RELATIONSHIPS BETWEEN CORE ENDURANCE,HIP STRENGTH,AND BALANCE IN COLLEGIATE FEMALE ATHLETES

Purpose/Background:

Lower extremity injuries such as Anterior Cruciate Ligament (ACL) tears remain a concern in collegiate female athletes. Core endurance and hip strength reportedly influence ACL and lower extremity injury risk. Good neuromuscular control, as measured by the Star Excursion Balance Test (SEBT) test is associated with decreased lower extremity injuries. The exact relationships between core endurance, hip strength, and balance (SEBT scores), and how they impact one another in the female collegiate athlete remain unclear. Thus, the purpose of this study was to investigate relationships between core endurance, hip strength, and balance in collegiate female athletes.

Methods:

Forty collegiate female athletes (19.6±1.1yrs, 163.1±7.8cm, 61.3±6.5kgs) performed the SEBT in anterior, posterolateral, and posteromedial directions bilaterally (% leg length), McGill''s anterior, posterior, and left and right plank core endurance tests (seconds), and hip abductor, flexor, extensor, and external rotator isometric strength tests bilaterally (N) using handheld dynamometry. Pearson''s product moment correlations examined relationships between core endurance, hip strength, and balance. A linear regression analysis examined whether core endurance and hip strength influenced balance (p≤0.05).

Results:

Anterior SEBT scores were fairly positively correlated with hip flexor and extensor strength. Posterolateral SEBT scores were fairly positively correlated with hip abductor, extensor, and flexor strength (p=0.02‐to‐0.004; r=0.26‐to‐0.45). Fair positive correlations existed between posterior core endurance and hip extensor strength bilaterally (right: p=0.02, r=0.37; left: p=0.003, r=0.47). Core endurance and SEBT scores were not correlated (p>0.05). Core endurance and hip strength did not influence SEBT scores (p=0.47).

Conclusions:

Overall, hip strength, but not core endurance was related to SEBT scores in collegiate female athletes. Females with greater hip flexor, extensor, and abductor strength also had better anterior and posterolateral SEBT scores. Having females participate in hip muscle strengthening programs may help improve their SEBT balance scores, as a measure of their neuromuscular control and influence their ACL and lower extremity injury risk.

Level of Evidence:

2b     

COMPARISON OF DYNAMIC BALANCE IN ADOLESCENT MALE SOCCER PLAYERS FROM RWANDA AND THE UNITED STATES

Purpose/Background:

Dynamic balance is an important component of motor skill development. Poor dynamic balance has previously been associated with sport related injury. However, the vast majority of dynamic balance studies as they relate to sport injury have occurred in developed North American or European countries. Thus, the purpose of this study was to compare dynamic balance in adolescent male soccer players from Rwanda to a matched group from the United States.

Methods:

Twenty‐six adolescent male soccer players from Rwanda and 26 age‐ and gender‐matched control subjects from the United States were screened using the Lower Quarter Y Balance Test during their pre‐participation physical. Reach asymmetry (cm) between limbs was examined for all reach directions. In addition, reach distance in each direction (normalized to limb length, %LL) and the composite reach score (also normalized to %LL) were examined. Dependent samples t‐tests were performed with significant differences identified at p<0.05.

Results:

Twenty‐six male soccer players from Rwanda (R) were matched to twenty‐six male soccer players from the United States (US). The Rwandan soccer players performed better in the anterior (R: 83.9 ± 3.2 %LL; US: 76.5 ± 6.6 %LL, p<0.01), posterolateral (R: 114.4 ± 8.3 %LL ; US: 106.5 ± 8.2 %LL, p<0.01) and composite (R: 105.6 ± 1.3 %LL; US: 97.8 ± 6.2 %LL, p<0.01) reach scores. No significant differences between groups were observed for reach asymmetry.

Conclusions:

Adolescent soccer players from Rwanda exhibit superior performance on a standardized dynamic balance test as comparison to similar athletes from the United States. The examination of movement abilities of athletes from countries of various origins may allow for a greater understanding of the range of true normative values for dynamic balance.

Levels of Evidence:

3b     

NEUROMUSCULAR CONTROL DURING PERFORMANCE OF A DYNAMIC BALANCE TASK IN SUBJECTS WITH AND WITHOUT ANKLE INSTABILITY

Design

Cross‐sectional, controlled laboratory study

Background

Lateral ankle sprains are common injuries and often lead to chronic ankle instability (CAI). Individuals who previously sustained a lateral ankle sprain, but did not develop CAI, termed copers, may have altered postural control strategies compared to individuals who have developed CAI. These altered postural control strategies may allow for more appropriate dynamic stabilization of the ankle joint after injury compared to those seen in patients who have developed CAI.

