNET, an observational study of patients with adrenomyeloneuropathy (P6-6.006)

Comparison of sway meter and Kinovea software as a tool of measurement for the sway parameters during quiet standing: An observational study

BackgroundSeveral attempts have been made to quantify postural sway, from simple observational techniques to advanced computer technology. Measuring sway using commercial motion tracking devices and force plates are expensive and not feasible in evaluation on non-standardised surfaces. Video cameras can be used as an affordable alternative to perform human motion capturing, and this data can be analysed using motion tracking software like Kinovea; a free, reliable software that provides valid data, and an acceptable level of accuracy in angular and linear measurements. This study evaluated the reliability of Kinovea software to measure the sway amplitude in comparison with sway meter. MethodsThirty-six young women were recruited by convenience to this prospective observational study. Sway amplitude of the participants were measured using a sway meter on three different surfaces, with eyes opened and closed conditions, using modified Lords sway meter and videography. Videos were later analysed using Kinovea motion analysing software. The quantitative data of sway parameters were analysed for reliability using intraclass-correlation co-efficient and Bland Altman plot. ResultsThere was an excellent correlation (>0.90) between the sway measurement values obtained from both methods irrespective of the surfaces. But the reliability was greater for the medio-lateral sway on the pebbled surfaces (0.981), and least for the anterior posterior sway on the same surface. ConclusionThis study concludes that, there is an excellent reliability for the video based sway analysis using Kinovea software. Hence this method can be used as an affordable alternative to measure the sway parameters.

Postural stability in blepharospasm: the effects of dual-tasking and botulinum toxin therapy

BackgroundBlepharospasm is a focal dystonia that presents as involuntary, intermittent, continuous contractions of the eyelids. Abnormal eyelid contractions in blepharospasm are expected to cause balance problems, but there is no...