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Body Posture Stability in Ski Boots Under Conditions of Unstable Supporting Surface

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Tchórzewski D., Bujas P., Jankowicz-Szymańska A.
Journal of Human Kinetics
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2013
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vol. 38
33-44
EN
The authors attempted to determine whether: (1) there are differences in stability between the conditions of standing in ski boots and barefoot, (2) the type of surface affects stability, and, (3) the level of stability differs between the frontal and sagittal planes. The study included 35 young male recreational skiers aged 20.71 ±0.63 years. Measurements of stability were taken by means of a Libra seesaw balance board. The conditions of soft surface were created by attaching an inflated cushion to the board. The experiment was carried out on both rigid and soft surface for both movement planes and two different conditions: maintaining the seesaw balance board in the horizontal position and performance of a particular balancing task. All the tests were performed with visual feedback. Restricted ankle joint mobility that results from wearing ski boots caused a reduction of stability in studied subjects, particularly in the sagittal plane. The differences found in the study were likely to be caused by the difficulty the beginners experienced in re-organizing muscular coordination in hip joint strategy and effectively using mechanical support of ski boots that reduces lower limb muscle tone. The use of the soft surface improved stability exhibited by the subjects in the frontal plane without compromising the stability in the sagittal plane. The soft surface might have contributed to a reduction in excessive corrective movements, thus improving stability in studied subjects.The aim of this study was to determine the effect of limitation of foot mobility and disturbances in afferent information from the plantar mechanoreceptors due to wearing ski boots on the level of postural stability in beginner skiers under conditions of the unstable support surface.
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Influence of Long-Lasting Balancing on Unstable Surface on Changes in Balance

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Tchórzewski D., Jaworski J., Bujas P.
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EN
Purpose. The goal of this thesis is to test the qualification of changes in balance as the effect of long-lasting balancing on a movable platform alternately in sagittal and frontal planes. It was expected to find answers to the following problems: 1. Does the effort caused by a 10-minute balancing in the given planes and in the given pattern have an influence on dynamic balance parameters? 2. Till which moment are the subjects able to improve their balancing skills in the given planes? 3. Do the possible changes progress in the same way in both planes considered? Basic procedures. 28 men aged between 24.3 and 33.8 years took part in this test. Average age of the subjects was 25.2 years. The tests were made on EasyTech Balance Platform. Tests consisted of a trial of balancing in a standing position with feet placed parallel on the platform. The subjects' task was to operate the platform through the right feet pressure to make the same sinusoid line as the pattern was. A ten-minute trial was made alternately in the sagittal and frontal planes. Individual dynamic parameters were recorded each minute of the test. Main findings. Significant improvement was noted in the first three minutes of the test. Between the 4th and 7th minutes parameters were relatively stable. The best results were recorded in the 8th minute of the test and this level was kept till the end of the trial. The character of the observed changes was analogous in the case of both planes. Conclusions. There was a statistically significant improvement in the dynamic body's stability noted in both planes in the test. Best results were recorded in the 8th minute of the test. The test used in the trial was long enough to establish the borderline between motor learning and the beginning of tiredness. The higher level of stability in the sagittal plane was affirmed in all successive minutes of the trials made.
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Involution of Simple and Complex Reaction Times Among People Aged Between 21 and 80 - The Results of Computer Tests

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Jaworski J., Tchórzewski D., Bujas P.
Human Movement
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2011
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vol. 12
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issue 2
153-158
EN
Purpose. The aim of this case study is to define the involution of simple and complex reaction times in groups of adult men and women. Basic procedure. The tests were carried out during the years 2007-2008 among 128 men and 136 women aged between 21 and 80. Those examined were divided into three groups according to their calendar age. In order to define the meaning of differences of the analyzed reaction time between the results of the three age groups, the analysis of variance (ANOVA) method for independent attempts was used. Additionally, normalized differences between the groups as well as indices of sexual dimorphism were defined. Main findings. Among both men and women, gradual deterioration of reaction time performance with age can be observed. The scale of normalized differences shows that the most distinct differences are noticed between the first and the third group. They amount up to 1.3 of the standard deviation in men and up to 1.7 in women. Conclusions. The results derived from the following study confirm a long period of relative stabilization for all simple and complex reaction times among both genders. Significant involution of reaction times can be observed for all analyzed features only after the age of 55. Indices of sexual dimorphism indicate that men gain better results in all age groups. Indices of sexual dimorphism diminish with age.
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