Patterns of postural sway in high anxious children

The influence of fear of falling on the control of upright stance across the lifespan

BACKGROUND

Standing at height, and subsequent changes in emotional state (e.g., fear of falling), lead to robust alterations in balance in adults. However, little is known about how height-induced postural threat affects balance performance in children. Children may lack the cognitive capability necessary to inhibit the processing of threat and fear-related stimuli, and as a result, may show more marked (and perhaps detrimental) changes in postural control compared to adults. This work explored the emotional and balance responses to standing at height in children, and compared responses to young and older adults.

METHODS

Children (age: 9.7 ± 0.8 years, n = 38), young adults (age: 21.8 ± 4.0 years, n = 45) and older adults (age: 73.3 ± 5.0 years, n = 15) stood in bipedal stance in two conditions: at ground level and 80 cm above ground. Centre of pressure (COP) amplitude (RMS), frequency (MPF) and complexity (sample entropy) were calculated to infer postural performance and strategy. Emotional responses were quantified by assessing balance confidence, fear of falling and perceived instability.

RESULTS

Young and older adults demonstrated a postural adaptation characterised by increased frequency and decreased amplitude of the COP, in conjunction with increased COP complexity (sample entropy). In contrast, children demonstrated opposite patterns of changes: they exhibited an increase in COP amplitude and decrease in both frequency and complexity when standing at height.

SIGNIFICANCE

Children and adults adopted different postural control strategies when standing at height. Whilst young and older adults exhibited a potentially protective "stiffening" response to a height-induced threat, children demonstrated a potentially maladaptive and ineffective postural adaptation strategy. These observations expand upon existing postural threat related research in adults, providing important new insight into understanding how children respond to standing in a hazardous situation.

The relationship between balance and urinary cortisol and neopterin in autistic children

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by stereotyped behavior, restricted interests and social/communicative deficits. The physiological etiology of ASD is not currently understood, however recent research has implicated dysregulation of the immune system as a central feature. The interplay between the stress systems, the immune system and the brain has been well-documented and implicated in other psychiatric and neurological disorders. This interplay suggests a role for the hypothalamic-pituitary-adrenal (HPA) axis in the etiology of ASD. We assessed levels of urinary cortisol and neopterin as markers of immune function and HPA activation in a cohort of 50 children from the central Johannesburg region. Additionally, we used the Autism Treatment Evaluation Checklist to assess autistic symptomatology and the Bruininks-Oseretsky Motor Proficiency Test (Second Edition) (BOT-2) to assess motor skills. No relationships were found between cortisol and autistic symptomatology. No relationships were found between neopterin and any of the other measures. However, a relationship was observed between urinary cortisol and performance on balance-related tasks from the BOT-2 (P < 0.05). Our findings support a theory of neurological interconnectedness between postural modulation and activation of the stress system, which has not previously been documented in children with ASD.

Movement variability in Pilates: a scoping review

Objective

This scoping review aimed to identify studies that analyzed movement variability in Pilates. Following a systematic approach to mapping evidence on this topic would highlight concepts, theories, sources, and knowledge gaps in this area.

Methods

This review used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) criteria for the selection, reading, and analysis of studies in this area. We searched five literature databases (Web of Science, SCOPUS, library catalog of the Faculty of Sport and Physical Education of the University of Coimbra-EBSCO Discovery Services, MEDLINE, and Google Scholar). Eligible articles contained the word "Pilates," and the human movement variability was analyzed. Any type of study (except reviews) could be eligible and must have been published between 1 January 2002 and 30 November 2022, in Portuguese, Spanish, French, or English.

Results

Our search identified five eligible entries. Only one study used the Pilates method in its intervention, pointing to a more significant variability of hip-knee coordination, suggesting more diversified coordination patterns, and maintaining the variability of the angular position of the joint.

Conclusion

Very few studies have examined movement variability in Pilates, and only one applied an ecological framework.

Standing Posture in Motor and Cognitive Dual-Tasks during Smartphone Use: Linear and Nonlinear Analysis of Postural Control

