Postural sway in volleyball players

Ground reaction forces better than center of pressure differentiate postural control between young female volleyball players and untrained peers

A comprehensive explanation of the relationship between postural control and athletic performance requires compare body balance in athletes with their never training counterparts. To fill this gap in relation to volleyball, the aim of this study was to compare the balance of intermediate adolescent female players (VOL, n = 61) with inactive peers (CON, n = 57). The participants were investigated in normal quiet stance during 20 s trials on a Kistler force plate. The traditional spatial (amplitude and mean speed) and temporal (frequency and entropy) indices were computed for ground reaction forces (GRF) and center-of-pressure (COP) time-series. The spatial parameters of the both time-series did not discriminate the two groups. However, the temporal GRF parameters revealed much lower values in VOL than in CON (p < .0001). This leads to three important conclusions regarding posturography applications. First, GRF and COP provide different information regarding postural control. Second, measures based on GRF are more sensitive to changes in balance related to volleyball training and perhaps to similar training and sports activity regimens. And third, the indicators calculated based on these two time series can complement each other and thus enrich the insight into the relationship between balance and sports performance level.

Postural Analysis Using Rasterstereography and Inertial Measurement Units in Volleyball Players: Different Roles as Indicators of Injury Predisposition

Background and Objectives: Acute and chronic injuries are frequent in volleyball. Biomechanics of sport-specific tasks can influence the risk of injury, which is also related to specific court positions. We investigated posture at raster-stereography, balance, and dynamic tasks using inertial motion units to find differences between roles, which can be predictive of a higher risk of injury. Materials and Methods: We cross-sectionally evaluated amateur volleyball athletes. Participants were divided into roles as outside hitters, setters, middle blockers, and opposite hitters. We excluded the "libero" position from our analysis. Results: Sixteen players were included in the analysis. A statistically significant difference was found in left lower limb stiffness among the outside hitter and setter groups. Conclusions: Differences in stiffness might be related to the different training and the different abilities among the two groups. Raster-stereography is extending its indications and should be implemented for non-invasive postural analysis. The use of inertial motion units provides objective measurements of variables that could go unrecognized within a clinical evaluation; its use should be considered in injury preventive programs.

The optimal method for improving postural balance in healthy young and older people: specific training for postural tasks encountered in personal physical practice

It is well known that regular exercise or physical activity (training) improves postural balance in healthy young and older subjects, but the optimal exercise or physical activity (i.e., likely to induce the greatest postural improvements) and the context in which it is carried out remain to be explored and determined for each population. The most beneficial adaptations would depend, in particular, on gestural conditions (body position, movement and gesture practiced) and material conditions (nature of the ground surface, sports equipment used, type of environment - stable or changing). In fact, the global postural adaptations induced by training do not result from the transfer between different trained and untrained postural tasks, but are the sum of the adaptations related to each trained postural task in healthy young and older subjects. Based on current knowledge, optimal training programs should include the full range of postural tasks encountered in personal physical practice for each population. To date, the method of implementing progressive postural balance tasks with different degrees of difficulty and instability has been used as the effective method to improve postural balance, but it should not be considered as the reference method. Instead, it should be considered as a complementary method to the one based on specific postural tasks. An intervention strategy is proposed for young and older adults consisting of three different steps (general, oriented and specific/ecologic training). However, some parameters still need to be explored and possibly reconsidered in future studies to improve postural balance in an optimal way.

Postural balance ability and vertical jumping performance in female veteran volleyball athletes and non-athletes

