Trend change analysis in the assessment of body balance during posture adjustment in reaction to anterior-posterior ground perturbation.

Postural adjustments (PA) occur to counteract predictable perturbations and can be impaired as a result of musculoskeletal and neurological dysfunctions. The most common way to detect PA is through electromyography measurements or center of pressure (COP) position measurements, where analysis in time domain and frequency domain are the most common. Aim of the research was to determine whether a new method of analyzing stabilographic measurements-the COP trend change analysis (TCI) of temporary posture corrections- can expand understanding of changes in balance strategy connected with PA. The study group involved 38 individuals (27women, 11men) aged 23±2.6 years. Measurements were performed using a stabilographic platform placed on a perturbation platform. The tests involved three measurements with forward and backward momentary movements of the platform. Participants were tested in three conditions-knowing the nature, time and direction of perturbation (Tr3), knowing only the nature of perturbation (Tr2) and without any information about the perturbation (Tr1). Statistically significant differences were revealed in the last second of Tr3 for the mean velocity of COP (p<0.05) and for two TCI parameters-TCI_dV (p<0.05) and TCI_dS (p<0.01). The increase in TCI_dV was related to the increase in the mean distance between trend changes (TCI_dS) and constant value of the mean time between trend changes (TCI_dT). The increase of the mean value of TCI_dS was the result of smaller number of posture corrections with the distance 0-2 mm and lager number with the distance 4-6 mm. Obtained results proved that the TCI analysis is a method enabling an extended analysis of PA, indicating the nature of changes occurring in posture corrections-longer momentary jumps of COP-related to a change in the strategy of maintaining balance before a known disorder, which has not been analyzed in this type of research so far.

Balance assessment in selected stages of Parkinson's disease using trend change analysis.

BACKGROUND: Balance disorders in patients diagnosed with Parkinson's disease (PD) are associated with a change in balance-keeping strategy and reflex disorders which regulate the maintenance of vertical body posture. Center of foot pressure (COP) displacement signals were analyzed during quiet standing experiments to define such changes. The research aimed to apply stock exchange indices based on the trend change analyses to the assessment of a level of the Parkinson disease progression on the grounds of the analysis of the COP signals. METHODS: 30 patients in two stages of PD, 40 elderly participants, and 20 individuals at a young age were studied. Each person was subjected to 3 measurements with open and closed eyes. A technical analysis of the COP displacement signal was performed, and the following quantities were determined: indices related to the number of trend changes (TCI), indices defining a mean time (TCI_dT), and mean displacement (TCI_dS) and mean velocity (TCI_dV) between such changes. RESULTS: The results indicate a higher TCI value for PD than for aged-matched control group (p < 0.05). In the case of PD patients, there was also an increase in the TCI_dS value by 2-5 mm, which mainly contributed to the increase in TCI_dV. Statistically significant differences for the TCI_dT values occurred between all groups in which differences in the average COP velocity were noted. CONCLUSIONS: The TCI and TCI_dV results obtained for the healthy participants enabled the development of indices supporting PD diagnostics. The causes of the TCI_dV changes in patients were determined, i.e., whether they resulted from an increase in the TCI_dT or TCI_dS between the moments of trend changes indicated by the developed algorithm. The developed methodology provides new information on the impact of PD on the strategy of maintaining balance, which was impossible to obtain using currently used analyses. Trial registration The conducted research is an observational study and does not include a health care intervention. Participants gave their consent to participate in the research and the procedure was approved by the Institutional Bioethics Committee.

Trend Change Analysis as a New Tool to Complement the Evaluation of Human Body Balance in the Time and Frequency Domains.