Analysis of the center of pressure (CoP) during cognitive or motor dual-tasking is widely used to characterize postural control. Most studies use traditional measures of CoP to quantify postural control, but given its complexity, nonlinear analysis of CoP is of growing interest in the area. This study aims to analyze CoP behavior in healthy young adults during standing posture performance while simultaneously performing motor or cognitive tasks on a smartphone, using linear and nonlinear analysis of CoP. Thirty-six healthy participants (23.08 ± 3.92 years) were found eligible for this study. They performed a single task (ST), cognitive dual-task (cog-DT), and motor dual-task (mot-DT). The total excursion of CoP, displacement of CoP in the anterior-posterior and medial-lateral directions, mean total velocity of CoP, and mean anterior-posterior and medial-lateral velocities of CoP were measured with a force plate. Approximate entropy (ApEn) of the anterior-posterior (ApEn-AP) and medial-lateral (ApEn-ML) displacement of CoP were also calculated. The results showed that dual-task costs for the total excursion, displacement in the anterior-posterior direction, mean total velocity, and mean anterior-posterior velocity of CoP were greater during the cog-DT than the mot-DT (p < 0.05). In the nonlinear analysis of the CoP, there was no difference (p > 0.05) between the cog-DT and mot-DT for ApEn values of the anterior-posterior and medial-lateral time series of the CoP. Both linear and nonlinear analyses showed differences between the cog-DT and ST (p < 0.05), revealing a decline in postural control during the cog-DT compared with the ST. In conclusion, performing a cog-DT causes sway impairments and lower postural control efficacy compared with motor single and dual-tasks. Furthermore, both linear and nonlinear analyses were able to distinguish between conditions.

Development of postural stability in children with autism spectrum disorder: a cross-sectional study

The purpose was to investigate the effects of age on postural stability for children with autism spectrum disorder (ASD). Twenty-nine children with mild ASD were assigned into one of the three groups: 6–8 years (U8), 9–11 years (U11) and 12–14 years (U14). Participants stood barefoot with both feet on a force platform and maintained stationary for 15 seconds during eyes-open and eyes-closed conditions. Center of pressure data were collected and variables were calculated, including displacements, total distances, sway areas, and sample entropy. The variables were compared among the three groups using a mixed-model ANOVA. The age group effect was significant for mediolateral center of pressure displacement (p = 0.04) and sway distance (p = 0.02). Post-hoc comparisons revealed that U8 exhibited greater mediolateral displacement and total distance compared to U14, regardless of test conditions. The U14 group exhibited improved mediolateral postural stability compared to U8, whereas no differences were found between U8 and U11 or between U11 and U14. This may suggest that children with ASD could slowly develop postural stability but only demonstrate significant changes over a long period of time. Early intervention programs aimed to improve complexity of postural control could be beneficial.

Overload of anxiety on postural control impairments in chronic stroke survivors: The role of external focus and cognitive task on the automaticity of postural control

Background

Despite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.

Methods

Postural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).

Results

Stroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.

Conclusions

The results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.

Autism - A Comprehensive Array of Prominent Signs and Symptoms

BACKGROUND

Autism Spectrum Disorder (ASD) is a multifaceted neurodevelopmental condition characterized by multiple psychological and physiological impairments in young children. According to the recent reports, 1 out of every 58 newly-born children is suffering from autism. The aetiology of the disorder is complex and poorly understood, hindering the adaptation of targeted and effective therapies. There are no well- established diagnostic biomarkers for autism. Hence the analysis of symptoms by the pediatricians plays a critical role in the early intervention.

METHODS

In the present report, we have emphasized 24 behavioral, psychological and clinical symptoms of autism.

RESULTS

Impaired social interaction, restrictive and narrow interests, anxiety, depression; aggressive, repetitive, rigid and self-injurious behavior, lack of consistency, short attention span, fear, shyness and phobias, hypersensitivity and rapid mood alterations, high level of food and toy selectivity; inability to establish friendships or follow the instructions; fascination by round spinning objects and eating non-food materials are common psychological characteristics of autism. Speech or hearing impairments, poor cognitive function, gastrointestinal problems, weak immunity, disturbed sleep and circadian rhythms, weak motor neuromuscular interaction, lower level of serotonin and neurotransmitters, headache and body pain are common physiological symptoms.

CONCLUSION

A variable qualitative and quantitative impact of this wide range of symptoms is perceived in each autistic individual, making him/her distinct, incomparable and exceptional. Selection and application of highly personalized medical and psychological therapies are therefore recommended for the management and treatment of autism.

The construct and concurrent validity of brief standing sway assessments in children with and without cerebral palsy

BACKGROUND

Standing postural sway is often quantified from center of pressure trajectories. During assessments of longer durations, children may fidget, thus limiting the feasibility and validity of sway recordings.

RESEARCH QUESTION

Do postural sway sample durations less than 30 s maintain construct and concurrent validity?

METHODS

In this case-control, observational study, we measured postural sway in 41 children (age 5-12 years, 23 typically developing (TD); 18 with spastic cerebral palsy (CP), 13 diplegic and 5 hemiplegic, 11 GMFCS level I and 7 level II) for 30-second eyes-opened and eyes-closed conditions. From a single recording, 5-second incremental durations of 5-30 s were considered in this analysis. We quantified anteroposterior, mediolateral, and transverse-plane sway using seven time-domain variables: root-mean-square error, total excursion, mean frequency, mean distance, sway area, and 95 % confidence circle and ellipse areas. Variables were calculated in eyes-opened and eyes-closed conditions, as well as the ratio of the two. Construct validity was evaluated by the persistence of large effect sizes (Glass's Δ ≥ 0.80) between CP and TD participants at shorter durations than 30 s. Concurrent validity was evaluated by the correlations of shorter duration measures to the 30 s measure.

