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1

A Complexity-Based analysis of postural stability dynamics during gait on dry and slippery surfaces

Yousefi Azar Khanian Mahdi, Hosseni Zahra Sadat, Gholpayeghani S. Mohammadreza Hashemi, Rostami Mostafa

Biocybernetics and Biomedical Engineering

|

2026

|

Vol. 46, iss. 1

1--8

EN

Human postural stability represents a complex, nonlinear system influenced by a range of biomechanical and environmental factors. The trajectories of the center of pressure (CoP) serve as key indicators of this system’s underlying dynamics and are increasingly being analyzed using nonlinear methods. However, the impact of surface-induced instability during gait remains underexplored. This study aimed to analyze CoP behavior during gait on stable (dry) and unstable (slippery) surfaces by testing three hypotheses: (1) task-induced instability is associated with an increase in CoP complexity; (2) individual variability amplifies dynamic fluctuations under unstable conditions; and (3) repeated exposure to the task attenuates this complexity. Twenty healthy young males completed each walking task three times. CoP dynamics were quantified using nonlinear analyses, including phase-space reconstruction (embedding dimension and time lag) and correlation dimension (CD). Complexity metrics, specifically the optimal embedding dimension and CD, were significantly elevated during the slippery surface condition, clearly distinguishing between the two task environments (p < 0.001, classification accuracy > 90 %). The greater variability in features observed under the slippery condition suggested broader dynamic adaptations to instability. Additionally, the reduction in CD across repeated trials indicated a moderating effect of prior exposure. The findings support all three hypotheses, demonstrating the effectiveness of CoP-based nonlinear measures in capturing adaptive postural responses to changing stability demands. This study contributes a novel multi-trial nonlinear analysis approach for evaluating dynamic postural control under environmental challenges.

2

Effects of stroboscopic disruption on static postural control in elderly individuals based on rambling and trembling analysis

Kong Lingyu, Zhang Yue, Liu Ziyi, Zang Wangli, Bao Jiawei, Xue Jingxian, Meng Xin, Mao Xiaokun, Zhang Qiuxia

Acta of Bioengineering and Biomechanics

|

2025

|

Vol. 27, no. 2

77--95

EN

This study investigated the effects of stroboscopic disruption (SD) on postural control strategies in elderly individuals by comparing center of pressure (CoP) variables between young and elderly individuals during bipedal standing tasks, with and without SD. Methods: Thirty-five participants, 15 young and 20 elderly, completed 60-second bipedal quiet standing trials on a force plate. Excluding the initial and final 10-second preparation and recovery phases, the central 40 seconds of CoP trajectory were quantified using time-domain and frequency-domain parameters across the medial-lateral (ML), anterior-posterior (AP), and resultant spatial (RS) directions. Rambling (RM) and trembling (TR) components were also extracted. Statistical analysis was performed using a linear mixed-effect regression (LMER). Results: SD significantly affected CoP control, with the elderly exhibiting greater changes in most variables than the younger group. During the transition from transparent to SD conditions, time-domain parameters showed a significant increase in mean movement distance and root mean square in the RS direction for both traditional and RM components among the elderly. Additionally, the 95% confidence circle and ellipse areas were larger in the elderly group. In the frequency-domain parameters, such as 80% power frequency, frequency dispersion, and concentrated frequency decreased in the AP and RS directions for both traditional and RM compo-nents in the elderly group. Conclusions: The reduction in visual inputs caused by SD leads to decreased flexibility and automaticity in the postural control of elderly individuals, making it more difficult for them to control CoP sway and adapt to changes in visual input com-pared to younger individuals.

3

The stock market indexes in research on human balance

Wodarski Piotr, Chmura Marta, Gruszka Grzegorz, Romanek Justyna, Jurkojć Jacek

Acta of Bioengineering and Biomechanics

|

2022

|

Vol. 24, no. 2

163--176

EN

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.