Lifetime participation in sports is associated with improved components of physical conditioning. The main purpose was to cross-sectionally investigate postural balance and vertical jumping performance in athletes with different histories of sports participation and secondarily to examine the restriction of vision on balance ability. A final aim was to investigate possible associations between balance and jumping performance. We hypothesized higher balance and jumping performance in active veteran volleyball athletes compared to retired athletes and non-athletes, suggesting a positive effect of continuous systematic training in active veteran athletes. We also hypothesized greater negative effect of vision removal on balance in the veteran compared to non-athletes due to athletes' stronger reliance on visual information. Eighty-one healthy middle-aged women (mean (standard deviation) 50 (5) years) were assigned to three experimental groups, a retired (n = 39, recreationally active former athletes), an active (n = 27, training 2days/week x 1.5 h/session) veteran volleyball athletes' and a control group (n = 15, sedentary participants). Participants completed an assessment of single-legged quiet stance trials with either left or right leg with eyes open while standing barefoot on a force plate and two-legged trials with both eyes open or closed. They also executed a protocol of countermovement jumps. Statistical analyses included univariate and full factorial ANOVAs with group and vision as fixed and repeated-measures factors and simple linear regression analysis. In the single-legged balance task, solely the mediolateral sway range was greater for the active (p < 0.001) and retired athletes (p < 0.001) compared to non-athletes, whereas in the two-legged stance, no differences among groups were found (p > 0.05). Restriction of vision deteriorated balance performance similarly in the three groups as a significant vision effect was found for path length (p < 0.001), anteroposterior (p < 0.001) and mediolateral sway (p < 0.05). The active and retired athletes had significantly (p < 0.001) greater height, mean and maximal power in countermovement jump compared to non-athletes. Results showed weak associations (average R² = 9.5%) of balance with jumping performance only in the veteran volleyball athletes' group. Overall, the findings showed that retired volleyball athletes exhibited similar balance ability and vertical jumping performance as the active ones, suggesting a positive impact of prior experience in systematic training.

Sport-specific training induced adaptations in postural control and their relationship with athletic performance

Effects of various exercise programs on postural balance control in athletes and their underlying physiological mechanisms have been extensively investigated. However, little is known regarding how challenging sport-specific conditions contribute to the improvement of body balance and to what extent these changes may be explained by sensorimotor and/or neuromuscular function adaptations. Analysis of the literature could provide useful information on the interpretation of changes in postural sway variables in response to long-term sport-specific training and their association with performance measures. Therefore, the aim of this scoping review was (1) to analyze the literature investigating postural control adaptations induced by sport-specific training and their relationship with measures of athletic performance, and (2) to identify gaps in the existing research and to propose suggestions for future studies. A literature search conducted with Scopus, Web of Science, MEDLINE and Cochrane Library was completed by Elsevier, SpringerLink and Google Scholar with no date restrictions. Overall, 126 articles were eligible for inclusion. However, the association between variables of postural balance control and measures of sport-specific performance was investigated in only 14 of the articles. A relationship between static and/or dynamic balance and criterion measures of athletic performance was revealed in shooting, archery, golf, baseball, ice-hockey, tennis, and snowboarding. This may be ascribed to improved ability of athletes to perform postural adjustments in highly balanced task demands. However, the extent to which sport-specific exercises contribute to their superior postural stability is unknown. Although there is a good deal of evidence supporting neurophysiological adaptations in postural balance control induced by body conditioning exercises, little effort has been made to explain balance adaptations induced by sport-specific exercises and their effects on athletic performance. While an enhancement in athletic performance is often attributed to an improvement of neuromuscular functions induced by sport-specific balance exercises, it can be equally well ascribed to their improvement by general body conditioning exercises. Therefore, the relevant experiments have yet to be conducted to investigate the relative contributions of each of these exercises to improving athletic performance.

Bilateral symmetry of vertical time to stabilization in postural sway after double-leg landing in elite athletes with unilateral chronic ankle sprain

Background

Lower limb asymmetry among athlete with unilateral chronic ankle instability (CAI) during bilateral landing can be a potential source of ankle sprain reinjury. The aim of study was to investigate the effect of bilateral symmetry of vertical time to stabilization (vTTS) in postural sway after double-leg landing (DLL) in elite athletes with unilateral CAI.

Methods

Twenty professional players with unilateral CAI and ten healthy controls were assigned to three groups (soccer, basketball, and control groups, n = 10 each). The postural balance during DLL tasks was assessed based on center of pressure (CoP) and vTTS. Multiple analysis of variance was conducted to statistically analyse the CoP and vTTS which followed by Bonferroni’s post hoc test (P < 0.05).

Results

The vTTS of the injured foot was significantly longer in the soccer and basketball players than in the control players (P = 0.006, p < 0.001 respectively). The intragroup comparison showed a significant difference in the vTTS of CAI and uninjured feet among the basketball players (mean difference = 1.3 s). The basketball group exhibited a worse balance in CoP oscillations results between groups.

Conclusions

The findings suggested that symmetry between double-leg vTTS values, may be important as much as the sooner vTTS in reduced CoP oscillations and enhanced balance after DLL. Balancing exercises should achieve sooner vTTS in soccer players and symmetry in the double-leg vTTS of basketball players with unilateral CAI while maintaining static balance during dynamic-to-static postural changes to reduce recurrent ankle sprain.