RESULTS

Seven sway measures had large between-group effects (Glass's Δ ≥ 1.02) for the 30 s measure that persisted (Glass's Δ ≥ 0.81) at shorter durations (5-25 s) and also maintained concurrent validity (r ≥ 0.83). Six of these seven measures were taken in the eyes-closed condition, and all seven measures were in the mediolateral direction or transverse plane.

SIGNIFICANCE

Our analysis suggests that sway durations less than 30 s can uphold construct and concurrent validity. These measures were primarily in the eyes-closed conditions and mediolateral direction. These results are a promising indicator that shorter-duration sway measures may be of utility when fidgeting prevents longer recordings.

Automated identification of postural control for children with autism spectrum disorder using a machine learning approach

It is unclear whether postural sway characteristics could be used as diagnostic biomarkers for autism spectrum disorder (ASD). The purpose of this study was to develop and validate an automated identification of postural control patterns in children with ASD using a machine learning approach. 50 children aged 5-12 years old were recruited and assigned into two groups: ASD (n = 25) and typically developing groups (n = 25). Participants were instructed to stand barefoot on two feet and maintain a stationary stance for 20 s during two conditions: (1) eyes open and (2) eyes closed. The center of pressure (COP) data were collected using a force plate. COP variables were computed, including linear displacement, total distance, sway area, and complexity. Six supervised machine learning classifiers were trained to classify the ASD postural control based on these COP variables. All machine learning classifiers successfully identified ASD postural control patterns based on the COP features with high accuracy rates (>0.800). The naïve Bayes method was the optimal means to identify ASD postural control with the highest accuracy rate (0.900), specificity (1.000), precision (1.000), F1 score (0.898) and satisfactory sensitivity (0.826). By increasing the sample size and analyzing more data/features of postural control, a better classification performance would be expected. The use of computer-aided machine learning to assess COP data is efficient, accurate, with minimum human intervention and thus, could benefit the diagnosis of ASD.

Nonlinear Measures to Evaluate Upright Postural Stability: A Systematic Review

Conventional biomechanical analyses of human movement have been generally derived from linear mathematics. While these methods can be useful in many situations, they fail to describe the behavior of the human body systems that are predominately nonlinear. For this reason, nonlinear analyses have become more prevalent in recent literature. These analytical techniques are typically investigated using concepts related to variability, stability, complexity, and adaptability. This review aims to investigate the application of nonlinear metrics to assess postural stability. A systematic review was conducted of papers published from 2009 to 2019. Databases searched were PubMed, Google Scholar, Science-Direct and EBSCO. The main inclusion consisted of: Sample entropy, fractal dimension, Lyapunov exponent used as nonlinear measures, and assessment of the variability of the center of pressure during standing using force plate. Following screening, 43 articles out of the initial 1100 were reviewed including 33 articles on sample entropy, 10 articles on fractal dimension, and 4 papers on the Lyapunov exponent. This systematic study shows the reductions in postural regularity related to aging and the disease or injures in the adaptive capabilities of the movement system and how the predictability changes with different task constraints.

Time-course investigation of postural sway variability: Does anxiety exacerbate the sensory reweighting impairment in chronic stroke survivors?

Although anxiety is one of the most prevalent psychological disorders in stroke survivors, its effect on sensory reweighting has not yet been fully studied. The aim of this work was to investigate how anticipation of collision avoidance events affects sensory reweighting in chronic stroke survivors with low and high levels of anxiety (LA-stroke and HA-stroke, respectively), as compared with healthy controls (HC), under the condition of perturbed proprioception. Eighteen LA-stroke and 18 HA-stroke survivors, as well as 18 gender- and age-matched HC, participated in this study. Postural sway variability (i.e. Root Mean Square (RMS) of the COP velocity) was measured for a duration of 180 s under two conditions: quiet standing and standing while predicting random virtual spheres to be avoided. Proprioceptive perturbation was simulated using bilateral Achilles tendon vibration at mid duration (60 s) for both conditions. The results showed that the HC were able to timely use visual anticipation to reduce the postural sway variability induced by tendon vibration. However, marked delay in using such anticipation was observed in stroke participants, especially in the HA-stroke group, as indicated by a significant decrease in the RMS of the COP velocity late in the vibration phase. This is the first study to consider the effect of anxiety while comparing sensory reweighting between stroke and healthy participants. The results indicated that chronic stroke survivors, particularly those with HA, could not efficiently use sensory reweighting to maintain balance in sensory conflicting conditions, which may subject them to loosing balance and/or falling. These findings are critical for future assessment and planning of rehabilitation interventions and balance in chronic stroke survivors.

