Relationship between static and dynamic balance abilities in Italian professional and youth league soccer players

The effects of six weeks of combined balance and plyometric training on postural control performance in elite badminton players: A pilot randomized, controlled study

Background/Objectives

The athletic performance in badminton players largely depends on the capability of dynamic postural control to quickly restore balance when performing high-paced movements (e.g., frequent single-leg jumps). Our aim was to examine the effects of a novel intervention that combines balance training on an unstable surface and plyometric training on the performance of restoring balance after jumping, as well as related postural control in elite badminton players.

Methods

Sixteen elite male badminton players were randomly allocated to either a combined balance and plyometric training group (CT, n = 8) or a plyometric training group (PT, n = 8). The CT group participated in a six-week training program, which included three training sessions per week. Each session comprised 40 min of plyometric exercises and 20 min of balance training. The PT group underwent plyometric training using the identical protocol as that of the CT group. All participants underwent identical technical training in badminton throughout the duration of the study. At baseline and immediately after the intervention, participants completed a single-leg jumping test. The capacity to restore balance was evaluated using the time to stabilization (TTS) after landing; and the related center of pressure (COP) fluctuations were also recorded. The effect of intervention was examined by two-way repeated-measures of ANOVA.

Results

The primary two-way repeated-measures ANOVA models showed no significant interactions between group and time on either the time to stability in the dominant leg (D-TTS) or the time to stability in the non-dominant leg (N-TTS) (p > 0.70). Significant main effects of time, group, and their interactions on dominant legs of the anterior-posterior displacement difference (D-COPAP) (time: p = 0.001; group: p = 0.001; interaction: p = 0.014), non-dominant legs of the anterior-posterior displacement difference (N-COPAP) (time: p < 0.001; group: p = 0.003; interaction: p = 0.021) and non-dominant legs of the medial-lateral displacement difference (N-COPML) (time: p < 0.001; group: p < 0.001; interaction: p = 0.026), that is, compared to baseline of both groups and post PT, the COP metrics were significantly reduced after CT. Secondarily, within the CT and PT group, after the intervention, the N-TTS (CT: p = 0.001, post: 0.58 ± 0.87; PT: p = 0.03, post: 0.71 ± 0.11) was significantly decreased compared to baseline (CT pre: 0.76 ± 0.16; PT pre: 0.88 ± 0.13).

Conclusion

This pilot study demonstrated that, compared to PT-only, the 6-week CT which combines balance training induced comparable improvements in the capacity to restoring balance after landing from a single-leg jump, and significantly improved the postural control performance as measured by COP metrics.

Things to keep in mind when selecting physical assessments in youth soccer: Correlations between test performances, interlimb asymmetries, and effects of maturation

A range of field-based tests have been proposed for inclusion in physical performance assessment batteries. However, there are obvious time and human resources constraints in applied settings. The knowledge of potential relationships between tests on performance, asymmetries, as well as maturation-induced changes, may help select the most informative and least time-consuming testing battery. The purposes of this study were: (1) to determine correlations in performance between different field-based tests, in interlimb asymmetry between those unilateral tests, and between asymmetry scores and test performances, and (2) to determine the influence of players' maturity status on test performances and asymmetries. A total of 309 male youth soccer players completed a nine-test battery including y-balance test, drop vertical jump, countermovement jump, single leg countermovement jump, standing long jump, single leg hop for distance, Illinois agility test, 10 m sprint, and 20 m sprint. The results revealed moderate-to-very large relationships between jump, sprint, and agility performances (r = 0.43-0.94), but weak-to-moderate correlations between these tests and balance scores (r ≤ 0.38). No relevant relationship (r ≤ 0.32) for asymmetries detected through different unilateral tests was found, nor between asymmetries and performance scores (r < 0.29). While maturity status clearly influenced players' performance, a limited impact on asymmetries was evident. Despite the mentioned relationships, the low shared variance between tests indicates that they should not be used interchangeably, and coaches should select those with the greatest specificity for the sport. Asymmetries do not influence performance, but their prevalence and unchanging nature with maturation can be seen as an opportunity for the identification of highly asymmetrical players and the application of interventions to improve the weaker limb, irrespective of the athlete's stage of development. To this end, the single leg countermovement jump might be viewed as an appropriate test in male youth soccer.

An integrated approach to the assessment of balance and functional mobility in individuals with history of severe traumatic brain injury

Individuals who experienced severe Traumatic Brain Injury (sTBI) are often characterized by relevant motor dysfunctions which are likely to negatively affect activities of daily living and quality of life and often persist for years. However, detailed objective information about their magnitude are scarce. The aim of this study was to quantitatively assess the extent of motor deficits in terms of postural control effectiveness under static and dynamic conditions and to investigate the existence of possible correlations between the results of clinical tests and instrumental measures. Postural sway and functional mobility (i.e., instrumented Timed Up and Go test, iTUG) were objectively measured in 18 individuals with sTBI and 18 healthy controls using a pressure plate and a wearable inertial sensor. Additionally, participants with history of sTBI completed the Rivermead Mobility Index (RMI). One-way ANOVA and Spearman's rank correlation analysis were employed to examine differences between the two groups and determine potential correlations between the instrumental tests and clinical scales. The results show that people with sTBI were characterized by larger sway area and longer iTUG walking sub-phase. Significant correlations were also detected between RMI scores and iTUG total duration, as well as the walking phase. Taken together, these findings suggest that, even years after the initial injury, individuals with sTBI appear characterized by impaired postural control and functional mobility, which appears correlated with the RMI score. The integration of instrumental measures with clinical scales in the routine assessment and treatment of individuals with sTBI would result in more comprehensive, objective, and sensitive evaluations, thus improving precision in treatment planning, enabling ongoing progress monitoring, and highlighting the presence of motor deficits even years after the initial injury. Such integration is of importance for enhancing the long-term quality of life for individuals with sTBI.

Relationship between static and dynamic balance in 4-to-5-year-old preschoolers: a cross-sectional study

BACKGROUND

Balance is crucial for physical development in preschool children. Exploring the relationship between different types of balance can help understand early physical development in children. Currently, research is mostly focused on the relationship between different types of balance in the adult population and lacks exploration of the preschool population. The aim of this study explored the relationship between static and dynamic balance in preschool children aged 4 to 5 years.

METHODS

A total of 128 preschool children between the ages of 4 to 5 years were selected. The following tests were conducted as they wore inertial sensors detecting their centers of mass (COM): T1, standing with eyes open; T2, standing with eyes closed; T3, standing with eyes open on foam; T4, standing with eyes closed on foam; and T5, walking on the balance beam. Static balance was measured by the angular velocity modulus (ω-T1-ω-T4) of the shaking COM, as well as the pitch angle (θ-T1-θ-T4) and roll angle (φ-T1-φ-T4) indicators in T1-T4 testing. Dynamic balance was measured by the time (t) and angular velocity modulus (ω-T5), as well as the pitch angle (θ-T5) and roll angle (φ-T5) indicators in the T5 test. The Pearson product-moment correlation coefficient was used to test the correlation between static and dynamic balance indicators.

