Y balance test: Are we doing it right?

Evaluation of hop tests based on Y-Balance test and FMS test outcomes in volleyball and basketball players to identify those prone to injury: a potential predictor of injury

BACKGROUND

The quest for a reliable and effective method to identify athletes at risk of injury holds the promise of significantly reducing injury rates and improving overall athletic performance. This research delved into the relationship between the Functional Movement Screen (FMS), Y-Balance Test (YBT), and Hop tests (Side hop, Medial triple hop, and Lateral step-down hop), aiming to determine the potential in predicting injuries of hop tests among division 1 volleyball and basketball players.

METHODS

This research was conducted with fifty-two participants from the Division 1 league, encompassing both volleyball and basketball players. The study rigorously employed the Functional Movement Screen (FMS), the Y-Balance Test (YBT), and various hop tests (side hop test, medial triple hop test, lateral step-down hop) to measure relevant variables. The data analysis used logistic regression, ensuring a comprehensive approach to the study.

RESULTS

Results showed no significant relationship between FMS and Hop test for predicting injuries, but there was a relationship between ΔY and side hop that shows side hop test can predict injury, but there was no relationship between Lateral step down, Medial triple hop, and ΔY.

CONCLUSIONS

Based on our findings, side hop, despite the medial triple hop and lateral step-down test, can be used as a sports injury predictor.

Correlation between gross motor coordination and basic coordination capacities in normal-weight and overweight/obese children aged 9-10 years

Background

Gross motor coordination (GMC) plays a crucial factor in children's motor development and daily activities. It encompasses various sub-capacities, such as spatial orientation, rhythm, and motor reaction, collectively referred to as basic coordination capacities (BCC). However, children who are overweight and obese (OW/OB) often display poorer GMC. This study aims to examine the impact of gender and weight status (BMI categories) on children's GMC and BCC. It also seeks to investigate the impact of BCC and BMI on GMC.

Method

The study involved 266 participants, 135 in the NW group (boys: n = 75; girls: n = 60) and 131 in the OW/OB group (boys: n = 68; girls: n = 63). An NW status is defined by a BMI z-score between ≥-2SD to ≤1SD, while an OW/OB status corresponds to a BMI z-score > 1SD. Physical activity was assessed using the Physical Activity Questionnaire for Children, developed by the University of Saskatchewan, Canada. We used six field tests to evaluate BCC, including single leg standing test (static balance), YBT (dynamic balance), rhythmic sprint test (rhythm), reaction time test (motor reaction), target standing broad test (kinesthetic differentiation), and numbered medicine ball running test (spatial orientation). GMC was evaluated with Kiphard-Schilling's Body Coordination Test (KTK).

Result

The motor quotient (MQ) was primarily affected by weight status (F = 516.599, p < 0.001; gender: F = 6.694, p = 0.01), with no significant interaction effect (F = 0.062, p = 0.803). In BCC, gender had a significant main effect on rhythm capacity (F = 29.611, p < 0.001) and static balance (F = 11.257, p = 0.001) but did not significant influence other sub-capacities (p > 0.05). Weight status impacted dynamic balance (F = 11.164, p = 0.001). The interaction of gender and weight status significantly impacted motor reaction (F = 1.471, p = 0.024) and kinesthetic differentiation (F = 5.454, p = 0.02), but did not affect other sub-capacities (p > 0.05). The physical activity was not significant affected by gender (F = 0.099, p = 0.753), weight status (F = 0.171, p = 0.679) and the interactions of two variables (F = 0.06, p = 0.806). In the regression analysis, except motor reaction (p > 0.05), other BCC sub-capacities influenced GMC to varying extents (β = -0.103-0.189, p < 0.05). Nonetheless, only two types of balance significantly mediated the relationship between BMI and GMC (BMI→MQ: β = -0.543, p < 0.001; BMI→YBT: β = -0.315, p < 0.001; BMI→SLS: β = -0.282, p < 0.001; SLS→MQ: β = 0.189, p < 0.001; YBT→MQ: β = 0.182, p < 0.001).

Conclusion

Compared to gender, the main effect of weight status on most GMC and BCC's sub-capacities was more pronounced. OW/OB children exhibited poorer GMC, which is related to their reduced static and dynamic balance due to excess weight. Kinesthetic differentiation, spatial orientation, and rhythm capacity are not significantly associated with BMI, but these sub-capacities positively influence gross motor coordination (GMC), except for hand-eye motor reaction.