Balance Performance in Autism: A Brief Overview

Children with autism not only have limited social and communicative skills but also have motor abnormalities, such as poor timing and coordination of balance. Moreover, impaired gross motor skills hamper participation with peers. Balance control is interesting from a cognitive science perspective, since it involves a complex interplay between information processing, motor planning, and timing and sequencing of muscle movements. In this paper, we discuss the background of motor problems in children with autism, focusing on how posture is informed by sensory information processing. We also discuss the neurobiological basis of balance problems, and how this is related to anxiety in this group. We then discuss possible avenues for treatment of autism spectrum disorder (ASD) symptoms, especially as regards movement-related interventions. Finally, we present a theoretical outlook and discuss whether some of the symptoms in ASD can be understood from an embodied cognition perspective.

Comparison of Neurological and Cognitive Deficits in Children With ADHD and Anxiety Disorders

OBJECTIVE

To compare the neuro-cognitive profiles among initial clinic referred medication naive sample of children with anxiety disorders (ANXs) and ADHD in a youth sample.

METHOD

Three groups of patients, ANX ( n = 40), ADHD ( n = 48), and ANX + ADHD ( n = 33), aged 7 to 12 years, were compared with respect to their Physical and Neurological Examination for Subtle Signs (PANESS) and cognitive measures (digit span, digit symbol, Trail Making Test [TMT]-A and TMT-B, Stroop test).

RESULTS

ADHD group performed worse than the other two groups with regard to soft signs and cognitive test performance; ANX + ADHD were impaired relative to ANX but better than ADHD. Significant differences were found for gait and station problems, overflows and timed movements, TMT error points, and Stroop interference scores. ADHD patients had more difficulty in warding off irrelevant responses and lower speed of time-limited movements.

CONCLUSION

This clinical evaluation study suggested that ANX and ADHD seem to have significantly different neuro-cognitive features: Poorest outcomes were observed among children with ADHD; rather than problems of attention, inhibitory control deficits were the most prominent differences between ANX and ADHD; and the presence of ANX appears to have mitigating effect on ADHD-related impairments.

Low- and high-anxious hypermobile Ehlers-Danlos syndrome patients: comparison of psychosocial and health variables

Despite the frequent co-ocurrence of hypermobile Ehler-Danlos syndrome (hEDS) and pathological anxiety, little is known about the psychosocial and health implications of such comorbidity. Our aim was to explore the association between high levels of anxiety and psychosocial (catastrophizing, kinesiophobia, somatosensory amplification, social support and functioning), health (pain, fatigue, BMI, tobacco/alcohol use, depression, diagnosis delay, general health), and sociodemographic factors in people with hEDS. In this cross-sectional study, 80 hEDS patients were divided into two groups according to self-reported anxiety levels: low and high. Psychosocial, sociodemographic and health variables were compared between the groups. Forty-one participants reported a high level of anxiety (51.2%). No differences were found in the sociodemographic variables between high-anxious and low-anxious patients. The percentage of participants with severe fatigue and high depressive symptomatology was significantly higher in the high-anxious group (80.5 vs 56.4; 26.8 vs 12.8%, respectively). High-anxious hEDS patients also showed significantly higher levels of pain catastrophizing, somatosensory amplification as well as a poorer social functioning and general health. Multivariate analyses showed that somatosensory amplification, pain catastrophizing and poor social functioning are variables that increase the probability of belonging to the high-anxious group. Despite limitations, this first study comparing high-anxious versus low-anxious hEDS patients with respect to health aspects, highlight the importance of considering the psychosocial factors (many susceptible to modification), to improve the adjustment to this chronic condition and provide support to those affected through a biopsychosocial approach.

Regularity of Center of Pressure Trajectories in Expert Gymnasts during Bipedal Closed-Eyes Quiet Standing

We compared postural control of expert gymnasts (G) to that of non-gymnasts (NG) during bipedal closed-eyes quiet standing using conventional and nonlinear dynamical measures of center of foot pressure (COP) trajectories. Earlier findings based on COP classical variables showed that gymnasts exhibited a better control of postural balance but only in demanding stances. We examined whether the effect of expertise in Gymnastic can be uncovered in less demanding stances, from the analysis of the dynamic patterns of COP trajectories. Three dependent variables were computed to describe the subject's postural behavior: the variability of COP displacements (A_CoP), the variability of the COP velocities (V_CoP) and the sample entropy of COP (SEn_CoP) to quantify COP regularity (i.e., predictability). Conventional analysis of COP trajectories showed that NG and G exhibited similar amount and control of postural sway, as indicated by similar A_CoP and V_CoP values observed in NG and G, respectively. These results suggest that the specialized balance training received by G may not transfer to less challenging balance conditions such as the bipedal eyes-closed stance condition used in the present experiment. Interestingly, nonlinear dynamical analysis of COP trajectories regarding COP regularity showed that G exhibited more irregular COP fluctuations relative to NG, as indicated by the higher SEn_CoP values observed for the G than for the NG. The present results showed that a finer-grained analysis of the dynamic patterns of the COP displacements is required to uncover an effect of gymnastic expertise on postural control in nondemanding postural stance. The present findings shed light on the surplus value in the nonlinear dynamical analysis of COP trajectories to gain further insight into the mechanisms involved in the control of bipedal posture.

