Search

Background: Achondroplasia is a rare genetic skeletal condition characterized by disproportionate short stature. There is limited evidence on postural control in adults with achondroplasia and how lower limb lengthening (intervention) interacts with body dynamics. This study investigated sway variability during quiet standing in adults with achondroplasia with natural growth (N) and with lower limb lengthening (LL). Methods: Sixteen adults performed bilateral/unilateral standing tasks. Linear (total excursion, amplitude, and ellipse area) and nonlinear (sample entropy and correlation dimension) center of pressure sway metrics were analyzed in the anteroposterior/mediolateral directions. Relationships between posture metrics, strength, and physical activity were explored. Between-groups statistics were calculated. Results: The LL group exhibited amplified linear sway, indicating larger postural deviations, and reduced sample entropy and correlation dimension, indicative of more rigid and repeated corrections. The N group exhibited more unpredictable and adaptive movement corrections. Numerous correlations emerged between strength and posture measures, with relationships altered by intervention. Conclusions: Adults with achondroplasia display distinct balance strategies influenced by intervention. The results indicate that LL is associated with altered variability and adaptability compared to natural development. Relationships with muscle strength spotlight a key role of muscle capacity in postural control modulation after growth alterations in this population.

Background: The Balance Error Scoring System (BESS) is a commonly used method for clinically evaluating balance after traumatic brain injury. The utilization of force plates, characterized by their cost-effectiveness and portability, facilitates the integration of instrumentation into the BESS protocol. Despite the enhanced precision associated with instrumented measures, there remains a need to determine the clinical significance and feasibility of such measures within pediatric cohorts. Objective: To report a comprehensive set of posturographic measures obtained during instrumented BESS and to examine the concurrent validity, reliability, and feasibility of instrumented BESS in the pediatric point of care setting. Methods: Thirty-seven participants (18 female; aged 13.32 ± 3.31 years) performed BESS while standing on a force plate to simultaneously compute stabilometric measures (instrumented BESS). Ellipse area (EA), path length (PL), and sway velocity (VM) were obtained for each of the six BESS positions and compared with the respective BESS scores. Additionally, the effects of sex and age were explored. A second BESS repetition was performed to evaluate the test–retest reliability. Feedback questionnaires were handed out after testing to evaluate the feasibility of the proposed protocol. Results: The BESS total score was 20.81 ± 6.28. While there was no statistically significant age or sex dependency in the BESS results, instrumented posturography demonstrated an age dependency in EA, VM, and PL. The one-leg stance on a soft surface resulted in the highest BESS score (8.38 ± 1.76), EA (218.78 cm2 ± 168.65), PL (4386.91 mm ± 1859.00), and VM (21.93 mm/s ± 9.29). The Spearman’s coefficient displayed moderate to high correlations between the EA (rs = 0.429–0.770, p = 0.001–0.009), PL (rs = 0.451–0.809, p = 0.001–0.006), and VM (rs = 0.451–0.809, p = 0.001–0.006) when compared with the BESS scores for all testing positions, except for the one-leg stance on a soft surface. The BESS total score significantly correlated during the first and second repetition (rs = 0.734, p ≤ 0.001), as did errors during the different testing positions (rs = 0.489–0.799, p ≤ 0.001–0.002), except during the two-legged stance on a soft surface. VM and PL correlated significantly in all testing positions (rs = 0.465–0.675, p ≤ 0.001–0.004; (rs = 0.465–0.675, p ≤ 0.001–0.004), as did EA for all positions except for the two-legged stance on a soft surface (rs = 0.392–0.581, p ≤ 0.001–0.016). A total of 92% of participants stated that the instructions for the testing procedure were very well-explained, while 78% of participants enjoyed the balance testing, and 61% of participants could not decide whether the testing was easy or hard to perform. Conclusions: Instrumented posturography may complement clinical assessment in investigating postural control in children and adolescents. While the BESS score only allows for the consideration of a total score approximating postural control, instrumented posturography offers several parameters representing the responsiveness and magnitude of body sway as well as a more differentiated analysis of movement trajectory. Concise instrumented posturography protocols should be developed to augment neuropediatric assessments in cases where a deficiency in postural control is suspected, potentially stemming from disruptions in the processing of visual, proprioceptive, and/or vestibular information.

Postural stability requires an interaction between cognitive, perceptual, sensory, and motor functions. Thus, impairment in any of these systems may affect postural balance. This study assessed the effect of visual input and surface slope on postural stability. The study was conducted on healthy participants, 11 females and 11 males who were 24–34 years of age. They were asked to perform still upright bipedal standing on flat and +/−20° sloped surfaces with eyes open (EO) and closed (EC). Six center of pressure (COP) parameters were measured by posturography. A significant relationship was observed between COP parameters, standing conditions, and body mass index. Gender had no significant effect on the COP. The loss of visual input within each standing condition did not affect the COP parameters. In contrast, differences were observed between standing on a flat surface and uphill with EC and between standing on a flat surface and downhill with EC and EO. When the participants were standing on inclined surfaces, the loss of vision significantly increased the postural instability. Young healthy adults demonstrated the greatest difficulty in standing uphill with EC. This was followed by standing downhill with EC and standing downhill with EO.

Individuals with Parkinson’s disease (PD) have postural instability and gait dysfunction that lead to falls and disability with disease progression. Increased fall risk is particularly seen during challenging gait tasks such as obstacle-crossing. The purpose of this study was to determine if there were differences in dynamic postural control during self-paced walking and obstacle-crossing between persons with mild-to-moderate PD and healthy controls. Participants included nine individuals with PD and nine age- and gender-matched controls (CON). This study examined margin of stability metrics using instrumented 3D motion analysis during the two-step sequence of the obstacle-crossing task. Dynamic balance variables and spatiotemporal (ST) parameters at distinct gait events related to the leading (step one) and trailing leg (step two) were compared for the PD and CON groups using a mixed-model ANOVA. No differences were found between groups for ST gait parameters during obstacle-crossing, except for a significantly reduced step length (p = 0.005) for the trailing limb for the PD group. The PD group demonstrated significantly larger mean values for mediolateral center of pressure–center of mass (COP–COM) distance at first double support (p = 0.004) and center of pressure–extrapolated center of mass (COP–XCOM) distance at second double support (p = 0.016) for the second step. Our results suggest that the margin of stability may be useful in discerning postural control adaptations during obstacle negotiation in persons with PD.

Accurate and reliable detection of the onset of gait initiation is essential for the correct assessment of gait. Thus, this study was aimed at evaluation of the reliability and accuracy of 3 different center of pressure--based gait onset detection algorithms: A displacement baseline--based algorithm (method 1), a velocity baseline--based algorithm (method 2), and a velocity extremabased algorithm(method 3). The center of pressure signal was obtained during 10 gait initiation trials from 16 healthy participants and 3 participants with Parkinson's disease. Intrasession and absolute reliability of each algorithm was assessed using the intraclass correlation coefficient and the coefficient of variation of center of pressure displacement during the postural phase of gait initiation. The accuracy was evaluated using the time error of the detected onset by each algorithm relative to that of visual inspection. The authors' results revealed that although all 3 algorithms had high to very high intrasession reliabilities in both healthy subjects and subjects with Parkinson's disease, methods 2 and 3 showed significantly better absolute reliability than method 1 in healthy controls (P = .001). Furthermore, method 2 outperformed the other 2 algorithms in both healthy subjects and subjects with Parkinson's disease with an overall accuracy of 0.80. Based on these results, the authors recommend using method 2 for accurate and reliable gait onset detection. [ABSTRACT FROM AUTHOR]

