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The aim of this study was to examine whether target width and target distance influence the planning phase of a fencing lunge (early and anticipatory postural adjustments) as well as the execution phase of a fencing lunge. Eight elite female fencers participated in the study. The displacement of the center of foot pressure, muscle activity of the tibialis anterior, and kinematics of center of mass were recorded using force plates. The results show that target width and distance have no effect on early and anticipatory postural adjustments as well as the acceleration and velocity of the center of mass at the moment of foot-off. However, a greater target distance was associated with a greater max center of mass acceleration and velocity, and larger target width resulted in a greater max center of mass acceleration during lunging (p < 0.05). We suppose that the effect of task parameters on preparing a fencing lunge may be mitigated due to the specific technique adopted by expert fencers and the ballistic nature of a fencing lunge.

Elderly individuals may be at increased risk of falls than their peers. Early identification of balance disorders and their appropriate intervention are crucial for patients with dementia. The aim of this study was to identify postural instability in patients from mild to moderate dementia while performing transitional locomotor tasks under different conditions. Fifty-four patients with dementia and 30 healthy controls voluntarily participated in the study. The transitional locomotor task was performed on two force platforms under four conditions: unimpeded transition, obstacle clearance, step-up and step-down trials. The recording of center of foot pressure displacements was divided into three distinct phases: 1st phase-quiet standing before the transitional locomotor task, 2nd phase-forward stepping, 3rd phase-quiet standing after the transitional locomotor task. Patients with dementia were characterized by a longer transitional locomotor task time than the control group under all conditions (P 0.03). Significant differences in quiet standing before the transitional locomotor task were observed between patients with dementia and the control group, but only in unimpeded transition and obstacle clearance trials (P 0.02). No significant differences in quiet standing after step transition were observed between patients with dementia and the control group (P 0.05). Postural control research in patients with dementia should focus on the functional motor task rather than on a simple motor task (quiet standing). Because even patients with mild dementia have impaired dynamic balance, the assessment of transitional locomotor tasks performed by patients with dementia might provide an indicator of an early diagnosis of dementia and might lead to better individualized physiotherapy.

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 CG (p

The aim of the study was to examine whether the width of the base of support (BOS) has an influence on early postural adjustments (EPA) and armed upper limb and COM kinematics during lunging. Eight elite female fencers participated in the study. The displacement of the centre of foot pressure (COP) and kinematics of centre of mass (COM) were recorded using force platforms. The kinematics of the wrist of the armed upper limb were obtained using a 3D accelerometer. The results show that EPA were characterised by a very small COP displacement (about 0.6 to 1.2 cm). The COP amplitude showed a tendency to decrease with an increase in BOS width under reaction time conditions. In contrast, a greater BOS width was associated with a significant increase in COM acceleration at foot-off and peak COM acceleration during lunging also under reaction time instructions. The kinematics of the wrist were not influenced by BOS. The results show that in elite fencers, the upper limb movement is dissociated from the whole body movement. We suppose that a small COP amplitude is a postural skill which is integrated into the lunging skill and might influence the acceleration of COM.

The uncontrolled manifold hypothesis is a method used to quantify motor synergies, defined as a specific central nervous system organization that maintains the task-specific stability of motor actions. The UCM allows for inter-trial variance analysis between consecutive trials. However, despite the large body of literature within this framework, there is no report on the number of movement repetitions required for reliable results. Based on the hypothetical hierarchical control of motor synergies, this study aims to determine the minimum number of trials necessary to achieve a good to excellent level of reliability. Thirteen young, healthy participants performed fifteen bilateral isometric contractions of elbow flexion when visual feedback was provided. The force and electromyography data were recorded to investigate synergies at different levels of hierarchical control. The intraclass correlation coefficient was used to determine the reliability of the variance indices. Based on the obtained results, at least twelve trials are required to analyze the inter-trial variance in both force and muscle synergies within the UCM framework.

Preschool age is fundamental for the development of gross motor skills. Timely detection of postural stability deficits using objective methods would facilitate early implementation of therapeutic strategies.What are the age- and gender-related differences in postural control between preschool children diagnosed with developmental delay in their first year of life and children with typical development?The study group consisted of 59 children diagnosed with developmental delay during infancy, who had received physiotherapy in the first year of their life for disorders of postural control and prone locomotion as well as abnormal distribution and magnitude of postural tone. The control group comprised 66 nursery school children with typical development and no history of postural control or movement deficits and no physiotherapy interventions in the first year of their life. The study and control groups were subdivided into four subgroups based on age (3-4 years, 5-6 years) and gender (boys, girls). The data were collected during quiet standing using a force plate. Three 30-second trials were recorded. Stabilographic recordings were analysed using the rambling-trembling approach.Three-way ANOVA revealed a gender effect on all measured variables (p0.05). The Tukey HSD (honest significant difference) post-hoc test showed that some of the values of sway range and mean velocity of COP, rambling and trembling in sagittal and frontal plane were significantly greater in control boys aged 3-4 years compared to other subgroups (p0.05).Long-term postural control monitoring by a pediatrician and/or physiotherapist seems justified and not only in children with a history of infantile developmental delay but also in their healthy peers, especially boys.