Static postural sway of women with and without fibromyalgia syndrome: A cross-sectional study

BACKGROUND

There is a frequent complaint about balance problems among fibromyalgia syndrome patients; however, there are not enough studies that have shown static postural sway of women with fibromyalgia syndrome. This study aimed to compare static postural sway of women with and without fibromyalgia syndrome.

METHODS

This is a cross-sectional study in which twenty-nine women with fibromyalgia syndrome and 20 without took part. A posturography evaluation was performed in six different situations (bipedal, right tandem and left tandem, with eyes opened and closed), and questionnaires for clinical depression symptoms, clinical anxiety symptoms, sleep quality, and Visual Analogue Scales for Pain and Fatigue were applied. Mann-Whitney U test was used to check differences among groups; Wilcoxon matched-pair test was used to check differences intragroup; Cohen d coefficient was used to measure effect sizes and Pearson Correlation Coefficient was used for correlations among variables. Level of significance adopted was 5%.

FINDINGS

Women with fibromyalgia syndrome have presented worse postural sway than women without fibromyalgia syndrome in all situations (P<0.05), and worse scores in all questionnaires (P<0.05). In the eyes closed situations, women with fibromyalgia syndrome presented worse postural sway than women without in the same conditions.

INTERPRETATION

Women with fibromyalgia syndrome have worse performance in the static posture test, more prominent in reduced support bases with eyes closed. Pain, fatigue, depression and anxiety may have directly influenced postural sway in fibromyalgia syndrome patients.

Tonic immobility differentiates stress responses in PTSD

BACKGROUND

Tonic immobility (TI) is a state of physical immobility associated with extreme stress and the development of posttraumatic stress disorder (PTSD). However, it is unknown whether TI is associated with a distinct actual stress response, i.e., objective immobility measured by a stabilometric platform. This study made a first step in exploring this as well as differences in body sway responses between PTSD patients and healthy controls. We hypothesized that PTSD would be related to increased body sway under stress, whereas TI would be related to decreased body sway under stress.

METHODS

Eye closure was selected as a PTSD-relevant stress induction procedure. Body sway and heart rate (HR) were measured in 12 PTSD patients and 12 healthy controls in four conditions: (1) maintaining a stable stance with eyes open, (2) with eyes closed, (3) during a mental arithmetic task with eyes open, and (4) with eyes closed.

RESULTS

As predicted, PTSD patients showed increased body sway from eyes open to eyes closed compared to controls and this effect was eliminated by executing the arithmetic task. Most importantly, retrospective self-reported TI was associated with lower body sway increases in PTSD and higher body sway decreases in controls from eyes-open to eyes-closed conditions.

CONCLUSIONS

These preliminary findings suggest that eye closure has a different effect on PTSD patients than controls and that high self-reported TI might indicate a distinct stress response pattern, i.e., a proneness for immobility. It may be relevant to take such individual differences in stress-response into account in PTSD treatment.

The influence of age, anxiety and concern about falling on postural sway when standing at an elevated level

Psychological processes may influence balance and contribute to the risk of falls in older people. While a self-reported fear of falling is associated with increased postural sway, inducing fear using an elevated platform can lead to reduced sway, suggesting different underlying mechanisms whereby fear may influence balance control. This study examined changes in postural sway, muscle activity and physiological measures of arousal while standing on a 65cm elevated platform, compared to floor level, in young and older adults. The older adults were classified as fall concerned or not fall concerned based on the Falls Efficacy Scale-International and anxious or not anxious based on the Goldberg Anxiety Scale. Fall concern did not affect the physiological and sway response to the elevated platform. In response to the postural threat, the anxious participants increased their sway frequency (p=0.001) but did not reduce sway range (p=0.674). Conversely, non-anxious participants showed an adaptive tightening of balance control, effectively reducing sway range in the elevated condition (p<0.001). Generalised anxiety in older adults appears to differentially affect postural control strategies under threatening conditions.