Holding an object has been found to reduce postural sway during quiet standing. However, people normally stand to accomplish suprapostural goals, such as fitting a key into a lock. Postural control should therefore be assessed by examining postural outcomes in the context of suprapostural task performance. This study assessed whether holding an object increased standing postural stability and improved the performance of a concurrent precision manual task. A total of 15 young adults performed a precision manual task with their dominant hand while holding or not holding an object in their nondominant hand. Postural stability was assessed using measures of postural sway and time to boundary. Suprapostural task performance was assessed as an error count. Holding did not influence postural sway or suprapostural task performance. Discrepancies among previous studies coupled with the present findings suggest that the effects of holding an object on standing posture are highly sensitive to the experimental context. The authors provide several explanations for their findings and discuss the limitations of previous suggestions that holding an object may have clinical relevance for balance-compromised populations. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relationship between postural regulation and tracking accuracy under static and moving visual target conditions in unipedal and bipedal standing postures. Postural time-to-contact stability boundaries decreased under more challenging visual target conditions for the unipedal posture, but this decrease was associated with lower visual tracking error. During bipedal support, there was independent control of the head and foot center of pressure, as higher frequencies at the head during the static visual task were associated with longer time-to-contact. These results demonstrate that decreased time-to-contact stability boundaries is a functional adaptation in postural tasks requiring visual control and provide evidence of the dependency of postural control on the nature of the suprapostural task. [ABSTRACT FROM AUTHOR]

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.

Abstract Background Local pain around the ankle joint is a common symptom in patients with chronic ankle instability (CAI). However, whether the local pain would impose any influence on the balance control performance of CAI patients is still unknown. Methods A total of twenty-six subjects were recruited and divided into the following two groups: pain-free CAI (group A) and pain-present CAI (group B). Subjects in both groups received two independent tests: the star excursion balance test and the single-leg stance test, in order to reflect their balance control ability more accurately. Results Compared with group A, the group B showed significantly more episodes of the history of sprains, decreased ankle maximum plantarflexion angle, and lower Cumberland scores (all p

Introduction: Recent studies found that wearable exoskeletons can reduce physical effort and fatigue during squatting. In particular, subject-specific assistance helped to significantly reduce physical effort, shown by reduced metabolic cost, using human-in-the-loop optimization of the exoskeleton parameters. However, measuring metabolic cost using respiratory data has limitations, such as long estimation times, presence of noise, and user discomfort. A recent study suggests that foot contact forces can address those challenges and be used as an alternative metric to the metabolic cost to personalize wearable robot assistance during walking.Methods: In this study, we propose that foot center of pressure (CoP) features can be used to estimate the metabolic cost of squatting using a machine learning method. Five subjects’ foot pressure and metabolic cost data were collected as they performed squats with an ankle exoskeleton at different assistance conditions in our prior study. In this study, we extracted statistical features from the CoP squat trajectories and fed them as input to a random forest model, with the metabolic cost as the output.Results: The model predicted the metabolic cost with a mean error of 0.55 W/kg on unseen test data, with a high correlation (r = 0.89, p < 0.01) between the true and predicted cost. The features of the CoP trajectory in the medial-lateral direction of the foot (xCoP), which relate to ankle eversion-inversion, were found to be important and highly correlated with metabolic cost.Conclusion: Our findings indicate that increased ankle eversion (outward roll of the ankle), which reflects a suboptimal squatting strategy, results in higher metabolic cost. Higher ankle eversion has been linked with the etiology of chronic lower limb injuries. Hence, a CoP-based cost function in human-in-the-loop optimization could offer several advantages, such as reduced estimation time, injury risk mitigation, and better user comfort.

Background: Although previous research in pediatric populations has reported performance enhancements following instability resistance training, the effects of different volumes on measures of balance, strength and power and lower limb asymmetry remain unclear. Objective: To compare the effect of two 8-week instability resistance training programs (IRT1: 2 sets x 8 repetitions, 20% one-repetition maximum (1RM); IRT2: 2 sets x 4 repetitions, 40% 1RM) in balance (center of pressure displacements), 1RM, single-leg jumps, and inter-limb asymmetry of prepubescent weightlifters. Methods: Thirty-two male athletes (10.94 ± 0.47 yrs, 17.05 ± 0.14 kg/m2, and 6.44 ± 0.93% bodyfat) voluntarily participated and combined IRT (front and back squat, lunge, and deadlift) with their usual weightlifting training. Nonparametric tests evaluated the differences between pre- and post-intervention. Results: Significant improvements were encountered in all the variables for both groups (effect sizes [ES] from 0.46 to 2.60), except the inter-limb asymmetry and the velocity of displacement of the center of pressure, which did not improve in IRT2. It is also worth highlighting that in the single-leg jumps and center of pressure displacements, whereas no significant differences were observed between IRT1 and IRT2 in the baseline, significant differences appeared in the follow-up measurements. Conclusion: IRT combined with weight-lifting training improves prepubescent weightlifters' performance; therefore, strength and conditioning coaches may consider including unstable devices with low loads into an overall conditioning program and warm-ups for prepuberal male weightlifters to promote their physical fitness and potentially decrease inter-limb asymmetry. Trial registration: This study does not report results related to healthcare interventions using human participants; therefore, it was not prospectively registered. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vision is the primary sensory system to maintain balance. Approximately 50% of visually impaired youth have an increased risk of falling. Chinese reports focus more on the epidemiological survey of the number of people with visual impairment, but ignore balance performance and control strategies in such people, especially the study of influencing factors. OBJECTIVE: To explore the effects of visual factors (degree of visual impairment: blind, partially sighted and normal vision group; vision condition: eyes open and eyes closed conditions) on balance function of young adults. METHODS: Forty-three young adults were recruited and divided into three groups: blind (n=12), partially sighted (n=9) and normal vision group (n=22), and then underwent the following tests: one-leg stance test (eyes open and eyes closed conditions) and functional reach test (normal vision group: eyes open and closed conditions; partially sighted or blind groups: daily state). Measurement parameters between groups were analyzed using one-way analysis of variance. Paired sample t-tests were used to compare differences between different vision conditions within groups. RESULTS AND CONCLUSION: In the one-leg stance test, the center of pressure trajectory length in the normal vision group with eyes open was significantly shorter than that in the blind and partially sighted groups (P < 0.05), and there was no significant difference between the groups when the eyes were closed (P > 0.05). Degree of injury and visual status had no significant effect on the static balance of visually impaired youth (P > 0.05). In the functional reach test, the reaching distance with eyes open was significantly greater than that with eyes closed in the normal vision group (P < 0.05) and the distance with eyes closed was significantly less than that of the blind group (P < 0.05). To conclude, visual impairment dramatically reduces the static balance of young adults, and vision conditions remarkably affect postural stability of the sighted youth, while the degree of visual impairment has no significant effect on static and dynamic balance of visually impaired youth. The lack of visual feedback can be compensated by non-visual factors in visually impaired youth. [ABSTRACT FROM AUTHOR]