Intrinsic and extrinsic variables impacting upper quarter Y-balance test scores in sporting cohorts: A systematic review

INTRODUCTION

The upper quarter y-balance test (YBT-UQ) is a functional screening tool used to detect musculoskeletal injury risk, aid rehabilitation, and monitor dynamic function, strength and control, yet little is currently known about intrinsic and extrinsic factors that influence reach scores.

OBJECTIVES

This systematic review aimed to determine if age, sex, or interventions influenced reach scores and whether between-limb differences were common in non-injured sporting populations, with a secondary aim to identify if sport impacted YBT-UQ reach.

METHODS

Web of Science, PubMed, and SportDiscus were systematically searched from January 2012 to November 16, 2023, revealing twenty-three studies satisfying inclusion criteria of published in English between 2012 and 2023, healthy participants of any age including both males and females, athletic populations, YBT-UQ use to assess upper limb mobility/stability, report normalised reach scores, and peer-reviewed full-texts. Methodological quality was evaluated via National Institutes of Health (NIH) quality assessment tools for controlled interventions, observational cohort and cross-sectional designs, and pre-post with no control group.

RESULTS

Age, sex, sport, and fatigue were influencing factors; greater reach scores were achieved in older athletes (i.e. >18 years), males, and in a well-rested state. Between-limb differences were not common in sporting populations; therefore, asymmetries may be useful for practitioners to aid injury risk identification.

CONCLUSION

This is the first systematic review investigating YBT-UQ influencing factors and thereby provides context for clinicians regarding characteristics that impact reach scores in sporting populations, from which normative values could be determined and further aid clinical decisions or areas to improve regarding injury risk.

Exploring the relationship between core stability and vertical jump in recreationally active male college students based on a suite of novel core stability assessments

Various assessments have contributed to inconsistent findings regarding the correlation between core stability and vertical jumps. Therefore, this study aimed to re-examine this correlation based on novel core stability assessments. Twenty-one recreationally active male college students (age, 21.7 ± 2.1 years; stature, 174.9 ± 6.7 cm; body mass, 67.7 ± 7.8 kg; leg length, 88.9 ± 4.8 cm; arm length, 87.8 ± 4.0 cm) participated in this experiment. Core stability was divided into static and dynamic core stabilities, with the static core stability measured using the Eight-Level Prone Bridge and Five-Level Side Bridge tests and the dynamic core stability measured using the Y Balance Test (YBT). These tests comprehensively evaluate core stability as it is defined. Kinematic and kinetic data on vertical jumps were collected to provide process information beyond the outcome performance. Subsequently, these data were correlated with core stability for a deeper insight into the relationship between core stability and the process and outcome performance of vertical jumps. The main results revealed that the Eight-Level Prone Bridge demonstrated moderate to substantial correlations with Δ F y ‾ , Δ I y , Δ D l e f t k n e e z , and Δ D l e f t a n k l e y (-0.62 ≤ r ≤ 0.52); the Five-Level Side Bridge exhibited moderate correlations with Δ F x ‾ , Δ F y ‾ , Δ I x , Δ I y , Δ D l e f t k n e e z , and Δ D l e f t a n k l e y (-0.52 ≤ r ≤ 0.59); YBT displayed moderate correlations with F z ‾ , F l e f t z ‾ , Δ D l e f t a n k l e y , Δ D r i g h t a n k l e y , Δ D l e f t a n k l e z , Δ D r i g h t a n k l e z , NΔ T a n k l e y ‾ , and N T l e f t a n k l e z ‾ (-0.54 ≤ r ≤ 0.54) during the propulsive phase of vertical jumps. However, no significant correlations were observed between static/dynamic core stability and jumping height. Therefore, individuals with greater core stability should experience improved process performance (better movement quality), although this benefit is ineffective in translating into jumping height improvement due to impaired explosive features. Coaches may consider core stability in training to trigger an improved process performance of the vertical jump when the technique is the key issue to be solved, although future studies are required to verify this further.

Correlation between hip muscle strength and the lower quarter Y-balance test in athletes following anterior cruciate ligament reconstruction

INTRODUCTION

The lower quarter Y-balance test (YBT-LQ), which measures dynamic postural control, has been reported to be predictive of lower limb injuries in athletes. It requires subjects to control their body while maintaining a single-leg stance, which necessitates sufficient strength of the hip muscles to maintain stability. The purpose of the study was to investigate the correlation between the performance of the YBT-LQ and the hip abductor or extensor muscle strength in athletes following anterior cruciate ligament reconstruction surgery (ACLR).