Trend change analysis is a tool that complements the assessment of human body stability and provides information on the number and frequency of postural corrections during an examination. The present research aims to determine the possibility of using this method of analysis to investigate postural stability during tests of standing with open eyes (OE) and closed eyes (CE). A total of 118 participants (67 females, 51males) aged 23 (SD 1.3) were assessed. Tests involved standing on a stabilographic platform for 50 s. Trend change analysis was used to evaluate displacement values of the center of pressure (COP). Values for the COP courses as well as values associated with trend change analysis, such as: TCI, MACD_t and MACD_V were determined. Histograms of distribution were plotted for TCI values. The present study provides information on alterations of the strategy used for maintaining balance, which are associated with the number of postural corrections and COP displacement between corrections for measurements taken during the standing test with CE in relation to OE measurements. The strategy demonstrated an ability to detect a smaller number of quick corrections, an increased number of corrections of longer duration, and the elongation of displacement between subsequent postural corrections. Slight standard deviations in TCI and MACD_t values calculated during trend change analysis, for both the OE and CE conditions, made it possible to classify these values as indexes of postural stability with significant sensitivity to slight changes.

The influence of isometric rotation of the lower limb on the functioning of the knee joint stabilizers and rotator muscles.

PURPOSE: This paper presents an assessment of the influence of isometric rotation of the lower limb in a standing position on the functioning of the muscles stabilizing the knee joint in the frontal plane with the use of modeling the loads on the musculoskeletal system. METHODS: The research was carried out in the AnyBody Modeling System software, performing multi-variant simulations of the musculoskeletal system during isometric rotation of the lower limbs. The simulations were carried out using as input data the values of rotating moments and the ground reaction forces acting on foot segments, which were measured using the proprietary Rotenso device and the position of the body segments. RESULTS: The result is the muscular activity of the lower limbs of the selected muscle groups during isometric rotation. Muscle activity was recorded for Sartorius, Tensor fasciae latae, Iliopsoas, Gluteus minimus, Gluteus medius, Gluteus maximus, Piriformis, Quadratus femoris, Obturator internus, Obturator externus, Gemellus inferior, Gemellus superior. CONCLUSIONS: Performing isometric rotation allowed for the activation of most of the knee joint stabilizing muscles and rotators of the lower limb. The results indicate that lower limb rotation exercises can be used in physiotherapy in patients with valgus knee.

The stock market indexes in research on human balance.

PURPOSE: The aim of the study was to demonstrate the possibility of using stock exchange indices to assess the ability to maintain balance as a supplement to analyzes using values determined in the time and frequency domains. METHODS: 83 healthy people (56 females, 27 males, age years 21 SD = 1.3 years) participated in the research. Measurements were performed with open and closed eyes and in the virtual environment with two sceneries oscillating at four frequencies. The results determined in the time and frequency domains were analyzed in relation to the results calculated with the use of stock exchange indicators for which the Trend Change Index was formulated. Performed measurements made it possible to determine the average COP speed, the average COP speed and range of movement towards AP, power spectral density PSD and stock exchange indices. RESULTS: In the case of PSD values for the ranges above and below 0.5 Hz, statistically significant differences occurred for most measurements. Obtained values of TCI coefficient were similar and no statistically significant differences were observed. The maximum values of the PSD medians were obtained in trials with the oscillating scenery. CONCLUSIONS: Conducted analyzes showed that use of stock exchange indicators broadens the interpretative possibilities of COP measurements by determining the number of consecutive skips (changes in the direction) of the COP and prioritizing according to the times between them. The applied stock market analysis methods also filtered out changes in the position resulting from noises that could not be removed with the use of standard low-pass filters.

The effect of selected lower limb muscle activities on a level of imbalance in reaction on anterior-posterior ground perturbation.