Eye Position Shifts Body Sway Under Foot Dominance Bias in the Absence of Visual Feedback

Purpose

The purpose of this study was to investigate whether information on extraocular muscle proprioception without visual information affects postural control.

Methods

Thirty-five healthy young volunteers participated in the study. Postural control outcomes included the center of pressure (CoP) for static standing, the total length of the sway of the CoP (LNG), and the sway area (SA), as well as the mean CoP in the mediolateral and anteroposterior directions. The following five eye-fixing positions were used: eye-up (E-Up), eye-down (E-Down), eye-right (E-Right), eye-left (E-Left), and eye-center (Center eye position). One-way ANOVA and Bonferroni correction was performed for statistical processing. Electrooculograms were recorded to detect eye orientation errors, measured with the eyes closed.

Results

The results of this study showed no significant difference between the LNG and SA results when comparing respective eye positions (E-up, E-down, E-right, E-left) relative to E-Center (control). However, the average CoP was shifted to the right at E-Up, E-Down, and E-Left.

Conclusion

These findings indicate that postural control may be affected by eye-body coordination depending on the position of the eyes, even without visual information.

The Role of Neuromuscular Control of Postural and Core Stability in Functional Movement and Athlete Performance

Balance and core stabilization exercises have often been associated with improved athlete performance and/or decreased incidence of injuries. While these exercises seem to be efficient in the prevention of injuries, there is insufficient evidence regarding their role in sport-specific performance and related functional movements. The aim of this scoping review is (1) to map the literature that investigates whether currently available variables of postural and core stability are functionally related to athlete performance in sports with high demands on body balance and spinal posture and (2) to identify gaps in the literature and suggest further research on this topic. The literature search conducted on MEDLINE, Scopus, Web of Science, PubMed, and Cochrane Library databases was completed by Google Scholar, SpringerLink, and Elsevier. Altogether 21 articles met the inclusion criteria. Findings revealed that postural stability plays an important role in performance in archery, biathlon, gymnastics, shooting, and team sports (e.g., basketball, hockey, soccer, tennis). Also core stability and strength represent an integral part of athlete performance in sports based on lifting tasks and trunk rotations. Variables of these abilities are associated with performance-related skills in cricket, cycling, running, and team sports (e.g., baseball, football, hockey, netball, soccer, tennis). Better neuromuscular control of postural and core stability contribute to more efficient functional movements specific to particular sports. Training programs incorporating general and sport-specific exercises that involve the use of postural and core muscles showed an improvement of body balance, back muscle strength, and endurance. However, there is controversy about whether the improvement in these abilities is translated into athletic performance. There is still a lack of research investigating the relationship of body balance and stability of the core with sport-specific performance. In particular, corresponding variables should be better specified in relation to functional movements in sports with high demands on postural and core stability. Identifying the relationship of passive, active, and neural mechanisms underlying balance control and spinal posture with athlete performance would provide a basis for a multifaced approach in designing training and testing tools addressing postural and core stability in athletes under sport-specific conditions.

Center of pressure-based postural sway differences on parallel and single leg stance in Olympic deaf basketball and volleyball players

In sports such as basketball and volleyball, loss of balance due to the inability to maintain body stability and lack of postural control adversely affect athletic performance. Deaf athletes appear to struggle with balance and postural stability problems. The purpose of this study was to examine postural sway values in parallel and single leg stance of Olympic deaf basketball and volleyball players and reveal differences between the branches. Twenty-three male athletes from the Turkish national deaf basketball (n=11) and volleyball (n=12) teams participated in the study. After anthropometric measurements, the subjects completed postural sway (PS) tests in parallel/single leg stances with open eyes and closed eyes on a force plate. PS parameters (sway path, velocity, and area) obtained from the device software were used for the statistical analysis. The Mann-Whitney U-test was used to compare differences in PS parameters between basketball and volleyball players, and the alpha value was accepted as 0.05. Volleyball players had significantly better results in parallel stance and dominant leg PS values than basketball players (P<0.05). There was no significant difference between the groups in nondominant leg PS values (P>0.05). We think that proprioceptive and vestibular system enhancing training practices to be performed with stability exercises will be beneficial in terms of both promoting functional stability and interlimb coordination. Trainers and strength coaches should be aware of differences in the postural control mechanism of deaf athletes.