METHODS

Fifteen athletes with post-ACLR participated in this cross-sectional study. The participants completed the YBT-LQ, followed by isokinetic measurement of the hip abductor and extensor muscles of both the legs. The peak and average torque of the hip abductor and extensor muscles were tallied with the composite score of the YBT-LQ for each limb.

RESULTS

No correlation was found between the strength of the hip muscles and the YBT-LQ composite score in both injured and non-injured limbs at all velocities except for the eccentric hip abductor and concentric hip extensor torques. The eccentric hip abductor average torque is strongly associated with the YBT-LQ (r = 0.663, p = 0.010) at a speed of 180°/s. The concentric hip extensor peak torque was weakly correlated with balance (r = 0.540, p = 0.046) at a speed of 180°/s.

CONCLUSION

Our study demonstrated a positive correlation between the YBT-LQ and eccentric hip abduction and concentric hip extension at higher velocities. This shows the importance of implementing velocity-oriented rehabilitation in an athletic population following ACLR.

The influence of different levels of physical activity and sports performance on the accuracy of dynamic lower limbs balance assessment among Chinese physical education college students

Background: Balance ability is the basis of human actions. Improving the accuracy of dynamic balance assessment can increase the efficiency of sports injury prediction. Objectives: This study aimed to investigate how physical activity and sports performance affect the dynamic balance ability of lower limbs and validate whether the Lower Quarter Y-Balance Test (YBT-LQ) is a reliable predictor of sports injury risk among Chinese physical education college students. Materials and Methods: In total, 169 voluntary participants completed the YBT-LQ at the beginning of a semester and provided some physiological information and an injury report at the end of the semester. The correlation between YBT-LQ performance and selected factors that can affect the dynamic balance control was analyzed based on data statistics. The receiver operating characteristic (ROC) and the area under curve (AUC) of the composite scores of the YBT-LQ were calculated to explore an optimal cutoff value for predicting sports injury risk. Results: The composite scores of the YBT-LQ exhibited strong correlations with both the sports performance level and sports injury, as well as a moderate correlation with physical activity level, age (negative), and metabolic equivalent (MET). In the entire study population, the area under the receiver operating characteristic (ROC) curves for the binary classification of composite YBT-LQ scores of the left and right legs to predict sports injury risk were 0.78 and 0.74, respectively. Stratifying the study participants based on their levels of physical activity and sports performance had an effect on the AUC values of ROC curves. The optimal cutoff scores of the YBT-LQ for predicting sports injury risk were variable, with values more or less than 95%. Specifically, the cutoff scores for participants with the highest level of sports performance were notably higher, reaching up to 106.5% (left) and 107.2% (right). Conclusion: Physical activity and sports performance can influence human dynamic balance control. Composite scores of the YBT-LQ can be used with acceptable efficiency to predict sports injury. Stratifying participants based on their levels of physical activity and sports performance leads to different optimal cutoff values of the YBT-LQ composite scores in predicting sports injury. This approach is preferable to relying solely on a uniform 95% cutoff. It is recommended to analyze individuals with higher levels of sports performance, such as elite athletes, separately from those with lower levels. This is because the former group has a higher optimal cutoff value compared to the latter.

Using the Y-balance Test as a Predictor Tool for Evaluating Non-contact Injuries in University League Football Players: A Prospective Longitudinal Study

Background Football is a highly competitive sport, and participants can experience various contact and non-contact sports injuries in the sporting process. In any elite sport, screening players using different scientific tools is an important injury prevention strategy. The Y- Balance test (YBT) was found to be a predictive tool for non-contact injury. However, the use of criteria from these tests to predict injuries has not been substantiated and should be further investigated. Purpose The aim of this study was to determine the predictors for injury among athletes using baseline YBT, number of matches, and minutes of physical activity; the cutoff scores for predictors of injury, including baseline YBT, number of matches, and minutes of physical activity; and the clinical prediction rules for predicting injury in this population. Methods A total of 39 young student football players were included in this study. The mean age was 20.28 years, and the mean body mass index (BMI) was 23.83 kg/m². A baseline assessment of the participant's characteristics was taken and each participant performed the YBT once before starting the league. After the university league football players had finished their tournament, we asked them questions related to non-contact injuries. Results The results showed that the prevalence of injury was 17.95% among this population. An increase in the YBT score was significantly associated with a decrease in the odds of having an injury [odds ratio (OR) 95% confidence interval (CI): 0.94 (0.88, 0.99), p = 0.047). In addition, the number of matches was significantly associated with an increase in the odds of having an injury p = 0.012. However, the minutes of physical activity were not statistically significant p = 0.065. The highest Youden index was ≤97.89, with a sensitivity of 87.50% and specificity of 71.43%, for the posterior medial reach and ≤92.88, with a sensitivity of 90.62% and specificity of 57.14%, for the posterior lateral reach. The clinical prediction rule was an area under the curve (AUC) of 0.88. Conclusions The results of the study provide evidence for the potential utility of the YBT as a predictor tool for evaluating non-contact injuries in university league football players. By identifying players with lower YBT scores who were at higher risk for injury, targeted interventions could be implemented to address functional movement deficits and potentially reduce injury risk.