4

Analysis of center of pressure displacements and head movements triggered by a visual stimulus created using the virtual reality technology

Wodarski Piotr, Jurkojć Jacek, Chmura Marta, Gruszka Grzegorz, Gzik Marek

Acta of Bioengineering and Biomechanics

|

2022

|

Vol. 24, no. 1

20--28

EN

The purpose of the study was to determine how a stimulus presented in the virtual reality environment as a simulation of a fall off the stairs, triggers a loss of balance. The study also examined if the head movement measurements and the analysis in the frequency domain could increase the range of interpretation. Methods: 11 healthy individuals were tested, two [A1] were identified as more susceptible to the introduced disturbance, and one reported having dizziness, car sickness and fear of heights. Measurements of center of pressure (COP) and head positions were performed in the real and in the virtual environment. The beginning of the simulation was either unexpected or preceded by a signal. The analysis included standard parameters determined in time domain as well as the amplitude of the first harmonic from the fast Fourier transform (FFT). Results: The analysis did not reveal statistically significant differences between results obtained: in real and virtual environments, with and without the warning signal. It was possible to notice the effect of virtual disturbance in the three selected individuals; this was particularly evident in the analysis of the first harmonic of the FFT. Conclusions: The conducted tests revealed that the limitation of the analyses exclusively to the time domain could be insufficient for a comprehensive interpretation. The effect of introduced disturbance was particularly noticeable in the analysis of the first harmonic for head movement. The application of this parameter could enable a more accurate investigation of a strategy aimed at maintaining balance.

5

A model of human postural control inspired by separated human sensory systems

Keyvanara Mahboubeh, Sadigh Mohammad Jafar, Meijer Kenneth, Esfahanian Mohsen

Biocybernetics and Biomedical Engineering

|

2021

|

Vol. 41, no. 1

255--264

EN

Postural balance, which has a big role in daily life, is generally known as one's strength to retain stability. Balance takes advantage of the integration of multisensory inputs that work together to stabilize one's standing. Understanding the duty of each body part in postural balance has led us into modeling the human postural control system paying attention to the vestibular system in addition to other body parts and senses. Via updating the model both for the young and old adults, it is possible to mathematically understand the differences between the vestibular system of the young healthy adults and of the healthy elderly. Also, using linear control modeling, we provide quantitative predictions of the balance behavior depending on changes in sensorimotor behavior of different parts of the body and sensorimotor system. The results of this study help to understand better why the elderly tend to feel dizzy more often and why they would use other strategies compared to the ankle strategy.

6

Changes in postural stability on balance platform in patients after meniscal repair – two years follow up

Żmijewska Kinga, Fąfara Alicja, Feluś Jarosław, Mikos Magdalena, Nawara Jolanta, Gądek Artur

Acta of Bioengineering and Biomechanics

|

2021

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Vol. 23, no. 4

75--83

EN

Purpose: The aim of this work was to evaluate postural stability on the balance platform averagely 2 years following meniscal repair. Methods: This is a retrospective, case-control comparative analysis of patients who underwent surgical repair for the isolated longitudinal traumatic meniscal tear versus matched healthy controls. The study group consisted of 30 patients (mean age 29.93 years; averagely 2.3 years after surgery) and the control group – of 30 people. Following physical examination and completion of the IKDC, and the Lysholm questionnaires, the evaluation of the postural stability using two single-leg stabilometry tests was performed. In the static test, the analyzed variables included deviations from the horizontal, vertical axes and the length of the balance path travelled. In the dynamic test, the length of the path travelled and the time to complete task were recorded. Between-limb and between-groups comparison of collected stabilometry tests were performed. Additionally, the IKDC and the Lysholm questionnaires scores were compared between the study and heathy groups. Results: No abnormalities were found on clinical examination in the study group nor any differences between the operated and contralateral knee (p > 0.05). In stabilometry: (1) in the study group, the operated extremity scored worse than the contralateral limb (length of path traveled in: A) static test x = 56.7 cm SD = 37.91 cm vs. x = 21.6 cm SD = 9.06 cm; p = 0.002 and B) dynamic test x = 82.57 cm, SD = 50.43 cm vs. x = 53.32 cm, SD = 13.82 cm; p = 0.003); (2) In the control group, no leg-related differences were noted (p > 0.05); (3) Between-group comparison revealed that the study group scored worse than the control group (length of path traveled in: A) static test x = 56.7 cm, SD = 37.91 cm vs. x = 17.23 cm, SD = 3.39 cm; p = 0.001 and B) dynamic test x = 82.57 cm, SD = 50.43 cm vs. x = 32.13 cm, SD = 9.41 cm; p < 0.001). Study group scored worse on IKDC scores (p < 0.001) but not on Lysholm score ( p > 0.05). Conclusions: Postural stability deficit persists despite a successful meniscal repair.