PURPOSE: We investigated whether an increase in muscular tone induced by the information about imminent posture destabilisation brings a positive result and prevents such destabilisation. METHODS: We measured forward and backwards movements of 38 participates (27 females and 11 males, aged 23 (SD 2.6)) on the treadmill (forward and backward movements). All participants were subjected to three test condition trials (Tr): 1) subject did not know the nature and time of perturbation (Tr1); 2) subject knew the nature of perturbation but did not know time (Tr2); 3) both the time and nature of perturbation were known precisely (Tr3). The tests resulted in the determination of muscular activity connected with a postural adjustment as well as values of pressure exerted by the forefoot on the ground, and the angle of flexion in the knee joint. RESULTS: In terms of postural adjustments, it was possible to observe statistically significant differences in muscular activity between Tr1 and Tr2 with reference to Tr3. No statistically significant differences were identified in all phases regarding values of forefoot pressure and those concerning the angle of flexion in the knee joint. An increase in the muscle tone before perturbation was correlated with the displacement and the velocity of the COP after perturbation. CONCLUSIONS: The results obtained indicate that knowledge of the expected time of perturbation is responsible for postural adjustment. Furthermore, muscle tone resulting from an adjustment of perturbation and responsible for the stiffening of lower limbs triggered greater displacement of the COP after perturbation.

The Use of Frequency Analysis as a Complementary and Explanatory Element for Time Domain Analysis in Measurements of the Ability to Maintain Balance.

Assessment of human balance is one of the most common diagnostic tests, both in medical applications and during sports training. Many new methods of measuring are introduced in these studies; however, the analysis of results is still carried out mainly based on the values determined in the time domain - the average COP speed or the ellipse field of the prediction. The aim of the current work is to present the possibilities for the practical application of frequency analyses in assessment of the ability to maintain body balance as a method supplementing standard analyses. As part of the study, measurements of the ability to maintain balance in sensory conflict conditions introduced in the form of an oscillating, three-dimensional, virtual scenery were carried out. 27 healthy volunteers (13 women and 14 men) took part in the study. The three-dimensional scenery, presented by means of the Oculus system, oscillated in the sagittal plane with frequencies equal to 0.7 Hz and 1.4 Hz. The frequency value during the measurement was constant or changed in the middle of the test. Measurements were conducted on the FDM Zebris platform. The results were analyzed using developed coefficients determined on the basis of the Short-time Fourier transform (STFT). The use of frequency-domain analyses confirmed that in the COP movement, one can observe a cyclical component corresponding to following the scenery, as well as the appearance of other cyclical components whose observation is important in terms of assessing the ability to maintain balance. It has been shown that the changes in the average COP speed that occur during the measurement can result from changes related to the movement of following the scenery as well as additional body movements indicating a greater or lesser loss of balance. It has been shown that there are differences in the COP movement provoked by the movement of the surrounding scenery, which depend on the parameters of the introduced disturbances - something that can only be observed in results obtained in the frequency domain. The conducted research shows that in measurements involving the ability to maintain one's balance conducted in sensory conflict conditions, standard time-domain analyses should be supplemented with other types of data analysis, e.g. frequency domain analyses.

Classic and indicative methods in the analysis of the foot arch and foot loads in professional folklore dancers on the basis of stabilographic tests.

PURPOSE: The proper shape of the foot determines its proper functioning and efficiency, which is significant as far as dancers are concerned. The aim of the study was to identify the arch of feet based on the Arch Index (AI), ability to maintain balance on the basis of stabilometric parameters and the distribution of loads acting on the feet of professional folk dancers. METHODS: The study group was composed of 37 folk dancers and the reference group consisted of 56 healthy adults aged 19-45. Balance measurements were performed using the Zebris FDM-S measurement platform, Romberg test with eyes open. Test results were exported to the Matlab 2019b computing environment. The algorithm developed by the Authors in relation was used to calculate Arch Index for the right and left foot, for each test participant separately. RESULTS: Statistical tests did not reveal statistically relevant differences between stabilometric parameters and loads affecting feet in the reference group and that of the dancers. The statistical tests revealed that the value of the AI differed significantly in the reference group and in the group of professional folk dancers ( p = 0.05). The differences were also observed in the group of females ( p = 0.003). No statistically relevant differences were observed in relation to the group of males ( p = 0.116). The percentage of the feet with high arch in the group of dancers amounted to 26%; 33% of dancers' feet were classified as the feet with low arch. CONCLUSIONS: The feet of professional folk dancers have a statistically more arched foot than the reference group.