Effects of Transcranial Direct Current Stimulation over the Primary Motor Cortex in Improving Postural Stability in Healthy Young Adults

Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) is of increasing interest to improve motor performance in healthy adults and patients with respective deficits. This study aimed to examine whether tDCS over M1 can improve static and dynamic postural stability in young healthy adults. Seventeen healthy participants (mean age = 25.14 ± 2.50 (standard deviation, SD) years) received sham and anodal tDCS (2 mA) over the vertex at the Cz electrode position for 15 min. Static and dynamic postural stability were evaluated before and immediately after tDCS. The center of pressure (COP) sway area (COPSA) and COP maximum displacements to medio-lateral (COPML) and antero-posterior directions (COPAP) were used to evaluate static postural stability. The anterior−posterior stability index (APSI), medial−lateral stability index (MLSI), vertical stability index (VSI), dynamic postural stability index (DPSI), and time to stabilization (TTS) in forward (FL), 45° anterior lateral (LL), and 45° anterior medial (ML) direction landing, as well as the Y-balance composite score (YBTCS) were used to assess dynamic postural stability. The results showed that the LL-TTS (p = 0.044), non-dominant leg COPSA (p = 0.015), and YBTCS (p < 0.0001) were significantly improved in the real stimulation as compared with the sham stimulation session, and anodal tDCS significantly changed dominant leg COPAP (p = 0.021), FL-APSI (p < 0.0001), FL-TTS (p = 0.008), ML-TTS (p = 0.002), non-dominant leg YBTCS (p < 0.0001), and dominant leg YBTCS (p = 0.014). There were no significant differences in all obtained balance values in the sham stimulation session, except for non-dominant leg YBTCS (p = 0.049). We conclude that anodal tDCS over M1 has an immediate improving effect on static postural stability and dynamic performance in young healthy adults. This makes tDCS a promising adjuvant rehabilitation treatment to enhance postural stability deficits in the future.

Dynamic postural control and physical stress: an approach to determining injury risk in real sporting conditions

Dynamic postural control is one of the essential factors in situations where non-contact injuries mainly occur, i.e., landing, cutting, or stopping. Therefore, testing of dynamic postural control should be implemented in injury risk assessment. Moreover, non-contact injuries mainly occur under loaded conditions when the athlete is physically stressed. Therefore, risk factors and mechanisms of these injuries should also be regarded under loading conditions and not only when the athlete is recovered. Current studies examining the influence of physical load on risk factors, such as dynamic postural control, often use cycling protocols to stress the participants. Nevertheless, most types of sports require running as a central element and the induced internal load after cycling might not be the same after running. Therefore, the current study aimed to examine the influence of a running and a cycling protocol on dynamic postural control and to determine the potential injury risk under representative conditions. In total, 128 sport students (64 males and 64 females, age: 23.64 ± 2.44, height: 176.54 ± 8.96 cm, weight: 68.85 ± 10.98 kg) participated in the study. They were tested with the Y Balance Test before and after one loading protocol. A total of 64 participants completed a protocol on a cycle ergometer and the other 64 on a treadmill. A mixed ANOVA showed significant interactions of time and load type. Dynamic postural control was reduced immediately after cycling but did not change after running. These findings indicate a load type dependence of dynamic postural control that must be considered while assessing an athlete’s potential injury risk and they support the need for more representative designs.

Effects of 8-Week In-Season Contrast Strength Training Program on Measures of Athletic Performance and Lower-Limb Asymmetry in Male Youth Volleyball Players

