A longitudinal investigation into the progression of dynamic postural stability performance in adolescents

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.

Sex-Specific Changes in Physical Risk Factors for Anterior Cruciate Ligament Injury by Chronological Age and Stages of Growth and Maturation From 8 to 18 Years of Age

OBJECTIVE

To critically assess the literature focused on sex-specific trajectories in physical characteristics associated with anterior cruciate ligament (ACL) injury risk by age and maturational stage.

DATA SOURCES

PubMed, CINAHL, Scopus, and SPORTDiscus databases were searched through December 2021.

STUDY SELECTION

Longitudinal and cross-sectional studies of healthy 8- to 18-year-olds, stratified by sex and age or maturation on ≥1 measure of body composition, lower extremity strength, ACL size, joint laxity, knee-joint geometry, lower extremity alignment, balance, or lower extremity biomechanics were included.

DATA EXTRACTION

Extracted data included study design, participant characteristics, maturational metrics, and outcome measures. We used random-effects meta-analyses to examine sex differences in trajectory over time. For each variable, standardized differences in means between sexes were calculated.

DATA SYNTHESIS

The search yielded 216 primary and 22 secondary articles. Less fat-free mass, leg strength, and power and greater general joint laxity were evident in girls by 8 to 10 years of age and Tanner stage I. Sex differences in body composition, strength, power, general joint laxity, and balance were more evident by 11 to 13 years of age and when transitioning from the prepubertal to pubertal stages. Sex differences in ACL size (smaller in girls), anterior knee laxity and tibiofemoral angle (greater in girls), and higher-risk biomechanics (in girls) were observed at later ages and when transitioning from the pubertal to postpubertal stages. Inconsistent study designs and data reporting limited the number of included studies.

CONCLUSIONS

Critical gaps remain in our knowledge and highlight the need to improve our understanding of the relative timing and tempo of ACL risk factor development.

The effects of footwear on dynamic stability and impact loading in jump landing

Research into the effect of footwear on dynamic stability and impact loading is still in its infancy. The aim of this study was to determine whether cushioned footwear influenced dynamic stability (dynamic postural stability index (DPSI) and time to stabilisation (TTS)) or impact loading (peak ground reaction force (pGRF) and loading rate (LR)) through a series of single-leg jump landings when compared to barefoot and minimalist shoes. Fourteen healthy, active participants (9 males, 5 females, Age: 21 ± 1 years; height: 174 ± 9.87 cm; weight: 75 ± 15.40 kg) were recruited to undergo a series of single-leg jump landings. Each participant randomly performed three jumps in each footwear condition. Repeated measures ANOVA was conducted to determine whether any differences occurred between condition. No statistically significant difference was observed for DPSI (p = 0.300, pη2 = 0.083) between footwear types. A statistically significant difference was determined between footwear condition for TTS (p = 0.001, pη2 = 0.52), and also for pGRF (p = 0.003, pη2 = 0.39), and LR (p ≤ 0.001, pη2 = 0.53). For TTS, pGRF, and LR, no differences were noted between minimalist and barefoot, but were worse in the cushioned shoe vs. both other conditions. Overall, this study determined that cushioned footwear can negatively influence both TTS and impact loading, but not DPSI.

Safety and Effectiveness of a Perturbation-based Neuromuscular Training Program on Dynamic Balance in Adolescent Females: A Randomized Controlled Trial

BACKGROUND

Adolescent females are at much greater risk for ACL injury than their male counterparts when participating in the same sports. Preventative and pre-operative rehabilitation neuromuscular (NM) exercise programs are often recommended to improve knee function and reduce injury rates. The effectiveness of perturbation-based NM training program has been established in an adult population but has yet to be investigated in the at-risk adolescent female population.

PURPOSE

To determine the effectiveness of a perturbation-based NM exercise program in a group of physically active adolescent females.

STUDY DESIGN

Prospective randomized trial.

METHODS

Twenty-four healthy and an exploratory group of 10 ACL-injured females (ages 12-18) were equally randomized into a perturbation-based NM training or control group and evaluated before and after a five-week intervention period. The primary outcome of dynamic balance was measured using the Y-Balance test (YBT); secondary outcome measures included lower limb strength, proprioception, and flexibility.

RESULTS

The perturbation-based NM training intervention was safely completed by all participants but had no significant effect on YBT scoring, lower limb strength, proprioception or flexibility in either the healthy or ACL-injured groups.

CONCLUSIONS

Perturbation-based NM training is safe, but may offer little preventative benefit for healthy or pre-operative rehabilitation benefit for ACL-injured adolescent females. Future research should examine whether the effectiveness of perturbation-based NM training is influenced by the length of the training intervention, training intensity, or when it is combined with other forms of prophylactic or pre-surgical rehabilitation frequently used with at-risk adolescent females who regularly participate in sport.

LEVEL OF EVIDENCE

Level 3.