Posturographic destabilization in eating disorders in female patients exposed to body image related phobic stimuli

Human postural control is dependent on the central integration of vestibular, visual and proprioceptive inputs. Psychological states can affect balance control: anxiety, in particular, has been shown to influence balance mediated by visual stimuli. We hypothesized that patients with eating disorders would show postural destabilization when exposed to their image in a mirror and to the image of a fashion model representing their body ideal in comparison to body neutral stimuli. Seventeen females patients attending a day centre for the treatment of eating disorders were administered psychometric measures of body dissatisfaction, anxiety, depression and underwent posturographic measures with their eyes closed, open, watching a neutral stimulus, while exposed to a full length mirror and to an image of a fashion model corresponding to their body image. Results were compared to those obtained by eighteen healthy subjects. Eating disordered patients showed higher levels of body dissatisfaction and higher postural destabilization than controls, but this was limited to the conditions in which they were exposed to their mirror image or a fashion model image. Postural destabilization under these conditions correlated with measures of body dissatisfaction. In eating disordered patients, body related stimuli seem to act as phobic stimuli in the posturographic paradigm used. If confirmed, this has the potential to be developed for diagnostic and therapeutic purposes.

The Influence of Motor Imagery on Postural Sway: Differential Effects of Type of Body Movement and Person Perspective

The present study examined the differential effects of kinesthetic imagery (first person perspective) and visual imagery (third person perspective) on postural sway during quiet standing. Based on an embodied cognition perspective, the authors predicted that kinesthetic imagery would lead to activations in movement-relevant motor systems to a greater degree than visual imagery. This prediction was tested among 30 participants who imagined various motor activities from different visual perspectives while standing on a strain gauge plate. The results showed that kinesthetic imagery of lower body movements, but not of upper body movements, had clear effects on postural parameters (sway path length and frequency contents of sway). Visual imagery, in contrast, had no reliable effects on postural activity. We also found that postural effects were not affected by the vividness of imagery. The results suggest that during kinesthetic motor imagery participants partially simulated (re-activated) the imagined movements, leading to unintentional postural adjustments. These findings are consistent with an embodied cognition perspective on motor imagery.

Dynamics of postural control in Parkinson patients with and without symptoms of freezing of gait

BACKGROUND

It has been suggested that dynamical measures such as sample entropy may be more appropriate than conventional measures when analyzing time series data such as postural sway. We evaluated conventional and dynamical measures of postural sway in Parkinson disease (PD) patients with and without freezing episodes.

METHODS

COP (center of pressure) data were recorded during quiet standing with eyes open, eyes closed and while performing a dual task. Data for 16 patients with freezing of gait, 17 patients with no history of freezing and 24 healthy subjects were analyzed. The amount of postural sway was quantified using conventional measures, whereas for the characterization of the temporal structure of the COP data the normalized sway path and sample entropy was calculated.

RESULTS

Mean radius was higher and sample entropy was lower in patients with freezing symptoms as compared to healthy subjects in all three conditions. Dual-tasking significantly increased sway path length in patients with freezing, while normalized sway path did not change over conditions in this group.

CONCLUSIONS

Our findings show that postural sway is characterized by a combination of large radius, short normalized sway path and high regularity of the COP only in patients with freezing. This pattern becomes most prominent in a dual-task paradigm. This may explain higher occurrence of gait freezing in dual task situations with subsequent higher risk of falls. Results suggested that dynamic measures may add valuable information for characterizing postural stability in PD patients.

Attentional and sensory contributions to postural sway in children with autism spectrum disorder

Postural control is known to depend on sensory and cognitive factors. Little is known about how children with autism spectrum disorder (ASD) regulate static balance, and to what extent vision and cognition contribute to the regulation of balance in this group. We compared a group of children with mild ASD and a group of age- and gender-matched controls on various postural tasks, standing on a Wii Balance Board. We tested a sensory disturbance (closing the eyes) and a cognitive disturbance (word memorization) on the control of quiet standing. Analysis of center-of-pressure excursions revealed moderate effects of cognitive load, but clear effects of vision. We found a greater destabilizing effect of closing the eyes (greater postural excursions in the medio-lateral direction) for the ASD group than for controls. No group differences were found on word recall and on a standardized balance test (Movement Assessment Battery for Children; M-ABC2). We suggest that the postural effects reflect tighter coupling between vision and motor adjustments in ASD than in controls, which is consistent with recent suggestions of greater reliance on vision in this group.

Attention and postural control in patients with conversion paresis

OBJECTIVE

Current theories of conversion disorder (CD) propose that motor symptoms are related to heightened self-monitoring and excessive cognitive control of movements. We tested this hypothesis using quantification of performance on a continuous perceptuo-motor task involving quiet standing.

METHODS

Twelve CD patients and matched controls maintained static balance on a force platform under various attention conditions: (1) with eyes open; (2) with eyes closed (requiring enhanced attention to proprioceptive information to regulate posture); and (3) while performing an attention demanding cognitive task.

RESULTS

Compared to controls, CD patients displayed a greater decrease in postural stability in the 'eyes-closed' versus 'eyes-open' condition. In contrast, cognitive distraction led to a normalization of balance in CD. Moreover, sensitivity to the balance interventions correlated significantly with trauma reports and dissociative symptoms.