The mechanical consequences of the motor actions used to maintain upright standing balance can be discriminated in two mechanisms: i) moving the center of pressure (CoP) within the base of support (M1); and ii) modifying the whole-body angular momentum (M2). Since the contribution of M2 to the whole-body CoM acceleration increases with postural constraints, a postural analysis focusing only on the CoP trajectory (i.e. M1) could ignore the majority of the control actions in challenging postural tasks. The objective of this study was to determine the contributions of the two postural balance mechanisms across postures with different areas of the base of support. Forty-one healthy young adults (19 females, 22.9 ± 2.9 years old) stood quietly on a forceplate, maintaining four different postures: bipedal, tandem, unipedal and unipedal on a 4-cm wooden bar; each with eyes open and for 60 s. Relative contributions of the two balance postural mechanisms were computed for each posture, in both directions of the horizontal plane. The posture impacted the mechanisms contributions, where the contribution of M1 decreased between each posture in the mediolateral direction as the area of the base of support was reduced. The contribution of M2 in the mediolateral direction was not negligible (about 1/3) in tandem and unipedal postures and became dominant (nearly 90% on average) in the most challenging unipedal posture. This suggests the contribution of M2 should not be neglected for the analysis of postural balance, and particularly in challenging standing postures. • The contributions of the two postural balance mechanisms were objectified. • CoP motion, the first mechanism, is dominant in bipedal postures. • But it only explains 12% of mediolateral CoM acceleration in a challenging posture. • Analysis of the two mechanisms is complementary and should be encouraged. [ABSTRACT FROM AUTHOR]

Introduction: Postural instability increases with age and is exacerbated in neurological disorders such as Parkinson's disease (PD). Reducing the base of support from bipedal to unipedal stance increases center of pressure (CoP) parameters and intermuscular coherence in lower-leg muscles of healthy older adults. To further develop an understanding of postural control in an altered state of neurological impairment, we explored intermuscular coherence in lower-leg muscles and CoP displacement in older adults with PD. Methods: This study measured surface EMG from the medial (MG) and lateral (LG) gastrocnemii, soleus (SOL), and tibialis anterior (TA), and examined EMG amplitude and intermuscular coherence during bipedal and unipedal stance on a force plate with firm (no foam) and compliant (standing on foam) surface conditions in nine older adults with PD (70±5 years, 6 females) and 8 age-matched non-Parkinsonian older adults (5 females). Intermuscular coherence was analyzed between agonistagonist and agonist-antagonist muscle pairs in the alpha (8-13 Hz) and beta (15-35 Hz) frequency bands. Results: CoP parameters increased from bipedal to unipedal stance in both groups (p < 0.01), but did not increase from the firm to compliant surface condition (p > 0.05). During unipedal stance, CoP path length was shorter in older adults with PD (2027.9 ± 1074.1 mm) compared to controls (3128.5 ± 1198.7 mm) (p < 0.01). Alpha and beta agonist-agonist and agonist-antagonist coherence increased by 28% from bipedal to unipedal stance (p > 0.05), but did not differ between older adults with PD (0.09 ± 0.07) and controls (0.08 ± 0.05) (p > 0.05). The older adults with PD also had greater normalized EMG amplitude of the LG (63.5 ± 31.7%) and TA (60.6 ± 38.4%) during the balance tasks (p > 0.05) than the non-Parkinsonian counterparts. Discussion: Older adults with PD had shorter path lengths during unipedal stance and required greater muscle activation than older adults without PD to perform the tasks, but intermuscular coherence did not differ between the groups. This may be attributable to their early disease stage and high motor function. [ABSTRACT FROM AUTHOR]

Objective: The probability density analysis was applied to automatically characterize the center of pressure (COP) data for evaluation of the stroke patients' balance ability. Methods: The real-time COP coordinates of 38 stroke patients with eyes open and closed during quiet standing were obtained, respectively, from a precision force platform. The COP data were analyzed and characterized by the commonly used parameters: total sway length (SL), sway radius (SR), envelope sway area (EA), and the probability density analysis based parameters: projection area (PA), skewness (SK) and kurtosis (KT), and their statistical correlations were analyzed. The differences of both conventional parameters and probability density parameters under the conditions of eyes open (EO) and eyes closed (EC) were compared. Results: The PA from probability density analysis is strongly correlated with SL and SR. Both the traditional parameters and probability density parameters in the EC state are significantly different from those in the EO state. The obtained various statokinesigrams were calculated and categorized into typical sway types through probability density function for clinical evaluation of the balance ability of stroke patients. Conclusions: The probability density analysis of COP data can be used to characterize the posturography for evaluation of the balance ability of stroke patients. [ABSTRACT FROM AUTHOR]

Proprioception deficit has been suggested as a possible mechanism contributing for the impaired postural control in low back pain (LBP) patients. Whether proprioception deficit is a result of or a cause of LBP has not been investigated. The purpose of this study was to compare proprioceptive postural control strategies between prolonged standing induced low back pain developers (PDs) and non-pain developers (NPDs). Thirty-two healthy subjects performed 1-h prolonged standing and their ratings of perceived LBP have been recorded. Eight quiet standing trials for 60 s performed immediately before and after the prolonged standing. Postural control was challenged by muscle vibration and different postural conditions during quiet standing. Data were recorded using a force platform. Forty percentage of participants is classified as PD. Before the prolonged standing, relative proprioceptive weighting was greater in the PD compared to NPD group (P =.029). Main effect of postural condition (F1,24 = 5.21, P =.032) and interaction of time by group (F1,24 = 8.08, P =.009) were significant for COP displacement in anteroposterior direction. Interaction of postural condition by group (F1,26 = 7.82, P =.010) and time by group (F1,26 = 9.71, P =.004) were significant for COP displacement in mediolateral direction. Main effect of postural condition (F1,26 = 6.31, P =.018) and interaction of postural condition by group (F1,26 = 7.07, P =.013) were significant for mean velocity in mediolateral direction. The PD group has altered proprioceptive postural control strategies before and after prolonged standing. Proprioception deficit should not be considered to be solely an adaptive response and may be causal for LBP development. [ABSTRACT FROM AUTHOR]

