Relationship between the strength of the ankle and toe muscles and functional stability in young, healthy adults

This study investigates the relationship between ankle and toe strength and functional stability in young adults, with a sample comprising sixteen females and fourteen males. The research employed force platform data to determine the center of foot pressure (COP) and calculated the forward functional stability index (FFSI) through foot anthropometric measurements. Strength measurements of toe and ankle muscles, during maximal isometric flexion and extension, were conducted using force transducers. Notable positive correlations were found between toe flexor strength and FFSI (left flexor: r = 0.4, right flexor: r = 0.38, p < 0.05), not influenced by foot anthropometry. Contrarily, no significant correlation was observed between ankle muscle strength and FFSI, despite a positive correlation with the COP range. The moderate correlation coefficients suggest that while toe flexor strength is a contributing factor to functional stability, it does not solely determine functional stability. These findings highlight the critical role of muscle strength in maintaining functional stability, particularly during forward movements and emphasize the utility of FFSI alongside traditional COP measures in balance assessment. It is recommended to employ a multifaceted approach is required in balance training programs.

How partnering changes the process of postural control?

The aim of the study was to identify changes in the mechanism of postural control among ballroom dancers between standing solo and standing with a partner during specific standard dance positions. Specifically, the study attempted to determine whether the male partner plays a stabilising role in the dance couple. A total of seven competitive dance couples participated in the study. The experimental procedure comprised four dance positions characteristic of international standard dances: standard, starting, chasse and contra check. The dance positions were staged twice - while standing solo and while standing with a partner. The assumption of the assessed position was preceded by a dance phase after which the participants were instructed to freeze on a force plate and hold the position for 30 s. To examine whether subjects standing solo or with partners had greater rambling (RM) or trembling (TR) components in their dance postural profile, the ratios of RM to the center of foot pressure (COP) and TR to COP were computed for velocity. No significant differences were observed in the velocity of COP between standing solo and standing with a partner (p > 0.05). However, during the standard and starting positions, female and male dancers standing solo were characterised by higher values of the velocity of RM/COP ratio and lower values of the velocity of TR/COP ratio than those standing with a partner (p < 0.05). According to the theory behind the RM and TR decomposition, an increase in TR components could indicate a higher reliance on spinal reflexes, which would suggest greater automaticity.

Age-Related Differences in Intermuscular Coherence EMG-EMG of Ankle Joint Antagonist Muscle Activity during Maximal Leaning

BACKGROUND

Intermuscular synchronization is one of the fundamental aspects of maintaining a stable posture and is of great importance in the aging process. This study aimed to assess muscle synchronization and postural stabilizer asymmetry during quiet standing and the limits of stability using wavelet analysis. Intermuscular synchrony and antagonistic sEMG-sEMG (surface electromyography) coherence asymmetry were evaluated in the tibialis anterior and soleus muscles.

METHODS

The study involved 20 elderly (aged 65 ± 3.6) and 20 young (aged 21 ± 1.3) subjects. The task was to perform a maximum forward bend in a standing position. The prone test was divided into three phases: quiet standing (10 s), dynamic learning, and maintenance of maximum leaning (20 s). Wavelet analysis of coherence was performed in the delta and beta bands.

RESULTS

Young subjects modulated interface coherences to a greater extent in the beta band. Analysis of postural stability during standing tasks showed that only the parameter R2b (the distance between the maximal and minimal position central of pressure), as an indicator for assessing the practical limits of stability, was found to be significantly associated with differences in aging.

CONCLUSION

The results showed differences in the beta and delta band oscillations between young and older subjects in a postural task involving standing quietly and leaning forward.

The effect of expertise on postural control in elite sport ju-jitsu athletes

Background

Due to the high postural control demands of sport ju-jitsu, it is likely that long-term sport ju-jitsu training may induce sport-specific adaptations in postural control, especially in positions directly related to combat. The aim of the study was to assess the differences in postural control between elite sport ju-jitsu athletes and untrained controls in non-ecological and ecological conditions and to investigate the relative contribution of spinal and supraspinal mechanisms to postural control in expert athletes.

Methods

The study was conducted on eleven male elite ju-jitsu athletes and ten non-athletes. The data was collected with the use of a force plate under two conditions: quiet standing and ju-jitsu combat stance. Apart from the standard analysis of the spatial–temporal parameters of center of foot pressure, non-linear measures were used, namely rambling-trembling and sample entropy. The non-parametric Mann–Whitney U test was used to compare both groups.