CONCLUSION

These results indicate that attention plays a crucial role in postural control in CD. More specifically, patients seem to inadvertently use deliberate control of posture (i.e., cognitive investment) of an otherwise nearly automatized perceptuo-motor task. Attentional distraction resulted in a temporary normalization of balance, which may be used to train individuals with CD to guide their attention in a more effective way.

Additive Effect of Repeated Bouts of Individualized Frequency Whole Body Vibration on Postural Stability in Young Adults

Whole body vibration (WBV) has been shown to improve force and power output as well as flexibility and speed, with improvements suggested to result from reduced electromechanical delays, improved rate of force development, and sensitivity of muscle spindles. Fixed frequency studies on postural control have been somewhat equivocal; however, individualized frequency protocols have shown promising results in other motor tasks. To assess this, 18 healthy young adults experienced three 4-minute WBV sessions with postural control assessed before vibration, after multiple exposures, and during recovery, with altered levels of sensory information available to the participants. Sway velocity, sway path length, and sway area were assessed in each environment. Study findings revealed that stability was impacted following WBV, with more challenging environments eliciting improvements persisting for 20 minutes. When the environment was less challenging, postural stability was impaired; however, the effects dissipated quickly (10-20 min). It was determined that exposure to individualized frequency WBV served to impair postural control when the challenge was low, but resulted in heightened stability when the overall challenge was high and vestibular information was needed for stability.

Self-reported mood, general health, wellbeing and employment status in adults with suspected DCD

Developmental Coordination Disorder (DCD) affects around 2-6% of the population and is diagnosed on the basis of poor motor coordination in the absence of other neurological disorders. Its psychosocial impact has been delineated in childhood but until recently there has been little understanding of the implications of the disorder beyond this. This study aims to focus on the longer term impact of having DCD in adulthood and, in particular, considers the effect of employment on this group in relation to psychosocial health and wellbeing. Self-reported levels of life satisfaction, general health and symptoms of anxiety and depression were investigated in a group of adults with a diagnosis of DCD and those with suspected DCD using a number of published self-report questionnaire measures. A comparison between those in and out of employment was undertaken. As a group, the unemployed adults with DCD reported significantly lower levels of life satisfaction. Whilst there was no significant difference between those who were employed and unemployed on General Health Questionnaire scores; both groups reported numbers of health related issues reflective of general health problems in DCD irrespective of employment status. While both groups reported high levels of depressive symptoms and rated their satisfaction with life quite poorly, the unemployed group reported significantly more depressive symptoms and less satisfaction. Additionally, the results identified high levels of self-reported anxiety in both groups, with the majority sitting outside of the normal range using the Hospital Anxiety and Depression Scale. These findings add to the small but increasing body of literature on physical and mental health and wellbeing in adults with DCD. Furthermore, they are the first to provide insight into the possible mediating effects of employment status in adults with DCD.

Mood impairments in adults previously diagnosed with developmental coordination disorder

BACKGROUND

Developmental coordination disorder (DCD) affects up to 6% of the population and is diagnosed on the basis of poor motor coordination. While we know rather little about its lifetime consequences, clear and significant difficulties remain through the lifespan for the majority. Reduced physical activity and, outside of the motor domain, significant mental health issues exist for many with DCD.

AIMS

This study provides the first investigation of the presence of mood disorders in adults with DCD.

METHOD

Symptoms of anxiety and depression were assessed using the Beck Depression and Spielberger Anxiety Inventories in 36 adults previously diagnosed with DCD vs. 49 age- and gender-matched typical controls. Amount and type of physical activity undertaken each week were also reported.

RESULTS

After controlling for their reduced level of weekly physical activity, the group with DCD reported significantly more symptoms of depression, state and trait anxiety than their peers.

CONCLUSIONS

This finding has important implications for consideration of intervention in DCD, as well as for investigation of the risk and protective factors at play in long-term outcome. Finally, the findings highlight the need for awareness of motor difficulties in those presenting with high levels of anxiety and depression, and vice versa.

Changes in postural sway frequency and complexity in altered sensory environments following whole body vibrations

Studies assessing whole body vibration (WBV) have produced largely positive effects, with some neutral, on postural control with frequencies between 25 and 40 Hz. However no conclusive evidence indicates that 25-40 Hz elicits the optimal beneficial effects. To address this issue, a larger range of vibration intensity (10-50 Hz at peak-to-peak amplitudes of 2 and 5mm) was employed while increasing the postural complexity (altered somatosensory and/or visual information) to assess acute effects of 4-min of WBV on postural control. Twelve healthy young adults underwent postural assessment at four time intervals (prior to, immediately following and 10 and 20 min post WBV). Findings revealed both postural sway frequency and sway complexity/regularity were affected by WBV. Baseline posture demonstrated increased sway frequency (p=.04) following WBV with no changes in sway complexity. When the support surface was altered, changes in both the frequency and complexity of sway were elicited (p=.027, .002, respectively). When both somatosensory and visual information were altered delayed improvements in postural control were elicited (p=.05 and .01, for frequency and complexity, respectively). Given the differential acute effects as a function of postural task complexity, future longitudinal studies could determine the overall training effect on sway frequency and complexity.