The troublesome symptoms of Achilles tendinopathy prompt patients to seek effective forms of conservative treatment. The main aim of the study was to determine the therapeutic efficacy of shock wave and ultrasound therapies for Achilles tendinopathy in reducing pain intensity. Treatment efficacy was also assessed using objective posturographic measurements.Thirty-nine patients patients were randomly allocated to one of three experimental groups that received shock wave therapy (group A), ultrasound therapy (group B) and placebo ultrasound (group C). Posturographic measurements and subjective assessment of pain intensity were taken prior to therapy and at weeks 1 and 6 of therapy completion.A comparison of percentage change in activity-related pain from baseline to 6 weeks post-therapy revealed a significantly greater pain reduction in group A compared to group B. The three-way ANOVA demonstated an effect of treatment type on all posturographic variables. The Bonferroni post-hoc test showed the means of all variables were significantly smaller for group A than group B. Limb condition also had an effect on the center-of-pressure trajectories in anteroposterior plane; the post-hoc test showed the mean values of the variables were significantly greater for the non-affected compared to affected limb.Shock wave therapy was significantly more effective than sonotherapy for alleviation of activity-related pain of Achilles tendinopathy. An association was also shown between shock wave therapy and more efficient postural control in patients with Achilles tendinopathy. The parameters of center-of-pressure trajectories in the sagittal plane were significantly greater for the non-affected compared to affected limb. The trial was prospectively registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12617000860369; registration date: 9.06.2017).

Balance can be a main factor contributing to success in many disciplines, and biathlon is a representative example. A more stable posture may be a key factor for shooting scores. The center of foot pressure (COP) is commonly recorded when evaluating postural control. As COP measurements are highly irregular and non-stationary, non-linear deterministic methods, such as entropy, are more appropriate for the analysis of COP displacement. The aim of our study was to investigate whether the longitudinal effects of biathlon training can elicit specific changes in postural control. Eight national-level biathletes, 15 non-athletes who prior to the experiment took part in 3 months of shooting training, and 15 non-athletes with no prior rifle shooting experience took part in our study. The data was collected with the use of a force plate. Participants performed three balance tasks in quiet standing, the shooting position (internal focus–participants concentrated on maintaining the correct body position and rifle), and aiming at the target (external focus–participants concentrated on keeping the laser beam centered on the targets). Biathletes obtained significantly lower values of sample entropy compared to the other groups during the shooting and aiming at the target trials (p

Background: Balance can also be a main factor contributing to success in many disciplines, and biathlon is a representative example. The center of foot pressure (COP) is commonly recorded when evaluating postural control. Because COP measurements are highly irregular and non-stationary, the non-linear deterministic methods are more appropriate for the analysis of COP displacement, such as entropy. The aim of our study was to investigate whether the longitudinal effects of biathlon training can elicit specific changes in postural control. Methods: 8 national-level biathletes, 15 non-athletes who prior to the experiment took part in 3 months of shooting training, and 15 non-athletes with no prior rifle shooting experience. The data was collected with the use of a force plate. Participants performed three balance tasks in quiet standing, the shooting position (internal focus), and aiming at the target (external focus). Results: Biathletes obtained significantly lower values of sample entropy compared to the other groups during shooting and aiming to the target trials (p0.05). External and internal focuses influenced the process of postural control among participants who had prior rifle shooting experience and the control group: they obtained significantly higher values of sample entropy during shooting and aiming to the target compared to the quiet standing trial (pConclusion: Specific balance training is associated with the ability to deal with a more challenging nonspecific task. The biathletes seemed to employ a different motor control strategy than the beginners and control group. They create repeating patterns (more regular signal for COP), which is a vigilant closed-loped strategy to keep one’s balance during the shooting and aiming to the target positions.