Results

The main findings of the study showed that in quiet standing, elite ju-jitsu athletes and non-athletes had comparable postural control in both the anterior–posterior and mediolateral planes. In contrast, in the combat stance, elite athletes had lower values of postural sway and rambling component (range and rms) and higher values of sample entropy in comparison to the non-athletes (p < 0.05). No differences were found in the trembling component of sway between groups in the combat stance (p < 0.05).

Conclusions

Smaller postural sway and its rambling component in sport ju-jitsu athletes may indicate the more precise control of center of foot pressure and improved ability in estimating its position. The sample entropy results confirmed that the displacement of center of foot pressure for sport ju-jitsu athletes was more irregular, which demonstrates greater automatization in postural control. The results also confirm the importance of ecological validity in investigating postural adaptations associated with sports expertise.

The effect of a light finger touch on the signal complexity during quiet standing

The purpose of the study was to investigate the influence of additional tactile information (light fingertip touch) on the postural sway and regularity of center-of-pressure (COP) fluctuations. Thirty-two young, healthy participants performed a quiet standing task (30 s) on a force platform with and without light fingertip touch. COP time-series were analyzed using standard postural sway measures (range, root mean square error, velocity), COP regularity was measured with Sample entropy. Participants demonstrated significantly smaller postural sway with a light touch, but only in the anteroposterior direction. The amount of sway with additional tactile information in the sagittal plane reached the level of sway in the frontal plane without this information. Similarly, COP fluctuations were more irregular during light touch condition only in the anteroposterior direction, as evidenced by significantly higher Sample entropy. Furthermore, COP regularity decreased in the sagittal plane and reached level in the frontal plane without light touch. These results suggest that postural sway is mostly controlled in the sagittal plane and that in the mediolateral direction the control is mostly automated. In conclusion, our results support the notion that the light touch provides additional information which enhances postural stabilization. Our results expand the relation between COP regularity and the attention invested in posture in the touch domain and prove that light touch, as an attentional demanding task, leads to increased COP irregularity. Nonlinear measures of signal regularity (i.e., SampEn) provide surplus insight into human postural control and can be used as an additional useful tool to traditional balance measures.

Detection of postural control in early Parkinson's disease: Clinical testing vs. modulation of center of pressure

INTRODUCTION

Little is known about the early stage balance changes in PD. Many clinicians assume that there are no postural issues in early PD because of failure to identify them on bedside and clinical testing. Here, we quantify balance changes in early and moderate stage PD and compared these values to healthy controls (HC) using clinical assessments of balance and posturography.

METHODS

We compared 15 HC with 15 early PD (PD-II; Hoehn and Yahr stage II) and 15 moderate PD (PD-III; H&Y stage III). Participants performed various clinical tests of balance and a standing postural task on a force platform. We quantified the spatiotemporal parameters of the center of pressure (COP), the sample entropy and power spectral density (PSD) of the COP.

RESULTS

The PSD of the COP differentiated PD-II from HC from 0-0.5 Hz and PD-II from PD-III from 0.5-1 Hz. Specifically, PD-II and PD-III manifested greater power than HC from 0-0.5 Hz, whereas PD-III exhibited greater power than PD-II and HC from 0.5-1.0 Hz (p<0.05). However, there were no significant differences between PD-II and HC in all clinical tests and in spatiotemporal parameters of the COP (p>0.05). Although the sample entropy was significantly lower in the PD groups (p<0.05), entropy failed to differentiate PD-II from PD-III.

CONCLUSION

The low-frequency modulation of the COP in this small cohort differentiated early PD from HC and from moderate PD. Clinicians should be aware that there are early balance deficits in PD. A larger sample size is needed to confirm these findings.

Age-related changes in postural control in older women: transitional tasks in step initiation

Background

Aging, being a natural process, involves many functional and structural changes within the body. Identifying the age-related postural changes will provide insight into the role of aging on postural control during locomotion. The aim of this study was to identify age-related postural changes during a transitional task under different conditions.

Methods

Sixty healthy females divided into three age groups: A (50-60 y/o), B (60-70 y/o), and C (70-80 y/o). The transitional task was measured by two force platforms. The procedure consisted of three phases: quiet standing, transfer onto a second platform, and quiet standing on the second platform. Four different conditions were applied: unperturbed transfer, obstacle crossing, step-up, and step-down. Double-support time, transit time, and stability time before and after the step task were analyzed.