Background & Aims: In recent years, different vision training has been used to improve visual skills and performance. One of these trainings is sports vision training. Sport vision training, that uses stimuli in optometric tasks (2,3), sport-specific videos or images (4), or stroboscopic interruption of vision (5,6), has been proposed under the idea that improving vision with oculomotor exercises, which might be associated with motor actions, would improve performance. For instance, Abernethy and Wood (2) used generic stimuli (e.g., alphanumeric symbols, shapes, patterns and colors) presented to athletes in a form of painted charts or apparatuses. Participants had to respond with simple ocular adjustments, which in some cases were combined with simple motor actions, such as pointing or touching targets (7). Although an increasing interest in vision training for sport performance, whether vision training would have a transfer to the field-sport setting remains unclear. Most of the intervention studies employed tasks based on optometric stimuli (e.g., hart charts and Marsden ball) and on computer programs (e.g., D2 Dynavision and Eye port) requiring simple ocular adjustments, and generic movements of hands as responses (2,3,11-14). The lack of evidences for supporting sport vision training efficacy to improve performance has been proposed to be related to methodological approaches resulting in a lack of ecological validity of the training stimuli (15). As such, generic and automated nature of the motor actions required as response might have limited the potential effects on the sport performance. This lack of transfer seems to support the idea, proposed in ecological framework by Gibson, that perception and action have a direct circular relationship mediated by the information within external environment (i.e. affordances), rather than by internal representations (16). Although the results of various studies have shown an improvement in visual skills and athletic performance based on sports vision training; but the main challenge is to examine the qualitative process versus the quantitative processes. Considering that balance is one of the main components in hockey (25), and considering that balance is created from the interaction of three visual, atrial and sensory- motor systems (26), The main question is whether sports vision training can improve the balance (kinetics) of hockey players or not? Therefore, the purpose of the current study was to examine the effect of sports vision training on balance and gaze behavior. Methods: The current study, according to the predicted goals, was a quasi-experimental research and the research design was pretest-posttest. Also, the current study was applied in terms of using the obtained results. Participants in the current study were 40 male hockey novices aged 15 to 20 years who were selected by convenience sampling. Participants were randomly divided into two groups of sports vision training and control. Criteria for inclusion in the study include normal vision, binocular vision, right leg and right hand. Exclusion criteria include withdrawal from the study, absence on the day of the test, and injury at various phases of the study. The measuring instruments included a force plate form and an eye tracking system. The present study included pre-test, intervention (practice) and post-test phases. In the pre-test phase, participants stood on a force platform to measure their balance. Participants were asked to stand barefoot on the force plate for 30 seconds while looking at the marked spot in front of them and trying to maintain their balance. At the same time, an eye tracking system was used to measure the gaze behavior of participants in performing balance skills. In the intervention phase (practice), which lasted for nine weeks and two sessions per week and each session lasted 90 minutes; the training group performed the relevant exercises while the control group performed their daily activities. The post-test phase was performed exactly after the last training session. At this phase, participants were asked to stand barefoot on the force plate for 30 seconds. At the same time, an eye tracking system was used to measure the gaze behavior of participants in performing balance skills. Data analyzed with paired sample t test and independent t test. Results: The results showed that the anterior-posterior displacement of the center of pressure was significantly improved by pre-test (29.25) to post-test (24.45) mm. Other results indicate that there is a significant difference between the groups in the anteriorposterior displacement of the center of pressure, and the sports vision group with an mean difference of 4.30 mm has a lower center of pressure displacement compared to the control group (P <0.05). Other results showed that the lateral-midlateral displacement of the center of pressure was significantly improved by pre-test (45.80) to post-test (39.90) mm. Other results indicate that there is a significant difference between the groups in the lateral-midlateral displacement of the center of pressure, and the sports vision group with an mean difference of 7.15 mm has a lower center of pressure displacement compared to the control group (P <0.05). Also, other results showed that fixation was significantly improved by pre-test (188.70) to post-test (248.60) ms. Other results indicate that there is a significant difference between the groups in fixation, and the sports vision group with an mean difference of 52.014 ms has a longer fixation compared to the control group (P <0.05). Conclusion: In general, the results of the current study showed that sports vision training improved balance and increased fixation of participants, so the results of the present study emphasize the importance of sports vision training on behavioral (balance) and process (fixation) characteristics. As a result, coaches and professionals working with novice hockey players are advised to pay attention to these exercises beforehand and use them in field and laboratory environments to improve performance and movement process. Also, according to the research results, trainers are advised to pay special attention to sports vision exercises and their possible effects on gaze behavior so that they can at least overcome the negative effects (psychological and physiological pressures). Although the current study and previous studies in this field have provided considerable insight into the value of sports vision training in understanding conscious perception, note that this work has been done almost exclusively using information processing paradigms. Other paradigms, such as ecological psychology and nonlinear dynamics, can provide new methods for the research gap identified in this study. [ABSTRACT FROM AUTHOR]

Few studies have evaluated the effect of a secondary motor task on the standing posture based on nonlinear analysis. However, it is helpful to extract information related to the complexity, stability, and adaptability to the environment of the human postural system. This study aimed to analyze the effect of two motor tasks with different difficulty levels in motor performance complexity on the static standing posture in healthy young adults. Thirty-five healthy participants (23.08 ± 3.92 years) performed a postural single task (ST: keep a quiet standing posture) and two motor dual tasks (DT). i.e., mot-DT(A)—perform the ST while performing simultaneously an easy motor task (taking a smartphone out of a bag, bringing it to the ear, and putting it back in the bag)—and mot-DT(T)—perform the ST while performing a concurrent difficult motor task (typing on the smartphone keyboard). The approximate entropy (ApEn), Lyapunov exponent (LyE), correlation dimension (CoDim), and fractal dimension (detrending fluctuation analysis, DFA) for the mediolateral (ML) and anterior-posterior (AP) center-of-pressure (CoP) displacement were measured with a force plate while performing the tasks. A significant difference was found between the two motor dual tasks in ApEn, DFA, and CoDim-AP (p < 0.05). For the ML CoP direction, all nonlinear variables in the study were significantly different (p < 0.05) between ST and mot-DT(T), showing impairment in postural control during mot-DT(T) compared to ST. Differences were found across ST and mot-DT(A) in ApEn-AP and DFA (p < 0.05). The mot-DT(T) was associated with less effectiveness in postural control, a lower number of degrees of freedom, less complexity and adaptability of the dynamic system than the postural single task and the mot-DT(A). [ABSTRACT FROM AUTHOR]

This study aimed to validate a sensorized version of a perceptive surface that may be used for the early assessment of misperception of body midline representation in subjects with right stroke, even when they are not yet able to stand in an upright posture. This device, called SuPerSense, allows testing of the load distribution of the body weight on the back in a supine position. The device was tested in 15 patients with stroke, 15 age-matched healthy subjects, and 15 young healthy adults, assessing three parameters analogous to those conventionally extracted by a baropodometric platform in a standing posture. Subjects were hence tested on SuPerSense in a supine position and on a baropodometric platform in an upright posture in two different conditions: with open eyes and with closed eyes. Significant correlations were found between the lengths of the center of pressure path with the two devices in the open-eyes condition (R = 0.44, p = 0.002). The parameters extracted by SuPerSense were significantly different among groups only when patients were divided into those with right versus left brain damage. This last result is conceivably related to the role of the right hemisphere of the brain in the analysis of spatial information. [ABSTRACT FROM AUTHOR]

Objective: The goal of our study was to determine how ankylosing spondylitis, a chronic inflammatory disease, affected patient's balance. Materials and Methods: Thirty-one healthy volunteers and thirty-five patients with ankylosing spondylitis and no comorbidities affecting their balance participated in the study. Bipedal balance analysis was performed with the subjects' eyes open and closed in each group. The position of the center of pressure during the measurement was evaluated. Results: The mediolateral deviation of the center of pressure (p=0.035) and the total path length (p=0.042) were significantly higher in the patient group when measured with eyes open. PL was significantly longer in the patient group when measured with eyes closed (p=0.002). Conclusion: We observed that ankylosing spondylitis negatively affected the balance in patients. Since this disease usually occurs in the young population, it should be taken into consideration that balance impairment can complicate daily life, especially in the professional world. Therefore, it can be useful to consider the balance disorder in the treatment, and the patients should be monitored for an extended period. [ABSTRACT FROM AUTHOR]

Introduction: The path of the center of pressure while walking reflects the general mechanics of the body. Also, the electrical stimulation system triggers movement units, including the lower limbs. The present study investigated the effect of the electrical stimulation system on gait and balance patterns in young athletes. Methods: This research is applied and semi-experimental. In this study, 15 male athletes were selected by convenience sampling. The present study was performed in February 1400 at Shahriar Health Club. Participants were asked to walk at a self-selected speed. In the middle of the walking path, a foot-scanning device was placed, which recorded information about the path of the center of pressure, the relative duration of the stance phases, and the forward angle in both positions with and without the muscle stimulation vest. After checking the normality of the data using the Shapiro-Wilk test, paired sample t-test was used to analyze the data. Results: The results showed that the electrical muscle stimulation system had a favorable effect on the gait pattern of athletes compared to those without a vest. Electrical stimulation led to a slight increase in pressure center oscillations and improved displacement of pressure fluctuations (p=0.001) in the vest mode, which showed the effectiveness of this method. Conclusion: The results of the present study showed that strengthening the muscles of the lower extremities by the electrical muscle stimulation system had favorable effects on athletes' gait pattern and foot pressure fluctuations. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the effects of posterior spinal correction and fusion on postural stability in patients with adolescent idiopathic scoliosis (AIS). The study included 41 female patients with AIS at our institution. All patients performed three 10 s single-leg standing trials on a force plate. The center of pressure (COP) was measured preoperatively, and at 1 week and 6 months postoperatively. The postural stability parameters were absolute minimum time-to-boundary (TTB), mean of the minimum TTB, mean COP velocity, standard deviation, range, and 95% confidence ellipse area. One-way repeated analysis of variance or Friedman test was applied to the postural stability parameters. Multiple comparisons were performed using the Bonferroni correction. The absolute minimum TTB and the mean minimum TTB showed a significant increase 6 months post-operation as compared to preoperatively and 1 week postoperatively. The COP velocity significantly decreased at 6 months post-operation compared to preoperatively and 1 week postoperatively. These changes in postural stability indicate that spinal correction and fusion can be considered to improve postural stability during single-leg standing tests in the postoperative period. [ABSTRACT FROM AUTHOR]