Wavelet Decomposition in Analysis of Impact of Virtual Reality Head Mounted Display Systems on Postural Stability.

This study investigated how spatial projection systems influences body balance including postural stability. Analyzing precisely defined frequency bands of movements of the center of pressure makes it possible to determine the effectiveness of the balance system's response to disruptions and disorders and may be used as an indicator in the diagnosis of motor dysfunction. The study involved 28 participants for whom the center of pressure was assessed in a test with open eyes, closed eyes and with virtual reality projection. Percent distributions of energy during wavelet decomposition were calculated. Changes in body stability were determined for the virtual reality tests and these changes were classified as an intermediate value between the open-eyes test and the closed-eyes test. The results indicate the importance of using safety support systems in therapies involving Virtual Reality. The results also show the necessity of measurements times in stabilographic evaluations in order to conduct a more thorough analysis of very low frequencies of the center of pressure signal.

Can Physical Activity in Immersive Virtual Reality Be Attractive and Have Sufficient Intensity to Meet Health Recommendations for Obese Children? A Pilot Study.

Immersive virtual reality (IVR) is a technology that blurs the line between the physical world and a digital environment. Using appropriate pointing devices, it is possible to engage in physical activity (PA). The main aim of the study was to assess the attractiveness and intensity of physical exercise while playing active video games (AVGs) in IVR on an omnidirectional treadmill by obese children and to present the results compared to health recommendations (PA). It was also assessed whether the AVGs storyline can effectively motivate the participants to undertake locomotor activity by increasing the intensity of their effort (moving in a limited space vs. having to follow a set route). Eleven children aged 8 to 12 years with diagnosed obesity participated in the experiment. The attractiveness of PA was assessed with a questionnaire, while the intensity of exercise was estimated on the basis of heart rate. The answers show that AVGs are attractive and more enjoyable for the respondents than conventional video games. All participants declared their willingness to practice this form of PA. The intensity of PA of obese children during two games was high but during the game where the player was supposed to follow a set route, it was significantly higher (83.3 ± 9.2% HRmax) than during the game whose storyline assumed moving in a limited space (77.4 ± 9.8% HRmax). Due to the high intensity of PA while playing the AVGs studied, it can be assumed that obese children can benefit for their health if the games are used on a regular basis. However, further research is needed to verify this thesis.

Movement Variability during the Flight Phase in a Single Back Sideflip (Wildcat) in Snowboarding.

Understanding the structure and variability of motion is essential for sports technique development and an effective training design. Biomechanical analysis is particularly important in new disciplines with spatially complex motions, such as snowboarding. This study aimed to evaluate the level of variability of the kinematic variables in a single backside snowboard flip known as a "wildcat". Forty-six correct flips performed by 7 experienced athletes (age: 24.9 ± 4.34 year; body mass: 71.6 ± 12.87 kg; body height: 177.4 ± 6.99 cm) were recorded using an optoelectronic VICON system in the controlled setting of an indoor freestyle park. Athletes were equipped with special boards with wheels and the geometry of the ramps corresponded to the actual on-snow conditions. The analysis revealed two distinct single flip strategies, which differed in the way the tuck position was sustained. For all the measured variables, the coefficient of variation was computed, which allowed to identify the athlete with the highest (average 45.3%) and lowest (average 20.5%) variability of kinematic variables. Moreover, it was shown that the lowest values of the coefficient of variation occurred at the end of the grouping phase (average 14%) and that among all the different variables, those related to the duration of motion were most unstable (average 63%, SD = 48.5%).

Assessment of gait stability and preferred walking speed in virtual reality.