Results

The transit time was longer by 30% for subjects over 70 y/o. The double-support time was longer by 11% among adults 60-70 y/o, while in people over 70 y/o it was longer by almost 50% compared to the 50-60 y/o subjects. The stability time before the transitional task was longer by 17% among adults over 60 y/o compared to middle-age subjects. The stability times before and after the transitional task were longer for adults in the 50-60 y/o category.

Conclusion

The proposed procedure is adequate for assessing age-related changes in postural control while undergoing a transitional task. An analysis of the double-support time and stability time before and after the step task enabled the detection of early signs of balance changes in middle-age adults. Independent of age, the transitional task parameters changed with the increasing difficulty of the tasks.

Rambling-trembling analysis of postural control in children aged 3-6 years diagnosed with developmental delay during infancy

BACKGROUND

Preschool age is fundamental for the development of gross motor skills. Timely detection of postural stability deficits using objective methods would facilitate early implementation of therapeutic strategies.

RESEARCH QUESTION

What are the age- and gender-related differences in postural control between preschool children diagnosed with developmental delay in their first year of life and children with typical development?

METHODS

The study group consisted of 59 children diagnosed with developmental delay during infancy, who had received physiotherapy in the first year of their life for disorders of postural control and prone locomotion as well as abnormal distribution and magnitude of postural tone. The control group comprised 66 nursery school children with typical development and no history of postural control or movement deficits and no physiotherapy interventions in the first year of their life. The study and control groups were subdivided into four subgroups based on age (3-4 years, 5-6 years) and gender (boys, girls). The data were collected during quiet standing using a force plate. Three 30-second trials were recorded. Stabilographic recordings were analysed using the rambling-trembling approach.

RESULTS

Three-way ANOVA revealed a gender effect on all measured variables (p < 0.05). The Tukey HSD (honest significant difference) post-hoc test showed that some of the values of sway range and mean velocity of COP, rambling and trembling in sagittal and frontal plane were significantly greater in control boys aged 3-4 years compared to other subgroups (p < 0.05).

SIGNIFICANCE

Long-term postural control monitoring by a pediatrician and/or physiotherapist seems justified and not only in children with a history of infantile developmental delay but also in their healthy peers, especially boys.

Fall-related measures in elderly individuals and Parkinson's disease subjects

Falls pose a serious problem in elderly and clinical populations. Most often, they lead to a loss of mobility and independence. They might also be an indirect cause of death. The aim of this study was to determine an objective predictor of the fear of falling and falls in elderly subjects (ESs) and Parkinson's disease (PD) subjects. Thirty-two ESs were examined in this study, of whom sixteen were diagnosed with PD. The testing procedures comprised force plate measurements (limit of stability test-LOS test) and clinical tests (Berg Balance Scale, Functional Reach Test, Timed Up and Go test, Tinetti test). The Falls Efficacy Scale International (FES-I) was used to evaluate the fear of falling. The range of the maximum forward lean was normalized to the length from the ankle joint to the head of the first metatarsal bone and was named the functional forward stability indicator (FFSI). The FFSI, derived from the LOS test, allowed us to demonstrate the real deficit in functional stability and individual safety margins. Moreover, the FFSI was highly correlated with the FES-I score and almost all clinical test results in elderly subjects (r>0,6; p<0.05). In PD subjects, the FFSI was poorly correlated with the fear of falling, the BBS score and the FR distance; however, a high correlation with the Tinetii test (r>0,6, p<0.05) was noted. The PD subjects presented a different balance strategy when close to their stability limits, which was also reflected in the lower values of sample entropy (t = (-2.40); p<0.05; d = 0.87). The FFSI might be a good predictor of the fear of falling in the group of elderly people. Additionally, the FFSI allows us to show real balance deficits both in PD subjects and in their healthy peers without the need for a reference group and norms. In conclusion, it is postulated that the popular clinical assessments of postural balance in PD subjects should be accompanied by reliable posturography measurements.