The purpose of this study was to determine the state of the art in the area of virtual reality in competitive athletes of different levels of expertise in various disciplines and point the areas of its application. Articles published before August 2018 were considered in our review. The PubMed, SCOPUS, SportDiscus and Medline databases were searched. A combination of the following search terms was used: virtual reality, virtual environment, virtual system, athletes, sports, physical training, sport performance, physical exercises. Studies involved healthy competitive athletes. A total of 18 articles met the inclusion criteria. There were three areas of application of virtual reality to sport: performance analysis, simulation improvement and virtual training. Competitive athletes were mostly examined in a semi‐immersive setting. In conclusion, virtual reality seems to play a marginal role in competitive athletes’ training. Due to the fact that virtual reality interventions bring significant improvements in clinical research, well‐designed randomized control trials with detailed virtual training programmes are required in the future. Practically, virtual reality is effectively and commonly used to analyse performance in competitive athletes. There is still a need of creating fully interactive VR, where athletes will be able to cooperate with a virtual partner and influence the environment.

The details on how the position of balance examination is achieved (preceding movement) and what is happening after (subsequent movement) is scarce. We hypothesised that the postural sway in quiet standing can differ due to demanded stability or mobility associated with the preceding and subsequent action. The body sway will be lower with high stability demand task than a condition with high mobility task. Thirteen female ballet students were examined (aged 15.1 ± 0.95 years). Participants were examined in the single-legged standing position as a part of gait initiation (G-I, high mobility) and termination (G-T, high stability) task with the use of force plate. The following Centre of Pressure (COP) variables were analysed: range and standard deviation of COP position, mean COP velocity for AP (anterio-posterior) and ML (medio-lateral) planes. The results showed that for ML plane, body sway was larger for G-I than G-T task. The lowest values of all variables in AP plane (except the COP range) were for G-T task. This difference, confirm our hypothesis, where this difference is not caused by the skills of the participants, but due to the measuring procedure and motor behaviour before and after achieving the measurement position. Our conclusion is limited to the specific posture and homogenous participants.

The aim of this study was to evaluate the effect of reduced effort on maximum countermovement jumps. Groups of unskilled and skilled jumpers performed countermovement jumps without an arm swing at 100% and 50% effort. The results revealed markedly reduced jump height and work performed at 50% effort, although the maximum force and power output remained virtually unchanged. The observed differences were consistent across individuals with different jumping skills. A possible cause of differences in changes across the tested variables was a reduced countermovement depth associated with the 50% effort jumps. It is known to cause an increase in maximum force and power outputs, but not in jump height. Therefore, the jump height and work performed may be more closely related to our sense of effort when jumping, rather than our maximum force and power output. From a practical perspective, the present findings reiterate the importance of maximizing effort for making valid assessments of muscle mechanical capacities, as tested by maximal vertical jumps and, possibly, other maximum performance tasks.

To determine the effect of virtual reality (VR) games on improving balance in different groups of neurological patients with a particular focus on the study quality and to determine the gold standard in VR training in these groups.A systematic review of controlled trials published between January 2009 and December 2017 was conducted. The PubMed, SCOPUS, SPORTDiscus, and Medline databases were searched. Studies involved patients with stroke or Parkinson's disease or children with cerebral palsy. The Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality of the included studies.A total of 20 studies met the inclusion criteria. The PEDro scores ranged from 4 to 8 points. Analysis of the rehabilitation programs revealed a very large discrepancy in the planned volume of exercises in different subgroups of patients.Overall, the comparison of VR interventions between conventional rehabilitation and no intervention exhibited significantly better results. However, these results should be interpreted with great caution due to the large diversity of the systems, games, and training volume used in the VR therapy. In all included studies, only several articles included objective methods to assess the effect of VR. In addition, most of the articles showed a high risk of bias, such as a lack of randomization and blinding or a small sample size. That is why further well-designed randomized control trials are required to evaluate the influence of VR on balance in different groups of neurological patients.

Our aim was to observe, through objective testing using an assessment module incorporated in a new exergaming system, whether elderly people’s static and functional balance is improved by a balance exergaming training program based on movements performed in everyday life. Thirteen healthy elderly women participated in 12 sessions of balance-based exergaming training (three times a week, 30 min per session). All objective outcomes, the quiet standing test, functional balance test (FBT), and limit of stability (LOS) test, were measured on three occasions: before intervention, after six training sessions, and after the completion of the four-week program. The results showed a significant improvement in LOS performance after the intervention. In FBT, participants exhibited a significant decrease (p &lt, 0.01, Kendall’s W = 0.5) in the average time to target hit after six trainings. The average center of pressure velocity increased after six and 12 sessions, however did not reach significance (p = 0.053), nevertheless the size of the effect was large (ηp2 = 0.22). The parameters of the quiet standing test were not significantly affected by the training. The results support the need for more definite and objective studies assessing exergaming for balance in elderly.