7

Altered postural stability in elderly women following a single session of head-mounted display virtual reality

Cieślik Błażej, Serweta Anna, Federico Sara, Szczepańska-Gieracha Joanna

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

107--111

EN

Purpouse: The aim of this study was to evaluate the effect of a single session of head-mounted display virtual reality on postural stability in elderly women. Methods: Forty-seven female subjects underwent a 20-minute virtual reality session. The mean age of the subjects was 70.12 years. As an immersive source, we used a relaxing virtual reality game with a head-mounted display device. The postural stability test was conducted using a Nintendo Wii force plate. Participants completed a set of three 30-s trials in which they took a quiet bipedal eyes-open stance while standing on a hard surface: before the virtual reality session, immediately after the virtual reality session, and 2 minutes after the virtual reality session. Centre of pressure parameters were analysed in the sagittal and frontal planes. Results: Analysing the results obtained immediately after the virtual reality session, significant differences were observed in almost all examined parameters. In the sagittal plane, centre of pressure path velocity increased by 10% (p < 0.01) and path standard deviation by 15% (p < 0.05). In the frontal plane, centre of pressure path velocity increased by 14% (p < 0.01). After 2 minutes, all examined parameters showed no significant difference compared to before the virtual reality session. Conclusions: Immediately after the virtual reality session, there was an increase in almost all examined parameters. However, after 2 minutes, all examined parameters had returned to baseline. Therefore, to reduce fall risk after a virtual reality session, it is recommended that the subject spend at least 2 minutes in a sitting position.

8

Analysis of the relationship between selected stability assessment indicators on the example of leaning out the human body from the upright position

Matuszewska Agata, Buśkiewicz Jacek

Vibrations in Physical Systems

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2020

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Vol. 31, nr 2

art. no. 2020219

EN

The objective of this paper is to study the margin of stability when trying to lean out the body forward and backward. The centre of mass of the body, the velocity of the centre of mass and extrapolated centre of mass were calculated for four participants. The analyzed movement was recorded by using BTS Motion Capture system. Recordings, in which participants were unable to return to the upright position, were also observed. In these cases, it was verified the usefulness of extrapolated centre of mass for predicting the foot support area that enables maintaining the body balance. The relationship between the applied stability indicators and anthropometric parameters was determined. The preliminary results obtained confirm the validity of the use of selected parameters in tests and in assessment of the stability of the human body, and indicate the directions of further tests for a larger group of participants and other movement activities.

9

Ocena stabilności posturalnej w funkcji różnego ustawienia stóp na podłożu przy wykorzystaniu miar dynamiki nieliniowej

Kędziorek Justyna, Błażkiewicz Michalina

Aktualne Problemy Biomechaniki

|

2020

|

z. 19

20--26

PL

Celem pracy była ocena stabilności posturalnej w różnych warunkach podparcia: stanie obunóż, jednonóż i w tandemie przy oczach otwartych. W badaniach wzięła udział grupa trzydziestu trzech zdrowych osób w wieku 21.88 ± 1.65 lat. Badania zostały przeprowadzone przy użyciu platformy AMTI AccuSway (30 sekund – każda próba). Do obliczeń eksportowano położenia środka nacisku stóp na podłoże (CoP) w płaszczyznach x i y. Następnie została policzona długość drogi CoP i współczynniki dynamiki nieliniowej: entropia próbkowa, wymiar fraktalny i wykładnik Lapunowa. Wykazano, że zmniejszenie pola powierzchni podparcia powoduje istotny wzrost współczynnika entropii próbkowej i wymiaru fraktalnego.

