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1

The stock market indexes in research on human balance

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

Acta of Bioengineering and Biomechanics

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2022

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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.

2

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

Chrzan Miłosz, Michnik Robert, Myśliwiec Andrzej, Wodarski Piotr, Suchoń Sławomir, Gzik Marek, Mitas Andrzej

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 4

139--146

EN

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.

3

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

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

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 3

135--146

EN

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.

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

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2022

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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

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

Gorwa Joanna, Nowakowska-Lipiec Katarzyna, Guzik-Kopyto Agata, Wodarski Piotr, Michnik Robert

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 4

53--61

EN

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.

6

Ocena zmian wybranych wielkości stabilograficznych na skutek oddziaływania wirtualnej rzeczywistości

Chmura Marta, Wodarski Piotr, Gruszka Grzegorz, Jurkojć Jacek

Aktualne Problemy Biomechaniki

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2020

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z. 20

29--36

PL

W niniejszej pracy dokonana została ocena zdolności utrzymywania równowagi w świecie rzeczywistym i wirtualnej rzeczywistości. Grupę badawczą stanowiło 9 zdrowych osób. Otrzymane wyniki umożliwiły analizę oraz określenie istotnych zmian wartości wybranych wielkości stabilograficznych dla wybranych par zbliżonych warunków w środowisku rzeczywistym i wirtualnym. Wykazano, że wyświetlanie wirtualnej scenerii działa destabilizująco w porównaniu do środowiska rzeczywistego, natomiast ciemna sceneria wywiera mniejszy efekt destabilizujący niż zamknięcie oczu.

EN

This study assesses the ability to maintain balance in both the real world and virtual reality. Research group consisted of 9 healthy people, and obtained results made it possible to analyze and determine significant changes in values of selected stabilographic quantities for chosen pairs of similar conditions in real and virtual environments. It has been established that patients are less stable while immersed in virtual environment than they are while standing in real world without visual stimuli, but dark scenery has lower destabilising effect than standing with closed eyes.

7

Assessment of gait stability and preferred walking speed in virtual reality

Wodarski Piotr, Jurkojć Jacek, Polechoński Jacek, Bieniek Andrzej, Chrzan Miłosz, Michnik Robert, Gzik Marek

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

127--134

EN

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.

8

Zakresy ruchów kręgosłupa podczas terapii poznawczo – ruchowej w przestrzeni wirtualnej w rehabilitacji pacjentów z wybranymi uszkodzeniami ośrodkowego układu nerwowego – wyniki wstępne

Małecka Elżbieta, Garbowska Iga, Dyba Monika, Szostek Joanna, Boratyn Monika, Wodarski Piotr, Jurkojć Jacek, Bieniek Andrzej, Guzik-Kopyto Agata, Pasek Jarosław

Aktualne Problemy Biomechaniki

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2019

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z. 17

59--67

PL

Uszkodzenia ośrodkowego układu nerwowego (OUN) wiążą się z upośledzeniem określonych funkcji poznawczo – ruchowych w organizmie człowieka. Następstwa uszkodzenia mózgu mogą objawiać się czasową bądź trwałą niepełnosprawnością i/lub ograniczeniami neurobehawioralnymi. Poszukiwanie nowych metod diagnostyki i rehabilitacji OUN często prowadzi do wykorzystania Technologii Wirtualnej Rzeczywistości. Terapia wirtualna jest interaktywna w czasie rzeczywistym i pozwala na ruch w trzech wymiarach. Celem pracy była ocena ilościowa i jakościowa zakresów ruchomości wybranych odcinków kręgosłupa podczas wykonywania ćwiczeń ruchowo-poznawczych w wirtualnej rzeczywistości. Badania przeprowadzono z udziałem 5 osób z uszkodzeniami OUN, które poddano 2-tygodniowej rehabilitacji. Oceny terapii dokonano na podstawie zmian ruchomości poszczególnych odcinków kręgosłupa przed i po terapii. Wyniki potwierdzają nowe możliwości diagnostyczne tradycyjnej terapii połączonej z Technologią Wirtualnej Rzeczywistości.

EN

Central nervous system (CNS) damage is associated with the impairment of certain cognitive - motor functions in the human body. The consequences of brain damage can be manifested by temporary or permanent disability and / or neurobehavioral restrictions. The search for new methods of CNS diagnostics and rehabilitation often leads to the use of Virtual Reality Technologies. Virtual therapy is interactive in real time and allows traffic in three dimensions. The aim of the study was the quantitative and qualitative assessment of ranges of mobility of selected spinal segments during exercise and cognitive exercises in virtual reality. The research was carried out with the participation of 5 people with CNS damage, which underwent 2-week rehabilitation. The assessment of therapy was made on the basis of changes in the mobility of individual spine sections before and after therapy. The results confirm the new diagnostic possibilities of traditional therapy combined with the Virtual Reality Technology.

9

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

Bibrowicz Karol, Szurmik Tomasz, Wodarski Piotr, Michnik Robert, Mysliwiec Andrzej, Barszcz Jacek, Mikołajewski Grzegorz, Mitas Andrzej

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 1

23--30

EN

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.