Lower Extremity Kinematics of the Y-Balance Test in Healthy and ACL Injured Adolescent Females

BACKGROUND

Adolescent females are at significant risk for sustaining an ACL injury. The Y-Balance Test (YBT) is frequently used to evaluate neuromuscular control and lower extremity function. However, few studies have quantified 2D lower extremity kinematics during performance of the YBT, and there is an absence of kinematic data specific to at-risk adolescent females.

PURPOSE

To examine lower extremity joint kinematics during execution of the YBT by healthy and ACL-injured adolescent females.

STUDY DESIGN

Prospective cohort.

METHODS

Twenty-five healthy and ten ACL-injured (mean time from injury 143 days) adolescent females were assessed using the YBT. Sagittal and frontal plane knee and ankle motion was video recorded during execution of the YBT anterior reach movement. Ankle dorsi-flexion, knee flexion, and knee valgus angles were quantified via kinematic analysis. ANOVAs with a post hoc Bonferroni correction were used to compare YBT scoring (%LL) and kinematic data between groups. Pearson product-moment correlations determined the relationship between kinematic data and YBT scoring.

RESULTS

Healthy and ACL-injured subjects demonstrated similar YBT scores and lower extremity kinematic data. Healthy subjects demonstrated a weak positive correlation between ankle dorsiflexion and YBT scoring, and a weak negative correlation between knee valgus and YBT scoring. These relationships did not exist for ACL-injured subjects. Kinematic data for both groups also demonstrated a large degree of variability, regardless of YBT score.

CONCLUSIONS

Adolescent females frequently utilize a variety of lower extremity movement strategies when performing a functional movement task, and scoring on the YBT offers limited insight regarding lower extremity joint kinematics and ACL-injury risk in a physically active adolescent female population.

LEVEL OF EVIDENCE

Level 3.

Influence of Anthropometry, Age, Sex, and Activity Level on the Hand Reach Star Excursion Balance Test

The influence of anthropometric measurements, age, sex, and activity level have been found to influence tests of dynamic postural control such as the star excursion balance test (SEBT). The hand reach star excursion balance test (HSEBT) measures different aspects of dynamic postural control. The purpose of the present study was to explore the influence of these factors on the HSEBT. A convenience sample of 223 subjects performed four horizontal (L45, R45, L135, and R135) and two rotational (LROT and RROT) reaches. The influence of anthropometric measurements (height, arm length, leg length, and wingspan) on reach measurements were assessed using stepwise multiple linear regression. Influence of age (young: <20 years; adult: >20 years), sex (male; female) and activity level (athletes; recreational) on reach measurements were analyzed using independent samples t-test (p < 0.05) and interpreted using effect size (Cohens d) and established values of minimal detectable change (MDC). Wingspan explained a significant portion of the variance of only R45 (34.6%) and L45 (11.7%) reach measurements and normalized (percentage of wingspan). A medium effect of age, sex, and activity level was observed for normalized L45 and R45 reaches (d = 0.50–72). Group differences greater than MDC values and a medium effect for age (d = 0.55) and activity level (d = 0.75) were observed for the R135 reach. L45 and R45 reaches should be normalized to wingspan, but not the other reaches. Between individual or group comparisons should consider age, activity level and sex as potential covariates.

The Effects of Maturation on Measures of Asymmetry During Neuromuscular Control Tests in Elite Male Youth Soccer Players

PURPOSE

Asymmetry is a risk factor for male youth soccer players. There is a paucity of data confirming the presence of asymmetry using practically viable screening tasks in players at different stages of maturation.

METHODS

A cross-sectional sample (N = 347) of elite male youth soccer players who were either pre-, circa-, or post-peak height velocity (PHV) completed the following assessments: single-leg Y-Balance anterior reach, single-leg hop for distance, single-leg 75% hop and stick, and single-leg countermovement jumps.

RESULTS

Single-leg countermovement jumps landing force asymmetry was higher in both circa- and post-PHV groups (P < .001; d = 0.41-0.43). Single-leg 75% hop and stick landing force asymmetries were also highest in circa-PHV players, but between-group comparisons were not statistically significant and effect sizes were small. Single-leg hop for distance and single-leg Y-Balance anterior reach asymmetries reduced with maturation; however, no group differences were significant, with small to trivial effect sizes (d ≤ 0.25).

CONCLUSION

Stage of maturation did not have a profound effect on asymmetry. Between-limb differences in functional performance seem to be established in early childhood; thus, targeted interventions to reduce this injury risk factor should commence in pre-PHV athletes and be maintained throughout childhood and adolescence to ensure asymmetry does not increase.

Inertial Sensor Technology Can Capture Changes in Dynamic Balance Control during the Y Balance Test

Introduction

The Y Balance Test (YBT) is one of the most commonly utilised clinical dynamic balance assessments. Research has demonstrated the utility of the YBT in identifying balance deficits in individuals following lower limb injury. However, quantifying dynamic balance based on reach distances alone fails to provide potentially important information related to the quality of movement control and choice of movement strategy during the reaching action. The addition of an inertial sensor to capture more detailed motion data may allow for the inexpensive, accessible quantification of dynamic balance control during the YBT reach excursions. As such, the aim of this study was to compare baseline and fatigued dynamic balance control, using reach distances and 95EV (95% ellipsoid volume), and evaluate the ability of 95EV to capture alterations in dynamic balance control, which are not detected by YBT reach distances.