RESULTS

There is no correlation between ω-T1-ω-T4 and t (P > 0.05), while ω-T1-ω-T4 and ω-T5 (r = 0.19-0.27, P < 0.05) and ω-T1-ω-T4 and θ-T5, φ-T5 (r = 0.18-0.33, P < 0.05) were weakly correlated. There is no correlation between θ-T1-θ-T4, φ-T1-φ-T4 and t (P > 0.05), while θ-T1-θ-T4, φ-T1-φ-T4, and θ-T5, φ-T5 were weakly correlated (r = 0.01-0.28, P < 0.05).

CONCLUSIONS

The relationship between static and dynamic balance in preschool children aged 4-5 years is weak. Static and dynamic balance in children needs to be intervened separately for the development of children.

Validity and Reliability of Dynamic and Functional Balance Tests in People Aged 19-54: A Systematic Review

Evaluating an impairment in an individual's capacity to maintain, achieve, or restore balance suggests a deficiency in postural control. For effective identification of individuals at risk for falls, balance assessment should exhibit reliability, validity, and ease of use. This systematic review concentrated on dynamic and functional balance assessment methods and their validity in healthy adults aged 19-54. The objective was to clarify the tools that health professionals can utilize to assess balance in this healthy population.

Methods

A systematic literature search conducted in August 2019 yielded nine articles meeting predefined selection criteria. Inclusion criteria required studies featuring healthy adult participants aged 19-54, published in English, and focusing on dynamic and functional balance testing. Exclusion criteria excluded studies involving participants with chronic diseases or musculoskeletal disorders, systematic reviews, professional athletes, and those lacking specific participant age information. The quality of the studies was evaluated using a modified PEDro scale.

Results

This review analyzed ten distinct postural balance tests. The Star Excursion Balance Test and Y-Balance Test exhibited moderate to high reliability, establishing them as dependable measures of dynamic balance. The Nintendo Wii Balance Board, Clever Balance Board, and Posturomed device also displayed excellent reliability for assessing dynamic postural balance. Comparing one-arm and two-arm functional reach tests, the one-arm reach test emerged as a more suitable option for evaluating dynamic balance among young adults. Moreover, an investigation comparing three dynamic balance tests (one-leg jump landing, Posturomed device, and stimulated forward fall) revealed a low correlation among these tests, indicating a measurement of different balance constructs.

Discussion

In conclusion, the Y-Balance Test stands out as the most practical dynamic balance assessment for clinical use, characterized by a standardized protocol, good repeatability, affordability, and ease of application. The Nintendo Wii Balance Board also presents itself as a cost-effective and reliable tool for dynamic balance evaluation in clinical settings. It is crucial to recognize that these tests appraise discrete postural skills, preventing direct comparisons between test outcomes. This review equips healthcare professionals with valuable insights into optimal balance assessment methods for the healthy, 19 to 54 aged population.

Levels of evidence

Level 3.

The effects of inspiratory muscle training on balance and functional mobility: a systematic review

INTRODUCTION

Inspiratory muscle training (IMT) has been widely used in both healthy and diseased populations especially in older adults, and its effects have been proven not only on inspiratory muscle strength but also on dyspnea, exercise capacity, quality of life, and other health parameters.

AIM

This study aims to review the effects of IMT on balance and functional ability of healthy and diseased populations.

METHODS

A systematic literature search was conducted on MEDLINE, EMBASE, AMED, and Cochrane Central Register of Controlled Trials (CENTRAL). Randomized control trials having participants > 18 years of age and having balance and functional mobility as primary or secondary outcomes were included. Two independent reviewers screened studies against the eligibility criteria, extracted the data, and assessed the quality of evidence. The protocol was prospectively registered on PROSPERO: CRD42021261652.

RESULTS

Ten studies were included in the review out of which eight had balance and six had functional mobility as an outcome measure. There was a significant improvement in balance of the participants after treatment with IMT, however the effect on functional mobility was inconclusive.

CONCLUSION

The review provided evidence of improvement in balance and functional mobility following inspiratory muscle training in both healthy and diseased adults. Future studies should be conducted to determine the optimal protocol and dosage of treatment.

The relationship of three-dimensional foot morphology to clinical assessments and postural stability in adolescent male footballers

BACKGROUND

Foot morphology is associated with altered loading of the ankle-foot complex in adolescent footballers, predisposing to pain and injury. However, usual singular plane clinical assessments do not accurately capture the 3D nature of foot morphology. A new approach is 3D laser scanning, with statistical shape model techniques creating individual-to-group comparison. However, no research exists on the adolescent, football-playing foot. Furthermore, a link between 3D foot morphology, and usual clinical and performance measures would be beneficial for practical implementation.

METHODS

Four hundred forty-seven 3D foot scans from 224 elite male footballers (U12-U19) in bilateral stance were collected and further processed with statistical shape model techniques. Weighted shape parameters for individual principal components (Modes) were extracted for each foot. Centre of pressure displacement expressed as total travelled way in millimetres was calculated for bilateral and unilateral postural stability measures. Clinical assessments (Clarke's Angle, Resting Calcaneal Stance Position) were calculated on the 3D foot scans. Differences in weighted shape parameters, postural stability measures, and clinical assessments between age groups were determined by ANOVA. Correlations determined the relationship of Modes and clinical assessments to postural stability measures. Linear regression established if clinical assessments predicted the mode describing foot arch variation.

RESULTS

Age groups significantly differed for Mode 1 (foot length), Mode 2 (foot arch), and Mode 5 (tibial rotation relative to the foot) (p < 0.05). Resting Calcaneal Stance Position (r = .663) and Clarke's Angle (r = -.445) were low-to-moderately correlated to Mode 2 (both p < 0.001), and linear regression found they were both significant predictors of Mode 2, though only moderately (R2 = .522). There were low correlations of foot morphology to the postural stability tests.

CONCLUSION

This is the first study to describe the 3D foot morphology of male football-playing adolescents, and discover the differences between age groups. This will improve understanding and assessment of foot morphology in male adolescents because 2D techniques, as discovered in this study, do not strongly correlate to, nor predict, the 3D foot arch. Foot morphology was only lowly correlated to postural stability, thus a multifaceted program would be required for improvements.

Sport dependent effects on the sensory control of balance during upright posture: a comparison between professional horseback riders, judokas and non-athletes

Introduction

Compared to judokas (JU) and non-athletes (NA), horseback riders (HR) may develop specific changes in their sensory control of balance.