EN

The aim of the study was to assess postural stability under different base of support: both foot standing, one-leg standing and tandem with eyes open. A group of thirty-three healthy persons aged 21.88 ± 1.65 years participated in the study. The tests were carried out using the AMTI AccuSway platform. The locations of the center of foot pressure (CoP) in the X and Y planes were exported. Then the CoP path length and nonlinear dynamics coefficients were calculated: sample entropy, fractal dimension and Lapunov exponent. It has been shown that the reduction of the support surface area causes a significant increase in the sample entropy factor and the fractal dimension.

10

Postural stability and functional disorders in patients with loosened hip prosthesis

Drzał-Grabiec Justyna, Truszczyńska-Baszak Aleksandra, Tarnowski Adam

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

41--46

EN

The number of primary hip arthroplasties is growing every year. One of the most common long complications is the aseptic loosening of the prosthesis leading to serious complications in patients life, pain and following surgeries. In the literature, there is a lack of studies regarding balance impairment in this group of patients, which is why there was a need to conduct the study in order to find possible falling risk factors and simple functional, diagnostic test. The aim of the study was to assess functional state and static balance disorders in patients admitted to orthopaedic department due to loosened hip prosthesis prior to its replacement or removal. Methods: The study population were 30 patients (15 women and 15 men) admitted to Orthopaedic Department for diagnosis and treatment of loosened hip prosthesis. Patients’ mean age was 71.67 ± 9.21, body height 169.20 ± 8.75 cm, body weight 77.83 ± 12.96 kg. The clinical control group consisted of 30 healthy subjects age-, body height- and weight-matched, without degenerative disorders of lower extremities. Function was assessed with Harris Hip score. The static balance test was conducted in the mornings, in quiet separate room on bi-modular stabilometric platform CQStab2P, registering the movement of centre of foot pressure (COP). Results: Measurements with eyes open and closed showed significant differences in limb loads – the load to the healthy limb was several times greater. Results of tests on the platform with eyes closed showed significantly worse balance in patients group. Their total statokinesiogram path was longer, and their COP sways number was greater. Similarly to the test with eyes open, the load of the healthy limb was much greater. Conclusion: Hip replacement loosening results in significant worsening of balance parameters. Balance assessment could be an additional useful diagnostic tool for hip replacement loosening available for physiotherapists.

11

Assessment of dynamic balance during step initiation in Parkinson’s disease patients and elderly – a validity study

Juras Grzegorz, Kamieniarz Anna, Michalska Justyna, Słomka Kajetan

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

3--10

EN

The aim of this study was to evaluate the reliability of the novel posturographic procedure and to investigate the relationships between parameters of this procedure and clinical tests. We hypothesised the proposed step initiation procedure to be reliable method of balance and motor disability assessment, especially in patients with neurological deficits. Also, we assumed high significant correlation between parameters of step initiation procedures and clinical tests. Methods: The 35 subjects with idiopathic PD and 35 agedmatched healthy controls participated in this study. The gait initiation was measured using two force platforms. The procedure consisted of three phases: (1) quiet standing on a first platform (2) crossing on the second platform, (3) quiet standing on a second platform. Testing was carried out in four conditions: unperturbed trial, obstacle crossing, step-up and step-down. Results: In the proposed gait initiation procedure, the vCOP, raCOP and rmsCOP showed an excellent reliability (ICC > 0.80). For transit phase, reliability of all variables in all conditions also was excellent (ICC = 0.8–0.9). There were only a few associations between Tinetti scores and posturographic variables in controls, but in PD patients the significant correlations were found between the proposed measures and the UPDRS, Tinetti, FRT, TUG and with the BBS. Conclusions: The proposed gait initiation procedure is reliable and very suitable for the assessment of patients with Parkinson’s disease. It can be used as an objective assessment of the clinical condition and dynamic balance, and help in the designing and programming of the appropriate rehabilitation and treatment.