PURPOSE: Analysis of human gait as well as diagnosis of human locomotion organ should always be conducted with velocity of gait equal to Preferred Walking Speed (PWS). The literature review shows that the PWS value is not the same in real and virtual environment. The aim of this study was to determine PWS values in both environments and to specify values of parameters used in equations enabling PWS calculations on the basis of lower limb length. METHODS: Research-related tests involved 40 subjects walking on the treadmill and wearing HMD goggles. The spatial scenery made participants feel like during a walk in the park. The tests included measurements of displacements of the COP, allowing for the calculation of the Lyapunov exponent and Floquet Multiplier. Both coefficients were used to identify stability at various gait velocities. RESULTS: The analysis revealed that the PWS in relation to gait on the treadmill with VR was lower than the PWS without VR. The final stage of research involved the determination of new values of coefficients of the formula enabling the identification of the velocity of comfort of gait in VR. CONCLUSIONS: Obtained results proved that PWS in real and virtual environment are different. The lower values were obtained for measurements in VR. On the basis of these results, value of the "a" coefficient, used in PWS calculations on the basis of lower limb length, was re-determined. The new value makes it possible to assess PWS for gait conducted on treadmill in virtual environment, what can be very important in gait evaluation.

Quality of body posture and postural stability in people with intellectual disability playing volleyball.

PURPOSE: The quality of body posture and its balance depends on the efficiency of the receptors, the good work of the central nervous system integrating and coordinating the postural system and the effective musculoskeletal system. Physical activity of people with intellectual disability can stimulate the processes of improving the posture and its postural stability, improving the quality of life. METHODS: The study was conducted in 2017. 20 randomly selected volleyball players with intellectual disabilities and 10 healthy players took part in it. Body posture was recorded using a photogrammetric system. To evaluate the use of the Frohner Posture Index and the Dolphens classification, stability of the posture was assessed on the Zebris FDM power plate, analyzing the basic stabilographic parameters sway path and sway area. RESULTS: Athletes with intellectual disabilities had significantly poorer posture and body balance than healthy players. There were no differences in postural stability between the groups studied. Some linear correlations were found between the quality of posture and balance and stabilographic variables. CONCLUSIONS: Incorrect postural patterns, observed in people with intellectual disabilities, require the development of special recovery programs. Qualified physical activity can help them improve their balance systems, reducing the risk of falls and injuries. The lack of the possibility of an unequivocal relationship between the quality of body posture and its stability requires research on a larger research material. New evaluation methods used (Frohner Posture index and Dolphens classification) confirmed their usefulness and gave new possibilities of application in postural research.

Applicability of Smartphone for Dynamic Postural Stability Evaluation.

The purpose of this study was to determine the accuracy of smartphone's gyroscope for dynamic postural stability among young healthy adults. The research included convenience sample of 85 healthy adults-37 women (mean age 22.1±1.6, body height 167.2±7.0) and 48 men (mean age 22.4±1.7, body height 176.1±13.8). In order to assess the accuracy of stabilometric measurement recorded by mobile phone, the raw data obtained at the same time by Sigma Balance Platform and Smartphone (SP) were correlated. Two thirty-second trials with one-minute interval break were performed (first in the frontal plane and second in the sagittal plane). A total of 170 measurements of postural stability were recorded (85 in frontal and 85 in the sagittal plane). The following parameters were included: the path of the stabilogram (in the case of SP, angular path) and the variation of the swing (standard deviation of the horizontal deflection of the platform). The results have shown strong and significant relationship between body sway variability measured by Sigma platform and smartphone in frontal (r=0.997) and sagittal (r=0.990) plane. For the geometric center of the platform and angular path distances, the correlation coefficient was also statistically significant and high, considering both lateral (r=0.999) and anterior-posterior sway (r=0.981). Our research shows that smartphones with gyroscope have potential for accurate assessment of postural balance, as an alternative for expensive and specialized equipment.

The influence of gender, dominant lower limb and type of target on the velocity of taekwon-do front kick.