Objective

To compare lower leg biomechanics, as well as electromyographic (EMG) activation of the tibilias anterior and peroneus longus muscles, during the posteromedial reach of the Star Excursion Balance Test (SEBT) in individuals with healthy ankles, copers, and those with CAI.

Participants and Methods

30 participants (12 control, 9 copers, 9 CAI) divided into three groups based on ankle sprain history and Cumberland Ankle Instability Tool score. Kinematic, kinetic, and EMG data were collected during three posteromedial reach trials on the SEBT.

Main Outcome Measures

Primary outcome measures include SEBT normalized reach distance in the posteromedial direction and average integrated EMG activation of the tibialis anterior and peroneus longus muscles during the reach. Secondary outcome measures included sagittal and frontal plane ankle complex angles and moments and sagittal plane knee angles and moments. Data were analyzed between groups using a one‐way ANOVA model.

Results

No significant differences in reach distance or kinematic and kinetic outcomes were found between groups. The activation of the tibialis anterior and peroneus longus muscles was significantly different between groups (p=0.033 and p=0.014, respectively). The post‐hoc analysis revealed that the coper group had significantly higher muscle activation compared to the control group, but not to the CAI group.

Conclusion

CAI did not alter kinematic, kinetic, or reach performance during the SEBT. When compared to controls, copers appeared to have greater activation of the ankle musculature, which may increase stability of the ankle complex during a dynamic balance task.

Level of Evidence

Prospective Cohort level II     

FUNCTIONAL MOVEMENT SCREEN™ (FMS™) SCORES DO NOT PREDICT OVERALL OR LOWER EXTREMITY INJURY RISK IN COLLEGIATE DANCERS

Purpose:Dance is a physically demanding activity, with 50-85% of dancers suffering injury during a single performance season. The majority of dancers’ injuries are in the lower extremity (LE) and chronic in nature. These injuries often arise when causal factors are not identified early and addressed before they ultimately result in an injury. Practitioners often use movement screens such as the Functional Movement Screen™ (FMS™) to detect and quantify kinetic chain dysfunction. Prior researchers have suggested that these screens can stratify at-risk individuals and allow practitioners to devise targeted interventions to reduce their injury risk. However, whether the FMS™ can identify at-risk dancers remains unclear. Thus, the purpose of this study was to examine whether FMS™ scores predicted injury risk in collegiate dancers.Methods:In this prospective study, 43 collegiate dance majors (34 female, 9 male; 18.3 ± 0.7yrs; 163.9 ± 7.3cm; 60.8 ± 8.1kg) in a program which emphasizes modern dance were scored on the seven FMS™ movements (scale 0-3, total maximum score=21) where 3=movement completed without compensation, 2=movement completed, but with compensation(s), 1=unable to complete movement, 0=pain during movement or during clearing tests as described in prior literature at the start of the academic year. An in-house certified athletic trainer documented dancer''s overall and LE injuries over an academic year (40 weeks). Separate Receiver Operator Characteristic (ROC) curve analyses examined whether composite FMS™ score predicted (1) Overall or (2) LE injury status.Results:The subjects FMS™ scores were 16.2 + 1.7 (range=11–19). Twenty dancers were injured, whereas 23 remained injury-free. Injured dancers had 55 overall (1.28 injuries/dancer) and 44 LE injuries (1.02 LE injuries/dancer). FMS™ score did not predict overall (AUC=.28, SE=.08, p=.02, 95%CI=.13-.43) or LE injury risk (AUC=.38, SE=.1, p=.21, 95% CI=.21-.56).Discussion:While nearly half of the dancers in this group suffered from injury over the year, composite FMS™ scores did not predict overall or LE injury risk in collegiate dancers. Dancers face unique and challenging physical demands that distinguish them from traditional sport-athletes including greater ranges of movement during performance. Thus, the FMS™ may not be sensitive enough to distinguish ‘appropriate’ from ‘excessive’ mobility and adequately identify injury risk in dancers. Overall, it is suggested that practitioners should use caution before using the FMS™ as a primary screening mechanism to identify collegiate dancers at overall or LE injury risk.Level of Evidence:2