Static balance performance differs depending on the test, age and specific role played in acrobatic gymnastics

BACKGROUND

Static balance performance appears to detect differences between roles played in team sports. Static balance can also be influenced by the subject's height and age, and the type of test used.

RESEARCH QUESTION

Could the static balance profile show differences among the role played depending on the specific test evaluated and the gymnasts' age?

METHODS

A cross-sectional design was applied. 46 acrobatic gymnasts (37 females and 9 males) were divided in four groups according to role (base or top gymnast) and stage of adolescence (early adolescent or mid-adolescent) during two different static tests: (1) unipedal with open and closed eyes (generic), and (2) headstand (specific). To test the effect of the role and the age group, a two-way analysis of variance (ANOVA) between groups was performed. Centre of pressure (COP) measurements were obtained and normalised relative to participants height, including length travelled on the anteroposterior and mediolateral axis (AP_CoP and ML_CoP) and the mean speed (SP_CoP).

RESULTS

Base gymnasts obtained lower values in the CoP excursion than Top gymnasts but only in unipedal tests for all the variables analysed (5.536 ≥ F_1,42 ≤ 10.589, 0.002 ≥ p ≤ 0.023), except for the AP_CoP in unipedal-closed. Mid-adolescent gymnasts obtained lower values in the CoP excursion regardless of the task than early adolescent (5.324 ≥ F_1,42 ≤ 14.805, 0.000 ≥ p ≤ 0.026).

SIGNIFICANCE

It has been observed a clear effect of age on the static balance manifested in acrobatic gymnastics, regardless of the subject's height, the role played, and the test performed. The effect of the role played in this team sport has been different depending on the type of test performed.

Discrimination of standing postures between young and elderly people based on center of pressure

Posturography is utilized to assess the influence of aging on postural control. Although this measurement is advantageous for finding group-level differences between the young and the elderly, it is unclear whether it has the potential to differentiate elderly individuals who are affected by various impacts of aging. The purpose of this study was to determine the utility of posturography to discriminate elderly individuals from young adults. We investigated the performances of the random forest classifiers constructed from center of pressure (COP) indices for discriminating standing postures between healthy elderly and young people. Postural sways in 19 young and 31 community-dwelling elderly participants were measured using force plates in 4 standing conditions: bipedal standing, standing on a narrow base, standing on foam rubber, and standing with eyes closed. We further verified the informative predictors that contributed to the prediction model. As the results, the classifier based on the COP indices for standing on foam rubber showed the best performance (accuracy: 93.4%, sensitivity: 94.4%, specificity: 93.6%, area under the curve of receiving operator characteristics: 0.95), followed by the classifier for standing with eyes closed. The informative predictors varied depending on the postural conditions. Our findings demonstrated the potential of posturography for identifying elderly postures. The evaluation of sensory re-weighting using the appropriate COP indices would be a useful clinical tool for detecting the progress of aging on postural control.

The Effect of Balance and Sand Training on Postural Control in Elite Beach Volleyball Players

The aim of this work was to evaluate the effectiveness of a 12-week-long balance training program on the postural control of elite male beach volleyball players and the effect on balance when swapping to specific sports training in the sand in the following 12 weeks. Six elite players were tested before and after the balance training program and also 12 weeks after the balance training had finished. To this aim, a pressure platform was used to collect the following center of pressure parameters: path length, speed, mean position, and root-mean-square amplitude in the medial-lateral and anteroposterior planes. Romberg quotients for the center of pressure parameters were also calculated. The results of the present study showed better static postural control after specific balance training: smaller path length and speed under open eyes condition in dominant (p = 0.015; p = 0.009, respectively) and non-dominant monopedal stances (p = 0.005; p = 0.004, respectively). Contrastingly, 12 weeks after the balance training program, the path length and speed values under open eyes condition in bipedal stance increased significantly (p = 0.045; p = 0.004, respectively) for sand training. According to our results, balance training is effective to achieve positive balance test scores. It is speculated, and yet to be proven, that sand training could be effective to improve dynamic and open eyes postural control during beach volleyball practice. In beach volleyball players, a balance training program is effective to develop static balance but the effect of ecological sand training on dynamic performance deserves specific investigation.