Methods

Thirty-four international-level JU, twenty-seven international-level HR and twenty-one NA participated. Participants stood upright on a plateform (static condition) or on a seesaw device with an instability along the mediolateral (ML) or the anteroposterior (AP) direction (dynamic conditions). These conditions were carried out with eyes opened (EO) or closed (EC), and with (wF) or without a foam (nF). Experimental variables included conventional (linear), non-linear center-of-pressure (COP) parameters, Romberg Quotient (RQ) and Plantar Quotient (PQ).

Results

Group effects. COP Surface (COPS) and standard deviation of COP along AP (SDY) were lower in HR than in JU in Static. SD Y was lower in HR than in JU in Dynamic AP. COP velocity (COPV) was lower in both HR and JU than in NA in Static and Dynamic. Sample entropy along AP and ML (SampEnY and SampEnX) were higher in HR than in JU in Static. SampEnY was higher in HR than in JU in Dynamic ML. Sensory effects. In EC, COPV was lower in JU than in NA in Dynamic AP, and lower in JU than in both HR and NA in Dynamic ML. In EO, COPV was lower in both JU and HR than in NA in Dynamic ML. RQ applied to COPS was lower in JU than in both HR and NA in Dynamic AP, and lower in JU than in HR in Dynamic ML. RQ applied to COPV was lower in JU than in both HR and NA in Static and Dynamic. PQ applied to COPS was higher in JU than in both HR and NA in Dynamic ML.

Conclusion

Results showed that the effects of sport expertise on postural control could only be revealed with specific COP variables and were directionally oriented and sport-dependant. HR seem to rely more on vision than JU, thus revealing that the contribution of the sensory inputs to balance control is also sport-dependent. Results open up new knowledge on the specificity of sport practice on multisensory balance information during upright posture.

One-Leg Stance Postural Sway Is Not Benefited by Bicycle Motocross Practice in Elite Riders

Balance has been positioned as an important performance skill in sport. Differences in postural control have been found between levels of expertise. However, this statement remains unanswered in some cyclic sports. This work aimed to describe the one-leg balance performance of a sample of elite BMX riders-racing and freestyle-compared to a control group formed by recreational athletes. The center of pressure (COP) of nineteen international BMX riders (freestyle, n = 7; racing, n = 12) and twenty physically active adults was analyzed in a 30-s one-leg stance test on both legs. COP dispersion and velocity variables were analyzed. Non-linear dynamics of postural sway were evaluated through Fuzzy Entropy and Detrended Fluctuation Analysis. BMX athletes did not show differences between legs in any of the variables. The control group did show differences between the dominant and non-dominant leg in the magnitude of variability of the COP in the mediolateral axis. Group comparison revealed non-significant differences. International BMX athletes did not show better balance parameters than the control group in a one-leg stance balance task. The adaptations derived from BMX practice do not have a significant impact in one-leg stance balance performance.

The Function of the Proprioceptive, Vestibular and Visual Systems Following Fatigue in Individuals With and Without Chronic Ankle Instability

To maintain postural balance, the proprioceptive, vestibular, and visual systems continuously provide body position and movement data to the central nervous system. In this study, our main aim was to examine, for the first time, the influence of anaerobically or aerobically induced fatigue on these separate functions in persons with and without chronic ankle instability (CAI). We obtained assessments pre- and post-fatigue protocols from 60 physical education students (Mage = 24.3, SD = 3.4) Twenty-seven students had CAI, and 33 students did not have CAI). To measure proprioception, we used the AMEDA device; for vision, we used near point of convergence (NPC); and, for vestibular function, we used subjective visual vertical (SVV). We found a pre-post proprioception (AMEDA) effect in the aerobic group (p < .001), and a visual (NPC) effect in both anaerobic and aerobic participant groups (both p < .001). There were no visual system (NPC) fatigue effect differences among aerobic or anerobic participants who had or did not have CAI (p = .047); there was a significant aerobic fatigue effect on proprioception (AMEDA) (p = .010) that favored participants without CAI. There was a significant interaction effect between time of testing and CAI for visual (NPC) (p = .003) in the aerobic group only. In both the anaerobic and aerobic groups, post-fatigue vestibular function (AMEDA) was significantly lower for those with than those without CAI (anaerobic: p = .030; and aerobic: p =.016). Thus, post-fatigue, participants with CAI showed worse proprioceptive, visual, and vestibular function than those without CAI. Future investigators should further examine each movement sense system in individuals with CAI.

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.

Isokinetic leg muscle strength relationship to dynamic balance reflects gymnast-specific differences in adolescent females

Balance, together with other motor qualities, plays an important role in the successful execution of specific gymnastic skills. However, it is also not clear whether different demands on dynamic balance and power produced by lower limb can be observed in sport-specific differences among gymnasts of various modalities. The question also is as to what extent isokinetic leg muscle strength contributes to anterior and posterior postural stability in gymnasts. Therefore, the aim of the study was i) to compare variables of dynamic balance and isokinetic leg muscle strength in rhythmic, artistic, and aerobic gymnasts, and ii) to investigate the relationship of reach distances in anterior, posteromedial, and posterolateral directions, as well as the composite score in the Y-balance test with an isokinetic muscle strength during knee extension and flexion at different velocities in female gymnasts of various disciplines. Altogether seven aerobic, five artistic, and six rhythmic gymnasts performed the Y-balance test and isokinetic leg muscle strength test at 60°/s, 180°/s, and 300°/s. Results showed significant between-group differences in the composite score in the Y-balance test of the dominant (F = 3.536, p = .041) and non-dominant symmetry (F = 4.804, p = .015). Similarly, average power produced during knee extension and knee flexion at 60°/s, 180°/s and 300°/s differed significantly among these groups (all at p˂0.05). In addition, there was a significant relationship between the composite score of the dominant limb symmetry and isokinetic dominant limb extension strength at 60°/s (r = .54), 180°/s (r = .87), and 300°/s (r = .84) in aerobic gymnasts. The composite score of the dominant limb symmetry was also associated with isokinetic dominant limb extension strength, albeit only at 60°/s in both artistic (r = .60) and rhythmic gymnasts (r = .55). Such between-group differences may be ascribed to their different demands on maintenance of balance under dynamic conditions and leg muscle power within their sport specializations. Taking into account significant association between the dominant limb symmetry and isokinetic dominant limb extension strength, it may be concluded that both muscle strength and fast speeds contribute to dynamic balance in adolescent gymnasts.

