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 control through force plate measurements in female AIS patients compared to their able-bodied peers.

The present understanding of the mechanisms responsible for postural deficit in adolescent idiopathic scoliosis (AIS) is still insufficient. This is important because some authors see one of the causes of this disease in the impaired postural control. Moreover, there is a reciprocal link between the level of postural imbalance and the clinical picture of these people. Therefore, we compared the center-of-pressure (COP) indices of 24 patients with AIS to 48 controls (CON) during four 20-s quiet stance trials with eyes open (EO) or closed (EC) and on firm or foam surface. This included sway amplitude, speed, sample entropy and fractal dimension. AIS had poorer postural steadiness only in the most difficult trial. In the remaining trials, AIS did as well as CON, while presenting a greater COP entropy than CON. Thus, the factor that made both groups perform equally could be the increased sway irregularity in AIS, which is often linked to higher automaticity and lower attention involvement in balance control. After changing the surface from hard to foam, puzzling changes in sway fractality were revealed. The patients decreased the fractal dimension in the sagittal plane identically to the CON in the frontal plane. This may suggest some problems with the perception of body axes in patients and reveals a hitherto unknown cause of their balance deficit.

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.

Characteristics of Standing Postural Control in Women under Additional Load.

The aim of this study was to evaluate the effect of additional load on postural-stability control in young women. To evaluate postural control in the 34 women in this study (mean age, 20.8 years), we measured postural sway (center of pressure, COP) in a neutral stance (with eyes open) in three trials of 30 s each. Three load conditions were used in the study: 0, 14, and 30 kg. In analysis, we used three COP parameters, variability (linear), mean sway velocity (linear), and entropy (nonlinear). Results suggested that a considerable load on a young woman's body (approximately 48% of body weight) had significant influence on stability. Specifically, heavy loads triggered random movements, increased the dynamics of postural-stability control, and required more attention to control standing posture. The results of our study indicate that inferior postural control mainly results from insufficient experience in lifting such a load.

Effects of Plyometrics Training on Muscle Stiffness Changes in Male Volleyball Players.

Dariusz, M, Krzysztof, M, Pawel, C, Edward, S, Marek, K, Tomasz, S, Dorota, B, Rektor, Z, and Jan, C. Effects of plyometrics training on muscle stiffness changes in male volleyball players. J Strength Cond Res 33(4): 910-921, 2019-We investigated whether 6 weeks of specific plyometric training (PT) impacts on changes in muscle stiffness and enhances the vertical jumping ability as the indirect evaluation of the explosive power of the lower extremities of male volleyball players. Sixteen male collegiate volleyball players participated in this experiment. Regular PT was performed twice per week for 60-90 minutes each time. During each PT session, heart rate and muscle stiffness data were collected. Two series of 10 single measurements of each muscle (23 points of the front and back legs) were measured the day before the first enhanced training session and after completing each week of PT. Participants were tested for maximum effort in vertical jumping using the squat jump (SJ) with hands on thighs, countermovement jump (CMJ), and CMJ with a 2-step to 3-step approach. Jumping motor ability tests were completed. Data were collected 1 day before PT. The last measurement was performed 3 days after completing the last week of PT. The 6-week PT program only had an effect on the statistically relevant increase in muscle stiffness in the tibialis anterior (highest value, 593.86 ± 60.24 N·m) and quadriceps. Improvements in the explosive power of leg muscles resulted in a significant increase in the vertical jumping ability; there were improvements in SJ and CMJ (p = 0.0338 and p = 0.0007, respectively). If PT involves a moderate workload and if players never exceed the intensity target of the workout, then less muscle stiffness and muscle soreness may occur.

The Relationship Between Postural Control and Self-Reported Engagement in Physical Activity in Young and Older Age.

Physical activity is known to have beneficial effects on a host of factors related to physical and mental health, and positively affects postural control. However, there is no agreement on which measures of postural control and to what extent they are dependent on the past and present physical activity in older adults. To answer this question we compared the postural performance in a 20-s quiet stance with eyes open on a Kistler force plate in 38 subjects, aged 60-92, who were formerly and are currently physically active (AA) with those who were always inactive (II) and those who were either formerly (AI) or are currently (IA) active. Results indicated that only current activity promoted better postural control while former activity was ineffective. Postural control in AA and IA was very similar and much better than in II and AI who, in contrast, displayed similarly deteriorated postural control.

Acute effects of cryotherapy on postural control.

To investigate the acute effects of whole-body cryotherapy (WBC) on postural control, we measured postural sway (COP) in a quiet stance with eyes open in four consecutive 20-second tests: before and 1, 6 and 11min after the WBC. Twenty-four healthy young subjects aged 19.3±0.9 were exposed to WBC (-110°C) for 2min. The time series recorded with a sampling rate of 100Hz was used to evaluate postural performance (COP variability) and strategies (COP frequency and entropy). There were no differences between the pre- and post-WBC values of these measurements in the frontal plane; however, in the sagittal plane postural sway increased immediately after WBC (p<0.05) and remained elevated throughout the experiment. Deteriorated performance brought about lagged changes in postural strategies, including a decrease in frequency and entropy. These changes remained sustained until the end of the experiment. In conclusion, the WBC caused a drop in complexity, adaptability, and automaticity in postural control, which accounted for specific constraints imposed on the postural system due to cooling.