Differences in static postural control between top level male volleyball players and non-athletes

It is argued that elite athletes often demonstrate superior body balance. Despite the apparent significance of perfect balance ability in volleyball, little is known about the specific nature of postural control adjustments among first-rate volleyball competitors. This study compared postural performance and strategies in quiet stance between world vice-champions and young, healthy, physically active male subjects. The center-of-pressure (COP) signals recorded on a force plate were used to compute several measures of sway. In both axes of movement, athletes had lower COP range, but not its standard deviation and higher COP speed and frequency than controls. These findings indicate that postural regulation in athletes was more precise and less vulnerable to external disturbances which support optimal timing and precision of actions. Postural strategies in athletes standing quietly were similar to those exhibited by non-athletes performing dual tasks. It demonstrates a significant effect of sport practice on changes in postural control. In anterior–posterior axis, athletes displayed a much higher COP fractal dimension and surprisingly lower COP–COG frequency than controls. This accounts for their high capacity to use diversified postural strategies to maintain postural stability and significantly reduced the contribution of proprioception to save this function for carrying out more challenging posture-motor tasks.

Postural control in top-level female volleyball players

Background

The aim of this study was to compare the postural control of the Poland national women’s volleyball team players with a control group of non-training young women. It was hypothesized that volleyball players use a specific balance control strategy due to the high motor requirements of their team sport.

Methods

Static postural sway variables were measured in 31 athletes and 31 non-training women. Participants were standing on a force plate with eyes open, and their center of pressure signals were recorded for the 20s with the sampling rate of 20 Hz in the medial-lateral (ML) and anterior-posterior (AP) planes.

Results

In both AP and ML planes, athletes had lower range and higher fractal dimension of the COP. They had also higher peak frequency than control group in the ML plane only. The remaining COP indices including variability, mean velocity and mean frequency did not display any intergroup differences.

Conclusion

It can be assumed that due to the high motor requirements of their sport discipline Polish female volleyball players have developed a unique posture control. On the court they have to distribute their sensory resources optimally between balance control and actions resulting from the specifics of the volleyball game. There are no clearly defined criteria for optimal postural strategies for elite athletes, but they rather vary depending on a given sport. The results of our research confirm this claim.

Trial registration

The tests were previously approved by the Bioethical Commission of the Chamber of Physicians in Opole. (Resolution No. 151/13.12.2007). This study adheres to the CONSORT guidelines.

Postural data from Stargardt's syndrome patients

The database is a collection of postural data acquired from 10 patients affected by the rare Stargardt's syndrome, all having the ABCA4 gene mutation, and from 10 control healthy subjects. Specifically, the database includes a file (.xlxs) called SubjectsData and 20 datasets (MATLAB structures) containing postural signals. Each subject performed a total of 15 postural tests, 5 postural tests for 3 different conditions (‘C’: eyes-closed; ‘O’: eyes-open, still target fixation; ‘M’: eyes-open, moving target tracking). For each postural test, 11 postural derived signals (the anterior-posterior force, the medio-lateral force, the vertical force, the plate moment about x axis, the plate moment about y axis, the plate moment about z axis, the plate moment about top plate surface about x axis, the plate moment about top plat surface about y axis, the x-coordinate of the center of pressure, the y-coordinate of the center of pressure, and the free moment about z axis) were computed from 8 raw signals, acquired at the Ophthalmic Hospital of Turin, Italy, through an 8-channel Kistler 9286A force platform connected to a Step32 system. Thus, a total of 285 postural signals (120 raw and 165 derived) are available for each subject. The database may be useful to: (1) investigate postural adaptations of patients affected by Stargardt's syndrome; (2) support definition of rehabilitative procedures to reduce postural instability of patients affected by Stargardt's syndrome; and (3) support investigation on visual control of balance in the general population.

The rapid recovery of vertical force propulsion production and postural sway after a specific fatigue protocol in female handball athletes

BACKGROUND

Muscle fatigue is characterized by a decrease in muscle performance, accompanied by an increase in perceived exertion to produce a desired amount of force. The duration of the fatigue effects is not completely clear regarding postural sway and force production in athletes.

RESEARCH QUESTION

What is the effect of a specific fatigue protocol in postural sway and force production in female handball athletes and the recovery time necessary for these variables?

METHODS

Twenty female handball athletes participated in this study. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. They stood upright in one-leg posture on a force plate. For the maximum propulsion force (F_MAX), they performed a countermovement jump on the force plate. The center of pressure (COP) and the F_MAX were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase.