PURPOSE: The current study aimed to quantify the main influences and the interactions (joint effects) of gender, leg and type of target on the biomechanics of front kick quality. Through the quantification, we tried to identify the relevant factors related to the kick accuracy and maximum velocity for coaching practice. METHODS: A ten-camera NIR VICON MX40 motion capture system (250 Hz) was used to determine the kicking foot maximum velocity from two well-trained subject groups (8 males and 6 females). Each subject performed both left and right front kicks in a lateral standing position into the air (without a physical target), to a board, to a table tennis ball and to a training shield. The target were set on a height corresponding to a height of solar plexus of each participant. RESULTS: The results showed that all the three factors (gender, leg and type of target) have significant influences on kicking speed ( p < 0.001) and significant interaction (joint effect) was only found between gender and target ( p < 0.001). Further analysis revealed that the males' kicking maximum velocity was affected more by board, while females' one was affected by the size of the target. CONCLUSIONS: The results would seem to suggest that, for males, kick-to-a-board may be the more effective method for increasing kick quality, compared to other type of target. For females, kick-to-a-small-ball appears to be effective method for increasing kick maximum velocity.

Application of Zebris dynamometric platform and Arch Index in assessment of the longitudinal arch of the foot.

BACKGROUND: Assessment of the foot arch is an important element of posture examination. In clinical practice, different methods are used. Reliability and repeatability of the techniques raises many doubts. OBJECTIVE: Development and verification of our own, automated diagnostic algorithm for evaluation of the longitudinal arch of the foot with the use of the Zebris FDM-S dynamometric platform. METHODS: This paper presents selected footprints assessment methods and Zebris dynamometric platform to assess the longitudinal arch of the foot. RESULTS: The results were compared to standard plantography examination. The outcomes show high correlation of the investigated parameters methods used. The ambiguity of classification criteria of foot arch was observed. CONCLUSIONS: 1/Examination confirmed strong linear correlation between the Arch Index results obtained during examinations on a stabilometric platform and plantography examination. 2/The proposed algorithm for AI evaluation using the Zebris FDM-S dynamometric platform enables simultaneous analysis of stabilometric and pedobarometric variables as well classifying the type of disorder arch longitudinal arch of the foot. 3/Qualitative analysis of the arch, based on plantography results and the Arch Index, shows inconsistency in results obtained with different methods. 4/The obtained results show further necessity to conduct more studies to develop methods of standardization of foot arch assessment.

Influence of changing frequency and various sceneries on stabilometric parameters and on the effect of adaptation in an immersive 3D virtual environment.

PURPOSE: The aim of the study was to examine the influence of different types of virtual sceneries and frequencies of movement of visual disturbances on stabilometric values as well as whether individual sceneries and changing frequency can minimize effect of adaptation of tested person to applied disturbances. METHODS: There were 23 healthy participants. A person has been standing on a Zebris stabilometric platform. Virtual 3D environment was displayed by means of HMD Oculus Rift system. An open (a meadow) and closed (a room) sceneries were used. The sceneries moved along the sagittal axis and rotated around horizontal axis. The measurement lasted 30 seconds and in the middle of it frequency of translational movement was changed from 0.7 Hz to 1.4 Hz or from 1.4 Hz to 0.7 Hz. RESULTS: The data were reported as medians of COP velocity and ellipse area. Visual disturbances caused the increase of these values in comparison with the tests conducted with open eyes. Results divided into periods (the first and the second 15 seconds) showed that in the first half of the test values were higher compared to the second half. The comparison of values obtained for open and closed scenery showed that higher values were recorded for open scenery. CONCLUSIONS: The comparison of both types of sceneries on the basis of COP velocity and ellipse area showed that open scenery had a greater impact on the measured stabilometric values. It was found out as well that people got accustomed to the applied disturbances, but this effect was lower in the open scenery.

The Upper Limb Motion Deviation Index: A new comprehensive index of upper limb motion pathology.