Evidence supports the view that postural sway in a quiet stance increases with clinical disease severity and dopaminergic therapy in idiopathic Parkinson's disease (PD), which, in turn, increases the risk of falling. This study evaluated the feasibility of combining disease-specific and balance-related measures as risk predictors for future falls in patients with PD. The patients with PD underwent postural sway measurements (area, length, and velocity traveled by the excursion of the center of pressure) and clinical functional scores (Parkinson's Disease Rating Scale [UPDRS] and Tinetti balance and gait score assessment) in both the on- and off-states of dopaminergic therapy. The outcome was defined as the development of a new fall. The sway area, velocity, and length increased after the medication administration. The Cox proportional hazards model showed that only previous fall history, Tinetti balance and gait score (on-state), and levodopa equivalent daily dose (LEDD) were associated with the development of future falls. The cumulative risk of fall development showed that the sway length and velocity were associated with future falls after more than six months. The combined LEDD, Tinetti balance and gait score (on-state), and velocity and length of postural sway (on-state) had the highest diagnostic accuracy (area under the curve = 0.9, p < 0.0001). Dopaminergic therapy can improve clinical functional scores but worsen balance-related measures. Increased sway length and velocity during the medication state are hallmarks of future falls, particularly in advanced PD. Combining disease-specific and balance-related measures can serve as an auxiliary diagnosis as risk predictors for future falls. [ABSTRACT FROM AUTHOR]

PURPOSE: This study evaluated the effects of an instrumented balance board on the balance parameters in children with spastic cerebral palsy by carrying out a pilot single-group pre-post clinical trial. METHODS: Five children aged 5 to 15 years with spastic diplegia and a Gross Motor Function Classification System level of I or II were included. All participants attended 20 sessions with an instrumented balance board, 45 minutes per session, 3 times a week for 7 weeks. The main outcome measures included the center of pressure excursion, velocity, and overshoot during quiet standing with open and closed eyes. The assessments were performed in the mediolateral and anteroposterior directions at pre- and one week post-intervention. RESULTS: Non-parametric tests showed that the excursion did not change significantly except in the mediolateral direction with eyes closed (p < 0.05). The velocity of the center of pressure improved in both directions and eye conditions (p < 0.05). Also, the maximum velocity decreased with eyes open (mediolateral, anteroposterior, and total) (p < 0.05), while the change was not significant with the eyes closed. The overshoot measurements did not change significantly. CONCLUSION: It is recommended to consider balance board training for improving balance parameters in children with cerebral palsy. [ABSTRACT FROM AUTHOR]

Postural stability is a crucial aspect of human balance and equilibrium. One way to quantify postural stability is by analyzing variations in the center of pressure under the feet. However, there are several factors involved in quantifying postural stability, and interpreting the information they provide can be challenging, especially in the context of pathological motion. The aim of this work is to reduce the confounding effects of these factors to the extent that measurable differences in results are primarily due to a pathological condition rather than secondary factors such as procedural variations. Materials and methods: The initial research conditions were established based on theoretical aspects of human standing stability. Thirteen normal subjects (5 female and 8 male) with a mean age of 21 ± 4.97 years and a mean BMI of 25.27 ± 4.53 kg/m² were recruited for the study. Four investigations were conducted, including eyes closed-closed base, eyes open-closed base, eyes closed-open base, and eyes open-open base conditions. Data collection was performed using the AMTI AccuGait force plate and Balance Clinic software. Spectral characteristics, composite multiscale entropy, and conventional stability parameters were computed for both the anterior-posterior (AP) and mediallateral (ML) directions. Results: Composite multiscale entropy shows no significant difference (p > 0.05) in both AP and medial-lateral (ML) directions. Whereas the frequency of oscillations in ML is more sensitive than other parameters with relatively large effect size (>0.9). Conclusion: The resulting set of variables provides a broad range of options for selecting specific variables related to a particular study topic. The benefit of this method is that it standardizes the analysis of the center of pressure and enables the comparability of variables gathered during various research measurements. For general standing stability measurements, composite multiscale sampling entropy is the most relevant factor that can be used to discriminate the stability state in both the anterior-posterior and medial-lateral directions. [ABSTRACT FROM AUTHOR]

Purpose. The evaluation has been limited to a single ability, such as agility or equilibrium, and has not been conducted in a series of movements. In addition, a measurement method that is less burdensome for the participants has not been established. In this study, we designed a new reaction balance test (RB T) that combines agility and equilibrium and examined its reliability and validity. Methods. The participants were 49 young people (17 males, 32 females). Their whole-body reaction time (WRT) and center of pressure (COP) during a 30-second trial (COP30) of single-leg standing with open eyes were measured to determine their agility and equilibrium, respectively. Overall, 4 COP parameters were evaluated during COP30. For RB T, the participants were asked to quickly raise one leg after sensing a light stimulus and stand on the other leg for 10 seconds (COP10). The test evaluated their single-leg reaction time (SRT) and the same 4 parameters as those in COP30. Results. The intraclass correlation coefficients between agility (WRT and SRT) and equilibrium (total length [TL] at COP30 and COP10) were all > 0.81. In addition, no proportional error was observed for COP30 or COP10, only for TL of the nondominant leg. There were significant associations between WRT and SRT for agility and between COP30 and COP10 for equilibrium for TL. Conclusions. It was suggested that the reliability and validity of RB T could be improved by evaluating TL by using the dominant leg for agility and the non-dominant leg for equilibrium. [ABSTRACT FROM AUTHOR]

The prevalence and impact of balance impairments and falls in older adults have motivated several studies on the characterization of human balance. This study aimed to determine the ability of recurrence quantification analysis (RQA) measures to characterize balance control during quiet standing in young and older adults and to discriminate between different fall risk groups. We analyze center pressure trajectories in the medial-lateral and anterior-posterior directions from a publicly available static posturography dataset that contains tests acquired under four vision-surface testing conditions. Participants were retrospectively classified as young adults (age< 60, n=85), non-fallers (age≥60, falls=0, n=56), and fallers (age≥60, falls≥1, n=18). Mixed ANOVA and post hoc analyzes were performed to test for differences between groups. For CoP fluctuations in the anterior-posterior direction, all RQA measures showed significantly higher values for young than older adults when standing on a compliant surface, indicating less predictable and stable balance control among seniors under testing conditions where sensory information is restricted or altered. However, no significant differences between non-fallers and fallers were observed. These results support the use of RQA to characterize balance control in young and old adults, but not to discriminate between different fall risk groups. [ABSTRACT FROM AUTHOR]