Strength training using high and lower load such as contrast training (CST) seems to be beneficial as it addresses larger adaptive reserves in youth athletes. Therefore, the aim of this study was to investigate the effects of CST on dynamic balance (composite score during dynamic balance test (CS-YBT)), one repetition maximum lower-limb back squat (1RM), jumping performance (single-leg hop (SLH) or countermovement jump height (CMJ)), lower-limb asymmetry (predicted from the single-leg jump performance between two legs [ILA]) in elite youth male volleyball players. Thirty-one male youth volleyball players aged 14 years were randomly assigned to a CST group (n = 16) or a control group (n = 15). The tests were performed before and after 8 weeks of training. Significant group × time interactions was observed for CS-YBT [p < 0.001, ηp2 = 0.70], 1RM [p < 0.001, ηp2 = 0.95], SLH with right and left leg [p < 0.001, ηp2 = 0.69 and 0.51], CMJ [p < 0.001, ηp2 = 0.47]), whilst it was not notable in ILA [p < 0.294]. Post hoc tests showed that CST group demonstrated greater improvement in all of the dependent variables from medium to large effect size (for all p < 0.001). As a result, 8 weeks of CST twice a week can be an effective and efficient training along with volleyball training to improve skill-related fitness measures, except for lower-limb asymmetry in young volleyball players.

Exploring the Y-Balance-Test scores and inter-limb asymmetry in soccer players: differences between competitive level and field positions

Background

The postural stability seems to be important in the physical development of the soccer player and the specific tasks related to the game. In addition, it is related to the injury risk and therefore, with the injury prevention and retraining processes. In this context, the Y Balance Test (YBT) is presented as a tool to assess dynamic postural control.

Objective

This study aimed to explore the differences and possible correlations in the YBT scores and inter-limb asymmetry for anterior (ANT), posteromedial (PM) and posterolateral (PL) directions by category and field position in soccer players.

Methods

173 males soccer players aged between 14 and 33 years old agreed to participate. Five categories and six field position were considered in this study. A standardised protocol was used at multiple clubs during the pre-season assessment of musculoskeletal function in soccer players. All the players performed the Y Balance Test (YBT) (official YBT Kit), assessing the dominant and non-dominant leg for three YBT directions (anterior-AN, posteromedial-PM and posterolateral-PL), inter-limb asymmetry and composite score.

Results

For AN, amateur and semiprofessional obtained the highest values for Dominant and Non-Dominant legs (Range_mean = 101.8–109.4%) and the lowest level in PRO players (mean: 62.0%). Concerning PM-PL, semiprofessional (Range_mean = 126.4–132.7%, dominant and non-Dominant respectively), followed by professional and amateur reported higher scores compared to youth categories. Inter-limb asymmetry showed higher values in lower age categories. The best composite scores were detected in semiprofessionals (Range_mean = 113.3–126.7% for dominant and Range_mean = 113.8–129.7% for non-Dominant leg), compared with the rest of the categories and for each field position evaluated.

Conclusion

Comparisons between field-positions revealed that centre-backs were worse than wingers and forwards. In order to explain variations in dynamic balance between competitive levels within the same age-group, special considerations about training programmes and related co-variables should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-022-00438-w.

Load-Induced Changes of Inter-Limb Asymmetries in Dynamic Postural Control in Healthy Subjects

Inter-limb asymmetries are associated with a higher potential risk for non-contact injuries. Differences in function or performance between the limbs might lead to imbalances and promote instability, increasing the potential risk for injuries. Consequently, an investigation of inter-limb asymmetries should be included in injury risk assessment. Furthermore, since non-contact injuries mainly occur under loaded conditions, an investigation of load-induced changes of inter-limb asymmetries can provide additional information on the athlete's potential injury risk. Therefore, the current study aimed to investigate the influence of physical load on inter-limb asymmetries in dynamic postural control, which is essential in situations with a high risk for non-contact injuries such as landing, cutting, or stopping. In total, dynamic postural control of 128 active and healthy subjects (64 males and 64 females, age: 23.64 ± 2.44, height: 176.54 ± 8.96 cm, weight: 68.85 ± 10.98 kg) was examined. Dynamic postural control was tested with the Y-Balance Test (YBT) before and after a loading protocol on a bicycle ergometer or a treadmill. The results showed no significant increase of the inter-limb asymmetries in anterior direction [F (1, 126) = 4.44, p = 0.04, η2 p = 0.03]. Moreover, there is high variation between the subjects regarding the magnitude and the direction of the asymmetries and the changes due to load. Therefore, a more individual analysis considering the magnitude and the direction of the asymmetries is required. Thereby, considering different modifying factors, e.g., sex, injury history, and baseline level of asymmetries, can be helpful. Moreover, an analysis of the changes during load might provide further insights, reveal possible differences, and help detect the reasons and mechanisms underlying inter-limb asymmetries and asymmetrical loading.