Transitional Locomotor Tasks in People With Mild to Moderate Parkinson's Disease

Background: People with Parkinson's disease (PD) exhibit deficits in maintaining balance both during quiet standing and during walking, turning, standing up from sitting, and step initiation. Objective: The purpose of this study was to examine balance disorders during a transitional task under different conditions in participants with PD. Methods: The research was conducted on 15 PD-II (mild) and 15 PD-III (moderate) individuals (H&Y II-III stage) and 30 healthy elderly. The transitional task was measured on two force platforms (A and B). The procedure consisted of three phases: (1) quiet standing on platform A, (2) crossing to platform B, and (3) quiet standing on platform B, each until measurements were completed. There were four conditions: crossing without an obstacle, crossing with an obstacle, and walking up and down the step. Results: There were no significant differences between mild PD individuals and healthy elderly during quiet standing before the transitional task and after completing the task. The temporal aspects describing the different transitional tasks were comparable between mild PD and healthy subjects. Moderate PD participants presented a significantly higher COP velocity after the transitional task compared to the healthy older adults (p < 0.05). Additionally, the moderate PD group showed significantly higher values for transit time relative to healthy subjects during the transitional task in all conditions (p < 0.05). Conclusions: Disease severity affects the temporal aspects of different transitional tasks in people with PD. The procedure of completing a transitional task under different conditions allowed differences between moderate and mild PD stages and healthy subjects to be observed.

Forward functional stability indicator (FFSI) as a reliable measure of limits of stability

Functional stability has been studied in diverse populations, yet the possibility to compare the results across them and the knowledge about actual performance referenced to the maximum capacity is limited. Our aim was to improve the functional limits of stability testing and introduced Forward Functional Stability Indicator (FFSI) as a reliable measure of functional stability. The study participants were not able to cross the projected forward anatomical stability limit (FASL). It is located at the level of first metatarsophalangeal joints and should be considered a mechanical limit of the maximal voluntary centre of foot pressure (COP) excursion (MVE). It was only true when the whole feet were in contact with the ground. There were statistically significant differences in limits of stability (LOS) test results in the conditions when the heels were raised and the toes muscles were contracted isometrically. The proposed forward functional stability indicator (FFSI) is a highly reliable measure of functional stability, which provides information about the actual performance with reference to maximum capacity and is easy to compare across normal and clinical populations.

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The proposed forward functional stability indicator (FFSI) is a highly reliable measure of functional stability.

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FFSI provides information about the actual performance with reference to maximum capacity and is easy to compare across normal and clinical populations.

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The forward anatomical stability limit (FASL) is located at the level of first metatarsophalangeal joints and should be considered a mechanical limit of the maximal voluntary centre of pressure (COP) excursion when certain measurement criteria are met.

A posturographic procedure assessing balance disorders in Parkinson's disease: a systematic review

Postural instability is common in Parkinson's disease (PD), often contributing to falls, injuries, and reduced mobility. In the clinical setting, balance disorder is commonly diagnosed using clinical tests and balance scales, but it is suggested that the most sensitive measurement is the force platform. The aim of this systematic review was to summarize the methods and various posturographic procedures used to assess the body balance and gait in PD. A systematic review was conducted of papers published from 2000 to 2017. Databases searched were PubMed and EBSCO. Studies must have involved patients with PD, used force platform or motion analysis system as a measurement tool, and described posturographic procedure. The Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality of the included studies. A total of 32 studies met the inclusion criteria. The PEDro scores ranged from 5 to 7 points. The analysis of the objective methods assessing balance disorders revealed a large discrepancy in the duration and procedures of measurements. The number of repetitions of each trial fluctuated between 1 and 8, and the duration of a single trial ranged from 10 to 60 seconds. Overall, there are many scales and tests used to assess the balance disorders and disabilities of people with PD. Although in many included studies the authors have used posturography as a method to evaluate the postural instability of PD patients, the results are contradictory. To solve this issue, it is indicated to establish a "gold standard" of procedures of measures of balance.

Standards of Virtual Reality Application in Balance Training Programs in Clinical Practice: A Systematic Review

OBJECTIVE

To determine the effect of virtual reality (VR) games on improving balance in different groups of neurological patients with a particular focus on the study quality and to determine the gold standard in VR training in these groups.

MATERIALS AND METHODS

A systematic review of controlled trials published between January 2009 and December 2017 was conducted. The PubMed, SCOPUS, SPORTDiscus, and Medline databases were searched. Studies involved patients with stroke or Parkinson's disease or children with cerebral palsy. The Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality of the included studies.

RESULTS

A total of 20 studies met the inclusion criteria. The PEDro scores ranged from 4 to 8 points. Analysis of the rehabilitation programs revealed a very large discrepancy in the planned volume of exercises in different subgroups of patients.

CONCLUSIONS

Overall, the comparison of VR interventions between conventional rehabilitation and no intervention exhibited significantly better results. However, these results should be interpreted with great caution due to the large diversity of the systems, games, and training volume used in the VR therapy. In all included studies, only several articles included objective methods to assess the effect of VR. In addition, most of the articles showed a high risk of bias, such as a lack of randomization and blinding or a small sample size. That is why further well-designed randomized control trials are required to evaluate the influence of VR on balance in different groups of neurological patients.