Quantitative evaluation of human stability using foot pressure/force measurement hardware and motion capture (mocap) technology is expensive, time consuming, and restricted to the laboratory. We propose a novel image-based method to estimate three key components for stability computation: Center of Mass (CoM), Base of Support (BoS), and Center of Pressure (CoP). Furthermore, we quantitatively validate our image-based methods for computing two classic stability measures, CoMtoCoP and CoMtoBoS distances, against values generated directly from laboratory-based sensor output (ground truth) using a publicly available, multi-modality (mocap, foot pressure, two-view videos), ten-subject human motion dataset. Using Leave One Subject Out (LOSO) cross-validation, experimental results show: 1) our image-based CoM estimation method (CoMNet) consistently outperforms state-of-the-art inertial sensor-based CoM estimation techniques; 2) stability computed by our image-based method combined with insole foot pressure sensor data produces consistent, strong, and statistically significant correlation with ground truth stability measures (CoMtoCoP r = 0.79 p < 0.001, CoMtoBoS r = 0.75 p < 0.001); 3) our fully image-based estimation of stability produces consistent, positive, and statistically significant correlation on the two stability metrics (CoMtoCoP r = 0.31 p < 0.001, CoMtoBoS r = 0.22 p < 0.043). Our study provides promising quantitative evidence for the feasibility of image-based stability evaluation in natural environments. [ABSTRACT FROM AUTHOR]

Inspiratory muscle training (IMT) is effective in improving postural stability and balance in different clinical populations. However, there is no evidence of these effects in soccer players. A single-blind, two-arm (1:1), randomized, placebo-controlled pilot study on 14 soccer players was performed with the main aim of assessing the effect of IMT on static balance, and secondarily, of examining changes in the respiratory muscle function. The experimental group (EG) received an IMT program with progressive intensity, from 20% to 80%, of the maximal inspiratory pressure (MIP). The sham group (SG) performed the same program with a fixed load of 20% of the MIP. Static balance and respiratory muscle function variables were assessed. A two-factor analysis of variance for repeated measures was used to assess differences after training. Statistical significance was set at p < 0.05. Significant increases were observed in the EG on length of sway under eyes open (from 2904.8 ± 640.0 to 3522.4 ± 509.0 mm, p = 0.012) and eyes closed (from 3166.2 ± 641.3 to 4173.3 ± 390.8 mm, p = 0.004). A significant increase in the maximal voluntary ventilation was observed for both groups (EG p = 0.005; SG p = 0.000). No significant differences existed between the groups. IMT did not improve the static balance in a sample of soccer players. Conducting a high-scale study is feasible and could refine the results and conclusions stemming from the current pilot study. [ABSTRACT FROM AUTHOR]

Abstract Background Toe-out gait is often used as a conservative technique to reduce knee adduction moment, which has been targeted to modify knee osteoarthritis progression. The center of pressure (COP) can not only be used to evaluate gait stability, but is also more reliable and practical than local plantar pressures as it does not depend on accurate foot zone divisions. However, to the authors’ knowledge, few study has reported the influence of the foot progression angle on the dynamic characteristics of the COP. Research question The aim of the study was to investigate the effects of the deliberately toe-out gait on the COP trajectory and stability during walking in healthy individuals. Methods Thirty healthy young adults were asked to walk along an 8-m walkway. A Footscan 1 m pressure plate was used to measure the center of pressure during walking. Results Compared to the normal gait, the COP of the toe-out gait shifted laterally during the initial contact phase, and shifted laterally and anteriorly during the forefoot contact phase. The mean anterior–posterior velocity of COP reduced by 0.109 m/s during the foot flat phase and the duration of the foot flat phase and forefoot push off phase increased by 4.5% and reduced by 7.0%, respectively. Significance Compared to the normal gait, the findings of this study suggest that biomechanical alteration of foot under our experimental conditions may decrease gait stability and increase forefoot load during toe-out walking. The situation may be improved by well-designed footwear or custom-made insole and the biomechanics analysis method can be used to test the efficacy of therapeutic footwear or insole for individuals with deliberately toe-out walking. Graphical Abstract

Abstract Background Children with obesity were found to show the greater postural instability compared to the normal-weighted children. However, it’s still unclear if their altered postural control ability would recover towards normal pattern after weight loss. The purpose of this study was to investigate the effect of weight loss on the center of pressure (COP) for obese children. Method Totally 147 children were conducted a follow-up study in three years. A total number of 22 participants aged 7–13 years were recruited for their remission of obesity problem after 36 months. Their dynamic plantar pressure data were collected by Footscan pressure plate. The normalized time of four sub-phases, displacements and velocities of COP in anterior–posterior (AP) and medial–lateral (ML) directions were calculated to perform the Kolmogorov–Smirnov test and paired sample t test for statistical analyses. Results After weight loss, children’s normalized time of forefoot contact phase (FFCP) increased significantly, and their duration of flat foot phase (FFP) decreased significantly. They also exhibited the more medial and posterior orientated COP path after weight loss. In ML-direction, the COP displacement during FFP and FFPOP increased, and the COP velocity during FFPOP increased. In AP-direction, COP velocity during FFP and FFPOP increased. Conclusions The findings indicated that weight loss would have effects on the COP characteristics and postural stability for obese children. COP trajectory can provide essential information for evaluating foot function. The findings may be useful for obese children, medical staff, and healthcare physician. Graphical Abstract

Abstract Background Low back pain patients suffer from balance disturbance. Balance allows a person to interact with the surrounding environment and to do his daily activities. As recent technology has facilitated patient monitoring and enhanced our ability to monitor patients remotely, smartphone apps have been developed to achieve this goal. There are various balance assessment instruments used nowadays. It may be subjective or objective assessments. This study was applied to verify if the measurements of balance Y-MED smartphone applications are valid and reliable compared to the HUMAC balance board in order to offer easy, fast, cost-effective, and time-effective valid and reliable balance assessment that can be used in a clinical setting. Methods Fifty-four patients (12 males and 42 females) with chronic mechanical low back pain for more than 3 months was volunteered to participate in the current study with an age range of 25–60 years and BMI range of 18–34 kg/m2. Compared with the HUMAC balance board, the validity of the balance Y-MED smartphone application is evaluated, and the test-retest reliability of the balance Y-MED smartphone application is obtained by the same examiner 3 times. Results For concurrent validity, the correlations between balance measurements by Y-MED smartphone application and HUMAC balance board were not significant in both eyes open (r = − 0.12, p = 0.38) and eyes closed (r = 0.26, p = 0.054). The smartphone application showed poor test-retest reliability measurement of balance with eyes open; (ICC was 0.279, with 95% CI − 0.117–0.554) and with eyes closed (ICC was − 0.159, with 95% CI − 0.814–0.287). Conclusions According to the evaluation scheme selected in this study, the researchers were unable to confirm the validity of the balance Y-MED smartphone application in the balance assessment of patients with mechanical chronic low back pain. More than that, the balance Y-MED smartphone application has been shown poor score reliability. This makes it inaccurate for use in assessment balance.