12

Absolute and relative reliability of several measures of static postural stability calculated using a GYKO inertial sensor system

Jaworski Janusz, Ambroży Tadeusz, Lech Grzegorz, Spieszny Michał, Bujas Przemysław, Żak Michał, Chwała Wiesław

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 2

93--99

EN

The aim of this study was to analyse absolute and relative reliability of a number of postural static stability measures obtained from a GYKO inertial sensor system in young adults. Methods: The study examined 29 healthy non-athlete young adults. A test was performed for 30 s while standing on one foot, without moving, with eyes open and arms relaxed along the sides of the body. The examinations were performed twice, with a one-week interval. Relative reliability was measured using the intraclass correlation coefficient (ICC) and the 95% confidence interval (95% CI), whereas the absolute reliability was evaluated based on the standard error of measurement (SEM) and the minimal detectable change (MDC). Results: The results of this study showed moderate to good relative reliability scores for all the postural stability measures, with ICC values ranging from 0.62 to 0.70. For most of the analysed variables, SEM% ranged from ca. 10 to 14%. Relatively high SEM% values were obtained only for two variables (Area, Convex Hull Area). Conclusions: The low costs of GYKO inertial sensor systems, the fast and easy installation, the mobility and high reliability of the measurement of postural stability show that it can be effective alternative to stabilographic platforms.

13

Ocena stabilności posturalnej podczas strzelania

Błażkiewicz Michalina, Kędziorek Justyna, Bańkowska Sylwia, Wit Andrzej

Aktualne Problemy Biomechaniki

|

2019

|

z. 17

5--10

PL

Celem pracy była ocena stabilności posturalnej podczas strzelenia z łuku. W badaniach wzięły udział dwie grupy: zawodowi łucznicy oraz amatorzy, tzn. osoby, które nigdy nie strzelały z łuku. Badania zostały przeprowadzone przy użyciu systemu Vicon i platform Kistler. Do obliczeń zostały eksportowane położenia środka masy ciała. Następnie została policzona długość drogi CoM w przestrzeni 3D oraz współczynniki entropii próbkowej. Wykazano, że długość drogi CoM w przestrzeni 3D jest istotnie (p = 0.0001) dłuższa u łuczników podobnie jak współczynnik entropii próbkowej wzdłuż osi pionowej (p = 0.0117).

EN

The aim of the work was to assess postural stability during archery. Two groups participated in the study: professional archers and amateurs, i.e. people who never shot a bow. The tests were carried out using the Vicon system and Kistler platforms. Body mass center positions were exported to calculations. Next, the CoM distance in 3D space and sample entropy coefficients were calculated. It was shown that the distance of the CoM path in 3D space is significantly (p = 0.0001) longer in archers, similarly as the sample entropy coefficient along the vertical axis (p = 0.0117).

14

Statistical analysis of impact of visual impairment on postural stability

Jureczko M., Jureczko P.

Modelowanie Inżynierskie

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2018

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T. 38, nr 69

37--42

EN

The main aim of the presented research was assessment of postural stability in patients with various degree of visual impairment. The article contains basic explanation and requirements for stabilography research. Statistical analysis of impact of degree of visual impairment on postural stability opposed to people perfectly sighted was also conducted. The studies were conducted on 45 patients with various degree of visual impairment and 15 patients perfectly sighted. Postural stability was tested using diagnostic platform Zebris. The test results showed relationship between postural stability and degree of impairment and in line with them it can be stated that visual control has a significant impact on stability.

PL

Głównym celem przeprowadzonych badań była ocena stabilności postawy u pacjentów z różnym stopniem niepełnosprawności wzrokowej. Artykuł zawiera podstawowe wyjaśnienia i wymagania dotyczące badań nad stabilografią. Przeprowadzono analizę statystyczną wpływu stopnia upośledzenia wzroku na stabilność postawy w stosunku do osób doskonale widzących. Badania przeprowadzono na 45 pacjentach z różnym stopniem zaburzeń widzenia i 15 doskonale widzących. Stabilność postawy testowano przy użyciu urządzenia diagnostycznego firmy Zebris. Przeprowadzone badania dały wyniki pokazujące wpływ stopnia upośledzenia wzroku na stabilność postawy człowieka. Badania wykazały, że kontrola wizualna ma znaczący wpływ na stabilność człowieka.