Association between Anthropometric Variables, Sex, and Visual Biofeedback in Dynamic Postural Control Assessed on a Computerized Wobble Board

Anthropometrics and sex influence balance performances, and visual information can change anthropometrics’ relation and the postural sway. Therefore, the aim of the present study was to evaluate the effect of anthropometric characteristics, sex, and visual biofeedback and/or their interaction on a computerized wobble board. Twenty-seven (14 females, 13 males) young adults performed three 30-s double leg stance trials on a wobble board during two conditions: with visual and without visual biofeedback. Visual biofeedback improved (p = 0.010) balance on a wobble board with respect to the condition without visual biofeedback. Regardless of sex, no differences between conditions were found (p = 0.088). When investigating the effect of anthropometrics variables, sex, and their interactions on conditions, a significant main effect of the lower limb/height ratio, sex, and their interaction on the condition without visual biofeedback was found (p = 0.0008; R2 = 0.57). For the visual biofeedback condition, significant effects for sex and body mass (p = 0.0012; R2 = 0.43) and sex and whole-body moment of inertia (p = 0.0030; R2 = 0.39) were found. Results from the present study showed (1) visual biofeedback improved wobble board balance performance; (2) a significant main effect of lower limb/height ratio, sex, and their interaction on the wobble board performances without visual biofeedback emerged; (3) significant effects were found for sex and body mass and sex and moment of inertia in the visual biofeedback condition. Findings from the present study could have an impact on training and evaluations protocols, especially when several populations such as children, athletes, older adults and people with balance disorders are involved.

The Effects of Eccentric and Plyometric Training Programs and Their Combination on Stability and the Functional Performance in the Post-ACL-Surgical Rehabilitation Period of Elite Female Athletes

BACKGROUND

The standard method to treat physically active patients with anterior cruciate ligament (ACL) rupture is ligament reconstruction surgery. The rehabilitation training program is very important to improve functional performance in recreational athletes following ACL reconstruction.

OBJECTIVES

The aims of this study were to compare the effects of three different training programs, eccentric training (ECC), plyometric training (PLYO), or combined eccentric and plyometric training (COMB), on dynamic balance (Y-BAL), the Lysholm Knee Scale (LKS), the return to sport index (RSI), and the leg symmetry index (LSI) for the single leg hop test for distance in elite female athletes after ACL surgery.

MATERIALS AND METHODS

Fourteen weeks after rehabilitation from surgery, 40 elite female athletes (20.3 ± 3.2 years), who had undergone an ACL reconstruction, participated in a short-term (6 weeks; two times a week) training study. All participants received the same rehabilitation protocol prior to the training study. Athletes were randomly assigned to three experimental groups, ECC (n = 10), PLYO (n = 10), and COMB (n = 10), and to a control group (CON: n = 10). Testing was conducted before and after the 6-week training programs and included the Y-BAL, LKS, and RSI. LSI was assessed after the 6-week training programs only.

RESULTS

Adherence rate was 100% across all groups and no training or test-related injuries were reported. No significant between-group baseline differences (pre-6-week training) were observed for any of the parameters. Significant group-by-time interactions were found for Y-BAL (p < 0.001, ES = 1.73), LKS (p < 0.001, ES = 0.76), and RSI (p < 0.001, ES = 1.39). Contrast analysis demonstrated that COMB yielded significantly greater improvements in Y-BAL, LKS, and RSI (all p < 0.001), in addition to significantly better performances in LSI (all p < 0.001), than CON, PLYO, and ECC, respectively.

CONCLUSION

In conclusion, combined (eccentric/plyometric) training seems to represent the most effective training method as it exerts positive effects on both stability and functional performance in the post-ACL-surgical rehabilitation period of elite female athletes.

Improvement of Physical Performance Following a 6 Week Change-of-Direction Training Program in Elite Youth Soccer Players of Different Maturity Levels