Associations of Masticatory Muscles Asymmetry and Oral Health with Postural Control and Leg Injuries of Elite Junior Soccer Players

The influence of asymmetry between masticatory muscles on postural control is still under debate and only few studies examined the impact of oral health on injury risk. The present study investigated the relationships between masticatory muscles asymmetry, oral health, postural control and the prevalence of (non-contact or traumatic) leg injuries in a sample of 144 male elite junior soccer players. sEMG of the masseter and temporal muscles was performed during maximum teeth clenching, postural control was tested by measuring sway velocity during the unipedal stance with eyes closed, while oral health and the number of leg injuries were assessed using a questionnaire. The time-1 assessment was repeated in a subgroup of 69 players after one year. Pearson and partial correlation coefficients and adjusted odds ratios (OR) were used to assess associations. Asymmetry between the masseter and temporalis muscles (AMTM, quantified as anteroposterior coefficient, APC) was associated with higher sway velocity on the dominant leg (using time-1 data partial r = -0.24, p = 0.004, using longitudinal data partial r = -0.40, p = 0.005). Higher prevalence of two or more leg injuries throughout a competitive season was associated with poor oral health (adjusted OR (95%CI) using time-1 data = 2.14 (1.02–4.46), using longitudinal data = 4.47 (1.25–15.96)). These results indicate that AMTM has a negative influence on the sway velocity of the dominant leg only, possibly because frequent balancing exercises on the non-dominant leg may counteract negative influences of AMTM. The association of oral health with leg injuries underlines the need for oral health promotion and monitoring strategies in sports.

Benefits of the Cybathlon 2020 experience for a prosthetic hand user: a case study on the Hannes system

BACKGROUND

Cybathlon championship aims at promoting the development of prosthetic and assistive devices capable to meet users' needs. This paper describes and analyses possible exploitation outcomes of our team's (REHAB TECH) experience into the Powered Arm Prosthesis Race of the Cybathlon 2020 Global Edition, with the novel prosthetic system Hannes. In detail, we present our analysis on a concurrent evaluation conducted to verify if the Cybathlon training and competition positively influenced pilot's performance and human-technology integration with Hannes, with respect to a non-runner Hannes user.

METHODS

Two transradial amputees were recruited as pilots (Pilot 1 and Pilot 2) for the Cybathlon competition and were given the polyarticulated myoelectric prosthetic hand Hannes. Due to COVID-19 emergency, only Pilot 1 was trained for the race. However, both pilots kept Hannes for Home Use for seven weeks. Before this period, they both participated to the evaluation of functionality, embodiment, and user experience (UX) related to Hannes, which they repeated at the end of the Home Use and right after the competition. We analysed Pilot 1's training and race outcomes, as well as changes in the concurrent evaluation, and compared these results with Pilot 2's ones.

RESULTS

The Cybathlon training gradually improved Pilot 1's performances, leading to the sixth place with a single error in task 5. In the parallel evaluation, both pilots had an overall improvement over time, whereas Pilot 2 experienced a deterioration of embodiment. In detail, Pilot 1, who followed the training and raced the Cybathlon, improved in greater way.

CONCLUSION

Hannes demonstrated to be a valuable competitor and to perform grasps with human-like behaviors. The higher improvements of Pilot 1, who actively participated in the Cybathlon, in terms of functionality, embodiment and UX, may depend on his training and engagement in the effort of achieving a successful user-prosthesis interaction during the competition. Tasks based on Cybathlon's ones could improve the training phase of a prosthetic user, stimulating dexterity, prosthetic integration, and user perception towards the prosthesis. Likewise, timed races or competitions could facilitate and accelerate the learning phase, improving the efficiency and efficacy of the process.

Measuring Recovery and Understanding Long-Term Deficits in Balance, Ankle Mobility and Hip Strength in People after an Open Reduction and Internal Fixation of Bimalleolar Fracture and Their Impact on Functionality: A 12-Month Longitudinal Study

To analyze how balance and other physical capacities evolved after surgery in patients with a bimalleolar fracture and how these capacities and clinical variables (immobilization or unloading time) contribute to restoring patients’ functionality, 22 patients and 10 healthy people (HC) were assessed for static and dynamic balance (Y-Balance test, YBT), dorsiflexion ankle mobility (ADFROM) and hip strength at 6 and 12 months after surgery. Patients’ functional status was assessed through the Olerud Molander Ankle Score (OMAS) and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Twenty-one patients with ankle fractures who completed the study showed a worse static and dynamic balance at 6 months. The YBT in the anterior direction (YBTA) revealed balance deficits in the operated limb at 12 months compared to the non-operated limb (−5.6%) and the HC (−6.7%). They also showed a decreased ADFROM compared to the non-operated limb (−7.4°) and the HC (−11°). In addition, medium-term (6 months) deficits in abductor strength hip but no hip strength deficits were found at 12 months after surgery. Relative weight analyses showed that ADFROM and hip strength explained 35–63% of the YBTA variance and AOFAS/OMAS scores. Balance, hip strength and ADFROM seem to be reliable indexes for assessing the functional status of these patients. These results could help to understand the relationship between these physical capacities and the patients’ perceived functional status.

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.

The relationships between knee extensors/ flexors strength and balance control in elite male soccer players

Background

Strength and balance are important factors for soccer players to be successful. This study’s aim was to determine the relationship between lower-limb muscle strength and balance control in elite male soccer players (n = 77).

Methods

Concentric isokinetic strength (peak torque of quadriceps (PT-Q) and hamstrings (PT-H), hamstrings/quadriceps (H/Q) ratio) was measured for the dominant and non-dominant leg at angular velocities of 60°s⁻¹and 240°s⁻¹, as well as the total work for extensors (TW-Q) and flexors (TW-H) for both legs (at an angular velocity of 240°s⁻¹only). Balance score (BAL score) was used for unilateral assessment of balance control using a Delos Postural System Test measurement tool. Hierarchical multiple regression analyses were performed to predict balance control using isokinetic knee strength performance for dominant and non-dominant legs.

Results

Final modelling included peak torque of hamstrings at 240°s⁻¹ and peak torque of the quadriceps at 240°s⁻¹ for the non-dominant leg (R² = 19.6%; p ≤ 0.001) and only peak hamstring torque at 240°s⁻¹ for the dominant leg (R² = 11.3%; p = 0.003) as significant predictors of balance score.

Conclusion

Findings indicate that balance control is widely influenced by peak hamstring torque and peak quadriceps torque at high angular velocity particularly in the non-dominant leg i.e., the supporting leg in soccer players.