15

The assessment of the relationships between body posture indices and the Y-Balance Test results in the adolescents

Walaszek R., Chwała W., Walaszek K., Burdacki M.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

149--157

EN

The purpose of this work was to assess the differences of the values of body posture indices, measured with the Moire’s method, between girls and boys aged 13 and the relationships of these values with the results of the Y-Balance Test. Methods: The study involved a group of healthy volunteers attending junior high schools in Cracow. The group consisted of 20 girls and 35 boys. Basic somatic parameters were measured within this work: body height and weight. Body posture was assessed according to the general methodology of the Moire’s technique and 14 body posture indices were obtained as a result: 6 in the sagittal plane, 1 in the axial plane and 7 in the coronal plane. Postural stability was assessed with the Y-Balance Test (YBT). Results: The studied girls and boys had practically the same body posture – statistical differences were found only in 3 out of 14 assessed indices measured with the Moire’s technique. Scoliosis was found in as many as 51% of the subjects, however, mean values of deviations from the C7-S1 line were not large. Conclusions: In the group of girls, the set of blades (below – above) was statistically significantly correlated with the global YBT result for the right inferior extremity, and in the group of boys – the set of the waist triangles (below – above) was statistically significantly correlated with the global YBT results for the right and left inferior extremities.

16

Effects of anthropometric factors on postural stability in individuals with hearing impairment

Zdrodowska A., Wiszomirska I., Kaczmarczyk K., Kosmol A.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 1

109--115

EN

Identification of factors that affect postural stability may help to improve diagnostic accuracy and enhance the quality of treatment and rehabilitation. This study sought to assess the relationship between postural stability parameters and anthropometric factors of persons with hearing impairment (HI). Methods: The study included 128 individuals – 42 subjects with HI and 86 without HI (healthy controls). Research methodology included an interview and a medical examination, anthropometric measurements and stabilometric tests on platforms with stable and unstable surfaces. Results: In the group of female study participants with HI, significant correlations were only noted between body height and the Fall Risk Index (FRI). In the group of male subjects with HI, the study revealed significant correlations between FRI and body mass, BMI, % MM (muscle mass percentage) and % FAT (fat percentage). Moreover, moderate correlation was found between COP path with eyes open and body mass, while high correlation was observed between COP path with eyes open and BMI, % MM and % FAT. No significant correlation was noted between FRI and body height in men with HI. Conclusions: The examination of correlations between postural stability and body build of persons with HI did not confirm the effects of body height on postural stability in the examined group of individuals with HI, but revealed a greater influence of somatic parameters (body mass, BMI, % MM, % FAT) on postural stability in hearing-impaired men.

17

Assessment of postural stability in patients after reconstruction of the anterior cruciate ligament with LARS and autogenous graft

Plocki J., Kotela I., Bejer A., Pelikan P., Granek A., Krawczyk-Suszek M.

Acta of Bioengineering and Biomechanics

|

2018

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Vol. 20, no. 4

9--14

EN

The aim of the study was to assess static balance after reconstruction of the anterior cruciate ligament (ACL), using gracialis tendons graft (GR) or semi-tendinosus (ST), compared to patients treated with the Ligament Advanced Reinforcement System (LARS). The study was performed within 36 to 48 months after the surgery. Methods: The study included 96 patients. The LARS group consisted of 44 patients, control group operated with ST/GR tendons included 52 patients. The stabilometric platform Alpha was used to assess the static balance. Two 30-second trials in the double-leg stance position with eyes opened and closed were performed. The distribution of loads in a free standing was also assessed. Results: In the test with open eyes the subjects from the LARS group had a significantly longer center of pressure (COP) path, a higher mean velocity, a greater mean COP sway in foot in the lateral direction and a larger path area occupied by the COP graph. During the tests with eyes closed, a significant difference occurred in the mean displacement of COP in lateral direction – greater in the LARS group. In addition, all parameters deteriorated during the tests with eyes closed in both groups. Conclusions: In static balance assessed with eyes closed, more proprioceptive deficits may appear in the LARS group.