Motor coordination and psychosocial correlates in a normative adolescent sample

OBJECTIVES

Previous research has revealed an important relationship between motor coordination difficulties and internalizing problems such as anxiety and depressive symptoms. However, further research is needed to understand the potential mediating factors in this relationship. The aim of the current study was to examine whether the association between motor coordination and emotional functioning is mediated by self-perceptions in a normative sample of adolescents.

METHODS

Participants included 93 adolescents aged 12 to 16 years. The Movement Assessment Battery for Children-2 provided 2 indicators of motor coordination; the Mood and Feelings Questionnaire and Spence Children's Anxiety Scale provided 2 indicators of emotional functioning; and the Self-Description Questionnaire--II provided 6 indicators for self-perceived competence.

RESULTS

Structural equation modeling revealed that motor coordination affects emotional functioning via self-perceptions.

CONCLUSIONS

These results suggest that the relationship between motor coordination and emotional functioning in adolescents from a normative sample may be understood in terms of a mechanism by which motor coordination has an indirect impact on emotional outcomes through various self-perception domains. These findings have important implications for increasing awareness and developing appropriate treatment programs for motor coordination and emotional difficulties.

Organization of voluntary stepping in response to emotion-inducing pictures

The present experiment was conducted to examine the expectation that emotion stimuli influence the initiation and execution of voluntary stepping, a highly coordinated activity involving a sequence of medio-lateral and anterio-posterior weight shifts. Thirty participants made forward (approach) or backward (avoidance) steps on a forceplate in response to the valence of visual stimuli. Posturographic parameters of the steps, related to automatic stimulus evaluation, step initiation and step execution, were determined and analyzed as a function of stimulus valence and stimulus-response mapping. The results revealed marked effects of emotion on the step parameters of interest; unpleasant images caused an initial "freezing" response, and a tendency to move away from the stimuli. Pleasant stimuli, in contrast, were not found to induce approach tendencies. The results demonstrated that affect, especially negative emotions, and whole-body movements such as voluntary stepping are coupled.

Contribution of each leg to the control of unperturbed bipedal stance in lower limb amputees: new insights using entropy

The present study was designed to assess the relative contribution of each leg to unperturbed bipedal posture in lower limb amputees. To achieve this goal, eight unilateral traumatic trans-femoral amputees (TFA) were asked to stand as still as possible on a plantar pressure data acquisition system with their eyes closed. Four dependent variables were computed to describe the subject's postural behavior: (1) body weight distribution, (2) amplitude, (3) velocity and (4) regularity of centre of foot pressure (CoP) trajectories under the amputated (A) leg and the non-amputated (NA) leg. Results showed a larger body weight distribution applied to the NA leg than to the A leg and a more regular CoP profiles (lower sample entropy values) with greater amplitude and velocity under the NA leg than under the A leg. Taken together, these findings suggest that the NA leg and the A leg do not equally contribute to the control of unperturbed bipedal posture in TFA. The observation that TFA do actively control unperturbed bipedal posture with their NA leg could be viewed as an adaptive process to the loss of the lower leg afferents and efferents because of the unilateral lower-limb amputation. From a methodological point of view, these results demonstrate the suitability of computing bilateral CoP trajectories regularity for the assessment of lateralized postural control under pathological conditions.

To freeze or not to freeze? Affective and cognitive perturbations have markedly different effects on postural control

Similar effects have been reported for diverting attention from postural control and increased anxiety on the characteristics of center-of-pressure (COP) time series (decreased excursions and elevated mean power frequency). These effects have also received similar interpretations in terms of increased postural stiffness, suggesting that cognitive and affective manipulations have similar influences on postural control. The present experiment tested this hypothesis by comparing postural conditions involving manipulations of attention (diverting attention from posture using cognitive and motor dual tasks) and anxiety (standing at a height), and by complementing posturography with electromyographic analyses to directly examine neuromuscular stiffness control. Affective and cognitive manipulations had markedly different effects. Unlike the height condition, diverting attention from balance induced smaller COP amplitudes and higher sway frequencies. In addition, more regular COP trajectories (lower sample entropy) were found in the height condition than the dual-task conditions, suggesting elevated attentional investment in posture under the affective manipulation. Finally, based on an analysis of the cross-correlation function between anterior-posterior COP time series and enveloped calf muscle activity, indications of tighter anticipatory neuromuscular control of posture were found for the height condition only. Our data suggest that affective and cognitive perturbations have qualitatively different effects on postural control, and thus are likely to be associated with different control processes, as evidenced by differences in neuromuscular regulation and attentional investment in posture.