PURPOSE: The aim of the research was to formulate a new index enabling assessment of the overall pathology of the upper limb movement. It defines the difference between the pathological movement and a normal movement pattern. METHODS: Methodology of determining the index is based on a mathematical algorithm for calculating the Gait Deviation Index which is based on advanced methods of image comparison. To calculate the ULMDI index, one must divide the analyzed movement into cycles appropriate to the nature of the movement (similarly in gait it is the gait cycle) and then determine kinematic quantities (courses of joint angles). RESULTS: A group of 23 healthy people (10 women: k1-k10 and 13 men: m1-m13) as the reference group and a group of 3 persons with mobility impairments (p1-p3) took part in the research. Time values of the angles of the joints on both upper limbs were registered and then ULMDI indexes were calculated. CONCLUSIONS: It has been shown that the developed ULMDI index allows to detect the deviations from the accepted norm in the performance of movements. The results showed that both the description of the motor dysfunction of examined person based on the diagnosis of the physician, a detailed analysis of kinematic waveforms received during the tests and the calculated values provide a coherent picture of the state of a human movement. The index analysis is less time-consuming for the doctor, and the comparison of the results at various stages of therapy gives an objective picture of the rehabilitation progress.

The Standard Deviation of Differential Index as an innovation diagnostic tool based on kinematic parameters for objective assessment of a upper limb motion pathology.

PURPOSE: Indexing methods are very popular in terms of determining the degree of disability associated with motor dysfunctions. Currently, indexing methods dedicated to the upper limbs are not very popular, probably due to difficulties in their interpretation. This work presents the calculation algorithm of new SDDI index and the attempt is made to determine the level of physical dysfunction along with description of its kind, based on the interpretation of the calculation results of SDDI and PULMI indices. METHODS: 23 healthy people (10 women and 13 men), which constituted a reference group, and a group of 3 people with mobility impairments participated in the tests. In order to examine possibilities of the utilization of the SDDI index the participants had to repetitively perform two selected rehabilitation movements of upper extremities. During the tests the kinematic value was registered using inertial motion analysis system MVN BIOMECH. RESULTS: The results of the test were collected in waveforms of 9 anatomical angles in 4 joints of upper extremities. Then, SDDI and PULMI indices were calculated for each person with mobility impairments. Next, the analysis was performed to check which abnormalities in upper extremity motion can influence the value of both indexes and interpretation of those indexes was shown. CONCLUSION: Joint analysis of the both indices provides information on whether the patient has correctly performed the set sequence of movement and enables the determination of possible irregularities in the performance of movement given.

The influence of frequency of visual disorders on stabilographic parameters.

PURPOSE: Defining the influence of parameters of visual disorders on ability of balancing turns out to be an important process in effective diagnostics. Current diagnostic methods relating mainly to determination of the coefficient of BRUTM (Balance Rehabilitation Unit Trade Mark) depend on lots of tests carried out in a disturbed environment created by Virtual Reality Technology. The aim of this study is to determine the effect of the frequency of visual disturbances on stabilographic values in the virtual reality environment. METHODS: The study was carried out involving one research group in Virtual Cave. There were induced visual disturbances with different frequencies and with the change of frequency during measuring the position of the center of pressure (COP) in the test. Before each test the reference test was performed. All tests were performed with disorders in two different sceneries: closed and open scenery. All measurements were carried out on an immobile Zebris platform which enables determination of feet pressure distribution. From the measured values of the position of the COP Short Time Fourier Transform (STFT) was calculated. RESULTS: The results of calculation are shown in graphs. Their analysis showed that changing the parameters of disorder frequency in world created using Virtual Reality Technology affects stabilographic parameters. The intensity of these changes is also affected by applied research scenery. CONCLUSIONS: Conditions have been set out to carry out similar studies in order to obtain reliable results. The study is the first step in a project to develop a system for diagnosis and rehabilitation of human movement using Virtual Reality Technology.