Identification of Neuromuscular Performance Parameters as Risk Factors of Non-contact Injuries in Male Elite Youth Soccer Players: A Preliminary Study on 62 Players With 25 Non-contact Injuries

Introduction: Elite youth soccer players suffer increasing numbers of injuries owing to constantly increasing physical demands. Deficits in neuromuscular performance may increase the risk of injury. Injury risk factors need to be identified and practical cut-off scores defined. Therefore, the purpose of the study was to assess neuromuscular performance parameters within a laboratory-based injury risk screening, to investigate their association with the risk of non-contact lower extremity injuries in elite youth soccer players, and to provide practice-relevant cut-off scores. Methods: Sixty-two elite youth soccer players (age: 17.2 ± 1.1 years) performed unilateral postural control exercises in different conditions, isokinetic tests of concentric and eccentric knee extension and knee flexion (60°/s), isometric tests of hip adduction and abduction, and isometric tests of trunk flexion, extension, lateral flexion and transversal rotation during the preseason period. Non-contact lower extremities injuries were documented throughout 10 months. Risk profiling was assessed using a multivariate approach utilizing a Decision Tree model [Classification and Regression Tree (CART) method]. Results: Twenty-five non-contact injuries were registered. The Decision Tree model selected the COP sway, the peak torque for knee flexion concentric, the functional knee ratio and the path of the platform in that hierarchical order as important neuromuscular performance parameters to discriminate between injured and non-injured players. The classification showed a sensitivity of 0.73 and a specificity of 0.91. The relative risk was calculated at 4.2, meaning that the risk of suffering an injury is four times greater for a player, who has been classified as injured by the Decision Tree model. Conclusion: Measuring static postural control, postural control under unstable condition and the strength of the thigh seem to enable a good indication of injury risk in elite youth soccer players. However, this finding has to be taken with caution due to a small number of injury cases. Nonetheless, these preliminary results may have practical implications for future directions in injury risk screening and in planning and developing customized training programs to counteract intrinsic injury risk factors in elite youth soccer players.

Utility of the anterior reach Y-BALANCE test as an injury risk screening tool in elite male youth soccer players

OBJECTIVES

Examine growth and maturation trends in dynamic balance using the anterior reach Y-Balance test, and its utility as an injury risk screening tool.

DESIGN

Cross sectional and prospective cohort.

SETTING

Elite male youth soccer players.

PARTICIPANTS

346 players grouped as pre, circa or post peak height velocity (PHV).

MAIN OUTCOME MEASURES

Pre-season anterior reach absolute and relative Y-Balance test scores and seasonal prospective lower extremity injury monitoring.

RESULTS

Absolute reach distances were greatest post-PHV (p < 0.05). Relative to leg length, pre-PHV achieved the highest scores and increased between-limb differences. Significant associations between injury and anterior reach scores were present in pre (OR: 0.94, CI: 0.91-0.98, p < 0.05) and circa-PHV (OR: 1.05, 95% CI: 1.05-1.10, p < 0.05). Increased age (OR: 1.49, 95% CI: 1.04-2.13, p < 0.05) and height (OR: 1.06, 95% CI: 0.99-1.13, p = 0.82) were risk factors post-PHV. No differences in injury occurrence were shown between players with absolute reach difference >4 cm in any group.

CONCLUSIONS

Anterior reach scores increased injury risk, but associations were small and inconsistent. The Y-Balance should be used with caution as a screening tool in this cohort.

Single leg hopping in children with fetal alcohol spectrum disorder: Dynamic postural stability and kinematics

BACKGROUND

This study compared dynamic postural stability (DPS) and lower limb kinematics during single leg hopping (SLH) performed by typically-developed children from urban and rural settings and children with Fetal Alcohol Spectrum Disorder (FASD) from a rural setting.

METHODS

Typically-developed nine-year-old children from an urban (n = 27) and rural setting (n = 14) (controls), and nine-year-old children with FASD from a rural setting (n = 14) (cases) performed SLH and landing on a pressure mat. Motion analysis systems described 1) Spatiotemporal and centre of pressure parameters (COP) and lower limb sagittal plane kinematics. Descriptive results are presented in median and ranges and differences between groups were determined by Kruskal-Wallis and Mann-Whitney U statistical tests. The level of significance was p < 0.05.

RESULTS

During hopping, the urban controls had longer stance and swing times (p < 0.001) than the rural groups. The urban controls remained in greater hip flexion compared to the case group (p = 0.02). The urban controls landed in more plantarflexion at initial foot contact (IFC) than the cases (p < 0.001) and the rural controls (p = 0.03). The rural groups landed with greater knee extension at IFC than the urban controls (cases p = 0.04; rural controls p < 0.001). During the landing motion, the urban controls moved into more hip flexion compared to the cases (p = 0.015) and the rural controls (p = 0.026). The cases displayed greater COP anteroposterior values during landing compared to both control groups, but the case group displayed the fastest time to stability.

CONCLUSION

The different hopping strategies observed provides an indication of the movement capabilities of these groups.

Bilateral Asymmetries Assessment in Elite and Sub-Elite Male Futsal Players

This study aimed to investigate morphological, functional, and neuromuscular asymmetries on futsal players’ lower limbs at different competitive levels. Sixteen male elite futsal players from the Spanish National Futsal League and thirteen male sub-elite futsal players from the third division participated in this study. Morphological asymmetry was assessed through bioelectrical impedance (fat-mass (g and %) and lean-mass (g)). Functional asymmetry was assessed by means of a 20-s static unipedal balance test. Finally, neuromuscular asymmetry was assessed using tensiomiography tests on both the rectus femoris (RF) and biceps femoris (BF) of each participant. The three tests conducted did not reveal significant bilateral asymmetries in elite players. On the other hand, sub-elite players showed significant bilateral asymmetry in fat-mass percentage between dominant and non-dominant limbs (+6%; CI95%: 1 to 11; ES: 0.88; p = 0.019). They also showed higher bilateral asymmetry in the delay time of the RF (+13%; CI95%: 7 to 21; ES: 1.3; p < 0.05). However, the static unipedal balance test (p > 0.05) did not evidence asymmetries regardless of the level of the participants. Elite futsal players do not develop bilateral asymmetries in lower limbs in the studied parameters. On the contrary, sub-elite players are likely to develop morphological and neuromuscular asymmetries between their dominant leg and non-dominant leg.

Immediate Effects of Ankle-Foot Orthosis Using Wire on Static Balance of Patients with Stroke with Foot Drop: A Cross-Over Study

The aim of this study was to investigate the immediate static balance effects of bare foot, UD-Flex ankle–foot orthosis (AFO), and AFO using wire (AOW) of patients with stroke with foot drop. Seventeen patients with stroke with foot drop (8 men and 9 women) were randomized to three conditions (bare foot, UD-Flex AFO, or AOW made with a flexible material). Static balance was assessed using the Zebris (Zebris GmbH, Isny, Germany) and BioRescue (RM Ingenierie, Rodez, France) pressure platform by a single examiner, who did not design the AOW. The order of testing with the equipment was random. The center of pressure path length (mm) measured using Zebris showed significant differences among the three conditions (bare foot, 484.47 ± 208.42; UD-Flex AFO, 414.59 ± 144.43; AOW, 318.29 ± 157.60) (p < 0.05). The bare-foot condition was not significantly different from the UD-Flex AFO condition (p > 0.05), but was significantly different from the AOW condition (p < 0.05). The surface area ellipse (mm²) measured using BioRescue showed significant differences among the three conditions (bare foot, 241.35 ± 153.76; UD-Flex AFO, 277.41 ± 381.83; AOW, 68.06 ± 48.98) (p < 0.05). The bare-foot condition was not significantly different from the UD-Flex AFO condition (p > 0.05), but the AOW condition was significantly different from the bare-foot (p < 0.05) and from the UD-Flex AFO conditions (p < 0.05). We suggest using the AOW made of flexible materials and wire instead of the UD-Flex AFO to improve immediate static balance of patients with stroke with foot drop after stroke. Further studies on the effects of dynamic balance and gait are required.