RESULTS

The F_MAX decreased ∼9.5% after the fatigue protocol, whereas de COP area increased 224%. During the recovery phase, the F_MAX and the COP area returned to baseline values after five minutes.

SIGNIFICANCE

The first five minutes immediately after the fatigue protocol represent the time interval where the fatigue effects are still present. Future studies willing to investigate the effects of fatigue in athletes should perform the analysis within this short time-window.

Wearable Inertial Sensors to Assess Standing Balance: A Systematic Review

Wearable sensors are de facto revolutionizing the assessment of standing balance. The aim of this work is to review the state-of-the-art literature that adopts this new posturographic paradigm, i.e., to analyse human postural sway through inertial sensors directly worn on the subject body. After a systematic search on PubMed and Scopus databases, two raters evaluated the quality of 73 full-text articles, selecting 47 high-quality contributions. A good inter-rater reliability was obtained (Cohen's kappa = 0.79). This selection of papers was used to summarize the available knowledge on the types of sensors used and their positioning, the data acquisition protocols and the main applications in this field (e.g., "active aging", biofeedback-based rehabilitation for fall prevention, and the management of Parkinson's disease and other balance-related pathologies), as well as the most adopted outcome measures. A critical discussion on the validation of wearable systems against gold standards is also presented.

Effect of four weeks of ocular-motor exercises on dynamic visual acuity and stability limit of female basketball players

INTRODUCTION

Visual skills are an integral part of most daily activities and an effective indicator of the functional ability of athletes, particularly in the fields of dynamic sports like basketball. Despite the important role of vision and effect of ocular exercises on functional skills in athletes, a few studies have been conducted in this regard. Thus, this study aimed to investigate the effect of ocular-motor exercises on dynamic visual acuity and stability limit of female basketball players.

METHODS

In this semi-experimental study 30 club elite female basketball players aged between 18 and 24 years, with at least three years of specialized basketball experience, were randomly assigned to two intervention and control groups. The athletes in the intervention group participated in the designed four-week program (six sessions per week) of the oculo_motor exercises. The control group did just their own daily routine exercises. The limit of stability was measured by the Biodex balance system SD and dynamic visual acuity was measured by the PowerPoint, which is for detecting dynamic visual acuity. Also, the SPSS software version 19 was used to analyze the data by using descriptive statistics methods: independent t and Paired t tests, at a significance level of P ≤ 0.05.

RESULTS

The results showed that doing four weeks of the oculo_motor exercises led to a significant increase in the overall stability index (OSI) from 28/66 ± 7/23 to 51/60 ± 6/38 (p = 0.001), as well as in dynamic visual acuity from 29/73 ± 4/19 to 56/20 ± 8/81(p < 0.001); in the intervention group, these changes were also statistically significant in comparison with the control group and before doing the exercise protocol (p < 0.05).

CONCLUSION

According to the obtained results, the oculo_motor exercises can be used to enhance the limit of stability and dynamic visual acuity in basketball players and other dynamic sports.

Static Postural Balance in Modern Pentathletes: A Pilot Study

Postural balance is a key element of shooting effectiveness, which determines the outcome of modern pentathlon competitions. The aim of the study is to examine the postural balance of 27 pentathletes (12 females and 15 males; mean age: 18.0 ± 1.8 years), and 26 physically active, untrained subjects (12 females and 14 males; mean age: 22.5 ± 1.4 years), and to investigate the impact of footwear on the stability of the shooting position in pentathletes. Methods: Static postural balance was examined during quiet stance in four test conditions (standing in footwear with eyes opened, standing in footwear with eyes closed, standing barefoot with eyes opened, and standing barefoot with eyes closed). During each postural balance measurement, the participant remained still on the platform, with their arms in front of their body. Postural balance in the shooting position was only evaluated in the group of pentathletes. The athlete was asked to assume a comfortable shooting position on the platform and to aim at the target. Standard pentathlon targets and pistols were used in the study. Measurements were carried out twice (barefoot and in footwear). Results: In all conditions, pentathletes achieved lower values of posturographic measures than in the control group. In non-visual conditions, measures describing the surface area of the centre of pressure decreased in pentathletes and increased in the control group. Both pentathletes and non-athletes were equally stable barefoot as in footwear. Footwear did not affect postural sway in the shooting position in pentathletes. Conclusions: Pentathletes were found to have significantly better stance stability and were less vision-dependent in postural balance than untrained subjects. Bearing in mind that the shooting position of pentathletes was as stable barefoot as in footwear, the main factors which were most likely responsible for minimising body oscillations in the pentathletes were their high level of concentration and conscious control of body alignment.