Ground reaction forces (GRFs) and center of pressure (COP) are essential for understanding human motion and evaluating biomechanical parameters, but measuring them with force plates is often limited in many scenarios. In this study, we propose a novel methodology for estimating GRFs and COP during normal gait based on a rigid foot–ground contact model, referred to as the COP phase transition continuity model (COP-PTCM). The GRFs and COP are calculated based on the Newton-Euler Equations during the single support phase (SSP). Considering the spatiotemporal continuity of the COP trajectory during normal gait, the COP data for the double support phase (DSP) is obtained by an improved logistic function fitted using the COP data from the SSP. GRFs during the DSP are optimized using the minimum energy hypothesis. The COP-PTCM method is used to estimate the GRFs and COP of ten participants during normal gait, and the results are compared with simultaneously measured force plate data, yielding the relative root mean square error (rRMSE) between measured and estimated GRFs in the anterior-posterior, vertical, and medial–lateral directions are 10.90±2.09 %, 4.73±1.44 %, and 15.17±1.69 %, respectively. Additionally, the rRMSE between measured and estimated COP in the anterior-posterior direction is 11.23±0.03 %. The above comparison validates the effectiveness and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Inadequate response to balance perturbations lead to posture instability in the elderly. The fall risks are increased by a reduced capacity to control the center of pressure (COP) displacement within the safety limit of the supporting base. This study developed an interactive evaluation and training platform. The system incorporated a computerized program with instantaneous force plate evaluation. Ten young subjects underwent a baseline evaluation and twenty-nine community-dwelling elderly received pre- and post-intervention testing. The ability to reach the stability limit was assessed by measuring the maximum voluntary excursion of the COP in anterior–posterior and medial–lateral directions. Functional mobility tests including Berg Balance Scale, Timed-Up-and-Go and functional reach were used as functional outcomes. The experimental group (n = 15) received a 40 min intervention three times a week for six weeks. The interactive game-based training focused on multi-directional weight shifting by tracing a COPcontrolled target to challenge an individual’s stability limit. The control group (n = 14) maintained daily activities as usual. The young group revealed a superior COP displacement through active ankle control than the elderly, especially in the anterior–posterior direction. The experimental group improved their COP displacement control more in the medial–lateral direction due to the predominant side-to-side gameplay movement. The functional outcome measures were also significantly improved after training. Using the COPcontrolled game-based program, the stability limit was challenged to facilitate dynamic posture control by an incremental increase in self-initiated perturbations. The platform system could assist in transferring the immediate training effects into daily functional mobility in the elderly.

This systematic review was conducted to provide an overview of the effects of chronic ankle instability (CAI) on the biomechanical organization of gait initiation. Gait initiation is a classical model used in the literature to investigate postural control in healthy and pathological individuals. PubMed, ScienceDirect, Scopus, Web of Science, and Google Scholar were searched for relevant articles. Eligible studies were screened and data extracted by two independent reviewers. An evaluation of the quality of the studies was performed using the Downs and Black checklist. A total of 878 articles were found in the initial search, but only six studies met the inclusion criteria. The findings from the literature suggest that CAI affects the characteristics of gait initiation. Specifically, individuals with CAI exhibit notable differences in reaction time, the spatiotemporal parameters of anticipatory postural adjustments (APAs) and step execution, ankle–foot kinematics, and muscle activation compared to healthy controls. In particular, the observed differences in APA patterns associated with gait initiation suggest the presence of supraspinal motor control alterations in individuals with CAI. These findings may provide valuable information for the rehabilitation of these patients. However, the limited evidence available calls for caution in interpreting the results and underscores the need for further research.

Considering the rising prevalence of smartphone usage among adolescents with intellectual disabilities and their frequent motor challenges, understanding its impact on their physical well-being is important. This study aims to investigate the impact of smartphone activities on postural balance in adolescents with intellectual disabilities. Two groups of adolescents participated in the study: an intellectual disability group (IDG) (n = 16) and atypical development group (TDG) (n = 12). Static postural balance, using a stabilometric platform on firm and foam surfaces, and dynamic balance, using the Timed Up-and-Go Test (TUGT), were performed under various conditions, such as playing a game, watching videos, video calls, and listening to music. The center of pressure (CoP) values significantly increased (p < 0.05) during all smartphone activities (except listening to music) compared to the control condition in both groups, with the IDG demonstrated a more pronounced increase (p < 0.05) during playing video games and video calls on the firm surface. TUGT scores significantly increased (p < 0.05) during smartphone activities, with greater changes observed in the IDG (p < 0.05), and significantly decreased (p < 0.01) during listening to music in both groups. Our study suggests that adolescents with intellectual disabilities need special tools and guidance to ensure their safety and well-being when using smartphones.

Preterm infants are more likely to demonstrate developmental delays than fullterm infants. Postural measurement tools may be effective in measuring the center of pressure (COP) and asymmetry, as well as predicting future motor impairment. The objective of this systematic review was to evaluate existing evidence regarding use of pressure mats or force plates for measuring COP and asymmetry in preterm infants, to determine how measures differ between preterm and fullterm infants and if these tools appropriately predict future motor impairment. The consulted databases included PubMed, Embase, Scopus, and CINAHL. The quality of the literature and the risk of bias were assessed utilizing the ROB2: revised Cochrane risk-of bias tool. Nine manuscripts met the criteria for review. The postural control tools included were FSA UltraThin seat mat, Conformat Pressure-Sensitive mat, Play and Neuro-Developmental Assessment, and standard force plates. Studies demonstrated that all tools were capable of COP assessment in preterm infants and support the association between the observation of reduced postural complexity prior to the observation of midline head control as an indicator of future motor delay. Postural measurement tools provide quick and objective measures of postural control and asymmetry. Based on the degree of impairment, these tools may provide an alternative to standardized assessments that may be taxing to the preterm infant, inaccessible to therapists, or not sensitive enough to capture motor delays.

A force plate is a device that measures the ground reaction force caused by a shift in the human body’s center of mass (CoM). Using a controlled change in the human body’s CoM, the human body’s center of pressure (CoP) is shifted in a 2D plane, along with an acceleration of the CoM along the plane perpendicular to the force plate, which allows for a generation of reference values for game control. In this paper, the development and validation of a system for game control based on a force plate are described. The game control system consists of a force plate, an electronic board used for measuring and PC communication via USB, and a PC application for data acquisition, system calibration, and game control. Based on the measured values of the player’s CoP and the CoM acceleration along a plane perpendicular to the force plate, the game control system simulates pressing the UP, DOWN, RIGHT, LEFT, and SPACE keyboard keys or moving the mouse and clicking the left mouse button, which allows players to control simple games. A mathematical model has been developed for the game control system which includes running system calibration procedures in the system for each individual player. The mechatronic game control system is described in detail, and experiments were run on said system for the purpose of system validation.

Abstract Objective Tibial cortex transverse distraction (TCTD) has been recently reported for the treatment of diabetic foot ulcers. Herein, we explored the characteristics of the impairments in static balance and plantar load distribution in patients. Methods We performed a retrospective study of 21 patients with diabetic foot ulcers who underwent TCTD, who were regularly followed up for > 1 year after surgery, and 20 healthy individuals (control group). A pressure platform was used to assess the standing balance functions of the lower extremities and the plantar load distribution. Results One patient underwent amputation because of severe infection. In patient group, center of pressure (COP) ellipse sway area, COP path length and angle θ were all larger, compared with those of control group (250.15 ± 98.36 mm2 vs. 135.67 ± 53.21 mm2, 145.15 ± 67.43 mm vs. 78.47 ± 34.15 mm, 39.75 ± 17.61° vs. 22.17 ± 14.15°), with statistically significant differences (P

Foot progression angle (FPA) is a gait-related clinical measurement commonly used for assessing the rotational profile of the lower extremity. This study examined the accuracy of two methods based on force-plate data for estimating FPA during walking by comparing them with a reference method using a motion capture system. Ten healthy adults performed a series of overground walking trials at three different speeds: slow, preferred and fast. FPA was estimated from two methods using data on center of pressure—one method previously reported in the literature, and a novel method proposed here. The FPA estimated by each of these two force-plate methods were compared with the reference FPA determined from kinematic data. Results showed that the novel force-plate method was more accurate and precise when measuring the FPA in the three speed conditions than the force-plate method previously reported in the literature. The mean absolute error obtained with this novel method was 3.3° ± 2.1° at slow speed, 2.0° ± 1.2° at preferred speed and 2.0° ± 1.2° at fast speed, with no significant effect of gait speed (p > 0.05). These findings suggest that the novel force-plate method proposed here is valid for determining FPA during walking at various speeds. In the absence of kinematic data, this method constitutes an attractive alternative for measuring FPA.