Preseason Dynamic Balance Performance in Healthy Elite Male Soccer Players

Lower limb musculoskeletal injuries in sports are linked with balance abnormalities and altered postural control. Dynamic balance screening should be performed in order to identify athletes at risk. The purpose of the study was to evaluate the preseason dynamic balance performance and side-to-side asymmetry of healthy elite male soccer players, using modified Star Excursion Balance Test (mSEBT). Seventy-three elite soccer players (23.8 ± 5.4 years) were evaluated using the mSEBT. Normalized reach distances, side-to-side asymmetries, and composite scores were determined. The composite scores were 93.33% ± 8.99% for dominant leg and 93.36% ± 9.23% for nondominant leg. No significant differences were found between dominant and nondominant limb in any direction. The mSEBT is an easy-to-use tool to measure the dynamic balance performance in elite athletes. It can be applied successfully during preseason physical examinations. Future studies are needed to establish predictive cutoff points in order to increase mSEBT use in screening soccer players for dynamic balance abnormalities and identify those at risk for noncontact lower limb injuries.

Effects of Soccer Training on Body Balance in Young Female Athletes Assessed Using Computerized Dynamic Posturography

The aim of this study was to determine the effect of regular soccer training on the balance system for young women. Computerized dynamic posturography of female footballers (n = 25) and control group (n = 50) was assessed during three tests: Sensory Organization Test, Motor Control Test, and Adaptation Test. Statistically significant differences between the groups was found in Composite Equilibrium Score with higher values, indicating better postural stability, for footballers. Regular trainees also showed better usefulness of vestibular system while maintaining balance. Weight symmetry of the lower limbs during Motor Control Test also showed statistically significant differences between the groups. This study shows that female footballers have better postural stability than their inactive peers and that regular workouts may improve the balance system.

Single-Leg Balance Performance in Sub-Elite Young Soccer Players and Swimmers as a Function of Age and Sports Experience

The present study investigated if accumulated, advanced, regular soccer practice (balance-demanding exercise) compared to regular swim practice (non-balance–demanding exercise) induces a more pronounced functional specialization in postural control. Therefore, single-leg balance performance in sub-elite young soccer players (under 13 [U13]: n = 16; U15: n = 18; U19: n = 15), and sub-elite young swimmers (U13: n = 7; U15: n = 4; U19: n = 5) was tested in different balance task conditions (i.e., static and dynamic balance on firm and foam surface). All athletes practiced 3–10 times per week. Single-leg balance of the dominant and non-dominant leg was measured using a force plate. The standard deviation of the center of pressure displacements in anterior-posterior and medio-lateral directions were used as dependent variables. Irrespective of age groups and type of sport, the results failed to indicate significant leg differences in single-leg balance performance. The soccer players showed significant better single-leg balance performance in anterior-posterior direction in the dynamic balance test on the firm and foam surface compared to the swimmers. Functional specialization was accompanied by the type of sport but not by accumulated practice.

The assessment of single-leg drop jump landing performance by means of ground reaction forces: A methodological study

BACKGROUND

Time to stabilization (TTS) and dynamic postural stability index (DPSI) are outcome measures based on ground reaction force (GRF) that are often used to quantify dynamic postural stability performance following a drop jump landing. However, their interrelations, as well as the overlap with other dynamic measures and static single-leg postural sway, are unknown.

RESEARCH QUESTION

What is the relation among TTS and DPSI, how are they related to impact forces and dynamic postural sway, and how are all these dynamic measures related to static postural sway?

METHODS

A sample of 190 elite soccer players performed four single-leg drop jump landings. TTS in three directions (vertical, anteroposterior, and mediolateral), and DPSI were intercorrelated (Pearson's r), and related to impact forces and the magnitude of horizontal GRF (HGRF) from 0.4 to 2.4 s and 3.0-5.0 s following landing. All these measures were also correlated to HGRF in the static phase (i.e., 5.3-11.7 s).

RESULTS

The TTS measures were significantly interrelated (r = 0.28-0.53), but were not significantly correlated to DPSI. TTS was more strongly related to HGRF0.4-2.4 s (r = 0.54-0.75) than to HGRF3.0-5.0 s (r = 0.32-0.54) or impact forces (r=-0.28-0.36). Vertical TTS was not significantly related to impact forces. The DPSI was most strongly related to the vertical peak force (r = 0.85), and was not significantly related to HGRF of the dynamic periods. Furthermore, TTS and dynamic HGRF were significantly related to static HGRF (r = 0.34-0.80), while DPSI and impact forces were not.

SIGNIFICANCE

TTS and DPSI do not represent similar aspects of single-leg jump landing performance. The ability to stabilize posture seems to be represented by TTS and dynamic postural sway, which partly overlaps with static postural sway. In contrast, DPSI and vertical peak force mainly reflect the kinetic energy absorption during impact. The findings can help to better understand the meaning of the outcome measures, and to translate results to rehabilitation or prevention programs.

A Review of Field-Based Assessments of Neuromuscular Control and Their Utility in Male Youth Soccer Players

Read, PJ, Oliver, JL, Croix, MS, Myer, GD, and Lloyd, RS. A review of field-based assessments of neuromuscular control and their utility in male youth soccer players. J Strength Cond Res 33(1): 283-299, 2019-Lower-extremity injuries in male youth soccer are common and equate to a substantial time loss from training and competitions during the course of a season. Extended periods of absence will impact player involvement in skill and physical development activities, as well as participation in competitive match play. Neuromuscular risk factors for lower-extremity injury in male youth soccer players can be categorized into quadriceps dominance, leg dominance, ligament dominance, trunk dominance, and reduced dynamic stability. Valid screening methods to identify risk factors that are practically viable are needed for youth athletes who may be at a greater risk of injury in soccer. Although field-based tests of neuromuscular control provide a reliable option for the assessment of injury risk in adults and females, less data are available in male youth soccer players, and further research is required to examine their ability to predict injury risk. This article provides a review of the current literature pertaining to field-based screening tests and critically appraises their suitability for use with male youth soccer players. Currently, the only method that has been validated in male youth soccer players is the landing error scoring system. Asymmetrical anterior reach measured during the Y-Balance test may also be considered because of its strong predictive ability in male youth basketball players; however, further research is required to fully support its use with soccer players.

Influence of biological maturity on static and dynamic postural control among male youth soccer players

BACKGROUND

Peak height velocity has been reported to be associated with the phenomenon of adolescent awkwardness, a temporary disruption in motor skills, and an increase in injuries in some adolescents. To date, it is not entirely clear which motor abilities are deficient during the phase of rapid growth.