Balance control during stance - A comparison between horseback riding athletes and non-athletes

Horseback riding requires the ability to adapt to changes in balance conditions, to maintain equilibrium on the horse and to prevent falls. Postural adaptation involves specific sensorimotor processes integrating visual information and somesthesic information. The objective of this study was to examine this multisensorial integration on postural control, especially the use of visual and plantar information in static (stable) and dynamic (unstable) postures, among a group of expert horse rider women (n = 10) and a group of non-athlete women (n = 12). Postural control was evaluated through the center of pressure measured with a force platform on stable and unstable supports, with the eyes open and the eyes closed, and with the presence of foam on the support or not. Results showed that expert horse rider women had a better postural stability with unstable support in the mediolateral axis compared to non-athletes. Moreover, on the anteroposterior axis, expert horse riders were less visual dependent and more stable in the presence of foam. Results suggested that horseback riding could help developing particular proprioceptive abilities on standing posture as well as better postural muscle tone during particular bipodal dynamic perturbations. These outcomes provide new insights into horseback riding assets and methodological clues to assess the impact of sport practice.

Postural Stability in Goalkeepers of the Polish National Junior Handball Team

The aim of the study was to assess postural stability of goalkeepers from the Polish national junior handball team. Eleven juniors of the Polish national handball team (age 16.82 ± 1.6 years, body height 191.27 ± 3.1 cm, body mass 88.41 ± 12.26 kg, BMI 24.18 ± 3.22 kg/m2) were selected for the study. The Biodex Balance System and AccuGait AM¬TI platform were used to evaluate postural stability. The obtained results indicated good postural stability of the subjects. During the Biodex Balance System platform tests, all subjects presented very good postural stability and maintained within Zone A. Postural sway was greater in the sagittal plane compared to the frontal one. Most of the participants demonstrated slight backward tilts, but maintained in Quadrant IV. During the AccuGait AMTI platform trial, Path Length and Average COP Speed significantly increased in the test performed with closed eyes. Furthermore, there were significant positive correlations between the number of variables obtained during the Biodex Balance System and AccuGait AMTI tests. Proper and stable posture are necessary conditions to be met to carry out most free movements and locomotion. They play a significant role in the game of a handball goalkeeper and for that reason, postural stability testing of handball goalkeepers is an important element of coordination training. Thus, the use of postural stability exercises implementing the biofeedback method on stabilo and dynamometric platforms is practical and justifiable.

Water-filled training tubes increase core muscle activation and somatosensory control of balance during squat

This study examined trunk muscle activation, balance and proprioception while squatting with a water-filled training tube (WT) and a traditional barbell (BB), with either closed (CE) or open eyes (OE). Eighteen male elite Gaelic footballers performed an isometric squat under the following conditions: BB-OE, BB-CE, WT-OE and WT-CE. The activity of rectus abdominis (RA), external oblique (EO) and multifidus (MF) was measured using electromyography, along with sway of the centre of pressure (CoP) using a force platform. Only the EO and the MF muscles exhibited an increased activity with WT (p < 0.01). In the medio-lateral direction both the velocity and range of the CoP increased significantly with WT (p < 0.01). Interestingly, the range of the CoP for the WT-CE condition was significantly lower than WT-OE (p < 0.05, d = 0.44), whilst the velocity of the CoP was marginally reduced (d = 0.29). WT elicited a greater level core muscle activation and created a greater challenge to postural stability when compared to a BB. It appears that WT does not benefit from vision but emphasises the somatosensory control of balance. The use of WT may be beneficial in those sports requiring development of somatosensory/proprioceptive contribution to balance control.

Specificity of Postural Control: Comparing Expert and Intermediate Dancers

The expert-novice approach is inappropriate for studying postural control in sport and dance when novices are completely unable to perform relevant postural tasks and experts cannot demonstrate specific skills on everyday postural tasks. We tested expertise-specific differences on 6 static everyday and 5 dynamic dance-like postural tasks of varying difficulty in 13 professional and 12 intermediate nonprofessional dancers. Results showed a clear expert advantage on sway area for dance-like postural tasks, but not for static everyday tasks. This effect was also found for the control parameter of root mean square (RMS) velocity and partly for RMS amplitude of the difference signal between CoP and CoG line location. Results indicate that the expert advantage is task-specific and deliver new insights into the specificity of experts' postural performance.