Effect of expertise in ballet dance on static and functional balance

RESEARCH QUESTION

The purpose of this study was to examine the postural sway characteristics of the ballet dance experts in quiet standing and at their limits of stability with an approach not used before in dancers.

METHODS

The study was conducted on thirteen female ballet dancers and thirteen non-training females. The data were collected with a use of a force plate. To gain a better insight into the postural control processes, we used the rambling-trembling and sample entropy analyses in the COP data processing.

RESULTS

The main findings of the study showed professional dancers to have higher values of postural sway characteristics in comparison to the non-trainees while performing simple motor tasks. Also, higher values of the trembling component in the group of dancers during quiet standing and the inclined positions were observed. This might be a sign of higher capacity of the postural system to deal with postural instability in dancers.

IMPORTANCE

Our results confirmed that the visual information is important in the process of postural control of dancers', which is proven by increased dislocations of the COP without visual feedback. The sample entropy results indicated more irregular characteristics of postural sway in ballet dancers representing more automated postural control. The data analysis methods showed high sensitivity to the subtle changes in postural control due to the dance training.

The Effects of Cryotherapy on Knee Joint Position Sense and Force Production Sense in Healthy Individuals

The proprioceptive information received from mechanoreceptors is potentially responsible for controlling the joint position and force differentiation. However, it is unknown whether cryotherapy influences this complex mechanism. Previously reported results are not universally conclusive and sometimes even contradictory. The main objective of this study was to investigate the impact of local cryotherapy on knee joint position sense (JPS) and force production sense (FPS). The study group consisted of 55 healthy participants (age: 21 ± 2 years, body height: 171.2 ± 9 cm, body mass: 63.3 ± 12 kg, BMI: 21.5 ± 2.6). Local cooling was achieved with the use of gel-packs cooled to -2 ± 2.5°C and applied simultaneously over the knee joint and the quadriceps femoris muscle for 20 minutes. JPS and FPS were evaluated using the Biodex System 4 Pro apparatus. Repeated measures analysis of variance (ANOVA) did not show any statistically significant changes of the JPS and FPS under application of cryotherapy for all analyzed variables: the JPS’s absolute error (p = 0.976), its relative error (p = 0.295), and its variable error (p = 0.489); the FPS’s absolute error (p = 0.688), its relative error (p = 0.193), and its variable error (p = 0.123). The results indicate that local cooling does not affect proprioceptive acuity of the healthy knee joint. They also suggest that local limited cooling before physical activity at low velocity did not present health or injury risk in this particular study group.

The influence of different intensity treadmill efforts on the sense of rhythm of non-professional runners - pilot study

PURPOSE

The purpose of this study was to determine how global effort affects the rhythm of multi-joint coordination in the global task. We wanted to examine how this specific kind of fatigue impacts sense of rhythm.

METHODS

In this study, fourteen non-professsional runners performed two effort trials of different intensity, where speed was set individually according to the speed of running when par- ticipants reached lactate threshold. Before and after each effort trial they had to perform the rhythm test.

RESULTS

Two-way analysis of variance ANOVA did not reveal significant differences among the variables of pre- and post-effort rhythm test. It is suggested that these results are supported by the application of different movement strategies to compensate for fatigue, and possible motor learning effect of simple timing performance.

CONCLUSIONS

In our opinion the training workout routine should include cyclic technical exercises after fatigue. Not only to develop and improve energetics of movement, but also to learn and perfect different movement patterns and develop novel movement strategies.

Balance Training Programs in Athletes - a Systematic Review

It has become almost routine practice to incorporate balance exercises into training programs for athletes from different sports. However, the type of training that is most efficient remains unclear, as well as the frequency, intensity and duration of the exercise that would be most beneficial have not yet been determined. The following review is based on papers that were found through computerized searches of PubMed and SportDiscus from 2000 to 2016. Articles related to balance training, testing, and injury prevention in young healthy athletes were considered. Based on a Boolean search strategy the independent researchers performed a literature review. A total of 2395 articles were evaluated, yet only 50 studies met the inclusion criteria. In most of the reviewed articles, balance training has proven to be an effective tool for the improvement of postural control. It is difficult to establish one model of training that would be appropriate for each sport discipline, including its characteristics and demands. The main aim of this review was to identify a training protocol based on most commonly used interventions that led to improvements in balance. Our choice was specifically established on the assessment of the effects of balance training on postural control and injury prevention as well as balance training methods. The analyses including papers in which training protocols demonstrated positive effects on balance performance suggest that an efficient training protocol should last for 8 weeks, with a frequency of two training sessions per week, and a single training session of 45 min. This standard was established based on 36 reviewed studies.