Introduction Although previous studies have contributed to our understanding of the effects of implementing the virtual reality as a rehabilitation tool in patients with Parkinson’s disease (PD), additional research is needed to examine the effects of applying balance-based exergaming training on quantitative biomechanical measures of balance. Research question To investigate the effects of balance-based conventional and exergaming training on posture parameters. Methods The study involved 24 patients with PD (Hoehn and Yahr stages II-III).Participants underwent twelve training sessions during the 4-week training period. The experimental group (n=12) was trained with a custom-made exergaming balance based training system, the control group (n=12) underwent a conventional balance training. All objective outcomes were measured before intervention and the day after completion of training program. Postural stability was assessed using the quiet standing test, dynamic balance was assessed using limits of stability (LOS) and functional balance (FBT) tests. Results After training, participants in both groups showed significantly better results in static balance performance. However, only exergaming training significantly improved LOS performance (higher values of Range of forward lean (p = 0.039, dz = 0.67) and leaning rate (p=0.007, dz=0.96). Also FBT test improved significantly only in experimental group (decrease in time to target hit (p=0.02, dz=0.76) and significant increase of average COP velocity (p=0.008, dz=0.93). Conclusion This study found that exergaming training created for patients with PD enhanced static and dynamic balance whereas conventional balance training improved static balance. Posturography is sensitive enough to reveal differential effects of training for both groups. These findings support the inclusion of our exergaming training in the exercise program for participants with PD.

Background Aging, being a natural process, involves many functional and structural changes within the body. Identifying the onset of age-related postural changes will provide insight into the role of aging on postural control during locomotion. The aim of this study was to identify age-related postural changes during a transitional task under different conditions. Methods Sixty healthy females divided into three age groups: A (50–60 y/o), B (60–70 y/o), and C (70–80 y/o). The transitional task was measured by two force platforms. The procedure consisted of three phases: quiet standing, transfer onto a second platform, and quiet standing on the second platform. Four different conditions were applied: unperturbed transfer, obstacle crossing, step-up, and step-down. Double-support time, transit time, and stability time before and after the step task were analyzed. Results The transit time was longer by 30% for subjects over 70 y/o. The double-support time was longer by 11% among adults 60–70 y/o, while in people over 70 y/o it was longer by almost 50% compared to the 50–60 y/o subjects. The stability time before the transitional task was longer by 17% among adults over 60 y/o compared to middle-age subjects. The stability times before and after the transitional task were longer for adults in the 50–60 y/o category. Conclusion The proposed procedure is adequate for assessing age-related changes in postural control while undergoing a transitional task. An analysis of the double-support time and stability time before and after the step task enabled the detection of early signs of balance changes in middle-age adults. Independent of age, the transitional task parameters changed with the increasing difficulty of the tasks.

Background Aging, being a natural process, involves many functional and structural changes within the body. Identifying the age-related postural changes will provide insight into the role of aging on postural control during locomotion. The aim of this study was to identify age-related postural changes during a transitional task under different conditions. Methods Sixty healthy females divided into three age groups: A (50-60 y/o), B (60-70 y/o), and C (70-80 y/o). The transitional task was measured by two force platforms. The procedure consisted of three phases: quiet standing, transfer onto a second platform, and quiet standing on the second platform. Four different conditions were applied: unperturbed transfer, obstacle crossing, step-up, and step-down. Double-support time, transit time, and stability time before and after the step task were analyzed. Results The transit time was longer by 30% for subjects over 70 y/o. The double-support time was longer by 11% among adults 60-70 y/o, while in people over 70 y/o it was longer by almost 50% compared to the 50-60 y/o subjects. The stability time before the transitional task was longer by 17% among adults over 60 y/o compared to middle-age subjects. The stability times before and after the transitional task were longer for adults in the 50-60 y/o category. Conclusion The proposed procedure is adequate for assessing age-related changes in postural control while undergoing a transitional task. An analysis of the double-support time and stability time before and after the step task enabled the detection of early signs of balance changes in middle-age adults. Independent of age, the transitional task parameters changed with the increasing difficulty of the tasks.

Healthy human postural sway exhibits strong intermittency, reflecting a richly interactive foundation of postural control. From a linear perspective, intermittent fluctuations might be interpreted as engagement and disengagement of complementary control processes at distinct timescales or from a nonlinear perspective, as cascade-like interactions across many timescales at once. The diverse control processes entailed by cascade-like multiplicative dynamics suggest specific non-Gaussian distributional properties at different timescales. Multiscale probability density function (PDF) analysis showed that when standing quietly while balancing a sand-filled tube with the two arms elicited non-Gaussianity profiles showing a negative-quadratic crossover between short and long timescales. A more stringent task of balancing a water-filled tube elicited simpler monotonic decreases in non-Gaussianity, that is, a positive-quadratic cancellation of the negative-quadratic crossover. Multiple known indices of postural sway governed the appearance or disappearance of the crossover. Finally, both tasks elicited lognormal distributions over progressively larger timescales. These results provide the first evidence that more stringent postural constraints recruit shorter-timescale processes into the non-Gaussian cascade processes, that indices of postural sway moderate this recruitment, and that more stringent postural constraints show stronger statistical hallmarks of cascade structure.