Methods

As part of this descriptive laboratory study, 15 healthy participants completed repeated YBTs at 20, 10, and 0 min prior to and following a modified 60-s Wingate test that was used to introduce a short-term reduction in dynamic balance capability. Dynamic balance was assessed using the standard normalised reach distance method, while dynamic balance control during the reach attempts was simultaneously measured by means of the 95EV derived from an inertial sensor, worn at the level of the 4th lumbar vertebra.

Results

Intraclass correlation coefficients for the inertial sensor-derived measures ranged from 0.76 to 0.92, demonstrating strong intrasession test-retest reliability. Statistically significant alterations (p < 0.05) in both reach distance and the inertial sensor-derived 95EV measure were observed immediately post-fatigue. However, reach distance deficits returned to baseline levels within 10 min, while 95EV remained significantly increased (p < 0.05) beyond 20 min for all 3 reach distances.

Conclusion

These findings demonstrate the ability of an inertial sensor-derived measure to quantify alterations in dynamic balance control, which are not captured by traditional reach distances alone. This suggests that the addition of an inertial sensor to the YBT may provide clinicians and researchers with an accessible means to capture subtle alterations in motor function in the clinical setting.

Postural Stability in Healthy Child and Youth Athletes: The Effect of Age, Sex, and Concussion-Related Factors on Performance

Background:

Postural stability plays a key role in sport performance, especially after concussion. Specific to healthy child and youth athletes, little is known about the influence development and sex may have on postural stability while considering other subjective clinical measures used in baseline/preinjury concussion assessment. This study aims to describe age- and sex-based trends in postural stability in uninjured child and youth athletes at baseline while accounting for concussion-related factors.

Hypotheses:

(1) Postural stability performance will improve with age, (2) females will display better postural stability compared to males, and (3) concussion-like symptoms will affect postural stability performance in healthy children and youth.

Study Design:

Cross-sectional study.

Level of Evidence:

Level 3.

Methods:

This study comprised 889 healthy/uninjured child and youth athletes (54% female, 46% male) between the ages of 9 and 18 years old. Participants completed preseason baseline testing, which included demographic information (age, sex, concussion history), self-report of concussion-like symptoms (Post-Concussion Symptom Inventory [PCSI]–Child and PCSI-Youth), and measures of postural stability (BioSway; Biodex Medical Systems). Two versions of the PCSI were used (PCSI-C, 9- to 12-year-olds; PCSI-Y, 13- to 18-year-olds). Postural stability was assessed via sway index under 4 sway conditions of increasing difficulty by removing visual and proprioceptive cues.

Results:

In children aged 9 to 12 years old, there were significant age- (P < 0.05) and sex-based effects (P < 0.05) on postural stability. Performance improved with age, and girls performed better than boys. For youth ages 13 to 18 years old, postural stability also improved with age (P < 0.05). In both child and youth subgroups, postural stability worsened with increasing concussion-like symptoms (P < 0.05).

Conclusion:

There are developmental and baseline symptom trends regarding postural stability performance.

Clinical Relevance:

These findings provide a preliminary foundation for postconcussion comparisons and highlight the need for a multimodal approach in assessing and understanding physical measures such as postural stability.

Y balance test has no correlation with the Stability Index of the Biodex Balance System

STUDY DESIGN

A cross-sectional study design.

BACKGROUND

The Stability Index of the Biodex Balance System (SI-BBS) and Y Balance Test (YBT) has been used in studies assessing postural stability but no studies have verified the association of the YBT with the SI-BBS.

OBJECTIVE

To analyze the association of the Y Balance Test (YBT) with the Stability Index of the Biodex Balance System (SI-BBS) to evaluate postural stability.

METHODS

Forty participants who engaged in recreational physical activities, 12 of whom had a history of injury to the lower limbs. Was used the SI-BBS and the anterior, posterolateral, posteromedial, and composite measures of the YBT. The order of execution of the tests and of the lower limbs evaluated was randomized and blind tested by two evaluators.

RESULTS

Pearson's correlation coefficient was used to check the strength of the relationship between the distances achieved on the YBT and the SI-BBS. The YBT showed excellent reliability in the anterior, posteromedial, and posterolateral directions. However, the YBT showed no statistically significant correlation with any variables in the SI-BBS, indicating poor validity between YBT and SI-BBS assessments of postural stability in people with and without history of lower limb injuries.

CONCLUSIONS

The results of this study showed the YBT is not correlated with the SI-BBS as an assessment of postural stability. This finding has implications for researchers and clinicians using YBT results as the only measure of postural stability.