RESEARCH QUESTION

We hypothesized that static as well as dynamic postural control is influenced by biological maturation.

METHODS

The study was conducted in a prospective, cross-sectional design. Maturity offset, a somatic indicator for biological maturation was captured for n = 99 male soccer players (13.7 ± 0.5 years). Static and dynamic balance were assessed by the Balance Error Scoring System (BESS) and the Y-Balance Test (YBT), respectively. Influences of biological maturation on balance performances have been analyzed by linear mixed models.

RESULTS

Linear mixed model analyses revealed that biological maturation is significantly associated with the total BESS score (p = 0.022, b = 2.195) as well as the YBT anterior (right leg: p = 0.023, b = -0.022; left leg: p = 0.015, b = -0.024) and posteromedial reach directions (left leg: p = 0.02, b = -0.029). No significant associations were found for the other YBT distances.

SIGNIFICANCE

Based on our results, maturation seems to have a considerable influence on postural control. It might be that deficits in balance performance contribute to the phenomenon of adolescent awkwardness and therefore lead to an increased injury risk during the adolescent growth spurt. To possibly prevent injuries in youth soccer, biological maturation should be taken into consideration in youth sport coaching.

Performance on a Single-Legged Drop-Jump Landing Test Is Related to Increased Risk of Lateral Ankle Sprains Among Male Elite Soccer Players: A 3-Year Prospective Cohort Study

BACKGROUND

Soccer has a high injury rate, with lateral ankle sprains being a common injury. Therefore, an approach to prevent or at least reduce the occurrence is warranted. Injury prevention can be improved by identifying specific risk factors and individuals at risk.

PURPOSE

To assess drop-jump landing performance as a potential predictor of lateral ankle sprain within 3-year follow-up.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Single-legged drop-jump landing tests were performed by 190 elite soccer players. Based on ground-reaction forces, 6 outcome measures were calculated that aim to reflect the impact and stabilization phase. Lateral ankle sprains were registered during up to 3 years of follow-up. Following a z score correction for age, a multivariate regression analysis was performed.

RESULTS

During follow-up, 45 players (23.7%) suffered a primary lateral ankle sprain. Of those, 34 were regarded as severe (absence >7 days). Performance was related to increased risk of ankle sprain ( P = .005 for all sprains and P = .001 for severe sprains). Low mediolateral stability for the first 0.4 seconds after landing (a larger value indicates more force exerted in the mediolateral direction, resulting in rapid lateral stabilization) and high horizontal ground-reaction force between 3.0 and 5.0 seconds (a smaller value indicates less sway in the stabilization phase) were identified as risk factors. A player that scored 2 SD below average for both risk factors had a 4.4-times-higher chance of sustaining an ankle sprain than a player who scored average.

CONCLUSION

The current study showed that following a single-legged drop-jump landing, mediolateral force over 0 to 0.4 seconds and/or mean resultant horizontal ground-reaction force over 3 to 5 seconds has predictive value with regard to the occurrence of an ankle sprain among male elite soccer players within 3 years.

Effects of sport on static balance in athletes with visual impairments

BACKGROUND

Proper balance is crucial for postural control and physical activity performance. Issues related to balance as well as effects of various factors on balance are in the center of attention of specialists in a number of fields including sport. Research results show that every sports discipline demands different motor preparation (including balance) and persons with visual impairments exhibit worse balance compared to their sighted counterparts. Therefore, this study sought to assess static balance in athletes with visual impairments with reference to the type of sport they did, the length of their training experience, training loads and dysfunction level.

METHODS

The study involved 57 men (shooters, tandem cyclists, football and goalball players) with visual impairments. AMTI stabilographic platform was used to assess static balance. The study participants performed the following tests: standing on both feet with eyes open and closed and single-leg stance with eyes open and closed.

RESULTS

Balance in tests performed while standing on both feet did not differentiate athletes in terms of the sport they did. Static balance of athletes with visual impairments significantly differs in the single leg stance. Better balance was observed in tests with eyes open. Taking into consideration sports disciplines practiced by the athletes, significant differences in balance in single left leg tests with eyes open and closed were observed. Athletes training more than five hours per week manifested better balance compared to those who practiced less than five hours per week.

CONCLUSIONS

The findings indicate that athletes performing particular sports may use strategies of maintaining balance that result from the structure of these sports. The lack of differences in balance among athletes with different degrees of dysfunction may indicate their high fitness levels and show how balance is affected by physical activity performance. Results of the analysis of balance with regard to the length of training experience may suggest that it is not this factor but rather the quality of training that may exert an influence on this ability.

Dynamic postural stability, is associated with competitive level, in youth league soccer players

OBJECTIVES

To assess the effect of competitive level on dynamic postural stability in young elite and sub-elite soccer players.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Fifty-four male soccer players of Under 16 and Under 17 categories (mean age 15.9 ± 0.6), divided into two groups who regularly compete at national (n = 28) and regional (n = 26) levels.

MAIN OUTCOME MEASURES

Dynamic Postural Stability Index (DPSI) and vertical Time to Stabilization (vTTS) for a forward-jump landing. Static postural sway was calculated on the basis of center-of-pressure trajectories for a 20 s one-legged stance.

RESULTS

Players at national level exhibit better dynamic postural control than those at regional level, as indicated by the significantly lower DPSI (0.327 vs. 0.373, p < 0.001) and vTTS (0.887 vs. 1.158 s, p = 0.003). In contrast, no differences between groups were found in any of the postural sway parameters for the static test.

CONCLUSIONS

Young soccer players at national level are characterized by better balance performance in terms of faster and more efficient stabilization after a forward jump, while one-leg static standing tests appear not challenging enough to reveal differences in balance abilities associated with the combination of superior technical and physical features.

Evidence of balance training-induced improvement in soccer-specific skills in U11 soccer players

The present study aimed to determine the role of balance training improving technical soccer skills in young players. Two U11 soccer teams were randomly assigned one to either balance training (BT; n = 22) or control group (Ctrl; n = 21). At the end of their habitual soccer training (identical in BT and Ctrl), BT underwent additional balance training for 12 weeks (3 sessions/week, 20 minutes per session), while Ctrl had a 20-minute scrimmage. Before and after the intervention, BT and Ctrl underwent two soccer-specific tests (Loughborough Soccer Passing, LSPT, and Shooting, LSST, Tests), and bipedal and unipedal balance evaluations. After intervention, both groups decreased the trials time and improved passing accuracy, with larger improvements in BT than Ctrl (LSPT penalty time [CI_95% ]: -2.20 seconds [-2.72/-1.68]; ES [CI_95% ]: -2.54 seconds [-3.34/-1.74]). Both groups improved balance ability, with BT showing larger increments in bipedal tests than Ctrl (static balance: -29 mm [-42/-16]; ES: -1.39 [-2.05/-0.72]; limit of stability: 4% [3/5]; ES 3.93 [2.90/4.95]; unipedal quasi-dynamic balance: 0.07 a.u. [0.03/0.11]; ES: 1.04 [0.40/1.67] and active range of motion: -5% [-8/-2]; ES -0.89 [-1.51/-0.26]). Low-to-moderate correlations between the players' technical level and unipedal balance ability were retrieved, particularly in the non-dominant limb (R from 0.30 to 0.48). Balance training improved some technical soccer skills more than habitual soccer training alone, suggesting that young soccer players may benefit from additional balance training added to their traditional training.