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

Purpose 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.

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

Objectives. The purpose of this study was to determine the effects of an 8-week complex balance training program on dynamic balance in skiers according to the new balance training protocol. Design. Intervention study, comprising 8 weeks of core stability, plyometric, balance, and stretching exercises. Participants. Ten young skiers volunteered to take part in this study (average age, height, and body mass were 16,44 +/- 1,07 years, 172,76+/-8,84 cm, and 67,4 11,44 kg, respectively (mean +/- SD)). Main Outcome Measures. Subjects’ dynamic balance performance was assessed and retested after training completion with the use of dynamic balance measurement within the Optojump Next System. Results. The results of 8-week complex balance training showed significant improvements for jump height (H) and flight time (FT) for the left leg and jumping area in both legs. Conclusion. The complex balance training program improved parameters of dynamic stability in young skiers and led to decreased asymmetry between lower extremities.

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

Research question The purpose of this study was to examine the postural sway characteristics of the ballet dance experts in quiet standing and at their limits of stability with an approach not used before in dancers. Methods The study was conducted on thirteen female ballet dancers and thirteen non-training females. The data were collected with a use of a force plate. To gain a better insight into the postural control processes, we used the rambling-trembling and sample entropy analyses in the COP data processing. Results The main findings of the study showed professional dancers to have higher values of postural sway characteristics in comparison to the non-trainees while performing simple motor tasks. Also, higher values of the trembling component in the group of dancers during quiet standing and the inclined positions were observed. This might be a sign of higher capacity of the postural system to deal with postural instability in dancers. Importance Our results confirmed that the visual information is important in the process of postural control of dancers’, which is proven by increased dislocations of the COP without visual feedback. The sample entropy results indicated more irregular characteristics of postural sway in ballet dancers representing more automated postural control. The data analysis methods showed high sensitivity to the subtle changes in postural control due to the dance training.

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

Whole-body vibration training has become a popular method used in sports and physiotherapy. The study aimed to evaluate the effect of different vibration frequency and peak-to-peak displacement combinations on men knee flexors and extensors strength in isokinetic conditions. The sample consisted of 49 male subjects randomly allocated to seven comparative groups, six of which exercised on a vibration platform with parameters set individually for the groups. The experimental groups were exposed to vibrations 3 times a week for 4 weeks. The pre- and post- isokinetic strength tests, with the angular velocities of 240°/s and 30°/s, were recorded prior to and 2 days after the training. After 4 weeks of whole-body vibration training, a significant increase was noted regarding the mean values of peak torque, average peak torque and total work for knee flexors at high angular velocity in Groups I (60 Hz/ 4 mm) and V (40 Hz/ 2 mm) (p

Purpose: To estimate the influence of global anaerobic fatigue on rhythm performance. Methods: Fifteen young males participated in the experiment. Anaerobic fatigue was induced with 2 consecutive running-based anaerobic sprint tests (RAST). The level of lactate was controlled before the first RAST and 3 minutes after each RAST. The rhythm performance was assessed by using Optojump Next (Microgate, Bolzano, Italy). The rhythm test was conducted 3 times, before fatigue and immediately after each RAST. Eight variables of the rhythm test were analyzed: the mean frequency of jumps for the assisted and unassisted phase (XfAP and XfUAP), SD of jump frequency for the assisted and unassisted phase (SDfAP and SDfUAP), and mean absolute error for the assisted and unassisted phases of the test (XERAP and XERUAP, respectively). Results: One-way repeated-measures analysis of variance showed a significant main effect of anaerobic effort on rhythm variables only in the unassisted phase of the test. Statistically significant differences were observed in XfUAP between the first and third rhythm measurements (F2,28 = 4.98, P ), SD of jump frequency for the unassisted phase (SDfUAP; F2,28 = 3.48, P = .05, ), and mean absolute error for the unassisted phase (XERUAP; F2,28 = 3.36, P = .006, ). Conclusions: The results show that rhythm of movement may be negatively influenced after intensive anaerobic fatigue. The exact mechanism of this phenomenon is not precisely defined, but both central and peripheral fatigue are suspected to be involved.