18

Acute effects of core stability exercises on balance control

Szafraniec R., Barańska J., Kuczyński M.

Acta of Bioengineering and Biomechanics

|

2018

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Vol. 20, no. 3

145--151

EN

The aim of this study was to investigate whether a single bout of core stability exercises improves body balance immediately after the bout of exercise and during a retention test. Methods: The study involved 16 women (age 22–25 years, body weight 60.5 ± 5.2 kg, height 166 ± 5.4 cm). Postural stability was assessed in the mediolateral (ML) and anteroposterior (AP) planes separately on a force plate (Kistler 9286 AA) during quiet standing on a soft support surface with the eyes closed. Subjects were measured 4 times: just before (T0), 1 minutes after (T1 m), 30 minutes after (T30 m), and 24 hours after the workout (T24 h). Postural balance was evaluated by five parameters based on the center of pressure (COP) signal: variability (VAR), mean velocity (VEL), sample entropy (ENT), frequency (FRE), and fractal dimension (FRA). Results: We observed a decrease in VAR and VEL in the ML plane at T30 m and T24 h, compared to T0. The COP entropy significantly increased in the ML plane at T24 h, compared to T0. Conclusions: A single bout of core stability exercises improved the control of the mediolateral body balance. This effect was evident within 30 minutes after exercise, and remained for at least 24 hours. In addition, 24 hours after exercise we observed an increased automaticity in the strategy to maintain a stable upright stance.

19

The influence of the acoustic stimulus on postural stability

Majewska A., Kawałkiewicz W., Hojan-Jezierska D., Jezierska A., Kubisz L.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 2

113--119

EN

The purpose of this study was to assess if 65 dB and 4000 Hz stimuli affect postural stability of young normal hearing people. Methods: Posturography examinations belong to clinical tests which evaluate the motor skills. Posturography can be divided into static posturography and dynamic posturography. In both, static posturography and dynamic posturography, patient stays on the platform with opened and closed eyes, but in the case of dynamic one, platform is unstable. In this study the Multitest Equilibre platform produced by FRAMIRAL was used. Patients took part in tests with opened and closed eyes, on stable and unstable platform. Additionally patients were exposed to 65 dB and 4000 Hz acoustic stimuli. The sound pressure level, and frequency was belonging to the best audibly frequency range. Results: Parameters such as velocity and surface were examined. The difference between velocity measured with acoustic stimuli and without acoustic stimuli was observed. On the other hand there was no difference in surface results. Conclusions: The statistically significant difference between velocity of patients center of gravity movements, measured on unstable platform, in the presence of 4000 Hz, 65 dB acoustic stimulus and without additional disturbances was observed.

20

Postural stability in Parkinson’s disease patients

Wilczyński J., Pedrycz A., Zieliński E., Ambroży T., Mucha D.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 4

135--141

EN

Purpose: The aim of the study was to analyze postural stability in Parkinson's disease patients. A total of 32 subjects were tested, including 26 (81.25%) women and 6 (18.75%) men. These were patients with advanced, idiopathic Parkinson’s disease. The disease duration was over 5 years. Methods: The study was conducted in the Posturology Laboratory at the Department of Medicine and Health Sciences, Jan Kochanowski University in Kielce (Poland). The Biodex Balance System was used for evaluation of postural stability. Postural Stability Testing was performed with both feet positioned on a stable surface with the eyes open. Results: The Overall Stability Index in the whole group was 0.5°. The higher Overall Stability Index in women is indicative of slightly worse postural stability compared to men, although in both groups, it was within norms (Z = 2.0545, p = 0.0399). Anterior-Posterior Overall Stability Index (A/P) was an average of 0.35°. The Medial-Lateral Overall Stability Index (M/L) was an average of 0.27°. Both women and men were observed to have higher postural sway in the sagittal plane than the frontal plane. The vast majority of the subjects maintained in Zone A during testing (99.94%), and was slightly bent backwards to the right and in Quadrant IV (61.53%). Conclusions: Regular control of postural stability in Parkinson's disease patients is significant due to the risk of falls.