The quiet standing test is used to detect diseases of the postural control system. The descriptive statistics of the center of pressure (COP) of older people during the test tend to be larger than those of healthy young people, but they cannot indicate structural problems in postural control. COP trajectories can be mathematically modeled with structural parameters such as viscosity, stiffness, and stochastic terms; however, the classification accuracy of older and fall-experienced people using such parameters has not been sufficiently verified. In this study, six structural parameters of a mass–spring–damper (MSD) model were estimated using two datasets, in which a total of 212 subjects performed quiet standing tests under four conditions. The estimated parameters were used for classification with a random forest algorithm to examine the differences in classification accuracy compared to seven conventional descriptive statistics methods. For the classification of older subjects, the classification accuracy of the MSD parameter method was the highest in foam condition, with positive likelihood ratios approximately 8.0. For the classification of fall-experienced subjects, the positive likelihood ratio of the MSD parameter method was 5.0, which is better than conventional descriptive statistics. Various MSD parameters revealed that aging and changing the floor surface and visual conditions cause oscillations in the COP behavior. While the MSD parameters were confirmed to help classify older subjects more accurately than the conventional descriptive statistics, there was room for further improvement in the classification accuracy of fall-experienced subjects.

IntroductionPostural instability increases with age and is exacerbated in neurological disorders such as Parkinson’s disease (PD). Reducing the base of support from bipedal to unipedal stance increases center of pressure (CoP) parameters and intermuscular coherence in lower-leg muscles of healthy older adults. To further develop an understanding of postural control in an altered state of neurological impairment, we explored intermuscular coherence in lower-leg muscles and CoP displacement in older adults with PD.MethodsThis study measured surface EMG from the medial (MG) and lateral (LG) gastrocnemii, soleus (SOL), and tibialis anterior (TA), and examined EMG amplitude and intermuscular coherence during bipedal and unipedal stance on a force plate with firm (no foam) and compliant (standing on foam) surface conditions in nine older adults with PD (70±5 years, 6 females) and 8 age-matched non-Parkinsonian older adults (5 females). Intermuscular coherence was analyzed between agonist-agonist and agonist-antagonist muscle pairs in the alpha (8-13 Hz) and beta (15-35 Hz) frequency bands.ResultsCoP parameters increased from bipedal to unipedal stance in both groups (p 0.05). During unipedal stance, CoP path length was shorter in older adults with PD (2027.9 ± 1074.1 mm) compared to controls (3128.5 ± 1198.7 mm) (p 0.05), but did not differ between older adults with PD (0.09 ± 0.07) and controls (0.08 ± 0.05) (p > 0.05). The older adults with PD also had greater normalized EMG amplitude of the LG (63.5 ± 31.7%) and TA (60.6 ± 38.4%) during the balance tasks (p > 0.05) than the non-Parkinsonian counterparts.DiscussionOlder adults with PD had shorter path lengths during unipedal stance and required greater muscle activation than older adults without PD to perform the tasks, but intermuscular coherence did not differ between the groups. This may be attributable to their early disease stage and high motor function.

Heelwork walking is a command that competitive obedience and working dogs are trained to perform. Unlike other canine sports, the research for competitive obedience sport is limited and no research regarding biomechanical gait adaptions during heelwork walking has been published. The aim of the study was to investigate the changes in vertical ground reaction forces, paw pressure distribution (PPD), and center of pressure (COP) of Belgian Malinois during heelwork walking. Ten healthy Belgian Malinois were included in the study. The dogs walked first without heeling (normal walk) and then while heeling on a pressure platform. The comparison between normal and heelwork walking was performed using mixed-effects models. Post-hoc analyses were performed using Sidak's alpha correction procedure. During heelwork walking, a significant decrease in the vertical impulse and stance phase duration (SPD) and a significant increase in the craniocaudal index and speed of COP was observed in the forelimbs compared to normal walking. At the hindlimbs, a significant increase in vertical impulse and SPD was observed during heelwork walking. Regarding PPD, a significant decrease of vertical impulse was observed at the cranial quadrants of the right forelimb and craniolateral quadrant of the left forelimb during heelwork. The area was significantly decreased at the craniolateral quadrant of the left forelimb and the time for the peak vertical force was prolonged significantly at the caudal quadrants of the right forelimb during heelwork walking. The vertical impulse was significantly increased in all quadrants of the hindlimbs except the craniolateral quadrant of the left hindlimb. The effect of these changes on the musculoskeletal system of working dogs should be investigated in further studies, using electromyography and kinematic analysis.

While the literature has characterized balance control during quasi-static and/or dynamic tasks, comparatively few studies have examined relationships across paradigms. This study investigated whether quiet-stance postural steadiness metrics were associated with reactive control parameters (during both stepping and restabilization phases) following a lean-and-release perturbation. A total of 40 older adults participated. Postural steadiness (center of the pressure range, root mean square, velocity, and frequency) was evaluated in "feet together" and "tandem stance" positions. During the reactive control trials, the step length, step width, movement time, and reaction time were measured, in addition to the postural steadiness variables measured during the restabilization phase following the stepping response. Out of 64 comparisons, only 10 moderate correlations were observed between postural steadiness and reactive spatio-temporal stepping parameters (P ≤.05, r = −.312 to −.534). However, postural steadiness metrics were associated with the center of pressure velocity and frequency during the restabilization phase of the reactive control trials (P ≤.02, r =.383 to.775 for velocity and P ≤.01, r =.386 to.550 for frequency). Although some elements of quasi-static center of pressure control demonstrated moderate associations with dynamic stepping responses, relationships were stronger for restabilization phase dynamics after foot-contact. Future work should examine the potential association between restabilization phase control and older adult fall-risk. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine changes in weight transfer, alignment, and shot outcome during golf shots from flat, uphill, and downhill slopes. Twelve elite male golfers hit 30 shots with a 6-iron from a computer-assisted rehabilitation environment used to create 5° slopes while collecting 3-dimensional kinematics and kinetics of the swing. A launch monitor measured performance outcomes. A shift in the center of pressure was found throughout the swing when performed on a slope, with the mean position moving approximately 9% closer to the lower foot. The golfers attempted to remain perpendicular to the slope, resulting in weight transfer toward the lower foot. The golfers adopted a wider stance in the sloped conditions and moved the ball toward the higher foot at address. Ball speed was not significantly affected by the slope, but launch angle and ball spin were. As the coaching literature predicted, golfers were more likely to hit shots to the left from an uphill slope and to the right from a downhill slope. No consistent compensatory adjustments in alignment at address or azimuth were found, with the change in final shot dispersion resulting from the lateral spin of the ball. [ABSTRACT FROM AUTHOR]

This study aimed to determine the relationship between postural asymmetry and falls in Parkinson's disease (PD). In total, 28 patients with PD were included. Postural control was analyzed in bipedal, tandem, and unipedal standing. Center of pressure (CoP) parameters were calculated for both limbs, and asymmetry was assessed using the asymmetry index. Logistic regression was used to predict/classify fallers through postural asymmetry. The Spearman correlation was performed to relate asymmetry and falls number. Poisson regression models were created to predict the number of falls in each condition. The results demonstrated that asymmetry can classify 75% of fallers and nonfallers. Asymmetry in anteroposterior-mean velocity of CoP in unipedal standing was related to the number of falls. Poisson regression showed that anteroposterior-mean velocity of CoP predicts falls in PD, indicating that increased asymmetry results in a greater number of falls. Anteroposterior-mean velocity of CoP seems to be a sensitive parameter to detect falls in PD, mainly during a postural challenging task. [ABSTRACT FROM AUTHOR]