Age-related changes in the range and velocity of postural sway

The aim of this analysis was to compare values of centre of pressure (CoP) measures, which describe the ability to maintain static body balance (range of body sway and velocity in antero-posterior and medio-lateral directions), in two age groups on the basis of a systematic review and meta-analysis of available data published worldwide. After a systematic review of publications presenting values of selected CoP measures, a numerical database with means and standard deviations was created. Data were classified by eye condition (open or closed) and by age group (18-35 or ≥56). Allocation to each group was based on the mean value of age of each sub-group in the numerical database. The Mann-Whitney U test was used to test the statistical significance of differences between age groups and eyes-open and eyes-closed conditions. This article shows mathematical equations, which quantitatively express increases in body sway and its velocity with age. On the basis of those equations, higher values have been shown for both displacement and velocity measures for the EC vs. the EO conditions and for the elderly vs. the young. The differences between age groups are greater for the velocity measures.

Effects of a 10-Week Introductory Judo Course on Postural Control During a Bilateral Reactionary Gripping Task

This study examined the effect of a 10-week introductory judo course on postural control during a bilateral reactionary gripping task using different stance conditions. A total of 20 volunteers were divided into experimental (JDO) and control (CON) groups. Countermovement jump was measured and center of pressure variables were evaluated while performing a bilateral reactionary gripping task under different stance conditions during pre- and posttesting. No interactions were observed for the center of pressure variables (p > .05), while both countermovement jump power (+165.4 W; p = .036) and height (+3.5 cm; p = .018) significantly improved in the JDO group following the 10-week course. Results indicate that 10 weeks of an introductory judo course has no effect on postural control while performing a bilateral reactionary gripping task using different stance conditions.

The role of central vision in posture: Postural sway adaptations in Stargardt patients

The role of central and peripheral vision in the maintenance of upright stance is debated in literature. Stargardt disease causes visual deficits affecting the central field, but leaving unaltered a patient's peripheral vision. Hence, the study of this rare pathology gives the opportunity to selectively investigate the role of central vision in posture. Postural sway in quiet stance was analyzed in 10 Stargardt patients and 10 control subjects, in three different conditions: (1) eyes closed, (2) eyes open, gazing at a fixed target, and (3) eyes open, tracking a moving target. Stargardt patients outperformed controls in the condition with eyes closed, showing a reduced root mean square (RMS) of the medio-lateral COP displacement, while their performance was not significantly different from controls in the antero-posterior direction. There were no significant differences between patients and controls in open eyes conditions. These results suggest that Stargardt patients adapted to a different visual-somatosensory integration, relying less on vision, especially in the medio-lateral direction. Hence, the central vision seems to affect mostly the medio-lateral direction of postural sway. This finding supports the plausibility of the "functional sensitivity hypothesis", that assigns complementary roles to central and peripheral vision in the control of posture.

Universal and individual characteristics of postural sway during quiet standing in healthy young adults

The time course of the center of pressure (CoP) during human quiet standing, corresponding to body sway, is a stochastic process, influenced by a variety of features of the underlying neuro-musculo-skeletal system, such as postural stability and flexibility. Due to complexity of the process, sway patterns have been characterized in an empirical way by a number of indices, such as sway size and mean sway velocity. Here, we describe a statistical approach with the aim of estimating "universal" indices, namely parameters that are independent of individual body characteristics and thus are not "hidden" by the presence of individual, daily, and circadian variations of sway; in this manner it is possible to characterize the common aspects of sway dynamics across healthy young adults, in the assumption that they might reflect underlying neural control during quiet standing. Such universal indices are identified by analyzing intra and inter-subject variability of various indices, after sorting out individual-specific indices that contribute to individual discriminations. It is shown that the universal indices characterize mainly slow components of sway, such as scaling exponents of power-law behavior at a low-frequency regime. On the other hand, most of the individual-specific indices contributing to the individual discriminations exhibit significant correlation with body parameters, and they can be associated with fast oscillatory components of sway. These results are consistent with a mechanistic hypothesis claiming that the slow and the fast components of sway are associated, respectively, with neural control and biomechanics, supporting our assumption that the universal characteristics of postural sway might represent neural control strategies during quiet standing.