Gender Differences in Static and Dynamic Postural Stability of Soldiers in the Army’s 101st Airborne Division (Air Assault)

Context: Postural stability is essential for injury prevention and performance. Differences between genders may affect training focus. Objective: To examine static and dynamic postural stability in male and female soldiers. Design: Descriptive laboratory study. Setting: Biomechanics laboratory. Participants: 25 healthy female soldiers (26.4 ± 5.3 y) and 25 healthy male soldiers (26.4 ± 4.9 y) matched on physical demand rating and years of service from the Army’s 101st Airborne Division (Air Assault). Interventions: Each person underwent static and dynamic postural stability testing. Main Outcome Measures: Standard deviation of the ground reaction forces during static postural stability and the dynamic stability index for dynamic postural stability. Results: Female soldiers had significantly better static postural stability than males but no differences were observed in dynamic postural stability. Conclusions: Postural stability is important for injury prevention, performance optimization, and tactical training. The differences observed in the current study may indicate the need for gender-specific training emphasis on postural stability.

Comparison of jump-landing protocols with Biodex Balance System as measures of dynamic postural stability in athletes

The objective of the study was to determine whether a relationship exists between the two common methods for assessing postural stability in athletes: the time-to-stabilisation (TTS) via force-plate and the Biodex Balance System (BBS). The conditions under which these measurements assess dynamic postural control may not provide sufficient feedback to practitioners. Fourty-four amateur soccer players with no history of musculoskeletal disorders volunteered for the study. Pearson correlation was used to compare the anterior-posterior (AP), medio-lateral (ML), and the overall stability indexes measured by BBS, with the corresponding parameters of TTS assessed via force plate. There was no significant correlation between any parameters of dynamic stability measured by force-plate and the stability indexes. However, there was a significant correlation between the resulting vectors and the AP component of TTS for each jump protocol. Furthermore, forward drop landing exhibited shortest TTS in AP direction, while lateral drop landing resulted in longer ML TTS relative to both forward jumps (p < 0.001). These results demonstrate that the TTS and BBS stability indexes should be used as distinct measures of dynamic postural stability. TTS protocols may be modified to target a specific training conditions or athletic population.

The Effect of Teeth Clenching on Dynamic Balance at Jump-Landing: A Pilot Study

The aim of this study was to analyze the effect of teeth clenching on dynamic balance at jump landing. Twenty-five healthy subjects performed jump-landing tasks with or without teeth clenching. The first 3 trials were performed with no instruction; subsequently, subjects were ordered to clench at the time of landing in the following 3 trials. We collected the data of masseter muscle activity by electromyogram, the maximum vertical ground reaction force (vGRFmax) and center of pressure (CoP) parameters by force plate during jump-landing. According to the clenching status of control jump-landing, all participants were categorized into a spontaneous clenching group and no clenching group, and the CoP data were compared. The masseter muscle activity was correlated with vGRFmax during anterior jump-landing, while it was not correlated with CoP. In comparisons between the spontaneous clenching and the no clenching group during anterior jump-landing, the spontaneous clenching group showed harder landing and the CoP area became larger than the no clenching group. There were no significant differences between pre- and postintervention in both spontaneous clenching and no clenching groups. The effect of teeth clenching on dynamic balance during jump-landing was limited.

Time series of ground reaction forces following a single leg drop jump landing in elite youth soccer players consist of four distinct phases

The single leg drop jump landing test may assess dynamic and static balance abilities in different phases of the landing. However objective definitions of different phases following landing and associated reliability are lacking. Therefore, we determined the existence of possible distinct phases of single leg drop jump landing on a force plate in 82 elite youth soccer players. Three outcome measures were calculated over moving windows of five sizes: center of pressure (COP) speed, COP sway and horizontal ground reaction force (GRF). Per outcome measure, a Factor Analysis was employed with all windows as input variables. It showed that four factors (patterns of variance) largely (>75%) explained the variance across subjects/trials along the 12s time series. Each factor was highly associated with a distinct phase of the time series signal: dynamic (0.4-2.7s), late dynamic (2.5-5.0s), static 1 (5.0-8.3s) and static 2 (8.1-11.7s). Intra-class correlations (ICC) between trials were lower for the dynamic phases (0.45-0.68) than for the static phases (0.60-0.86). The COP speed showed higher ICC's (0.63-0.86) than COP sway (0.45-0.61) and GRF (0.57-0.71) for all four phases. In conclusion, following a drop jump landing unique information is available in four distinct phases. The COP speed is most reliable, with higher reliability in the static phases compared to the dynamic phases. Future studies should assess the sensitivity of information from dynamic, late dynamic and static phases.

Examination of Age-Related Differences on Clinical Tests of Postural Stability

BACKGROUND

The modified Balance Error Scoring System (mBESS) and Y-Balance Test are common clinical measurements of postural control, but little is known about the effect of age on performance of these tasks. The purpose of this study was to examine how healthy child and adolescent athletes perform on 2 common clinical measurements of postural control.

HYPOTHESIS

Younger athletes would demonstrate poorer postural control compared with older athletes.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Three hundred eighty-nine athletes between the ages of 10 and 18 years underwent an evaluation of postural control. Each participant completed the mBESS in the double-leg, single-leg, and tandem stances as well as the Y-Balance Test. Postural stability data were analyzed between age groups (10-12, 13-15, and 16-18 years) using univariate analyses of covariance.

RESULTS

The youngest athletes (10-12 years) had a greater mean number of errors in the single-leg stance of the mBESS than the 13- to 15-year-old and 16- to 18-year-old athletes (3.8, 3, and 2.5 errors, respectively; P < 0.01). They also had greater right to left asymmetry compared with the 16- to 18-year-old athletes on the Y-Balance Test in the posterolateral (6.8 and 3.8 cm, respectively; P = 0.006) and posteromedial (5.3 and 3.6 cm, respectively; P = 0.014) directions of movement.

CONCLUSION

Athletes between the ages of 10 and 12 years performed worse on the single-leg stance of the mBESS and demonstrated more asymmetry on the Y-Balance Test in the posterolateral and posteromedial directions compared with older athletes.

CLINICAL RELEVANCE

In the absence of a baseline balance test for athletes younger than the age of 13 years, caution should be used in interpreting postural stability assessments, as age may be a modifying factor in performance.