Step-Initiation Deficits in Children with Faulty Posture Diagnosed with Neurodevelopmental Disorders during Infancy

BACKGROUND

Early detection of movement deficits during step initiation will facilitate the selection of the optimal physiotherapy management strategy. The main aim of the study was to assess potential differences in step initiation between 5- and 6-year-old children with faulty posture who had been diagnosed with neurodevelopmental disorders during infancy and healthy children.

METHODS

The experimental group consisted of 19 children aged 5-6 years with faulty posture, who had been diagnosed with neurodevelopmental disorders during infancy and were given physiotherapy in the first year of their lives. The control group comprised 19 nursery school children aged 5-6 years with no postural defects, no history of postural control or movement deficits, and no physiotherapy interventions in the first year of their lives. Step initiation was performed on force platforms under various conditions, i.e., with and without an obstacle, stepping up onto a platform placed at a higher level, stepping down onto a platform placed on a lower level. The recording of center of foot pressure (COP) displacements was divided into three phases: phase 1 (P1)-quiet standing before step initiation, phase 2 (P2)-transit, phase 3 (P3)-quiet standing until measurement completion.

RESULTS

The Tukey post hoc test showed that the means of sway range (raCOP) and mean velocity (vCOP) in sagittal (_AP) plane for phase 1 and vCOP in frontal (_ML) plane for phase 3 registered in the step-up trial were significantly higher (p < 0.05) in children with faulty posture compared to children with typical development. P1vCOP_ML, P3vCOP_AP, P3raCOP_ML, and P3vCOP_MLof the step-down trial were also significantly higher in children with faulty posture (p < 0.05).

CONCLUSION

Inclusion of functional movement exercises (stair-walking tasks) in physiotherapy interventions for children with postural defects seems well justified.The trial was registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12617001068358).

Evaluation of reliability and concurrent validity of two optoelectric systems used for recording maximum vertical jumping performance versus the gold standard

PURPOSE

The objective of this study was to evaluate the reliability and validity of two alternative systems used for jumping performance measurement.

METHODS

Two groups of subjects were tested. The first group consisted of 15 male adults (21.3 ± 1.7 years) and the second group consisted of 16 female volleyball players (17.2 ± 0.9 years). We used three different systems of data collection in the study. Two of the used systems are based on optoelectric components. The Optojump Next system is referred to as the optoelectric system, and BTS Smart-E is refered to as the video system. Concurrent validity of these systems was verified with the use of "gold standard" which is force platform. All systems were used to estimate the height of vertical jumps.

RESULTS

Both optoelectric systems turned out to be highly reliable with the ICCs = 0.98 for Optojump and 0.9 for BTS Smart. Their concurrent validity with the force platform data was also very high r = 0.99 and r = 0.97, respectively.

CONCLUSIONS

Comparison of these two systems shows distinct differences between them. Out of the two systems, Optojump system is more suitable for quick and reliable sports testing while when BTS-Smart is better for research and clinical testing.

Directional measures of postural sway as predictors of balance instability and accidental falls

Despite the obvious advantages and popularity of static posturography, universal standards for posturographic tests have not been developed thus far. Most of the center-of-foot pressure (COP) indices are strongly dependent on an individual experimental design, and are susceptible to distortions, which makes results of their analysis incomparable. In this research, we present a novel approach to the analysis of the COP trajectory based on the directional features of postural sway. Our novel output measures: the sway directional indices (DI) and sway vector (SV) were applied to assess the postural stability in the group of young able-bodied subjects. Towards this aim, the COP trajectories were recorded in 100 students standing still for 60 s, with eyes open (EO) and then, with eyes closed (EC). Each record was subdivided then into 20, 30 and 60 s samples. Interclass correlation coefficients were calculated from the samples. The controlled variables (visual conditions) uniquely affected the output measures, but only in case of proper signal pretreatment (low-pass filtering). In filtering below 6 Hz, the DI and SV provided a unique set of descriptors for postural control. Both sway measures were highly independent of the trial length and the sampling frequency, and were unaffected by the sampling noise. Directional indices of COP filtered at 6 Hz showed high to very high reliability, with ICC range of 0.7-0.9. Results of a single 60 s trial are sufficient to reach acceptable reliability for both DI and SV. In conclusion, the directional sway measures may be recommended as the primary standard in static posturography.