Background: Change-of-direction (CoD) is a necessary physical ability of a field sport and may vary in youth players according to their maturation status. Objectives: The aim of this study is: to compare the effectiveness of a 6-week CoD training intervention on dynamic balance (CS-YBT), horizontal jump (5JT), speed (10 and 30-m linear sprint times), CoD with (15 m-CoD + B) and without (15 m-CoD) the ball, in youth male soccer players at different levels of maturity [pre- and post-peak height velocity (PHV)]. Materials and Methods: Thirty elite male youth soccer players aged 10-17 years from the Tunisian first division participated in this study. The players were divided into pre- (G1, n = 15) and post-PHV (G2, n = 15) groups. Both groups completed a similar 6-week training program with two sessions per week of four CoD exercises. All players completed the following tests before and after intervention: CS-YBT; 5 JT; 10, 30, and 15 m-CoD; and 15 m-CoD + B, and data were analyzed using ANCOVA. Results: All 30 players completed the study according to the study design and methodology. Adherence rate was 100% across all groups, and no training or test-related injuries were reported. Pre-PHV and post-PHV groups showed significant amelioration post-intervention for all dependent variables (after test > before test; p < 0.01, d = 0.09-1.51). ANOVA revealed a significant group × time interaction only for CS-YBT (F = 4.45; p < 0.04; η² = 0.14), 5JT (F = 6.39; p < 0.02; η² = 0.18), and 15 m-CoD (F = 7.88; p < 0.01; η² = 0.22). CS-YBT, 5JT, and 15 m-CoD improved significantly in the post-PHV group (+ 4.56%, effect size = 1.51; + 4.51%, effect size = 1.05; and -3.08%, effect size = 0.51, respectively), more than the pre-PHV group (+ 2.77%, effect size = 0.85; + 2.91%, effect size = 0.54; and -1.56%, effect size = 0.20, respectively). Conclusion: The CoD training program improved balance, horizontal jump, and CoD without the ball in male preadolescent and adolescent soccer players, and this improvement was greater in the post-PHV players. The maturity status of the athletes should be considered when programming CoD training for soccer players.

The Influence of Physical Load on Dynamic Postural Control-A Systematic Replication Study

Dynamic postural control is challenged during many actions in sport such as when landing or cutting. A decrease of dynamic postural control is one possible risk factor for non-contact injuries. Moreover, these injuries mainly occur under loading conditions. Hence, to assess an athlete's injury risk properly, it is essential to know how dynamic postural control is influenced by physical load. Therefore, the study's objective was to examine the influence of maximal anaerobic load on dynamic postural control. Sixty-four sport students (32 males and 32 females, age: 24.11 ± 2.42, height: 175.53 ± 8.17 cm, weight: 67.16 ± 10.08 kg) were tested with the Y-Balance Test before and after a Wingate Anaerobic Test on a bicycle ergometer. In both legs, reach distances (anterior) and composite scores were statistically significantly reduced immediately after the loading protocol. The values almost returned to pre-load levels in about 20 min post-load. Overall, findings indicate an acute negative effect of load on dynamic postural control and a higher potential injury risk during a period of about 20 min post-load. To assess an athlete's sports-specific injury risk, we recommend testing dynamic postural control under loaded conditions.

Discriminative validity of the lower and upper quarter Y balance test performance: a comparison between healthy trained and untrained youth

Background

The Lower (YBT-LQ) and Upper (YBT-UQ) Quarter Y Balance Test have been widely used for the assessment of dynamic balance and shoulder mobility/stability, respectively. However, investigations on the validity of the two tests in youth are lacking. Therefore, we performed two studies to determine discriminative validity of the YBT-LQ (study 1) and the YBT-UQ (study 2) in healthy youth.

Methods

Sixty-nine male soccer players (age: 14.4 ± 1.9 yrs) and 69 age-matched untrained male subjects (14.3 ± 1.6 yrs) participated in study 1 and 37 young swimmers (age: 12.3 ± 2.1 yrs) as well as 37 age−/sex-matched individuals (age: 12.5 ± 2.0 yrs) took part in study 2. Absolute (cm) and relative (% leg/arm length) maximal reach distances per reach direction and the composite score of the YBT-LQ/UQ were used as outcome measures. One-way analysis of variance and the receiver operator characteristic curve analysis (i.e., calculating the area under the curve [AUC]) were conducted to assess discriminative validity.

Results

Concerning the relative values, youth athletes showed significantly better YBT-LQ (study 1: p < 0.001, d = 0.86–1.21) and YBT-UQ (study 2: p < 0.001, d = 0.88–1.48) test performances compared to age- and sex-matched untrained subjects. Further, AUC-values indicated a chance of ≥74% (YBT-LQ) and ≥ 71% (YBT-UQ) to discriminate between youth athletes and controls. These findings were confirmed when using the absolute data for analysis.

Conclusions

According to our results, the YBT-LQ and the YBT-UQ seem to be useful test instruments to discriminate trained and untrained healthy youth performance for dynamic balance and shoulder mobility/stability, respectively.

Change-of-Direction Performance in Elite Soccer Players: Preliminary Analysis According to Their Playing Positions

Our objective was to examine the relationship between change of direction (CoD) performance, with (CoDb), and without the ball (CoDwb), and selected measures of physical fitness (jump performance, speed, balance) in elite soccer players, according to players’ positions. Forty elite male soccer players performed the change-of-direction and acceleration test (CODAT) with (CODATb), and without the ball (CODATwb), 5- and 20-m sprint tests, the 5-jump test (5JT), and the Y-balance test (YBT). Analyses of the whole sample showed significant correlations between all CODAT measures (CODATwb and CODATb, respectively) and sprint 5-m (r = 0.72, p < 0.001; r = 0.52, p < 0.01), sprint 20-m (r = 0.54, p < 0.03; r = 0.45, p < 0.05), jump (r = −0.62, p < 0.01; r = −0.64, p < 0.01) and balance (r = −0.50, p < 0.01; r = −0.83, p < 0.001) performances. Correlations were significantly different between player positions (defender, midfielder and striker). When examining the entire sample, the single best predictor of CODATwb was performance in the 5-m test with an explained variance of 52% (p < 0.001). For CODATb, the Y-balance performance explained 68% of the variance of performance (p < 0.001). In conclusion, soccer coaches and fitness trainers are advised to improve players’ CoD using neuromuscular training that mimic crucial match actions. Meanwhile, CoD testing and training should be designed in line with the demands of playing position.

A novel approach to measuring wobble board performance in individuals with chronic ankle instability

Computerized wobble boards (WB) are used to objectively assess balance in healthy and chronic ankle instability individuals. As in field setting health professionals might not own WB, objective evaluations are not always feasible. Therefore, the aim of this tudy was to investigate the contribution of sagittal plane joints angular-displacement and anthropometrics to predict equations to estimate WB performance by portable two-dimensional motion analysis (2D-MA) and cross-validate the developed equations in chronic ankle instability individuals. Thirty-nine healthy and twenty chronic ankle instability individuals stood on a WB in single stance position. The balance test consisted of three 30s trials per limb keeping the platform flat at 0°. Trials were video recorded, and three time-segments joints angular-displacement analyzed with 2D-MA: segment 1 (T1) including 30s data, segment 2 (T2) from second 0 to 10, segment 3 (T3) only the first 5s. Mixed regression for multilevel models was used to estimate WB performance for each time-segment and to examine limb differences for the predicted WB performance in chronic ankle instability sample. The accuracy of the equations to detect injured limbs was calculated via area under the curve for receiver operating characteristic. Ankle and knee angular-displacement parameters, body height and lower limb length were the major predictors of WB performance for the extrapolated models (p < 0.05; R² = 0.83-0.56). The measured WB performance and T1 model showed significant (p < 0.05) performance differences between the injured and uninjured limbs. Receiver operating characteristic analysis showed an asymptotic significance of 0.03 for T1 equation with area under the curve of 0.70. The proposed models provide different methods to quantify the performance and accurately detect the injured limb in individuals with unilateral chronic ankle instability, when measuring balance via WB might not be feasible. App-makers may use the equations to provide an automatic all-in-one system to monitor the performance status and progress.

The "Journal of Functional Morphology and Kinesiology" Journal Club Series: PhysioMechanics of Human Locomotion

We are glad to introduce the Third Journal Club of Volume five, the third issue. This edition is focused on relevant studies published in the last years in the field of PhysioMechanics of Human Locomotion, chosen by our Editorial Board members and their colleagues. We hope to stimulate your curiosity in this field and to share with you the passion for the Sports Medicine and Movement Sciences seen also from the scientific point of view. The Editorial Board members wish you an inspiring lecture.

Differences in Balance Ability and Motor Control between Dancers and Non-Dancers with Varying Foot Positions

The purpose of this study was to investigate balance and motor control in dancers and non-dancers with different foot positions. Physically active female dancers (n = 11) and non-dancers (n = 9) randomly completed two balance tests in a single visit: 1) Y-balance test (YBT), and 2) motor control test (MCT). Each test was completed with two different foot positions: 1) first ballet position in which heels were touching and feet were externally rotated to 140 degrees, and 2) sixth ballet position in which heels were spaced 10 cm apart and forward parallel. For the YBT, participants completed three attempts at anterior, posteromedial, and posterolateral reaches, which were averaged and standardized to limb length for a composite score. For the MCT, participants completed a multi-directional target test on a Biosway balance system, and accuracy and time to completion were analyzed. Findings revealed no differences in YBT score (p = 0.255), MCT score (p = 0.383), or MCT time (p = 0.306) between groups in the sixth position. However, dancers displayed better YBT scores (p = 0.036), MCT scores (p = 0.020), and faster MCT times (p = 0.009) in the first position. Results suggest that superior balance and motor control in dancers may be limited to less innate dance-specific foot positions.